polyphase gut shots....

[pinkjimiphoton]

hi scruffie,
i've been sidetracked for a while on other stuff... a bud's amp blew, and had to rebuild the whole thing. eek.

and a couple fuzzes, and gigs, and life.
gotta gig tonite, got it on my bench tho. i can't get it working. that one weird cap on there i wonder if that may be the problem?

i dunno, will get to it soon, sorry bro!

[Scruffie]

hi scruffie,
i've been sidetracked for a while on other stuff... a bud's amp blew, and had to rebuild the whole thing. eek.

and a couple fuzzes, and gigs, and life.
gotta gig tonite, got it on my bench tho. i can't get it working. that one weird cap on there i wonder if that may be the problem?

i dunno, will get to it soon, sorry bro!

No worries bud! I've been busy my self, in no rush was just wondering.

I really wouldn't just focus on random parts cause they look strange to solve the issue  it's a massive circuit, could be lots of things.

[pinkjimiphoton]

well, just wondering if i got the polarity there wrong, if that may explain why i don't get any effect at all anymore.

i really wanna get to it tho, cuz i think having a proper schem will make my life a LOT easier, this is way above my paygrade, i'm just really beginning to understand very little, ya know?

[Morocotopo]

How you gettin' on there Jimi? Unit up and running yet?

Morocotopo, as I mentioned, I think from tracing (and your pictures confirm I got the right resistors, thanks for that! Makes it much easier to follow) the mixing resistors are actually 22k, not 3k6 and the 15k pull down being 5k6 which would be a discrepancy, that's the only one I could be near-sure of that might not just be the band colours not showing up great on camera.

Also R35 on your overlay, should be 43k, looks like Red, Orange, Orange, Yellow? A Yellow could be mistaken for gold making it 23k but a Red Tollerance band?

Hi Scruffie.

Haven´t got around to continue work on this one, struggling with a Dipthonizer currently (Jimi and his videos are to blame for that!). But my main concern up to now was getting the correct schem in terms of connections. Those differences are easily tested on breadboard or on a PCB. As soon as I finish some other stuff this goes on the breadboard. Only problem is, one of those things is an AC30 clone, including the cabinet work!! That will take some time...

My latest schem posted here has R35 as 43K, the other R´s are different as you note. Or do you want me to confirm those values for you with the pics?

[Scruffie]

How you gettin' on there Jimi? Unit up and running yet?

Morocotopo, as I mentioned, I think from tracing (and your pictures confirm I got the right resistors, thanks for that! Makes it much easier to follow) the mixing resistors are actually 22k, not 3k6 and the 15k pull down being 5k6 which would be a discrepancy, that's the only one I could be near-sure of that might not just be the band colours not showing up great on camera.

Also R35 on your overlay, should be 43k, looks like Red, Orange, Orange, Yellow? A Yellow could be mistaken for gold making it 23k but a Red Tollerance band?

Hi Scruffie.

Haven´t got around to continue work on this one, struggling with a Dipthonizer currently (Jimi and his videos are to blame for that!). But my main concern up to now was getting the correct schem in terms of connections. Those differences are easily tested on breadboard or on a PCB. As soon as I finish some other stuff this goes on the breadboard. Only problem is, one of those things is an AC30 clone, including the cabinet work!! That will take some time...

My latest schem posted here has R35 as 43K, the other R´s are different as you note. Or do you want me to confirm those values for you with the pics?

Wow! Sounds like you're gunna be busy, i've also got quite a few projects on the go so i'll be away from this for a little bit too but I have plenty of plans for it down the line.

Ah, i've not been working on schematic connections being correct now i'm happy with what the overall schematic looks like, i'm trying to verify actual unit values compared to the schematics so I know what to socket on the PCB to test and to be sure it's as close to an original unit as possible for suitable LDR & Alternate Vactrol testing.

