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Problem with Stereo mod for Tonepad Small Clone

Started by Govmnt_Lacky, July 10, 2010, 02:19:11 PM

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Govmnt_Lacky

July 10, 2010, 02:19:11 PM
I recently built the Small Clone Chorus from the tonepad layout. I incorporated the stereo mod as shown in the instructions. The problem that I have is that there is NO chorus effect on the stereo output. It is just the dry guitar signal. I get great chorus from the mono output.
The site claims that there should be a chorus effect on BOTH outputs. Am I wrong on this?
I have traced the entire board and it all seems fine. Any ideas? Anyone else having this problem? Is the stereo chorus claim on the Tonepad site wrong?
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#1
July 10, 2010, 03:56:52 PM
Just thought I would add this. This is directly from the Tonepad website:

"The PDF now includes an add-on schematic for stereo outputs, this is done inverting the phase of the modulated singal and mixing it back with dry signal on a second output. This way there is chorus on both outputs and when used in a stereo amp setup the effect is really superb!"

Seems pretty simple that there should be a chorus effect on BOTH outputs. Am I wrong?

A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

PRR

#2
July 10, 2010, 04:28:46 PM
Delayed comes in wire D, dry comes in wire A.

You need -both- mixed together to get "chorus". (The Delayed alone won't have any strong effect; just a bit bent and some hiss.)

B has 4.5V bias. C and E are the +9V and zero V power feeds.

Measure DC voltages in this chip. One at zero, one at 9V, all others essentially 4.5V?

Disconnect wire A. Now what is on OUTPUT2?

Put wire A back.

Disconnect wire D. Now what is on OUTPUT2?

Put wire D back.

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Govmnt_Lacky

#3
July 10, 2010, 04:42:23 PM
I will put the DMM to this tonight and will post the results tomorrow. A bit or armchair troubleshooting as I do not have the unit with me right now:

Since I am getting the "dry" signal out of the stereo output, is it safe to say that the problem lies somewhere between where the delay signal (D) comes into the stereo board and where it is "mixed" with the dry signal? (the 22K/20K/10K resistor junction). This would include the 100K input, 100K feedback, IC1a, and the 20K mix resistor.
I read out the trace runs on the stereo board and they are all good. The IC (JRC4558D) on the stereo board read 8.6V at pin 8, 4.5V at pin 3, and 0V at pin 4. I did not read the other pins.
Also, I may need to double check the resistor values. I am 99% sure they are correct however, another look could not hurt. My number 1 suspect would be an incorrect value in the 20K spot. Could that cause my problem?

Thanks for all the help from everyone.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#4
July 10, 2010, 05:43:36 PM
Has anyone out there built the Tonepad Small CLone and had this same problem?
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

PRR

#5
July 10, 2010, 05:55:07 PM
> Since I am getting the "dry" signal out

I don't think that is proven. The delay is small. The "effect" does not happen until the direct and delayed are MIXed. So unless you are sure you don't have BBD hash, it could be the delayed without the direct.

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Govmnt_Lacky

#6
July 10, 2010, 05:58:26 PM
So, what you are saying is that the "delay" sounds identical to the "dry" signal? I ask because when I plug into the stereo output, it sounds identical to the bypassed signal to include the volume level.

What do you mean by BBD hash?
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#7
July 10, 2010, 08:33:13 PM
Could incorrect resistor values on the stereo board cause the direct signal not to "mix" with the delayed signal? The output from the stereo out jack sounds identical to the input so I don't know how it could possibly be the delay signal w/o the direct signal mixed in.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#8
July 11, 2010, 02:19:05 PM
Update on my problem:

Stereo board IC voltages:

Input voltage - 9.2V

JRC4558D Pin 1 - Oscillating from 4.25 to 4.45V
Pin 2 - Same as Pin 1
Pin 3 - Same as Pin 1
Pin 4 - 0V
Pin 5 - Same as Pin 1
Pin 6 - Same as Pin 1
Pin 7 - Same as Pin 1
Pin 8 - Oscillating from 8.2 to 8.75V

I verified all resistor values and placement on the stereo board. All are good.

Already verified the traces with a DMM. All are good.

Still no CHORUS effect out of the "stereo" output!!!!

I used a standard enclosed mono jack for the stereo output with the output from the stereo board soldered to the tip and the sleeve is soldered directly to the sleeve of the non-stereo output (the one WITH chorus effect) which is jumpered to the rest of the grounds.

