^$&%$@! EA Trem fixed!!!

pbrommer · July 12, 2005, 05:28:26 PM

1.What does it do, not do, and sound like? After debugging the crap for a few hours, I'm left with a very nice clean MOSFET boost.
2.Name of the circuit = ROG EA Tremolo
3.Source of the circuit (URL of schematic or project) = http://www.runoffgroove.com/eatremolo.html
4.Any modifications to the circuit? Just wired a 100kA in reverse to change the taper.
5.Any parts substitutions? Changed the 1uF electrolytic to a 1uF film in case it got fried when I was changing the orientation.
6.Positive ground to negative ground conversion? N/A
7.Voltage at the circuit board end of the red battery lead = 9.47V
Voltage at the circuit board end of the black battery lead = 0V

Q1
D = 4.86V
G = 3.199V
S= 1.357V

Q2 --- This is the problem, I know it
D= 0V
S= 0V
G= 0V

Q3
C= 7.75V
B= 0.516V
E= 0.00V

There is no flashing LED, a nice clean boost, and absolutely no voltage at the JFet... On the + of the 22uF electrolytic (replaced) but the - shows 0.00V. Secondly, when the rate pot is turned all the way up, the beep mode beeps from lugs 1-2 and 2-3... Unlike anything else I've seen. Can you help me sort out my problems? Where do I need to look? After sucessfully debugging two ROG projects I goofed (Pepper and Odie -- very nice I must say), I'm lost. Help please.

Stevo · July 12, 2005, 05:45:27 PM

Make sure the orientation of your fet is right...some have different pin outs I dont know the voltages ...the 100k pot at the end seems to big , the rate one, set it in the middle to see if it will work? it needs to be a 50K with a 4.7K to the caps...You need to use nonpolar 1uf caps like the scheme says any smaller and it will be to fast..Is your led orientated right cathode to the tranny.....I used electro caps nonpolar. You should really look hard because you can see what the scheme is so you should see the problem..Hope this helps Thanks...

Stevo · July 12, 2005, 05:49:45 PM

Also wire up your pots like you would normally gound to the right side...I had to change mine the 123 setup I dont know what they mean!!!

mat · July 12, 2005, 06:06:27 PM

Quote from: pbrommer1.What does it do, not do, and sound like? After debugging the crap for a few hours, I'm left with a very nice clean MOSFET boost.
2.Name of the circuit = ROG EA Tremolo
3.Source of the circuit (URL of schematic or project) = http://www.runoffgroove.com/eatremolo.html
4.Any modifications to the circuit? Just wired a 100kA in reverse to change the taper.
5.Any parts substitutions? Changed the 1uF electrolytic to a 1uF film in case it got fried when I was changing the orientation.
6.Positive ground to negative ground conversion? N/A
7.Voltage at the circuit board end of the red battery lead = 9.47V
Voltage at the circuit board end of the black battery lead = 0V

Q1
D = 4.86V
G = 3.199V
S= 1.357V

Q2 --- This is the problem, I know it
D= 0V
S= 0V
G= 0V

Q3
C= 7.75V
B= 0.516V
E= 0.00V

There is no flashing LED, a nice clean boost, and absolutely no voltage at the JFet... On the + of the 22uF electrolytic (replaced) but the - shows 0.00V. Secondly, when the rate pot is turned all the way up, the beep mode beeps from lugs 1-2 and 2-3... Unlike anything else I've seen. Can you help me sort out my problems? Where do I need to look? After sucessfully debugging two ROG projects I goofed (Pepper and Odie -- very nice I must say), I'm lost. Help please.

check the Q2's pinouts. the Gringo's pcb has error in it, i think..

cheers,
mat

pbrommer · July 12, 2005, 06:41:31 PM

It's all perfed out. Trust me.. The pinout is right, otherwise none of the other ROG projects I've done wouldn't have worked

. I'll try the nonpolars, though I've read the electros do work there in the LFO.. Well, I think I'll see what's happening.. LED is correct. Curses! Will report with updates in a couple hours. Thanks for the ideas.

Patrick

puretube · July 12, 2005, 07:06:23 PM

0V is OK for Q2... no DC there - it`s just a VCR... (AC)

mat · July 12, 2005, 07:45:10 PM

Quote from: pbrommerIt's all perfed out. Trust me.. The pinout is right, otherwise none of the other ROG projects I've done wouldn't have worked . I'll try the nonpolars, though I've read the electros do work there in the LFO.. Well, I think I'll see what's happening.. LED is correct. Curses! Will report with updates in a couple hours. Thanks for the ideas.

