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?
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?
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.
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.
Has anyone out there built the Tonepad Small CLone and had this same problem?
> 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.
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?
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.
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!!!!!
Sorry people. Bumping this because I need to try to fix this today! Any help would be appreciated PLEASE!!!!!!! ;D
Another bump. Any help is greatly appreciated!!
Another annoying BUMP! Please help me save what little hair I have left over this project!!!!!!!!
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.
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.
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.
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!
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 ....
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.
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?
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!!!!!
I am thinking that the resistor values (100K) should be lower. Any other ideas about this crazy circuit??
Quote from: Govmnt_Lacky on July 12, 2010, 11:01:43 PM
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!!!!!
this suggests your IC1a is malfunctioning.
It may either be the IC itself or the 220k resistor on the main board providing the bias voltage.
This resistor might have a different value according to ic specs
Fender,
Can you explain your reasoning behind your faulty IC1a claim. It will help me if I understand your thinking. Possibly the ENTIRE IC is bad as I lose not only the wet signal after the 100K (possibly due to internal grounding if IC1a at Pin 2)..... AND I lose the dry signal after the 10K (possibly due to internal shorting of IC1b at Pin 6.
Your thoughts????
well,
you have chorus signal at D and you haven't it after the phase inverter (IC1a)...
then you have a signal at pin 7, so IC2b should be functional...
remember that a wrong bias voltage brings you to the same results (no signal)
try and change it (either a 100k trimmer instead of the 2 56K bias resistors or changing the 220k resistor),
swapping the ic with another one is simplier indeed... :)
Fender,
Thanks for the input. It is a great help. I agree that I should probably swap out the IC first (Not looking forward to it as I did not use a socket due to space restraints) however, let me ask you this... you said that since I have dry signal at Pin 7 that my IC2b should be functioning properly. If this is true, then why do I not get an audio probe signal when I probe Pin 6? Shouldn't I get something there?
I never used Aron's probe, since I have a signal generator, and usually check signals with my scope...
so I don't know if you miss the reading 'cause a wrong tension provided by ic1a (if malfunctioning) or 'cause the impedance on pin 6 or whatever. But, signal on pin7 means the op-amp is working (with a scope you could check for the proper gain (~1 feeding A).
I guess I will start with replacing the IC (socket it this time as I think I can make room) and go from there.
Quote from: Govmnt_Lacky on July 12, 2010, 08:41:58 PM
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 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?
That's correct behavior of this configuration (both IC1a and IC1b of STEREO MOD board form Inverting Amplifier (http://www.electronics-tutorials.ws/opamp/opamp_2.html)), where inverting input makes "virtual ground". Check pin 1 (wet-signal-invertor output) instead, you should hear the same signal as at D point..
T.
EDIT: Sorry guys, if I'm saying something already said, I did miss page [2] of this thread :icon_mrgreen:
Thome,
I think I posted earlier.... I get the "wet" signal at the input ("D") and on the input side of the 100K resistor (the one immediately following input D) but, that is the only places I get the wet signal.
There is NO signal on ANY pin of the IC except for Pin 7 which is the dry signal.
Thanks for the help, do you have any top suspects? I am thinking bad IC
Quote from: Govmnt_Lacky on July 13, 2010, 10:11:25 AM
If this is true, then why do I not get an audio probe signal when I probe Pin 6? Shouldn't I get something there?
..and I see that my previous post has still it's value :)
Quote from: Govmnt_Lacky on July 13, 2010, 12:15:32 PM
Thome,
I think I posted earlier.... I get the "wet" signal at the input ("D") and on the input side of the 100K resistor (the one immediately following input D) but, that is the only places I get the wet signal.
There is NO signal on ANY pin of the IC except for Pin 7 which is the dry signal.
Thanks for the help, do you have any top suspects? I am thinking bad IC
OK, turn it off and check (visually and by DMM) that:
(1) - left* leg of the first 100k (between D and IC1/pin2) is properly connected with D
(2) - right* leg of the first 100k is properly connected with IC1/pin2
(3) - left leg of the second 100k (between IC1/pin2 and IC1/pin1) is properly connected with IC1/pin2
(4) - right leg of the second 100k is properly connected with IC1/pin1
(5) - IC1/pin3 and IC1/pin5 are properly connected
(6) - value of both 100k is really 100k
(7) - there is no bridge between IC1/pin1 and IC1/pin2
(8 ) - there is no bridge between IC1/pin2 and IC1/pin3
*(left and right sides are related to the schematic) If all answers are YES, IC1a is most probably dead (if you are really 100% sure, that there was no signal at IC1/pin1)..
T.
Thom,
I will check this tonight and post this evening or tomorrow. Thanks for all your help. Tune in tomorrow for the results.
Here's my voltages. I colored mine red. None of mine oscillate. They were all steady as far as I could tell. I'll try to audio probe mine later and you can compare.
Stereo board IC voltages:
Input voltage - 9.2V - 9.02
JRC4558D Pin 1 - Oscillating from 4.25 to 4.45V - 4.02
Pin 2 - Same as Pin 1 - 4.02
Pin 3 - Same as Pin 1 - 3.90
Pin 4 - 0V - 0
Pin 5 - Same as Pin 1 - 3.90
Pin 6 - Same as Pin 1 - 4.0
Pin 7 - Same as Pin 1 - 3.98
Pin 8 - Oscillating from 8.2 to 8.75V - 7.96
Thanks bside. So now the questions are:
What would cause the Pins on the stereo IC to oscillate like that?
What does this problem have in common with my other posted findings?
This is getting challenging.... Could a bad IC cause the oscillations? Stray voltage?
CALLING ALL EXPERTS.... NEED HELP!!!
SUCCESS!!!!!
I guess it was the IC! I pulled out the 4558 from the stereo board and replaced it with a socket and the first replacement IC worked!
Thanks to all who helped out. This forum is an invaluable tool for diy'ers
Believe it or not, had the same problem. Exact same problem. Effect was working mono, stereo module was dry. Tried replacing the IC to no avail. Using an audio probe checked "D" track. Dodgy joint between D pad and 100K on the stereo board. Re-soldered, fixed!
Thanks for everyone who posted in this thread and govmnt_lacky for your persistance ;-)
CS
Quote from: Govmnt_Lacky on July 14, 2010, 08:16:50 AM
I guess it was the IC! I pulled out the 4558 from the stereo board and replaced it with a socket and the first replacement IC worked!
as a way of thanking the forum, can you describe your process of trouble-shooting so that others can benefit from where you made your mistakes? and while you're at it, how's about posting a soundclip? that would be a nice gesture of thanks to all of us that took time out from our day to assist you ...
the next time that you have a pedal problem, how are you going to handle it?
i built the tone pad small clone stereo chorus pedal i get great stereo wet signal but when in bypass i only get output on the mono side. so i thought to myself why no run a line from the bypassed leg of the 3pdt switch to the stereo jack. when i did that it had great signal loss and sucked all high end out of it almost as if doing the broadcaster mod on a tele and using the 3rd pos. any ideas on getting dry signal through both jacks?