SOLVED Vhs- no sound except bypass

[miyagishredz]

I’ve built 6 pedals from pcb all with breakout boards. This is the only pedal I haven’t been able to get to work and I’ve exhausted many hours troubleshooting and looking for some help and tips please.

What I’ve done so far:
Uncased and traced the entire board to the best of my beginner knowledge with the schematic checking 3.3v pins, VREFs (which was around 4 volts shouldn’t it be 9? But it’s right after a 1M resistor so maybe not) and ground continuity. So far not finding an issue.

I resoldered leds, jack connections, and even a new switch and break out board.

Before and after equal same results. All leds come on and I get sound in bypass but no sound at all when engaged with any mode selected.

 

[miyagishredz]

Also I confirmed R1 was a 1M ohm resistor, which someone else had an issue like that were tayda gave them 140k instead.

Im wondering if it could be the surface mount IC that came preinstalled?

 

[EGRENIER]

Do your LEDs go on as you flip the switches ?

‘Do you have the ability to trace the signal to see where it stops ? You may need an audio probe at this point.

 

[miyagishredz]

Do your LEDs go on as you flip the switches ?

‘Do you have the ability to trace the signal to see where it stops ? You may need an audio probe at this point.

All LEDs light as expected - when flipping on the Volume/Overdrive one, there is a noticeable increase in gain or hiss, but still no sound. no clipping sound when turning it on, the chorus and reverb switch have a light pop sound when turning on . LEDs work perfect.

I do not have an audio probe, if that is what you are asking to trace. I did check continuity of grounds in the schematic, and I also just checked all ICs voltages which I am attaching now. I also switched from a battery clip to a steady Power supply, and VREF went up to 4.7 at both checkpoints, and 9.4 coming in. I also reflowed every bit of solder this morning on the board.

I have spent so many hours troubleshooting this. even though im somewhat of a beginner, ive had zero issues with other builds, including vero, and custom modular synths. I am ready to throw this in the trash (but could really use a chorus and reverb)... so maybe a probe is my next step in this hobby? looking forward to more suggestions. it has to be the FV1 chip methinks, but IDK.

Thanks!

 

[EGRENIER]

All LEDs light as expected - when flipping on the Volume/Overdrive one, there is a noticeable increase in gain or hiss, but still no sound. no clipping sound when turning it on, the chorus and reverb switch have a light pop sound when turning on . LEDs work perfect.

I do not have an audio probe, if that is what you are asking to trace. I did check continuity of grounds in the schematic, and I also just checked all ICs voltages which I am attaching now. I also switched from a battery clip to a steady Power supply, and VREF went up to 4.7 at both checkpoints, and 9.4 coming in. I also reflowed every bit of solder this morning on the board.

I have spent so many hours troubleshooting this. even though im somewhat of a beginner, ive had zero issues with other builds, including vero, and custom modular synths. I am ready to throw this in the trash (but could really use a chorus and reverb)... so maybe a probe is my next step in this hobby? looking forward to more suggestions. it has to be the FV1 chip methinks, but IDK.

Thanks!

I’m a beginner also, so I can’t comment on your voltage reading. But I’m not new to troubleshooting and if you have double checked all your values and voltage. Tracing the signal would be my next step. This will allow you to pin point where you lose it and then focus on that point.

The hardest point to troubleshoot is the FV-1, but if you lose the signal before of after the FV-1, your problem may be simple. You’ll need some very expert people to troubleshoot the FV-1, until then excluding all other variable will help.

I wouldn’t give up on the board yet, but that’s up to you. I find troubleshooting and solving issues as gratifying as the building part of the hobby. I’m also pretty stubborn, so I wouldn’t like to admit defeat. I can’t speak for @PedalPCB, but if you think you received a faulty board, you should give him the opportunity to discuss before blaming the board.

 

[EGRENIER]

All LEDs light as expected - when flipping on the Volume/Overdrive one, there is a noticeable increase in gain or hiss, but still no sound. no clipping sound when turning it on, the chorus and reverb switch have a light pop sound when turning on . LEDs work perfect.

I do not have an audio probe, if that is what you are asking to trace. I did check continuity of grounds in the schematic, and I also just checked all ICs voltages which I am attaching now. I also switched from a battery clip to a steady Power supply, and VREF went up to 4.7 at both checkpoints, and 9.4 coming in. I also reflowed every bit of solder this morning on the board.

I have spent so many hours troubleshooting this. even though im somewhat of a beginner, ive had zero issues with other builds, including vero, and custom modular synths. I am ready to throw this in the trash (but could really use a chorus and reverb)... so maybe a probe is my next step in this hobby? looking forward to more suggestions. it has to be the FV1 chip methinks, but IDK.

