I think I need a little help with my Maestro Fuzz FZ-1A clone.
This is the schematic I used: http://fuzzcentral.ssguitar.com/schematics/fz1a.gif
Everything on my PCB is great, and perfectly after the book, all components are great, my hard-to-find very-expensive transistors (2N2613) work, and my 1,5V PSU (1,7V like a new fully charged battery) work great and stabile without hum and noise (I've tried with a 1,5 bat. too).
But inspite of all that, my transistors won't switch "on". When I set up everything I just get a loud humming noise from the amp.
Does any of you have experience with that kind of guitar pedals?
FYI. The transistors are PNP Germanium
With com on the emitter on the first trans, from base to emitter, I get -1.5mV. In my head I should get around -600mV..
From collector to emitter I get full supply voltage...
I'll post a pic of the schematics with my measurements. Red point is + on my voltmeter, and black points are the com-port.With com on the emitter on the first trans, from base to emitter, I get -1.5mV. In my head I should get around -600mV..
From collector to emitter I get full supply voltage...
I'll post a pic of the schematics with my measurements. Red point is + on my voltmeter, and black points are the com-port.
(http://i.imgur.com/XlsOhCO.png?1)
You say that "everything on my PCB is great" but you don't say whether you made the board or purchased it. If it's a home-made board, maybe there's a problem with a trace. Also, are you sure that all of the transistors are inserted correctly? C, B, and E in their right places?
I did an NPN clone of this thing:
http://diy.smallbearelec.com/Projects/FuzzE-One/FuzzE-One.htm
and my notes on how I lined it up might help you.
when you do your measure, put the black lead on the ground connection, then put the red probe on c - b - e. that way all the voltages are referred to ground. can you repost your voltages using this method, please? we'd next ask for pictures of your build, and I should have sent you to read "what to do when it doesn't work", on the "building your own stompbox" index page, but haven't.
and welcome to the forum.
isn't the ring connection on the input connecting to ground when a cable is inserted? i'm not good with positive ground wiring tho, but it looks like the + battery lead is connected to ground when a cable is in... maybee its just a naming convention and all the grounds are actually positive... but then wouldn't whatever previos pedal's sleeve ground be connected to the + battery when cable connected... and thus ground the battery?!?
sorry, just something to check... like i said , i don't know positive ground basics, just seems weird to me...
smallbearelec:
I made a very fine little PCB at first. No shorts ore anything. When I found out it didn't work, and after hours of trouble shooting I decided to try and make a new PCB (not that great looking, but all right) but with the new PCB I get the same results.
Your build looks very tempting. Do you have any audio-examples?
duck_arse:
Thanks :)
First trans: E: -27mV B: -28mV C: -1.79V
Sec. trans: E: 0.0mV B: -7mV C: -1.76V
3'rd trans: E: 0.0mV B: 0.0mV C: -1.76V
Pics will follow in a sec.
You get links to the big files:
http://imgur.com/XCZtenL
http://imgur.com/T58ccKX
This is the ugly test PCB.
The first was very fine, with beautiful wirering and all. :icon_cry:
Quote from: goatsounds on February 18, 2015, 04:34:21 AM
You get links to the big files:
http://imgur.com/XCZtenL
It seems to me that you've wired the Input (green cable from tip) straight to the centre lug of Volume pot...!!!
(an the upper lug of the same pot to PCB In...)
Quote from: antonis on February 18, 2015, 04:49:10 AM
Quote from: goatsounds on February 18, 2015, 04:34:21 AM
You get links to the big files:
http://imgur.com/XCZtenL
It seems to me that you've wired the Input (green cable from tip) straight to the centre lug of Volume pot...!!!
(an the upper lug of the same pot to PCB In...)
Hmm. I've wired the input (black plug to the left) to the switch and then to the input on the PCB. Output from the PCB goes to the left lug of the volume pot. Center lug goes in the switch, and then to the output plug (open plug to the right)
Quote from: goatsounds on February 18, 2015, 05:27:45 AM
Hmm. I've wired the input (black plug to the left) to the switch and then to the input on the PCB. Output from the PCB goes to the left lug of the volume pot. Center lug goes in the switch, and then to the output plug (open plug to the right)
Stereo jack confused me... - thought it served as Input jack
Given those voltage readings, I suspect some error in the PCB pattern. Make a clean copy of the schem. Set your multimeter to continuity. Probe between the Base of Q1 and the hot side of the 1 Meg resistor. If you get the BEEP, mark off on the schem with a highlighter and test another connection; if not, figure out WHY there's no continuity. Do this for every joint and trace on the board, and you will find something that's not right. Also make sure that you have correctly identified and connected Tip, Ring and Sleeve of the input jack and Tip and Sleeve of the output jack.
I'm sorry that I didn't know you when you started this project; making your own PCB has numerous land mines, and the learning curve is steep. I usually suggest breadboarding and then learning to wire on perf before attempting to design a PCB layout.
A number of people have built my version successfully, and it sounds suitably splatty. The schem you have will work if all is wired correctly and the devices are good.
Hi all,
Apologies in advance for my inexperience. As this seems to be the most current FZ-1A thread, I thought it might be a good place to ask for help.
