Trem Face...someone please, please help me! RG Keen, this involves you!

[Graemey]

My 1st post here:

I am following this thread with great interest.

I have an original circuit board from an old Trem Face (no round enclosure sadly) that an old guy gave me about 15 years ago.
Since I have become a DIY-er I have wanted to get the thing working. I wired the thing up using RG's diagram but, sadly, no trem effect!

Don't worry guys, Im not going to crash this thread any start with the questions. Im going to work through it and use the info already posted.

Hopefully I'll find the fault(s) and all will be well. If not, I will wait til Toddy has his pedal working then I will explain more and possibly send RG into a Trem Face induced breakdown! (just kidding!)

When all Trem Face problems are solved and the onions are peeled I will join you guys in an onion beer celebration! Cheers!

[Toddy]

I had a chance this morning to resolder R8 and re-measure. I guess it was a cold joint because now R8 reads 0.0v on the top and 3.7v on the bottom. I measured the Z1 to see what that was and it was down to, you guessed it...3.7v. How could a diode go bad? Well, I mean a non-Germanium diode (I've have a germanium diode go bad on me.) Still the voltages haven't changed on the other components. I'm beginning to agree with the bad karma idea!

I also checked the voltage on the input jack from the ring to the sleeve with the battery in and the guitar cord in. It measured 1.1V across the two lugs. Alone, when the guitar cord is not plugged in but the battery is, it measures 9.0v from the positive (+) wire to the ground (-) wire.

There is a Trem Face on e-Pay for a totally ridiculous $899.99. Guess who's not going to bid on it. I'd think about it if it were under $200. I should put mine up for more.

OK, back to reality.
Toddy

[R.G.]

I also checked the voltage on the input jack from the ring to the sleeve with the battery in and the guitar cord in. It measured 1.1V across the two lugs. Alone, when the guitar cord is not plugged in but the battery is, it measures 9.0v from the positive (+) wire to the ground (-) wire.

If we can believe your meter, then three pieces of bare metal touching one another do not provide a solid connection.

Measure again, this time, from the soldered connection of the sleeve on the input jack to the bare metal of the guitar cord plug while it's inserted into the jack, being careful not to touch other things, just the sleeve of the plug. Record that.

Now measure from the soldered lug of the ring contact to the sleeve of the guitar plug, again with the plug in the jack. If there is 1.1V across three things in series, then the 1.1V is composed of the sum of the voltages across the two contacts. In this case, the contacts in series are from the sleeve lug of the input jack to the sleeve of the guitar cord plug, and from the sleeve of the guitar cord plug to the ring contact in the jack. One or both of those is having something like a 1.1V drop across it where there should be unmeasurably small voltage drop.

[Toddy]

This morning I re-tested the jack as you suggested. I tell you, this thing is ALIVE and has a mind of its own!! I checked the input jack with the battery in and the guitar plug in. My results were that today anyway there was 0.0v between the ring lug with the battery positive (+) wire and the sleeve lug with two wires, one to the output jack sleeve and the other to the PC ground buss. But now there is 1.1v between the tip lug (which connects to R4) and the sleeve lug. And I measured from the ring lug to the guitar cord plug sleeve and got 0.0v.

Next, I measured directly from the battery positive (+) connection on the PC board to the lugs and got the same results. I was figuring to see if I had bad connections on the jack.

What else is there to measure that we haven't yet?
Is there a single part on the board that makes the electrical jump from the power signal to the LFO oscillation signal that we are overlooking?
Would the output jack connections or the switch have anything to do with the power droppage in the circuit?

We can't give up hope yet...let's give her all she's got, Scotty!
Toddy

[jacobyjd]

this thread is full of win.

[Toddy]

Today I have a couple hours that I am going to dedicate to this circuit, so I will test every part on the board and list the voltages. I should hopefully have enough time to do an audio probe test on the circuit, also. I even bought new batteries (notice the "ies", yes, more than one). There is something that doesn't want to be found in there. I hope that today we can finally expose it.



Wish me luck, I'm goin' in,
Toddy

[newfish]

<salutes>

Go get 'em!

