Build Your Own Clone Message Board

Hey all

New builder here. Thank you in advance for your help and patience.

Im was enjoying the process so much on my initial build that I made a few careless mistakes. I put a transistor (Q1) in backwards and may have damaged the pad. Though, the connection seems solid even if its ugly. Im enjoying learning to troubleshoot and diagnose issues (thats why I’m building pedals in the first place). But I may have over tinkered and damaged the board/components. Ive somewhat reached the limits of my skills and Im hoping to get pointed in the right direction.

So, issue is my LED isn’t getting power consistently. It will blip when I plug it in but lays dormant after that. If I bypass the circuit it lights up, so its not burnt or backwards.

I get signal when in bypass but nothing when the pedal is engaged. Or vice versa, I don’t know because theres no light to act as a signifier.

I rigged an audio probe up and there is definitely Audio in in certain areas (this might be advanced for me right now as I couldn’t really isolate a problem area).

Ive reflowed my soldier joints twice.
Ive checked and rechecked my wiring.
Mapped the circuit and labeled all components based on the Schematic.
Ive tested placing the TL022 in the 4558 socket and had solid LED (i saw this in an earlier post)

Ive tested the voltage of my ICs.
TL022
1. 8.05
2. 4.30
3. 6.86
4. 0.00
5. 8.73
6. 0.63
7. 5.43
8. 4.30

3102
1. 8.44
2. 4.08
3. 0.00
4. 4.09
5. 7.88
6. 2.74
7. 7.56
8. 0.81

4558
1. 4.42
2. 4.42
3. 4.35
4. 0.00
5. 8.73
6. 4.42
7. 4.46
8. 4.39

3207
1. 0.00
2. 4.09
3. 3.75
4. 7.88
5. 5.15
6. 5.14
7. 4.07
8. 8.44

Im worried at this point Ive damaged my PCB or components. If its an IC or something else but if its the board it feels like it may be hopeless.

Thanks again. Lmk if you need pictures.


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Yes, please. Large, well-lit & well-focused, including both sides of the PCB and all of the switch & jack wiring.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

In anticipation that while I am typing this I will get scooped on requesting ("letting you know") about photos that would be helpful for us to see, I'll first make some other comments and then return to request the photos if scooping didn't happen.

(1) First of all, congrats for taking a good stab at sorting out the problems yourself; now we are happy to help.

(2) Congrats also for getting an audio probe on the case; that could turn out to be quite useful.

(3) I have a suspicion from the IC pin voltages you report that you may have some of them numbered incorrectly. For example, pins 5 and 2 of the TL022 should connect directly together and therefore have the same voltage. Perhaps what you have done is inverted the ordering of pins 5 through 8 for the 8-pin ICs. Here's a little picture that shows the corrected numbering scheme; the pins go 1 through 8 CCW from pin 1.



(4) Could you say a bit more about the status of the LED? Note that in "bypass" you are bypassing the effect circuitry so that the signal goes pretty directly from the input jack to the output jack, and the LED should be OFF; when the effect is switched in (and you hope to be hearing the chorus-y stuff) the LED is supposed to be ON.

(5) Did you try to remove and re-orient Q1, and is that what led to some PCB damage? If it is still in backwards, then perhaps removing it is not yet indicated, as that transistor may still work (just sub-optimally) in its backward configuration. (Not all transistors would work if reversed, but this one might.) After other problems are sorted out, you could try re-installing. If you already did re-install it, fine; carry on; we'll have a look at your photos.

Hey Thanks for the quick replies.

I checked my pin labeling. Its possible i mis labeled but I noticed some funny business.

1.) Here is the updated TL022
1.) 7.94
2.) 4.25
3.) 6.75
4.) 0.00
5.) 4.25
6.) 4.53
7.) 0.63
8.) 8.62

2.) Onto funny business. When the switch is pressed AND the LED is illuminated pin #1 on the TL022 drops to 0.64.

Also when I touch pin #6 with the prob the LED lights up.

3. As to your question about the status of the LED. When I plug the pedal in, the LED will do one quick flash, then stay off no mater the position of the footswitch. However, sometimes, the footswitch will activate the LED. The LED stays at full brightness until the footswitch is pressed again (no blinking or dimming). This “function” only lasts for a few attempts and then stays off. Also, if the pedal is unplugged from the DC jack while this “function” is “working” and then plugged back in, the LED wont light up when the footswitch is pressed again.

4. Yes, I reorientated Q1








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Update: Ive run the audio probe through the circuit when the LED IS ILLUMINATED and I get audio all the way through the “signal path” section of the circuit. I get nothing through the LFO & Clock Driver section.


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(FWIW I have looked more at your IC pin voltages and have seen enough to be certain that for all of them, the ordering of pins 5 thru 8 are reversed--so anyone reading those in the top post, be aware of that.)