I have an old, original FZ-1A that was given to me quite a while back. I haven't used it in a long time, and taking out recently I see that it's ceased to function. When bypassed with the footswitch, signal passes through fine. But when turned on with the footswitch, I get nothing at all.
I have some decent experience with soldering, and have a multimeter, but sadly no real experience troubleshooting a circuit.
Would any of you have any suggestions where to start? New battery, and reading correct voltage at the ends of the battery leads, but that's about as far as I can get.
What are the most likely suspects? Are there any documents anywhere that might note what measurements I should expect at different parts of the circuit?
Sorry again for being clueless. Any help would be greatly appreciated.
Thanks!!
I'm surprised nobody has responded to this yet. I was hoping someone would so I could learn from a more experienced member what the first few steps might be...
Anyway though, the FZ-1A is a simple enough circuit and I think we should be able to get to the bottom of this.
First, I would check that all of the components on the board look connected and that there are no broken solder joints. Especially check that the wires at the jacks and stompswitch look OK. Whew, looking at the guts of some of these old fz-1a right now... those are uggggleeey on the inside. It might take you more than a minute to visually inspect everything.
If it looks that everything is mechanically connected then I suppose that checking the voltages at the legs of each transistor is a good place to go next. Give us these voltage values with the pedal turned on:
Q1Collector
Q1Base
Q1Emitter
Q2C
Q2B
Q3E
Q3C
Q3B
Q3E
hints:
-before you take the readings you will need to (A) locate which transistor is Q1, Q2, and Q3, (for this you will need a schematic) and (B) locate which leg is which according to a datasheet of that specific transistor. It may be hard to find a datasheet and if worst comes to worst just give the values at semi random (use the same order even though you don't know which is collect, base or emmiter) and we should be able to figure something out from that.
-put the black lead on the metal of the enclosure, and the red lead at the specific transistor leg to get the value.
-no value should read more than 1.7 volts
Thanks so much for the response. I've been poking around this thing all morning, googling what I can, and haven't had any luck. I've been hoping to learn more about this for a while, and as you said, this seems like a simple enough circuit, so I'm glad to get a chance.
I've visually checked all the connections and haven't found anything amiss yet, as far as I can see.
Regarding the transistors, a disclaimer: I'm very new to reading schematics. I've found what looks like the most reliable schematic online, and hopefully have identified which transistor is Q1, Q2, etc., as well as the relevant legs. But it's definitely possible that I've made a mistake. In any case, here goes ...
Q1C - 0
Q1B - .66
Q1E - .74
Q2C - .28
Q2B - 1.12
Q2E - 1.17
Q3C - .08
Q3B - 1.16
Q3E - 1.17
Thanks so much again -- grateful to have some help!
PS - I have some rechargable AA batteries, and I had a thought that I'd use one of those instead of wasting a battery through all this testing. But I noticed it gets extremely hot, so I've taken it out and gone back to the regular battery. Do you think this has anything to do with the problem, or are rechargable batteries just a no-no for these kinds of pedals?
Here's (hopefully, if this works) an image in case it helps.
(http://s7.postimg.org/4d3kltobb/20150301_130323.jpg) (http://postimg.org/image/4d3kltobb/)
batteries getting hot indicates some kind of short from -1.5 to ground... also you've got -1.17 at q2e and q3e but only -.74 at q1e... thaat spot should be connected directly to - side of the battery, so theres a short somewhere beween q1e and ground...
Thanks, Quackzed -- that makes sense. I'll see if I can find anything in that area now. (Also hoping that I didn't incorrectly identify the transistor legs.)
Call me slow, but i'm not sure that what quackzed makes sense to me.
You should be getting 0 volts at Q2E and Q3E b/c they are directly connected to ground. Also you should be getting battery voltage (1.5-1.7v) at Q1C.
Did you accidentally put the battery in backwards?
I'm referencing the Maestro FZ-1A schematic by Jack Orman copyrighted 1995
Hmm ... well, the battery is inserted as you can probably see in the photo. Positive to the positive mark on the battery holder and red wire.
Is there any potential harm in trying to reverse the battery to see if that works?
(By the way, I cannot find anything that would cause a short between Q1E and ground, and I get no continuity between ground and Q1E on meter.)
There could be harm, don't do that. Hmmm
Could Q1 be bad?
A couple other pictures, closer up, in that area, in case it sparks any thoughts ...
(http://s18.postimg.org/6i7tqtpmt/20150301_150436.jpg) (http://postimg.org/image/6i7tqtpmt/)
(http://s16.postimg.org/hu82cu3ep/20150301_150235.jpg) (http://postimg.org/image/hu82cu3ep/)
what the voltage of the battery you're using? 1.17v?
Sorry, the last ones weren't very close up.
(http://s22.postimg.org/6qrdvvgct/20150301_152039.jpg) (http://postimg.org/image/6qrdvvgct/) (http://s1.postimg.org/ao0o6rgln/20150301_152024.jpg) (http://postimg.org/image/ao0o6rgln/)
It's 1.22 with no load. Has it gone down too low?
just had a small convo about the confusing 'positive ground' naming convention, but the short answer is that with these 'positive ground' pedals, what is labeled as ground is more positive than the - battery supply voltage, so instead of referencing voltages (black probe) to the - battery lead (normal negative ground pedals), you reference(black probe) to the +battery lead and measure negative voltages for the emitters or whatever you're measuring.all of which are more negative than 'ground'. usually ground is the most negative reference in a circuit, but with the 'positive ground' circuits, its the most positive point...