Thanks!

I just looked at your measurement… are you reading negative voltage ? If so, that’s sound like a issue as the 3.3V should be positive voltage no ?

 

[Robert]

Jumper this point to ground and see if you get a signal.

 

[miyagishredz]

All LEDs light as expected - when flipping on the Volume/Overdrive one, there is a noticeable increase in gain or hiss, but still no sound. no clipping sound when turning it on, the chorus and reverb switch have a light pop sound when turning on . LEDs work perfect.

I do not have an audio probe, if that is what you are asking to trace. I did check continuity of grounds in the schematic, and I also just checked all ICs voltages which I am attaching now. I also switched from a battery clip to a steady Power supply, and VREF went up to 4.7 at both checkpoints, and 9.4 coming in.

All LEDs light as expected - when flipping on the Volume/Overdrive one, there is a noticeable increase in gain or hiss, but still no sound. no clipping sound when turning it on, the chorus and reverb switch have a light pop sound when turning on . LEDs work perfect.

I do not have an audio probe, if that is what you are asking to trace. I did check continuity of grounds in the schematic, and I also just checked all ICs voltages which I am attaching now. I also switched from a battery clip to a steady Power supply, and VREF went up to 4.7 at both checkpoints, and 9.4 coming in. I also reflowed every bit of solder this morning on the board.

I have spent so many hours troubleshooting this. even though im somewhat of a beginner, ive had zero issues with other builds, including vero, and custom modular synths. I am ready to throw this in the trash (but could really use a chorus and reverb)... so maybe a probe is my next step in this hobby? looking forward to more suggestions. it has to be the FV1 chip methinks, but IDK.

Thanks!

I have spent so many hours troubleshooting this. even though im somewhat of a beginner, ive had zero issues with other builds, including vero, and custom modular synths. I am ready to throw this in the trash (but could really use a chorus and reverb)... so maybe a probe is my next step in this hobby? looking forward to more suggestions. it has to be the FV1 chip methinks, but IDK.

Thanks!

I just looked at your measurement… are you reading negative voltage ? If so, that’s sound like a issue as the 3.3V should be positive voltage no ?

no negative voltages... I like to just put hyphens in front of things like bullet points. haha.

I just found a video on diy audio probe, so I will give that a go next.

 

[zgrav]

audio probe will let you know pretty quickly whether you have audio reaching the FV1 on pins 1/2, and whether you have sound leaving the chip on pin 28

 

[fig]

Jumper this point to ground and see if you get a signal.

Enable internal ROM...ahh

 

[EGRENIER]

Enable internal ROM...ahh

So that takes out the 24cl ?

 

[fig]

I just found a video on diy audio probe, so I will give that a go next.

just connect a wire from the output jack tip....the other end is an audio probe.

 

[EGRENIER]

just connect a wire from the output jack tip....the other end is an audio probe.

No need for cap ?

 

[miyagishredz]

Jumper this point to ground and see if you get a signal.

View attachment 23549

Yes, Jumpering R5 10k there to ground gives me a signal and effects. What does that mean, and best way to finalize this knowing that?

Thanks!

 

[EGRENIER]

Yes, Jumpering R5 10k there to ground gives me a signal and effects. What does that mean, and best way to finalize this knowing that?

Thanks!

If I understand the test it points to the 24LC and it’s ability to contrôle the FV-1.

 

[fig]

No need for cap ?

It wouldn't hurt, in the event you probe outside the audio path, but I do it regularly when breadboarding or testing a build and have never run into issues.

 

[Robert]

Take a close look at the solder connections on pins 14 and 15 of the FV-1, and on IC2 (24LC32A).

If those are all good it sounds like the EEPROM might be corrupt. If so I'll ship you another one.

 

[EGRENIER]

Take a close look at the solder connections on pins 14 and 15 of the FV-1, and on IC2 (24LC32A).

If those are all good it sounds like the EEPROM might be corrupt. If so I'll ship you another one.

14 and 15 in relation to 5 and 6 of the eeprom works in close relation to the serial clock (24CL pin 6)… Could a faulty crystal be source of timing issues between the FV1 and the 24CL ? Could a crystal swap be a valuable test before concluding on bad eeprom ?

 

[EGRENIER]

It wouldn't hurt, in the event you probe outside the audio path, but I do it regularly when breadboarding or testing a build and have never run into issues.

So with my shaky hands, I should put a cap to avoid blowing my amp.

 

[zgrav]

the cap is a good idea to keep voltage out of your audio path and the long lead on a capacitor is not a bad probe (assuming the other lead is bent back and taped along the cap body or stuck inside a pen cap, etc).