[Toddy]

Here are my measurements from this morning. Somewhere within this data the answer lies, it has to, we've tried nearly everything else besides totally rebuilding it. With a fresh battery (9.4v), the black wire of the probe clipped onto the input jack sleeve, the guitar cord plugged in, and the red probe touching the parts, here are the measurements.

R4 0.0   0.0
     top     bottom
R5 0.0        0.0
R6 -0.004  -1.97
R7  0.0       0.0
R8 -9.48    -1.97
R9  0.0        0.0
R10 0.0       0.0
R11 -9.48    -2.69
R12 -9.48    -2.81
R13 -2.6      -0.43 ~ -1.1 (waivers
R14 -2.7      0.0
R15 -4.5~-1.1(waivers)     0.0

C3     0.0      0.0
C4    -9.48    0.0
C9    -9.50    -2.8
Z1    -1.97     0.0 

     right     left
C5 0.0      -2.70
C6 0.0       0.0
C7 -0.43     0.0
C8  0.0      waivers too much

JFET
G 0.0
S 0.0
D -0.002

E -2.82
B -2.79
C -4.3
empty B -2.79

I do not have a chance to do an audio probe this morning but with such low voltage there is probably no need.

Z1 is really a mystery why it is failing. Or, maybe it's not because since there is not enough voltage on the board it may be giving a false reading.

And that's the way it is...
Toddy

[R.G.]

Here are my measurements from this morning. Somewhere within this data the answer lies, it has to, we've tried nearly everything else besides totally rebuilding it.

You're correct - the answer, or at least some more answers lie in this.

With a fresh battery (9.4v), the black wire of the probe clipped onto the input jack sleeve, the guitar cord plugged in, and the red probe touching the parts, here are the measurements.

Good measurements. We can work with this.

top     bottom
R6 -0.004  -1.97

You're absolutely correct, this is a problem. Looking at all the measurements, I think the copper trace which includes the JFET gate is shorted to ground. If you add to R6 the item that

R8 -9.48    -1.97

and

JFET
G 0.0
S 0.0
D -0.002

... you have that the JFET gate is held at ground (0V) and one end of R6 is at 0V, when they should be at -1.97, because the JFET gate is not supposed to be able to conduct that way. So I suggest removing the battery, then setting your meter to ohms and seeing if the copper trace which includes the gate, the top end of R6 and the left size of C8 is not shorted to ground. Probably it's at the bottom side of R7, but could be anywhere. Look for solder threads or remaining copper. If you find it shorted, get out the magnifying glass and go find the short. Cut it with a knife or single edged razor blade, or melt the solder away. It is possible that this accounts for the low voltage on the zener as well.

I was tempted to look at the rest of the voltages as well, but let's clear this one fault, then run a new set of voltages.

[Toddy]

Finally got a chance to test the circuit yet again. But this time I had the fresh eyes, hands and ideas from a good buddy of mine. There is no shorts in the trace that you suspected. BUT...the battery connector was bad (so I will change that out). The LFO and all the components are now up to full voltage, as they should be. Here are our thoughts.

The LFO was working perfectly! The guitar signal is not going through the circuit at all so that just leaves the 1uF capacitor and the JFET orientation in question. The cap reads -9.4v on the ground side but 0.0v on the positive (+) side that goes to the JFET source. No voltage is getting to the JFET.

Swung by that Tandy Corporation store again on my way home for new battery clips (more rugged ones), and a 1uF (@50V) electrolytic cap. When I get a chance I will remove the 2N5485 (JFET) and measure it to make sure I put it back in the right way. I may or may not have to change the cap, so the new one is just insurance.

Oh, the suspense is killing me!
Toddy

PS If you noticed my last post I referenced Walter Cronkite. This strangely was just hours before he passed away. I met Walter back in 1980 alone on a beach with his wife in Cape Cod. I had a quick three sentence conversation with him which he actually initiated. For the 15 year old kid that I was, it was like saying "Hi!" to God. I was and still am in awe of him and he was my idol. My heart is sad today.

[Graemey]

My 1st post here:

I am following this thread with great interest.

I have an original circuit board from an old Trem Face (no round enclosure sadly) that an old guy gave me about 15 years ago.
Since I have become a DIY-er I have wanted to get the thing working. I wired the thing up using RG's diagram but, sadly, no trem effect!