Just to make sure I understand ...
I should remeasure the voltages, but with the black probe to the + battery lead, and the red probe to each leg of the three transistors? And that I should expect to see negative voltages instead of positive?
not too low for finding a short, or working properly... might sound a tad different with a fresh battery... can you maybee bend move those leads a bit so the parts leads arent almost touching,, also one of the transistor leads looks like it could be touching its case... maybee GENTLY bend some of those leads away from each other and the tranny case? also that 1m resistor away from the tranny case...
Ok, will do.
Also, here are the new measurements:
Q1C: -1.22
Q1B: -.34
Q1E: -.31
Q2C: -.03
Q2B: -.03
Q2E: 0
Q3C: ranging from -.1 to -.4
Q3B: 0
Q3E: 0
Thank you guys again.
yes, but you're already doing that, because the + battery lead IS ground... or its directly connected to ground through the input jack when a plug is inserted to the jack... look at the schem you'll see the +battery connected to the 'ring' of the input jack, and when you plug in a mono cable the cable sleeve connects the 'ring' connection to the sleeve which is connected to 'ground'...not trying to confuse you... i get confused enough all by myself. dont sweat over my way of thinking just keep measuring how you were doing it. and look for the short... and dont flip the battery around backwards or anything...
Sorry, ignore the previous measurements. After securing the pots and output back in place, I have different measurements:
Q1C: -1.13
Q1B: -.45
Q1E: -.42
Q2C: -.76
Q2B: -.05
Q2E: 0
Q3C: -1.05
Q3B: 0
Q3E: 0
hmm, those measurement seem ok to me...
if you set up to play with your guitar and amp and give a REALLY hard strum (i mean don't break a string or something) do you hear anything form the amp?
Actually, yes! Just cranked the volume up on the amp, and with the volume and attack knobs all the way up, I get a little something coming through.
It's barely there, though, and not loud enough to tell whether it's affected or not by the fuzz. I can just make out the decay of the reverb if I leave the reverb up.
hmm interesting, i was expecting the sound to come barreling through at a certain strumming threshold, not to just barely be there...
the battery getting hot definitely indicated a short though like Qauckzed said though
I think the signal path is involved with this short as well, and so your guitar signal is being grounded unintentionally. Try looking around the q2 and q3 connections.
i'm gonna sit on this for a bit and stop muddying the water
and it's been my pleasure trying to help btw, good luck!
Well, the only update I can offer for now is that:
1) The battery is no longer getting hot. Even with a freshly charged rechargable in there. Not sure what this could mean. I've been going through all the connections making sure nothing can be shorting ... perhaps I unknowingly got rid of a short? But the pedal still is in the same state of not working.
2) With the fresh battery, the voltage measurements have changed. Doesn't seem like anything major, but figured I'd post just to be safe:
Q1C: -1.38
Q1B: -.52
Q1E: -.51
Q2C: -.81
Q2B: -.05
Q2E: 0
Q3C: -1.88
Q3B: 0
Q3E: 0
Pupil, you mentioned before that nothing should read over 1.7v. Is Q3C a problem? Or is it different now that the readings are negative (sorry if that's a ridiculous beginner question)?
I was under the impression that a fresh AA battery is 1.7 volts. Whatever a fresh AA battery voltage is should be the max voltage of any point in your circuit.
What's your fresh new unloaded battery voltage?
Only 1.38v ... :-\
hmm, at least that makes sense as to the measurement at Q1C.
A capacitor must be involved to get a voltage point higher than the actually voltage source?
I'll pondering this
wiggle the input plug a bit while you strum? maybee a not-great connection there... otherwise your voltages aren't far off...
Many many thanks to you both.
No luck on the input wiggle. Also, again, signal is completely fine when the pedal is turned off at the footswitch.
Minor update: I figured out the battery short. Where the leads are soldered to the battery holder, there's a bit of a swivel on both sides, and both sides were swiveling down so that they were touching the metal C bracket that goes around the battery, and shorting out.
Fuzz still not working, but that explains that, at least.
cool! i'm always most suspicious of anything that moves, if it can move it can break... also why i recommended wiggling the input cable in the jack... old jacks can get worn etc... pots can too.. they move...
onward and upward!!
ha -- yes! happy to have at least one mystery solved!
Quote from: pupil on March 01, 2015, 01:06:21 PM
I'm surprised nobody has responded to this yet. I was hoping someone would so I could learn from a more experienced member what the first few steps might be...
yer doing an excellent job so far.
riinehart, just for me, take the battery out. put yr black lead to the shield of the co-ax I can see in yer pic and measure the resistance between there and the sleeve of the jack. then measure the resistance to each battery clip. what results.
something i just learned... you probably know this BUT... the jack you plug a cable into is the output, and goes to the amp. the wired cable coming out of the box goes to your guitar. i would have assumed the wired cable went to the amp, but it's the other way around...just figured i'd point this out, having just learned this myself...
Thank you guys -- so happy to finally be learning some of these things.