Patrick

all right, i trust you

sorry for not being more helpful. i had the q2 problem in my pcb-version (couple of others had this issue too), hope you solve it - it is a great effect.

mat

pbrommer · July 12, 2005, 07:51:10 PM

Quote0V is OK for Q2... no DC there - it`s just a VCR... (AC)

You're absolutely sure about this? Doesn't make much sense to me.. Oh well. Changed the electros to 1uF film caps. Still nothing. No blinky, no throbbing, Nada.

Any other ideas?

mat-- didn't mean to seem snippy. it was a good idea to check the pinout.

Stevo · July 12, 2005, 08:08:29 PM

The rate pot will give you a problem.... if you crank it up in either direction it will not work set it correctly and put it in the middle position to see if it will work...If you go to far in either direction something happens to the circuit that is why I changed mine to a 50K pot wired like it should to a 4.7 K resistor.. etc...not like the 123?? whatever that means ...Its a cool tremelo have to say is worth digging at it!! The depth pot should work in the whole range of selection as long as that is wired correctly be careful of the 123 designation I dont understand that?

puretube · July 13, 2005, 03:06:36 AM

are you sure, the collector Q3, LED, 2M2, and the 2 caps (0.47& 1Âµ), are all wired together?

(ahh, how I hate un-numerated schems without dots at nodes... :roll: )

[about 0V @ Q2: well, I wrote that late at night after coming home from the beergarden... :lol: ]

[EDIT]: then again: where would any DC come from... I see one lead blocked by a 22Âµ, one blocked by 0.47Âµ, and the 3rd grounded...

btw: the "beep" tells you, that you wired the rate-pot correctly according to the schem: wiper is connected to ccw lug, and when turned up, it touches the cw end, and shorts it to gnd, coz that`s what happens when a pot is wired as a variable resistor...

pbrommer · July 13, 2005, 10:39:42 AM

puretube-

Yup. All wired together at the node right above Q3's collector, then connected down to the collector in a socket. I pretty much redid the LFO last night (new film caps, new 2M2 for Q3 C/B junction area). Maybe something is up with that 15k resistor.. I did some voltage measurements before posting all this junk, and here is a picture (I hope):

Patrick

gez · July 13, 2005, 11:56:09 AM

If the LED isn't blinking, what does this tell you? The LFO isn't working, right?! Q3 is the problem.

If you look in the archives (every problem that could ever go wrong with this circuit has been covered by numerous posts, so it's not hard to find the info) you'll see that there's no DC bias on Q2, the readings are fine.

The collector voltage looks a bit iffy on Q3.

Didn't check the perf layout (sorry), I hate layout diagrams...

gez · July 13, 2005, 11:59:02 AM

PS What trannie have you used for Q3? Did you sub something in?

puretube · July 13, 2005, 12:39:04 PM

when you short collector Q3 to ground (momentarily, with a wire...),
you should see the LED light up a little - does it?

pbrommer · July 13, 2005, 03:54:52 PM

puretube-- You are correct. It does light up with Q3 collector shorted to ground. What does this tell me?

gez-- read all the information I could, but no specific answer I could find was found. I changed the 5088 to a 5089 on the off chance.

EDIT: somebody slap me please.. Please? Damnit... Stupid pinout.... :twisted: :twisted: :twisted:

puretube · July 13, 2005, 05:02:27 PM

it tells us, that the LED functions, is correctly orientated, gets a "B+", got the right value series-resistor, and that the problem lies "south" of it...

Stevo · July 13, 2005, 06:25:03 PM

So now it is working that is great what do you think of it? Did you change anything to your taste in the rate depth etc...Interested I really like this thing :lol:

gez · July 13, 2005, 06:33:06 PM

Quote from: pbrommergez-- read all the information I could, but no specific answer I could find was found.

I think you'll find wrong pinout is covered in the archives...

Anyway, congrats.

pbrommer · July 14, 2005, 11:03:20 AM

Yeah. It works and I like it... I thought (note thought) that everything was all set up, except bassackwards transistor 3.

Oh well, chalk one up to a stupid error.

gez and puretube --- thanks for the help! I would've been beating my head for numerous hours/days/months/years and still missed the most obvious.

Patrick

puretube · July 14, 2005, 11:39:14 AM

hehe - now we are beating our heads for again having believed everything posted in a forum on the web ...

QuoteTrust me.. The pinout is right, otherwise...

ok, ok, ok: to your rescue: you was referring to the FET, while we were at Q3 already...

glad it worx - enjoy it!

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^$&%$@! EA Trem fixed!!!