Don't worry guys, Im not going to crash this thread any start with the questions. Im going to work through it and use the info already posted.

Hopefully I'll find the fault(s) and all will be well. If not, I will wait til Toddy has his pedal working then I will explain more and possibly send RG into a Trem Face induced breakdown! (just kidding!)

When all Trem Face problems are solved and the onions are peeled I will join you guys in an onion beer celebration! Cheers!

Thanks to the info on this thread I just got my vintage Trem Face working after YEARS of gathering dust. Thanks RG and the best of luck to Toddy

[Toddy]

YEAY Graemey!! Great going!!  What was wrong with your's? (It may be what's holding me up.)
Is it possible for you to post a sound clip of it?

Sniff, sniff. Do I smell onion beer on your breath?

My JFET is installed correctly afterall. Just like I mentioned before. I'm going to attack the 1uF cap next then do an audio probe test.

Can now feel success is finally near due to Graemey's triumph!
Toddy

[liveloveshare]

I keep checking this thread waiting for the "I got it working!!!!!!!!!1111" post.
I am amazed at both your guys persistence...

[R.G.]

Finally got a chance to test the circuit yet again. But this time I had the fresh eyes, hands and ideas from a good buddy of mine. There is no shorts in the trace that you suspected. BUT...the battery connector was bad (so I will change that out). The LFO and all the components are now up to full voltage, as they should be. Here are our thoughts.

That would explain a lot about the constantly-changing voltage measurements. So we have a fourth fault - bad battery clip - to add to the list. One more layer deep.

The LFO was working perfectly!

Good. Turning the transistor around in the holes fixed that.

The guitar signal is not going through the circuit at all so that just leaves the 1uF capacitor and the JFET orientation in question.

So this has now changed from the last time when we found audio on both sides of R4?

The cap reads -9.4v on the ground side but 0.0v on the positive (+) side that goes to the JFET source. No voltage is getting to the JFET.

Which cap? C3 (1uF) doesn't go to the JFET source. And it's supposed to be Non Polar (NP) and not having a + side. If you mean C4 (100uF), it *is* supposed to have 0V on the + side that goes to the JFET source; it's also supposed to have -9.x on the negative side. Which cap?

Swung by that Tandy Corporation store again on my way home for new battery clips (more rugged ones), and a 1uF (@50V) electrolytic cap. When I get a chance I will remove the 2N5485 (JFET) and measure it to make sure I put it back in the right way. I may or may not have to change the cap, so the new one is just insurance.

Let us know.

PS If you noticed my last post I referenced Walter Cronkite. This strangely was just hours before he passed away. I met Walter back in 1980 alone on a beach with his wife in Cape Cod. I had a quick three sentence conversation with him which he actually initiated. For the 15 year old kid that I was, it was like saying "Hi!" to God. I was and still am in awe of him and he was my idol. My heart is sad today.

I think we all are. Cronkite could be trusted to tell the news clearly and in an unbiased way, not at all like the axe-carrying standins for news people we have today. He'll be missed.

My JFET is installed correctly afterall. Just like I mentioned before. I'm going to attack the 1uF cap next then do an audio probe test.

Remember that "the cap", if it's C3, is supposed to be NP. I would do an audio probe test first.  Also remember that the trimpot needs to be set correctly. If it's wrong, audio could be being squelched all the time. Remember the test where we twiddled the depth and trimmer pots?

[GREEN FUZ]

CHAMP, wake up, Champ!

[Graemey]

YEAY Graemey!! Great going!!  What was wrong with your's? (It may be what's holding me up.)
Is it possible for you to post a sound clip of it?

Sniff, sniff. Do I smell onion beer on your breath?

My JFET is installed correctly afterall. Just like I mentioned before. I'm going to attack the 1uF cap next then do an audio probe test.

Can now feel success is finally near due to Graemey's triumph!
Toddy

Yes Toddy, the sweet smell of success, and onion beer, is near!

My original circuit was a gift from an old buddy of mine who used to repair and build amps and pedals in the 70's and 80's.
He passed it my way and told me it had a bad transistor but could be fixed and wired up to work without to much bother.
I checked both trannys with my semiconductor analyzer and found the Jfet to be the problem. I replaced that then, you guessed it, no trem effect.