Speaking of, Turns out Red is 2% Tollerance (shoulda just looked that up but it seemed so strange) so that is 43k so only those 3 mixing resistors are not as on any of the schematics so far.

[Morocotopo]

A little preview to get you drooling...






http://soundcloud.com/truemostro/polyphase-breadboard-first

Damn, how the hell do you get the Soundcloud player to show? I HATE Flash codes!

[pinkjimiphoton]

SUH-WEEEEEEEET!

[alparent]

First time looking at this thread. Cannot help in any way at all.
But I suggest we all get together and pay Jimi some photography lessons.
1st "How to use the MACRO setting!"

Sorry, I'll go away now 

[pinkjimiphoton]

LOL... there IS  no macro setting on this POS phone... the pics it takes are huge, but by the time they get "txted" to my computer, they BLOW.

[Morocotopo]

A little more detail.

I replaced all those stupid non standard values for the nearest commonly available one. My take on that is that EH used whatever they had/could buy cheap that worked. No sense in sweating over those R´s values, this is not a precision circuit. I made the Rev 0.3a schem that I posted earlier. Other changes: the mixing R´s are 22K.The transistors are BC549/BC559 in place of 2N5088/2N5087. No R57 or thermistor. D6 is a 1N4007. Powered by an external LM317 power supply, so all the power supply part of the schem is not there. Power consumption is from 45 to 55 mA when the optos are lit more of the time (rate pot at max). I didn´t even adjust the trimmer! Seems to be unitiy gain as is. C 18 is just a standard green cap, no precision part there. R73 is not there, no sense in parallelling a 1M with a 15K.

More testing and an updated schem later.

Of course now I (we) have to think about how to power the thing. I was thinking an LT1054 voltage doubler followed by a 7815 regulator, I hate 18V pedals, forces me to add another power supply to the pedalboard. Yes, I know that nowadays many power supplies have 18V outs, but mine does not, so! Anyway, I´ll test the thing with lower voltages, maybe we can get it to work with 9V, although I doubt it.

[Morocotopo]

Well, I´m testing the thing and I found something that has to be resolved. In sweep mode, there´s ticking from the LFO, that is, the one made from the CD4013/CA4130 and associated circuitry. Strangely enough, the other LFO made with the LM1458 is totally silent...

The ticking is not super loud but it´s there. First thing I´ll try is decoupling power to all the IC´s. The original schem doesn´t have ANY decoupling, even with two LFO´s onboard... If any of you have an original, could you test it for ticking? Specially on sweep mode.

Of course the thing is on breadboard, so the ground scheme is less than optimal, and flying leads everywhere. The one thing I observed on the original PCB pics is that the grounding layout is star-type grounding.

More testing to follow.

[Morocotopo]

OK, more investigation.

The original board has ground "branches" connected to a central point, those are:

- U6, U7, Q3, Q4, and associated parts. That is to say, the sweep LFO.

- U2, U3, U4, U5. The phase stages.

- C22, C21, C24, trimpot, R72, U9. The other LFO an some parts of the envelope detection circuit, BUT not the env opamps themselves.

- All the rest

So, clearly the LFO´s grounds are separated from the audio grounds. The big question is, would that type of ground layout be enough to solve the ticking problems? Hmmm. It´s curious that the original schem doesn´t have ANY power decoupling, except for U9 that has a resistive divider in the power, but I don´t know if that is decoupling or simple a voltage, er, "reducer".

So, I have to gather courage and modify the grounding in my breadboard. That will be complicated, since it´s quite a cramped situation there.

Any opinions?

[Scruffie]

Nicely done work Morocotopo

Proper grounding and neat wiring is gunna help things yeah, especially keeping those grounds seperate.

Little bit of decoupling wouldn't hurt though if it can be managed.

[Morocotopo]

A little more advance in this:



Added decoupling to the schem and designed the PCB, as you can see. Now i have to drill and start loading the parts! It´s getting closer. I have precious little time to do this, so it´s going slowly. But surely. This will fit in a 1790 box, with two footswitches: one for on/off, the other for env/sweep mode, that´s why the PCB shape.