Quackzed -- yes, fortunately I learned that strange fact about this pedal long ago, and everything is connected correctly (though I wish it were something that easy!).
duck_arse -- i'm going to make myself sound stupid here and ask what you mean by the shield of the coax. Also will I be measuring the resistance between the battery clips and the sleeve of the output jack? Or between the battery clips and the shield of the coax? Will give it all a shot tonight when I get home from work and will post results. Thanks again!
by shield of the co-ax he means twisted strands of copper wire coming out of the input cable wire. not the smaller inner wire... and i think he wants you to measure resistance between that spot and each battery lead and also the sleeve of the jack. so leave your black probe on the thick twisted copper wires coming from the cable and with the red probe measure the jack sleeve then the + battery terminal then the - battery terminal... with
no battery inserted.
Got it -- thanks again, Quackzed!
Ok, measured what duck_arse suggested. Here's what I found:
Resistance between coax shield and output jack sleeve: .6 ohms (I notice this seemed to fluctuate a bit, up to 1.5 ohms ... maybe the battery in my meter is getting low? Or could something else cause that?)
Resistance between coax shield and positive battery lead: .6 ohms
Resistance between coax shield and negative battery lead: [no connectivity/no reading]
Any thoughts?
Thanks again.
(http://i.imgur.com/XlsOhCO.png?1)
hope you wont mind if i reply to these questions duck_arse. , just trying to keep pluggin away! feel free to chime in with anything i missed or messed up :)
QuoteResistance between coax shield and output jack sleeve: .6 ohms (I notice this seemed to fluctuate a bit, up to 1.5 ohms ... maybe the battery in my meter is getting low? Or could something else cause that?
the out jack shield is connected to ground and the coax shield of input wire is connected to ground, you cant see it on the schem but you measured .6 or 1.5 ohms so they are both connected to ground. a resistance of a few ohms or even 10 or 20 ohms can be considered 0 ohms, a little bouncing around by the meter is expected, nothing to worry over. compared to 470,000 ohms or even 10,000 ohms a a reading of 1 ohm or 10 ohms is relatively no resistance... good.
QuoteResistance between coax shield and positive battery lead: .6 ohms
same here, the + side of the battery is supposed to be grounded and a reading of less than an ohm resistance can be considered directly connected to ground ... good.
QuoteResistance between coax shield and negative battery lead: [no connectivity/no reading]
the negative of the battery has a few paths to ground, but most of em are blocked by caps, so they wont read as a resistance... the only path where the - battery lead CAN get to ground through resistors only is through that 470k ---2k2---22k--- path.(theres a fork at the fuzz pot, but thats just another resistance to ground so dont worry about that) so i'll bet if you crank up your meter to read high resistance, if it has settings for ohms set it to a high resistance setting close to 500k and you should get a reading of @ 500k resistance... a little above or below is good, resistors arent exact, they're within usually 10% of their marked value... if so good!!
next you can go around to all the resistors and measure 'em.one probe on each side of each resistor, just check em to make sure that they read close to the value they're supposed to... set the meter to the appropriate ohm setting then probe em-- and as a bonus you'll get acquainted with your meter, it will serve you well!!! just dont tell anyone you know how to use it or all your weekends will be ruined with O.P.P (other peoples projects :-\ ) ;D
oh yeah, do another transistor voltage reading now that you sorted out the shorting battery leads...
actually do this before you go and measure the resistors...
quack.
quackzed - that circuit with the voltages is extremly confusing. is the red dot the red probe, and the black lead is moving? and you're getting (+)'s above and (-)'s below? bad form, old sport!
another something I thought was to measure from the plug sleeve back to the circuit ground, as cable that old (if original) might be shot. and like quack is about to say I was going to say, measure the resistance from the minus terminal of the battery clip to each collector, then the resistance from ground to each emitter. this thing will be so resistance measured by the time we're finished.
I'd better get some Ge's on the bb, see what volts pop-up. I don't think those collectors, with respect to ground, should show full/more than indicated supply V.
oops, yeah, disregard the dodts/voltages. it's just the schematic that had been posted on page 1,and doesn't reflect the latest readings or anything. :icon_redface: sorry bout the confusion i agree the red dots/voltages are confusing. ive just been ignoring the dots and notes and using the underlying schematic... just re-posted it to not have to keep flipping back to the first page of this thread... probably should have posted a schem without the added stuff...oh well just ignore the notes/dots...
Can't thank you guys enough. Should have some time tonight to poke around and get all the new measurements.
Ok, some new measurements.
Resistance between plug sleeve and circuit ground - .4 ohms (the cable was replaced a few years ago -- not the old original one).
Resistance between minus terminal and each collector - I'm not getting a reading on any of these. Is that normal?
Resistance from ground to ...
Q1E - 5.2k
Q2E - .4
Q3E - .5
Also, new voltage measurements at each of the transistor legs:
Q1C: -1.3
Q1B: -.6
Q1E: -.35
Q2C: -.96
Q2B: -.05
Q2E: 0
Q3C: -1.24
Q3B: -.01
Q3E: 0
(Q3C, which was previously -1.8v, is now back down below the battery voltage. So perhaps that was due to the short during the last reading.)