It lay around for a while til I decided to finally get it working. That's when I discovered this thread.

I started to measure some voltages using the info posted here by RG and discovered some problems around the four .68uf caps.
I remember reading RG's Trem Face write-up where he strongly recommends changing these caps to non polar types so I decided to replace the original tantalum beads with film caps.
I plugged it in and, after many years of owning the old circuit board, it sprung to life and started tremelo-ing away! Result!

I have wired mine as an original which means it has TERRIBLE bypass to keep the levels constant but the trem effect is very nice. Quite an old, warm, tubey character to it.

Im a bit busy at the moment but when I get time, I will post a youtube video and report back here to give you the link.

Keep working on yours Toddy, the onion beer is on ice and there's a MASSIVE one with your name on it!!

Thanks also to RG for everything: you've saved another old Trem Face from that great pedalboard in the sky.

Graemey.

[Toddy]

There comes a time sometimes when you can feel the love run out of something. Well, that time has come for this Trem Face build. After numerous attempts, tests, trials and tribulations, this project has come to an anticlimatic ending. The Trem Face is on its way to get looked at (and hopefully brought to life) by R.G. in person. As I told R.G., At this point in time, I just want to play through it and not just work on it.

So for those of you who enjoyed our little journey through this tremolo adventure, I thank you for all your support in its ups and downs. I hope you are not disappointed in our outcome and my decision to avoid insanity. Most of all, I have learned so much through this process and I know many others have, too. A few of you have used this thread as a personal tutorial for your own project reparing. And that's what makes this forum so valuable; free, open, and selfless sharing to aid others to succeed or learn.

Keep building. Even if it doesn't work, there's no need to stop doing what you love. And if I haven't said this before...and I know I did...R.G. you are the MAN!!

Toddy

[ppatchmods]

wow...this is so like the ending of "Wicker Man" with Nicholas Cage!!!...except R.G. wasn't there to resurrect Nicholas Cage. 

[arma61]

There comes a time sometimes when you can feel the love run out of something. Well, that time has come for this Trem Face build. After numerous attempts, tests, trials and tribulations, this project has come to an anticlimatic ending. The Trem Face is on its way to get looked at (and hopefully brought to life) by R.G. in person. As I told R.G., At this point in time, I just want to play through it and not just work on it.

So for those of you who enjoyed our little journey through this tremolo adventure, I thank you for all your support in its ups and downs. I hope you are not disappointed in our outcome and my decision to avoid insanity. Most of all, I have learned so much through this process and I know many others have, too. A few of you have used this thread as a personal tutorial for your own project reparing. And that's what makes this forum so valuable; free, open, and selfless sharing to aid others to succeed or learn.

Keep building. Even if it doesn't work, there's no need to stop doing what you love. And if I haven't said this before...and I know I did...R.G. you are the MAN!!

Toddy

Hi there

I'm quite sure R.G. will definitely get it working!

... but please please please please let us know the end of this wonderful sort of episodes movie, let's call it  "Journey to the center of a Trem Face" ! you can't leave us hanging in the limbo...we need to see the light!!     

Cheers m8s
Armando

[R.G.]

Ok, I got the trem face board today. The trem face is now tremming.

Recapping the long saga, we found multiple real problems: wrong kind of input jack, LFO transistor turned around, some connection problems. Once those were fixed, we ran into very inconsistent debugging issues. Voltages changed from reading attempt to reading attempt. And that ultimately put an end to the long distance debugging. But we have now identified the final culprit. May I have the envelope, please? And the enemy was...

Stiff solid-core hookup wire! And for best supporting actor we have low experience at soldering.

What was happening once we got past the first issues was that the hookup wire was so stiff it was pulling the pads off the board and cracking connecting traces by level action. So what you read on your meter was dependent on how you pressed on the hookup wires. The + lead to the battery was completely severed, and while I was tinkering with it, two more popped loose. I replaced all of the wires coming out of the PCB with more flexible stranded wire, remelted the solder joints, cleaning up a few iffy ones, and it ran just fine. Basically it arrived here working, except for the intermittent wires.

So, Toddy, you did good. It's hard to fix multiple errors. It's hard to fix intermittent errors. It's mind-blowingly difficult to fix multiple intermittent errors which can recur because you moved the PCB around.