You haven't said whether it sounds chorus-y or not. I'll assume it doesn't, but if it does, you can probably ignore this post ...

All of that sounds like good news. The audio signal isn't supposed to go through the LFO (LF = low frequency = sub-audio) circuit; you might hear something at IC4 = MN3102 if you encounter a pin (2 or 4) with the clock signal and it is running at a low enough frequency, but you won't *want* to hear it.

If I get a chance this evening I will prod my own working BYOC Analog Chorus pedal and see if my IC pin voltages are in accord with yours.

In the mean time, perhaps another test you could try with your audio probe is to see whether the modulated ("wet") signal sounds different from the original ("dry") signal at all. You can do this by, for example, comparing the signal at the input jack tip, or the Q1 emitter (E), or IC1 (4558) pin 1 ("dry"), with the "wet" signal at IC2 (MN3207) pins 7/8 (check the picture above to get the correct pin(s)!) or Q3 emitter (E), or various points in between those two. Try it esp. for the DEPTH and RATE knobs turned clockwise. If the "wet" signal isn't wobbly, the issue is possibly with the BBD chips or with the LFO parts.

And do continue to try to describe for us any problems with the switching/power/LED, as there may also be some wiring or soldering (or switching) issues that need to be addressed.

Oh yes. You are correct, I have reversed the labeling of my ALL pins of my pins 5-8. My apologies.

Good point, I get NO chorus effect whatsoever.

Im getting dry signal at the Input tip and at the base of the Q1 but not the E pin. This is the transistor/pad I was worried I had damaged. Im not getting any audio signal from any pins on the 4558 or MN3207. While i was trying this the LED wouldn’t light up at all, so the Audio probe experiment remains inconclusive for now.

For now Im going to try to remove to (Q1) transistor and see if i can clean up the area and hopefully get a better connection after I reinstalled it.


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I will try to devise some tests you can do to check the wiring/power/switching sections, because it sounds as if just getting some basic parts of the circuit to work is problematic--they are behaving intermittently. It does not surprise me that there is a correlation between no audio through the circuit and the LED not being on, as you yourself point out ("it's inconclusive for now").

When you have the PCB & other parts out of the box, you might consider *leaving* them out while you explore and troubleshoot the circuit. You'll just have to make sure you set it on a non-conductive surface, and guard against static electricity, but apart from that it may be easier to troubleshoot that way. In any case, while it is out, try to get us a photo that shows clearly the wiring at the three jacks and the footswitch.

I have inspected my own Analog Chorus and have been reminded that I have a slightly different version, with 3007 and 3101 chips instead of the 3207 and 3102 in your version. Also, the sweet spot of my voltage trimpot gives me a surprisingly non-0.5*(9V) voltage (where you have about 4.4 on the 4558 I have about 5.2 in spite of the fact that my "battery" voltage is lower than yours). As a result I don't think a direct comparison of my voltages with yours will be as useful as I'd previously hoped. HOWEVER, I do recommend the following experiment:

While having the rate and depth knobs CW (clockwise) is useful for listening for the chorus modulation (whether for the "wet" or for the overall mix), you may also find it instructive to turn the RATE knob fully CCW (counterclockwise) to get the lowest rate, and then check the voltages on the TL022 pins. (Leave the DEPTH knob turned up, CW.) On my unit, at slowest rate it takes about 3.5 seconds for a full cycle and I am able to see the voltages change using my multimeter, esp. on pins 1, 3, and 7. If you cannot similarly see voltage changes there, then it could be that some of your problem is in the LFO section.

Are you using a 9V battery or a power supply at the DC input jack? It seems that a lot of the problems could be explained by an intermittent connection of the +9V into the circuit. There could be a faulty DC jack, or poor solder connections at the jack or with the wires that connect to it (or at the PCB pads they meet), or a faulty 9V battery snap if that is what you are using.

It appears that the LFO section of your circuit isn't functioning, so you're getting no chorus effect and no LED, which is driven off the LFO circuit so that it modulates with the speed of the chorus effect. If the LFO was working, you'd see voltage modulation on pins 1, 3 and 7 of the TL022, but you've reported steady voltage values there. I would suggest referring to the schematic and carefully inspecting the components in that section of the circuit to insure that the solder joints are clean & solid and that you haven't made any component placement errors. I mention this last point because I recently repaired a BYOC Bass Chorus (essentially the same circuit as the Analog Chorus, but with a clean/wet blend control) where a 4.7K and 47K resistor had been switched in the LFO section and caused it (and the LED) not to work. Such errors are easy to make with those resistor color bands.

Your 4558, 3102 and 3207 pin voltages look very reasonable, though you may want to adjust the trimpot to get the 1, 2, 3, 5, 6 & 7 pin voltages on the 4558 up over 5V, once you get the chorus effect working. This circuit seems to require that voltage level to get a clean chorus effect. But that's not your problem at the moment.