Any thoughts? Many thanks again!!
well, now, that ain't right. looking at the circuit, you can see the (-) of the battery [clip] connects hard to Q1-C, and via 10k each to Q2//Q3-C's. so either your supply volts is missing, or ........ no, it shouldn't be the jack plug, because that switches battery/ground, doesn't? and Q1-E should show 10k to ground, no?
I hadda go on the bb tonight, and got Q2 and Q3 volts similar to yours. Q1 I'm not sure about. it might be time to do the "search for audio probe" that we so often recommend.
yeah, agreed,resistances: q1's base shouldn't be at or near ground, and its emitter should read @ 10k... are you sure your guitar cable isn't shot? ... take a close look under q1, check that no wires are touching that shouldn't be, or arent connected through q1's case... also maybee clean between the battery clip pad and the pad under q1...looks like something is connecting q1's base and emitter to ground...
hey guys. sorry for the delay, just got back from work. thanks so much again for your thoughts on this.
unfortunately i'm a little confused. you probably already know this, but just to clarify and make sure, the first set of measurements i wrote in that post was for resistance to each emitter. the second set was voltage measurements at each leg of each transistor, as quackzed suggested i remeasure them now that the battery short is no longer happening.
are you both saying that, according to the schematic, there should be 10k ohms resistance between Q1E and ground, and, since there is only 5.2k, it must be connecting to ground somehow? i checked the color code of the resistor (3 bands, brown/black/orange) and it should be 10k. but i'm too dumb to follow exactly how the wiring connects compared to the actual schematic.
do any of the other numbers seem out of whack?
i've checked over and over again that nothing is touching that could possibly connect Q1 to ground. have also checked the cable and all is well. and again, signal is perfect with pedal switched off.
would there be any benefit to resoldering the junctions on the board?
i also started learning about how to make an audio probe and am excited to try working with that. i should have it set up by tonight or tomorrow.
oops. :icon_redface: i ass-umed the resistance readings were for q1 c b e ... my brain and or my eyes must have been crossed. still , between q1's emitter and ground should be @10k... this might be a good clue though. try checking resistance between q1's emitter and ground again, this time with the fuzz pot all the way down, then again with the fuzz pot all the way up... if you get @ 6k one way and @ 2k the other way, then i think we've got our killer!!! The 1uf cap off of q1's emitter in the library with the candlestick!
no problem at all, thanks for clarifying!
not much fluctuation when i turn the attack knob. goes from around 5.12k to around 5.29k.
quackzed - please note:
Quote from: Riinehart on March 03, 2015, 11:22:11 PM
Resistance between minus terminal and each collector - I'm not getting a reading on any of these. Is that normal?
this can't be right, either circuit or measuring method is failing here.
true, i'm guessing measuring method, due to voltage measurements being close?, but who knows... time for ze audio probe!
** man i really thought that cap was goin' downtown!!! **
yea, i think probably safest to assume i screwed something up or somehow didn't measure correctly. i remember trying all of the different resistance settings on my meter and only seeing a "1" no matter where i turned the dial. but i will try again when i'm home and see if i can figure it out. i'll also get the audio probe put together. i didn't have a capacitor on hand but it should be arriving today.
the cap on the schematic says 1uf, but the cap in your picture actually reads 106 which is a 10uf cap...you can always swap em later it wont effect the circuit working or not...
i think i need to take a step back and ask a stupid question: when i measure resistance between the minus terminal and each collector, should i have the battery in place or not?
doesn't matter. either way, the resistance should be the same... voltage measurements need the battery in...
hey, thanks quackzed for all the quick answers!
i'm still stuck on this situation of resistance between the negative battery clip and the collectors. duck_arse had asked me to make this measurement, and i wrote back that i wasn't registering anything on my meter, and he responded back that that couldn't be correct.
so now as i am measuring again, i realize i get different measurements depending on whether the pedal is on or off and whether the battery is in or out:
- 1.8m with battery in and pedal turned off (via on/off switch on volume pot)
- 1.0m with battery in and pedal turned on
- with the battery out, i can't get any reading. my meter is not auto-ranging, it's the kind where you turn the dial depending on the amount of resistance, but no matter where i turn the dial the reading stays at "1"
does that make sense? is there anything i should try?
fwiw, i'm building the audio probe now ... hopefully that'll help figure things out.
you can try measuring the 10k brown black orange resistor closest to the yellow purple yellow resistor then measure the other 10k resistor right next to it ... set your meter for closest setting above 10k...probably the 20k setting and you should get @ 10k for each one... if you get a reading of "1" on your meter set it to the next higher setting till you get a reading... it helps if you look up the color codes on the resistor and know what resistance to expect and set your meter accordingly... but you CAN just go up setting by setting till you get a reading of 'some' resistance value... a 1 with no decimal usually means the resistor is too high for that setting...
also, looking at your pics, i can see some dried up schmutz on the top of a transistor and in other spots... its possible something got spilled into the box and dried up... might be a good idea to get some alchohol and q- tips and clean the board and around all the parts(with the battery OUT ;) )... if the spill was beer or juice or soda it's conductive and will mess up accurate resistance readings as well as prevent the circuit from working... if it worked before and now it doesn't it's possible something got spilled on/in it and dried and that might be why its not working now... might come to life after a good cleaning...