[pinkjimiphoton]

nekro zombie bump!!!!

hey guys, you ever get this thing done?

i figured out finally, all these years later, that the "weird cap" i had wasn't a cap, it was the thermistor.

i can't even see any of the crap from photobucket anymore, any chance one of you guys may have any of them gutshots i posted before?

basically, i need to figure out where the thermistor WAS so i can replace it. in my youthful-er ingnorance i think i put an electro in there, but can't remember where.

it passes signal, zero phasing. greg at black cat said replace the vactrols, so i have them, but i just wanna try and button up any other issues it might have.

ariel, did you end up putting this on your site?

scruffie, if you can hip me to the approx location of the varistor, i'd be indebted.

the glaucoma thing is making it really hard to tell color bands on things, i have to rely on my meter or the marking on the little bags now.

any info would really help a lot. you can email it to me thru the forum i think, or phatjbp at g(*****)mail

i just dug this out, its been sitting in parts for years, and i really wanna get it going again.

then i gotta finish the maestro rhythm n sound g 1 thats been sitting open on my bench for the last 4 years

[Scruffie]

It should work without the thermistor in it as it's used as a parallel resistor, my theory on its purpose is to keep the bias steady as the transformer heats the inside of the enclosure.

Anyway, I could never find an exact match for that part and the original is long out of production but a Tayda 100k thermistor should probably do fine.

I wouldn't jump the gun on replacing the vactrols (especially all 3 of them) there's plenty else that could be wrong that would cause it not to phase, you need to post voltages up.

Edit: As to the location of the thermistor, if the layout is the same as the one I have, it should be next to a trio of transistors under the Env. Sense pot.

[pinkjimiphoton]

thanks scruffie!
still trying to find all the gut shots.. goddamn botophucket screwed the whole internet.

i know i can leave it out, the problem is i had thought it was a cap all those years ago and replaced it with one, now i can't remember where it is before i did that, i could get some phasing happening messing with the knobs, so i wanna get it outta there.
i will look on mine and see if that's the right place. i seem to remember it being clustered in the middle somewhere.

at the shop, when a vibe fails, its usually the vactrols from what i've been told. the one BC vibe i did repair work on, the vactrols had failed.

i will try and post voltages, i gotta take a bunch of readings and stuff... all these years later i'm way behind the 8 ball

i am gonna TRY and dissapear to my dungeon for the day, and will try and get some voltages happening. its a little confusing after so long.

[Scruffie]

I e-mailed you some shots of it

I have to disagree with your shop, while vactrols can and do fail, they're not the first suspect, especially when the LFO uses two static sensitive parts and as you said you got some phasing before when messing with the knobs, that makes it seem a lot less likely.

[pinkjimiphoton]

thanks scruffie,
i found the pics on my phone, and located where the varistor was. yeahhhh!!!
gonna take it out. i suspect replacing it with a cap messed up everything.

gonna have to buy a new set of pots for it, the ones in there are fairly wasted at this point.

i will up a link to an imgur album with all the gut shots in a second.
thanks for the help bro!!!

https://imgur.com/gallery/KHjn0

here's all my original shite gut shots botophucket screwed

if the link doesn't work, i'll up the pics individually

[Scruffie]

Awesome I did e-mail the photos to the correct address though didn't I?

How bad are the pots? Those D-Shafts are impossible to find these days so i'd buy them off you if they're still usable and you're getting rid of them anyway, always handy for repairs.

Pictures are working fine and it looks to be the same layout as the shots I have which is handy.

I'd take voltages of the 4013, 3140 and the transistors first... I seem to recall you saying your env/sweep toggle had only 3 wires too, it's possible it was rewired wrong as it should have 6 connections and that'd definitely stop it working.