You should definitely get audio signal at the emitter of Q1, which is the input buffer. If you've damaged the emitter eyelet on the back of the PCB and aren't getting a connection there, you can repair it by just applying a dab of solder between the stub of the emitter lead and solder joint for the 10K resistor (R3) immediately adjacent to it. I've marked these two solder joints on a section of your photo below.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Ok i took some time to take everything apart and clean up my wiring.



I also removed Q1 and was able to get audio output the the E pin as well as the base. From here I was also able to get audio from pins 1,7 on the 4558 IC and pin 3 on the 3207 IC. But no chorus effect at all. It didnt matter if the button was pushed or the position of either pots. From there I checked the pins on all the ICs I had to get to bed so I havent been able to record the values but I know there was no variation at all. I was getting static readings across the board.

And, the LED still doesnt work :/


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[mention]duhvoodooman [/mention]i was able to get audio out after i cleaned that area of the circuit and resoldered everything back in place! Good to know if that pad fails again i can jump it safety and easily!

Ill spend some time tomorrow evening double checking all the components in that part of the circuit. I looked through the capacitors tonight but not the resistors. Ive already made placement errors, in no way is it out of the question I made more…Sighhhh

Thanks! Ill report back with progress tomorrow!


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OK, that's good progress that you're getting clean signal at the Q1 emitter and further downstream now.


...because your LFO isn't oscillating. See my previous post.


Don't worry about the LED. Once you get the LFO section working, that'll take care of itself.

Don't get discouraged--we've solved much tougher problems here!

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

duhvoodooman wrote:



Thanks for this observation. I found yesterday on my Analog Chorus with a 9V battery providing a whopping 7.9 V that the "(1/2)V" I needed to dial in was about 5.2 V, and I was amazed at first that this left enough headroom for what the op amps needed to do. (In retrospect, it seems less problematic.) On my trimpot, this corresponds to the dial at the 11 o'clock position (note that the instructions quite reasonably say to start at "noon" and adjust from there). With my trimpot at noon or at 10 o'clock, I get NO chorusing--it needs to be within 1/2 hour of 11 o'clock.

In the photos from the OP we can see that the trimpot is at the noon position; and the IC pin voltages indicate that the "(1/2)V" is very close to half of the power supply voltage (look at the 4558 pin voltages). Not having read duhvoodooman's post until this morning, I haven't had time yet to check my own pedal again, but it seems possible** that my lack of chorus at noon or 10 o'clock was caused by lack of LFO oscillations. It might be a good idea for the OP to add to the troubleshooting regime the slight adjustment of that trimpot. Of course, the other investigations (checking the resistor placements, checking solder joints, etc.) are still indicated.

** edit to add: The schematic doesn't give me any clues that this should be the case, since R30/R31 are used to establish a local (1/2)V for the TL022. It may be that an interaction with the MN3207 requires the quiescent signal level to be elevated above what the "noon" trimpot position would give. I don't mean to distract the OP from fully investigating the LFO oscillations, particularly the "eye" test at the LED, but rather I want to point out that the "ear" test for modulations could fail if the trimpot is not tweaked properly. So, I am endorsing duhvoodooman's recommendation to fully investigate the LFO in whatever ways are possible.

... and edit again, to correct my atrocious spelling ... apologies to duhvoodooman for that ...

(DangerMDV--you can largely ignore the following! Just a side discussion between WMP1 and me.)


Yes, the TL022 has it's own 50/50 voltage divider, so the trimpot won't affect it. What it does affect (strongly!) is the cleanliness of the chorus effect, as described on pg. 11 of the instructions:

"You will need to adjust the trimpot when you are finished building the pedal. It controls the circuit’s bias voltage. You start by setting the trimpot at the middle of its rotation or “noon”. This will get you started and should definitely produce a chorus sound when you plug in for the first time. You fine tune the trimpot by strumming or plucking as hard as you can and dialing the trim pot til you get the least amount of distortion. If you have a guitar with hotter pickups, you should use it for this step."

Set to the middle of its sweep, the pedal output will be noticeably distorted, but not mute--at least, this is what I've found on my own Analog Chorus and the Bass Chorus that I recently repaired. I have the same version of the AC that you have, with the 3101/3007 chipset, and below are my pin voltages. When I set up the pedal, I had a rather "hot" power supply, putting out just about 10.0V, and I had my trimpot "1/2Vb" set at ~5.7V to get a squeaky clean chorus effect.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Ok! Good news! I called in sick to work!

I went back and checked the resistors in the LFO & Clock circuit. I found i had reversed R33 (330k) and R34 (33k). At this point I decided id check all my resisters. I had also reversed R17(330k) and R41(33k) as well. Ive swapped them out made some progress. The LED is functioning as designed!!!

