VHS, no sound, FV-1 issue? (SOLVED)

[irvmuller]

So, I built a 2 in 1 pedal. It’s a VHS going into a Phase II. I’m getting clean signal though the pedal. The Phase II works perfectly. The VHS, when I engage it it gives me a hiss sound and no bass signal. I notice when I switch on the Chorus or Reverb there is a loud pop. No pop when I switch on the Boost. There don’t seem to be any power issues. All the LEDs light up perfectly. I accidentally ordered Film Caps for 1u instead of Electrolytics and just used film. The Film Caps were too big to be on top and so I connected them from underneath.
Any input is helpful.

 

[irvmuller]

Here is a pic of the other side...

 

[dlazzarini]

Here is a pic of the other side...
View attachment 6074

I think the build docs call for your 1uF caps to be polarized electrolytics. I know in certain situations non polarized caps can be used in place of electros but I’m not that schooled yet so this may or may not have anything to do with your hiss

 

[whiiiskey]

I think you've discovered the main reason electrolytics are used. they generally take up less space for their capacitance value. You might want to use an audio probe to track down at what point the noise enters the signal path.

Also according to this there are technical reasons for using them as parts of power supplies, some of the explanation is beyond my paygrade ?https://www.arrow.com/en/research-a...itors-simple-in-concept-not-in-implementation

 

[Boba7]

All the 1uf caps are in the signal path, so no worries with them being film instead of electrolytics. Maybe one leg is shorting against another pad?
When it's out of the enclosure, does it still not work?

 

[irvmuller]

I don't think the 1uf caps are the issue in and of themselves because they are only in the signal path. I did recheck them and the legs aren't touching anything they shouldn't. HOWEVER, all this talk about the 1uf caps made me remember I had to pull one of the caps a little hard in order to get it to fit and I was slightly concerned it could have jacked it up. Specifically, it was the one in the back that's touching the switch. I had to really stretch it to make it fit. So, today I'm getting electrolytic caps delivered and I will change that one out first and see if that fixes things. I'll get back with you guys if it does.

Thanks for all the input.

 

[irvmuller]

Update...
Changed the 1uf cap but still not working. Finally made myself a audio probe. I’m finding the signal drops at the 3rd spot in the FV-1. I don’t know if the issue is with the FV-1 that pedalpcb installed or with the 10u that it grounds to there. I’m changing out the 10u electrolytic and seeing if that helps.

If anyone knows how the FV-1 works please let me know.

 

[Boba7]

Update...
Changed the 1uf cap but still not working. Finally made myself a audio probe. I’m finding the signal drops at the 3rd spot in the FV-1. I don’t know if the issue is with the FV-1 that pedalpcb installed or with the 10u that it grounds to there. I’m changing out the 10u electrolytic and seeing if that helps.

If anyone knows how the FV-1 works please let me know.

I dont think there is any signal going to pin3, so dont bother changing the cap.
Is there any signal coming in at pin1&2 and coming out at pin 28?

 

[Boba7]

Also, you should probably post voltages for all ICs in your build.

 

[irvmuller]

Pins 1 and 2 do have signal. Checking voltages next. Never had to do that so I’m gonna look it up. I do have a good multimeter.

 

[Boba7]

No signal at pin 28?

 

[irvmuller]

No signal at pin 28?

no signal at pin 28...

 

[irvmuller]

Also, you should probably post voltages for all ICs in your build.

FV-1
1. 1.65
2. 1.65
3. 1.65
4. 0
5. 1.2
6. 3.3
7. 0
8. 3.3
9. 1.4
10. 1.16
11. 0
12. 0
13. 3.3
14. 3.3
15. 3.3
16. 0
17. 0
18. 0
19. 0
20. 1.95
21. 2.7
22. 0
23. 3.3
24. 0
25. 0
26. 3.28
27. 0.87
28. 1.04

IC2
0
0
0
0
3.3
3.3
0
3.3

IC1
4.54
4.54
4.5
0
4.5
4.55
4.55
9.09

 

[irvmuller]

FV-1
1. 1.65
2. 1.65
3. 1.65
4. 0
5. 1.2
6. 3.3
7. 0
8. 3.3
9. 1.4
10. 1.16
11. 0
12. 0
13. 0
14. 3.3
15. 3.3
16. 0
17. 0
18. 0
19. 0
20. 1.95
21. 2.7
22. 0
23. 3.3
24. 0
25. 0
26. 3.28
27. 0.87
28. 1.04

IC2
0
0
0
0
3.3
3.3
0
3.3

IC1
4.54
4.54
4.5
0
4.5
4.55
4.55
9.09

Also the L78L33

Input 9
Ground 0
Output 3.3

 

[irvmuller]

So, I noticed this build up of white crusty stuff along the VH-1. I used some contact cleaner to clean it off. An hour later and this was on there... normal? not normal?

 

[Robert]

So, I noticed this build up of white crusty stuff along the VH-1. I used some contact cleaner to clean it off. An hour later and this was on there... normal? not normal?

Looks like the residue from "No-Clean" flux.... It looks awful but I haven't seen it cause any issues so far.

I was just complaining about this stuff in another thread the other day.

 

[Boba7]

FV-1
1. 1.65
2. 1.65
3. 1.65
4. 0
5. 1.2
6. 3.3
7. 0
8. 3.3
9. 1.4
10. 1.16
11. 0
12. 0
13. 0
14. 3.3
15. 3.3
16. 0
17. 0
18. 0
19. 0
20. 1.95
21. 2.7
22. 0
23. 3.3
24. 0
25. 0
26. 3.28
27. 0.87
28. 1.04

IC2
0
0
0
0
3.3
3.3
0
3.3

IC1
4.54
4.54
4.5
0
4.5
4.55
4.55
9.09

I'm no FV1 expert, I haven't used that chip much, so you may need some help from someone else

Your voltages look fine to me, except for pin 13 of the FV1, that should be about 3.3v I believe. Other than that it all seems fine. Did you check all your resistor values, and your soldering?

Also, definitely not your issue here, but careful with those leds by the footswitches, their legs could short against the enclosure quite easily.

Good luck !

 

[irvmuller]

I'm no FV1 expert, I haven't used that chip much, so you may need some help from someone else

Your voltages look fine to me, except for pin 13 of the FV1, that should be about 3.3v I believe. Other than that it all seems fine. Did you check all your resistor values, and your soldering?

Also, definitely not your issue here, but careful with those leds by the footswitches, their legs could short against the enclosure quite easily.

Good luck !

pin 13 was 3.3. I put 0 down on accident. I edited the original comment.

I noticed others had 3.3 on pin 16 as well. I rechecked it but turned on the switches this time. It read at 3.3 as well.

 

[Boba7]

I honestly don't know.

Check continuity between the FV1 pins and the surrounding resistors and caps. Check again all the parts values.
Hopefully someone smarter than me will come up with an idea!

 

[Boba7]

Did you try another opamp? It would be a good idea to socket the ICs and transistors/votlage regulators
And check if there's any bridges on the switch board.