ok, more embarrassingly stupid questions ...
how do i measure the resistors while they're in the circuit? do i just take the battery out and measure from each side of the resistor?
if so, they are 7.42k and 8.14k respectively.
or is there a different way i should be measuring?
fortunately no spills or anything. it's just the dried fiberglass from the insulation that's stuffed into the pedal.
but cleaning it sounds like a good idea regardless. will try it.
i also just finished making an audio probe. any ideas where i should start?
measuring resistance - the multimeter puts some known volts across its probes, and Ohm's Laws the resistance resulting. I think. this is why we always measure resistance with the power OFF. the circuit supply will just confuse the meter. when measuring in circuit, just probe each leg. other circuit connections may affect the reading, but it will only ever read lower than the marked value. the most accurate way is to desolder and lift one leg of said resistor, then measure.
I should have been clearer in what I wanted earlier. the circuit shows the collectors connected either hard-to or via 10k resistors to the battery minus terminal, no? so, take the battery out, switch the unit on, plug in a plug if it has that type power switch, then measure the resistance fro the battery clip itself to each of the collector pins of the transistors. they can't be O/L or -1- or open circuit if the circuit is going to work.
and how to use an audio probe. there is 2 way to do, fit battery, switch on, etc, then either monitor the output and inject/probe Q3 base, then Q2 base, then Q1 base, or inject into the input jack, and monitor at Q1 emitter, then Q2 collector, then Q3 collector. Q1 E should be same loud as input, but each next collector will probably be louder. start with monitor amp volume low, turn it up till you hear good/bad, then turn down again before next probe point.
I should probably point out that I have only ever used a cro, never an audio probe, but I've read nearly everything GibsonGM has typed about correct use.
duck_arse, thanks so much again.
re: resistance, in that case the measurements i last posted are true, regarding the two 10k resistors that quackzed was asking about: 7.42k and 8.14k
i also had a chance to try the audio probe, using the first way you suggested.
at Q3B, i have barely audible signal (the same that i get when i try to use the pedal). at Q2B, it is the same. but at Q1B, i have full signal (clean, no fuzz).
any idea what this could mean, or how i could troubleshoot further?
possible breakthrough ...
i don't even have audio coming out the other end of the stomp switch when the switch is on.
in other words, with the audio probe, i can verify that i have audio going into the switch (it's the first thing that the input cable hits), but when the pedal is on i have nothing (or very very little) coming out of either terminal on the other end of the switch.
when the switch is off, i have audio coming out of the terminal that goes directly to the output jack for bypass.
bad switch??
that could be it. if you have an alligator clip you could clip around the switch to check, one side to the terminal that goes to the effect and one side to the input terminal... make sure the switch is switched to the effect on side so that the signal isnt also going directly to the output jack... ill cross my fingers for ya!
damn ... unfortunately no.
even when it's alligator-clip'd around the switch, i get the same lack of signal on the effect side of the switch.
even if i bypass the volume pot, and jumper from the input cable to the output of the volume pot, same thing happens. i'll have full signal on the end of my alligator clip, but as soon as i clip it into the circuit, signal is dead.
i'm lost ..... :-\
damn! another close but no cigar... onward!!! ok , seems like you have a better handle on measuring resistances so lets figure out q1.
Quotehow do i measure the resistors while they're in the circuit? do i just take the battery out and measure from each side of the resistor?
if so, they are 7.42k and 8.14k respectively.
thats pretty close to 10k ,your meter battery might be getting low...
ltes do some measuring...
the other 10k resistor:
the 1M resistor near it:
the 100k at the input(br bl yel):
hell... go ahead and measure the other 3 as well... first we'll check that all the resistors are close to their right values...
and, plug something into the mt jack, so I don't need to worry which is the captive cable. now measure resistance from the input tip to the output tip. result? work the byapss, what now? then, measure from the input tip to the R1 100k on the board. result? work the bypass, what? then, do the same for the output tip, to the vol pot wiper. result, work bypass and result?
Sorry for the LONNNG absence. Life got in the way for a bit, but today I'm finally back at it. Thanks to all for the previous help and suggestions ... and if by any chance you're still around, I'm going to post the answers to the last round of questions below. Still stumped!
At Quackzed's suggestion, I measured all the resistors, and many of them are significantly off from what this schematic says they should be (hope this image works):
(http://s13.postimg.org/oadws9x8j/Resistor_Values.jpg) (http://postimg.org/image/oadws9x8j/)
And duck_arse, here are the answers to the questions you last asked. I was a little unsure of what you are referring to as the "input tip" and the "output tip." Do you mean the input and output tips of the cable inserted into the mt jack? Or do you mean, once a cable is inserted into the mt jack, to measure from the tip of that cable to the tip of the other cable (the instrument cable)?
I tried to check for both:
Resistance from input tip to output tip of cable in mt jack: No resistance. When in bypass, also no resistance.
Resistance from tip of cable in mt jack to tip of instrument cable: No resistance. When in bypass, no connection at all.
Resistance from tip of mt jack cable to R1: 115k. When in bypass, no connection.
Resistance from Tip of instrument cable to R1: 115k. When in bypass, also 115k.
Resistance from output tip to volume wiper: Full connection, no resistance. When in bypass, no connection.