Ive fiddled with the trim pot and depth and rate pots to see if i could get that pot of gold chorus effect but no luck, yet.

Ive recorded the voltages in the ICs and checked with the audio probe. I am getting audio in at pin 1 on the 4558IC and nothing but some humming at the 7,8 pins on the 3207.

TL022
1. 8.05-0.65
2. 4.50-4.05
3. 6.80-1.90
4. 0.00
5. 4.50-4.05
6. 3.58
7. 6.60-1.98
8. 8.79-8.72

4558
1. 4.45
2. 4.48
3. 4.42
4. 0.00
5. 4.46
6. 4.48
7. 4.48
8. 8.76

3207
1. 0.00
2. 8.60
3. 3.77
4. 8.08-8.02
5. 8.66-8.59
6. 0.00
7. 0.15
8. 0.20

3102
1. 8.66-8.59
2. 0.00
3. 0.00
4. 8.68-8.60
5. 8.66-8.59
6. 0.00
7. 7.53-7.47
8. 8.10-8.03

How about with the audio probe at the base or emitter of Q2? That's part way down the road between 4558pin1 and 3207pins7,8.

Ha! I doubt that your boss/supervisor would see it that way, but what they don't know won't hurt 'em!

OK, looks like the LFO is oscillating properly, and the LED is now behaving as it should. The TL022 & 4558 voltages look good.

But your new 3207 and 3102 voltages vary WIDELY from what you posted before. I would expect some differences, but those values seem out of whack. Unfortunately, my own AC doesn't have the same BBD/Clock Driver chipset as yours, so I can't compare directly. Did you by any chance remove those ICs while you were fixing the resistor swaps and maybe not reinstall them correctly?

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Yeah likewise mine, but I'm not gonna let that keep me from cribbing off of my Analog Vibrato, if it comes to that. But since I didn't call in sick, it will have to wait a few hours.

edit: Now that I think of it, first I'll check to see what chips I have in my Bass Chorus ... unless I get scooped again ...

Hmmm

I did not remove them…would heat damage them? Or could a short somewhere? Im just curious as im new and trying to learn as much as I can from my mistakes.

I just took measurements again and adjusted the trim pot to get my 4558s above 5V.

3207
1. 0.00
2. 8.60
3. 4.45
4. 8.08
5. 8.60
6. 0.00
7. 1.60
8. 1.58

3102
1. 8.60
2. 0.00
3. 0.00
4. 8.64
5. 8.63
6. 0.00
7. 7.50
8. 8.07

Im getting organized to order parts for a different project. Would you recommend I add another set of these to my list?

Too much heat can damage anything. For future reference, a good procedure to follow, if you are re-applying heat to a number of different points, is to avoid heating different parts of the same same component without a bit of rest in between. For example, when I am stuffing a PCB board, I put three to five components in, solder one end only of each of them, then go back and do the other end of each of them, probably in the same order. When I solder an IC socket in, I avoid soldering neighboring pins right after each other.

You could also consider removing an IC from its socket before reflowing the solder joints of its socket's pins, but you would have to weigh that against the wear and tear on the IC itself--each insertion or removal is an opportunity to bend a pin. A bent pin can often successfully be unbent, but I prefer avoiding needing to do that. So I reflow carefully, and allow a rest period between pins.

And yes, too much heat can damage other components, too. I try in particular to avoid too much heat for too long on transistors and diodes (including LEDs).

A slip of a probe can sometimes cause a short. A lot of shorts are survivable, but it is true that some are not.

We don't know yet that there is trouble with your ICs. It may be that by tomorrow we'll have a better handle on that.

But if you are in a hurry to get going on another project or three, well, I understand that too. I've recently ordered & received a few more BBD chips, in part to have in case I screw something up, so we're on the same page there.

Well, something is amiss in how you've reported these values. This is evident because the points labeled A, B & C are directly connected to each other as indicated on the schematic. So both A's should show the same voltage, as should both B's and both C's. But only the C values in your latest reported measurements agree:


Please double-check how you've reported the voltages vs. their pin numbers.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

My guys, I have big news…

I was just sitting here scratching my head looking at the schematic, the PCB, the ICs, my multimeter, the schematic, the PCB, the dog, the multimeter. I was lost. I stopped, I walked my dog. And decided to listen to the advice I’ve read on these boards so many times before. I went back to make sure the resistors I swapped had solid connections. Sure enough on of them was out.

I am the proud new owner and operator of a beautiful working BYOC Analog Chorus pedal!!!

Thank you so much for all your help!

Great news, glad to hear it! Analog Chorus may be the BYOC pedal I use most frequently.

(I think you have spared me the trouble of trying to make a nice presentable table of my results of measuring the TL022, 4558, 3102, and 3207 chips in my Bass Chorus, which I did with my multimeter and 'scope.)

Enjoy your pedal, and let us know how your next projects work out.