This one is pulling my hair out!!!!!! PLEASE HELP!!!!!
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#9
July 11, 2010, 04:19:23 PM
Sorry people. Bumping this because I need to try to fix this today! Any help would be appreciated PLEASE!!!!!!! ;D
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#10
July 11, 2010, 06:44:42 PM
Another bump. Any help is greatly appreciated!!
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#11
July 11, 2010, 07:53:30 PM
Another annoying BUMP! Please help me save what little hair I have left over this project!!!!!!!!
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

PRR

#12
July 11, 2010, 08:37:31 PM
Quote from: PRR on July 10, 2010, 04:28:46 PMDisconnect wire A. Now what is on OUTPUT2?

Put wire A back.

Disconnect wire D. Now what is on OUTPUT2?

Put wire D back.
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Govmnt_Lacky

#13
July 11, 2010, 08:40:35 PM
PRR,

I did neglect to do this. I will have to ground the A and D inputs to the stereo board individually as I basically "hard wired" the stereo board to the mother board. I will try this tonight and post tomorrow. Thanks.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

bside2234

#14
July 12, 2010, 12:37:01 PM
I built this a while ago and I think I had the same issue. I'll have to take mine out and see. I haven't used it in a long time.

Govmnt_Lacky

#15
July 12, 2010, 01:02:52 PM
bside,

THAT WOULD BE AWESOME!!!! This thing has been killing me for a few days now. If you could look into yours and let me know if there were any wiring changes, component changes, different IC voltages, etc. it would be greatly appreciated. I have tried to contact Fp but he NEVER answers his email!
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

stringsthings

#16
July 12, 2010, 07:16:27 PM
Quote from: Govmnt_Lacky on July 10, 2010, 02:19:11 PM
I recently built the Small Clone Chorus from the tonepad layout ... Is the stereo chorus claim on the Tonepad site wrong?

if the stereo chorus claim on the Tonepad site was wrong, do you not think someone would've pointed this out to Tonepad before?  .... it sounds to me as if you are getting a bit too excited about what you are doing .... my advice:  set the build aside for a bit and then come back to trouble-shooting with a clear head .... the world won't come to an end if you cannot get a pedal working ...

and if you really, really need a chorus ASAP, you can always go purchase one off the shelf ....

bside2234

#17
July 12, 2010, 07:24:29 PM
Well I got mine out and played it for a while. I do get chorus out of both outputs. I don't know if I would call it stereo though. It sounds just like the same signal passed to both amps like I just tapped the second output jack off the main output jack.
I forgot the problem with mine was I did a tremolo mod to it and that doesn't translate into stereo. I get straight chorus out of one amp and tremolo out of the other which is kind of cool in it's own way.

I'll try to get some time tonight to open it up and get some voltages of the stereo board for you.

Another reason I put this on the shelf was that something seems to go wacky every I plug it in. It seems the trimmer needs adjusting from time to time. My build is very unstable for some reason.

Govmnt_Lacky

#18
July 12, 2010, 08:41:58 PM
OK... I pulled out my trusty audio probe (Thanks Aaron) and got to testing the stereo board inputs. Here is what I have found:

When I meter the wet signal input to the stereo board at point "D" I do in fact get the wet chorus effect. Thats the GOOD news...

Next, when I put the audio probe to the "D" side of the 100K resistor, I get good chorus effect. Still good news.

Now, when I put the audio probe on the other side of the 100K resistor (the side leading to IC Pin 2 / other 100K resistor) I LOSE ALL SIGNAL!!!

I checked all aspects of the board and there are no shorts and the component values are all correct.

Is the Tonepad layout wrong? Should this resistor be a different value? Or others?

A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#19
July 12, 2010, 11:01:43 PM
More audio probe info:

When looking at the Tonepad stereo board on the pdf file, here are my findings.

I get dry guitar signal at Point A, Through the 22K resistor, and at the left of the 10K resistor.

I also get dry guitar signal at Pin 7 of IC, top of 33K, through 1K and 6.8K, to the right of .01 cap (but not through it), through the 1uF electro, and out.

I DO NOT get dry signal anywhere between the right of the 10K, the left of the .01 cap, the bottom of the 33K and Pin 6 of IC. Nowhere in that junction do I get dry signal????

If I jumper from "D" to the 22K/20K/10K junction, I do get a chorus output however, it is extremely louder than the normal output.

THIS ONE IS RACKING MY BRAIN!!!!!!! BUT I CANT PUT IT DOWN.... MUST.....FIND.......FIX!!!!!
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'
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