Sorry again for the long silence in this thread. If anyone is still interested in helping, I'd be extremely appreciative. I'd love to get this guy working. Thanks so much again!
riinehart - you'll have to try harder than that to get rid of us. it has been a long time, and I have forgotten what we were looking at .......
anyway. when I same "mt jack", I mean "the empty jack", that which has nothing plugged in. and when I say "input (or output) tip", I mean the hot/signal/tip connection of the jack, or of a cable plugged into. they are named tip in both cases, with the ground on the sleeve connection. so measuring from tip-in to tip-out is to check that the signal will get from in to out when bypassed, and that at least something happens to that connection when you un-bypass.
and then I wanted to know from tip-in to the board-in when un/bypass, and from the board-out to the tip-out as well. these are the basic steps to find where you may have made a switch/jack wiring error.
115k to R1 is ok, if the reading is 0 at the other end of R1, the board input. are you measuring with the battery disconnected? and if you can lift one end of the 470k and the 1M, and remeasure, that'd be nice.
Ha -- that's a huge relief!! I'm so grateful for the help!
Just a reminder/recap -- so far I haven't changed anything on the pedal. It used to work. But I didn't use it for a while, and it stopped working. In bypass, full sound gets through; but when the pedal is on, there is only the faintest little bit of signal (almost inaudible).
Also, yes, I was measuring resistance with the battery disconnected -- and indeed I am getting a reading of 0 at the other end of R1.
With one leg lifted on both the 470k and 1M, they both read correctly!
Tip-in to board-in ... 115k. With bypass, I get no reading.
Any idea what this means??
Thank you again!
Also -- I'm sorry, I'm still not sure what you mean by "tip-out".
Please excuse my crappy MS Paint drawing, but hopefully this makes sense:
(http://s13.postimg.org/9y9ngwaoj/Tip_Out.jpg) (http://postimg.org/image/9y9ngwaoj/)
Thanks again!
ah-hah. I was thinking you had an input socket and an output socket. so which has the captive cable, the input? then the output socket tip connection would be "tip-out". can you audio-probe the transistors again, post findings? I'm hopping for quakzed to come back and help.
Yes, it's kind of a strange cable set-up on this pedal.
The captive cable goes to instrument, and the mt-jack goes to amplifier.
When I'm home from work tonight I'll do the audio probe test again.
Thanks!
OK, I checked the transistors again with the audio probe.
I get full (clean) signal at Q1 base and collector, and no signal at any other leg of any of the transistors.
:-\
not the collector, surely, it's connected to supply. well, I'd say replace the 1uF's between stages, use poly if you have them. but that's only if you've got good voltages on Q2 ..... and you could try injecting your test signal into the base of the second transistor, via a known good cap, and listen w/ probe at its collector. same for third transistor, will prove they are still good.
Thanks, duck_arse -- I'll start searching for some poly 1uf's.
Could you advise what good voltages should look like at Q2?
mmmmm, well, maybe. with grounded emitter, the base can only ever get ~-0V3, both those transistors. my theory, such as it is, fails at the collector voltages when the E is grounded, I'm afraid. it'll be more than -1V5, less than -0V3, though.
OK, thanks again! I'll check when I get home later and will post.
OK, good news, I suppose: -1.3V at Q2 collector.
Any idea what to look for next?
Thanks again!!
well, to measure the DC's, I just put a transistor on the bb in the Q1 circuit, then as Q2, then Q3, if you follow. with -1V66 battery, I got:
* Q1 C=-1V66 B=-0v4 E=-0V3
* Q2 C=-1V27 B=-82mV E=0V (fuzz at maxx)
* Q2 C=-1V63 B=-10mV E=0V.
so my -300mV at the bases was way off. your Q2 C looks ok by my figures. did you try the signal injections?
I'm sorry, I have to once again show my ignorance ... I'm not sure what some of these things mean.
Could you explain a little more? Also, what do you mean by signal injections, and how would I do it?
Sorry for the extra questions and thanks again for being so helpful.
when you do signal tracing w/ the audio probe, you inject signal into an input and listen/monitor at an output. so, you can apply signal to the input cable tip , and listen at the output socket. but! nothing comes out the third stage, leading us on this merry dance, no? so, back up, listen at the output of the second stage, Q2 collector. nothing! so go to the first stage output, Q1 collector. something there, but not Q2?
well, now you can inject your signal into Q2 base, via the audio probe's blocking cap, and monitor at the output socket. anything? if not, monitor Q2 collector. this will prove/disprove the Q2 stage workings.
and then, for completeness, or because we still haven't found the prob, inject your signal at the base of Q3, listen to the output. if each stage input provides stage output, but there is no thru-put from Q1-in to Q3-out, you'll now know what and where and why.
each transistor is a separate stage, the signals (out-in-out-in etc) are joined by those caps. so test each stage functions as some sorta amplifier by self, then string them all together for a working fuzz.
can't thank you enough for taking the time to explain this.
makes total sense. i'll get back on it tonight.
thanks!!!
duck_arse, thanks to you I think I may have this figured out.
When I inject signal into the base of Q1, I get no output (of course).
But, when I inject signal into the base of Q2, I DO get output. And likewise, when I inject into the base of Q3, I get output.
After Q2 is the 1uf cap. If I inject signal before the cap (between Q1 and the cap), I get no output.
However, if I inject signal after the cap, I get output.
So ... replace the cap?
Please let me know if that makes sense to you.
Also, if so, anything particular I should look for in a replacement? The markings on the cap are:
1064+
1MFD+
6v
I don't know a lot of the terminology, so I'm having trouble finding an exact match online.
Thanks so much again.
if by
QuoteAfter Q2 is the 1uf cap. If I inject signal before the cap (between Q1 and the cap), I get no output.
you mean "after Q1 is the 1uF .... ", then yes, this is exactly what I have been leading you to.
as for the cap, if you want the real 100% mojo, replace with a similar (replace both those 1uF, take the first fail as a warning) size/type. if you just want the pedal working again, replace with "a 1uF capacitor". a 6V, 10V, 16V, 25V, 35V, 63V (etc) electro will be OK. but, if you want to not worry about those caps again, find a 'plastic' type, a box-cap or a grrencap or an orange drop or a tropical fish ...... any of the non-polar types, 1uF, will do. again, they might be 50V, 63V, 100V ...... some like using 630V.
whatever you can get, that fits, that you like the look of, that you can afford, marked 1uF or 106 (don't worry too much about tolerance, J, K, 5%, 10%, 20%, like that), at any voltage, will do the job. even disc ceramic. and I think that "1064+" may well indicate a cap made 10th week of 1964. it is not quite as old as me!
[edit :] oooopppss!! obviously, as you've spotted by now, not "106", but
105. you don't want a 10uF in there.
Thanks so much, duck_arse. I'm so excited to finally have a potential solution.
Do you think these would be good replacements?
http://www.ebay.com/itm/METALLIZED-POLY-FILM-CAPACITOR-AXIAL-1UF-400VDC-220VAC-NEW-2-PKG-/190816529448?hash=item2c6d8d2c28
those will do, yes, but they show shipping to australia as $21.25 !!
I also found this on hebay:
http://www.ebay.com/itm/2x-105MPW400K-Metallized-Polypropylene-Film-Axial-Capacitor-1UF-400VDC-220VAC/121280140273?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D33278%26meid%3Dd1c79c2535184c60af3ff07e4f5af86b%26pid%3D100005%26rk%3D1%26rkt%3D3%26sd%3D190816529448
but really, maybe smallbear. I found these, all are ok:
http://smallbear-electronics.mybigcommerce.com/tropical-fish-1-mf-250v-10/
http://smallbear-electronics.mybigcommerce.com/tex-cap-1-mf-axial-200v-10/
http://smallbear-electronics.mybigcommerce.com/sec-mpc2s-1mf-50v/
http://smallbear-electronics.mybigcommerce.com/roederstein-mkt-series-1-mf-250v-5/
This is great -- thanks so much again. Excited to post some results!
For signal caps, as DA indicated, polypro is worthy. You might consider the Wima 1uF 50 volt cap (40 cents)
http://www.mouser.com/ProductDetail/WIMA/MKS2B041001C00KSSD/?qs=sGAEpiMZZMv1cc3ydrPrFwgzP98AO9idwFKwdAiDxsI%3d (http://www.mouser.com/ProductDetail/WIMA/MKS2B041001C00KSSD/?qs=sGAEpiMZZMv1cc3ydrPrFwgzP98AO9idwFKwdAiDxsI%3d)
I'm holding my breath and crossing my fingers for ya' Riinehart...
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTFhXujrNrE1VaF4TWTyGQ72ll__yhh1-55_-4b4dq-gYkB9BkG)
You guys are the best!
Ordered the caps, will put them in as soon as they come and will keep you posted.
Huge thanks again.
me too, quackzed.
(also, congrats on the upgrade to all 5 doughnuts.)
Huzzah!!! It's alive!
My most sincere thanks to you all, especially duck_arse and Quackzed. I could not have gotten this thing working without you.
I ended up ordering the tropical fish caps from Small Bear, and they finally arrived today. As soon as I put them in, everything was fine. In fact, it sounds quite a bit better than I remember. Maybe the caps were degrading for a while?
Anyway, huge thanks. I hope I can return the favor someday. And hopefully this thread helps someone down the road, too.
Cheers!
Ahhh, Satisfaction!!! 8) 8) 8) 8) 8)
Ha! Yes! Exactly!! Thanks x1000!!!
now you can show us a photo of the working thing, insides esp. and good work (and get in and measure all the transistor voltages, for the database .... ).
absolutely -- will do.
which legs of the transformers should i measure? all of them?
anything else that would be helpful?
OK, here are the voltages at the transformers with the pedal (finally!) functioning normally:
Q1c: -1.29
Q1b: -.6
Q1e: -.6
Q2c: -.77
Q2b: -.06
Q2e: 0
Q3c: -1.19
Q3b: -.01
Q3e: -.6
I hope I've measured and written them correctly. If something seems out of whack, just let me know. I wouldn't be surprised if I made a mistake.
If there is anything else that'd be helpful to post, just let me know.
Here's a pic.
(http://s14.postimg.org/itq718ne5/20150909_205748.jpg) (http://postimg.org/image/itq718ne5/)