PedalPCB VHS - No output from FV-1

[MarX Halvick]

Hi !
My VHS build is not as successfull as I thought it would be.

At first, I had some sound when I moved/touched something, but now I get no output at all (except when it's bypassed)

Facts :

• I purchased a FV-1 from StompboxParts, which I think is a reliable supplier
• I tried 3 different L78L33 but they all are from Ebay (But get the job done, I get +- 3,33v on the output) but IT GETS REALLY HOT !
• I tried another crystal (when I touched the first one, I got sound output ! thought it was defective so i replaced it, now I have no more spare)
• I tried another TL072
• I reflowed every solder
• I traced the input sound on the following diagram :
  • Yellow : Input sound continuity (probed !)
  • Pink : Continuity on ground
  • Green : +-3,3v continuity
• 

Here are some pictures of the build :

The case I hope I will be able to use :

The voltages from every IC :

Component	Pin	Voltage
9v	-	8,99​
D1 (1n5817)	1​	8,99​
D1 (1n5817)	2​	8,68​
L78L33	1​	8,68​
L78L33	2​	0​
L78L33	3​	3,26​
FV-1	1​	1,85​
FV-1	2​	1,85​
FV-1	3​	1,62​
FV-1	4​	0​
FV-1	5​	0​
FV-1	6​	3,26​
FV-1	7​	0​
FV-1	8​	3,26​
FV-1	9​	1,49​
FV-1	10​	1,41​
FV-1	11​	0​
FV-1	12​	0​
FV-1	13​	3,26​
FV-1	14​	3,26​
FV-1	15​	3,25​
FV-1	16​	3,26​
FV-1	17​	3,26​
FV-1	18​	0​
FV-1	19​	0​
FV-1	20​	3,26​
FV-1	21​	3,26​
FV-1	22​	0​
FV-1	23​	3,26​
FV-1	24​	0​
FV-1	25​	0​
FV-1	26​	3,26​
FV-1	27​	1,62​
FV-1	28​	1,63​
tl072	1​	4,36​
tl072	2​	4,36​
tl072	3​	4,31​
tl072	4​	0​
tl072	5​	4,31​
tl072	6​	4,36​
tl072	7​	4,36​
tl072	8​	8,69​
eeprom	1​	0​
eeprom	2​	0​
eeprom	3​	0​
eeprom	4​	0​
eeprom	5​	3,26​
eeprom	6​	3,26​
eeprom	7​	0​
eeprom	8​	3,26​

If anybody could lead me to a solution, I would apreciate a lot !

Thank you !

 

[PJS]

You diagram suggests no connectivity around the crystal? Or did you not check that?

A heating regulator suggests that it is trying to supply more current than it is rated for. The most likely reason for that would be a short. A dead short to ground would be heating to the point where it would be dangerous to touch and probably smoking, but I would definitely be checking all your solder joints around the EEPROM and FV-1 for a short. Your photos of the board are not showing for me, so I can't have a look and see if I can see anything that looks sus.

 

[MarX Halvick]

Hi PJS,
Yes, I have connectivity with the crystal

I uploaded the photos here if you want to see : https://photos.app.goo.gl/XUJNF22vBNmSou4B9

Thank you for your time !

 

[PJS]

It looks to me as if a lot of your FV1 pins do not have quite enough solder on them. Pins 5 and 8 are suspicious, and quite a few of the pins on the other side look as if they lack solder.

 

[MarX Halvick]

I reflowed everything on the FV-1 and still, no luck. Maybe I got a defective chip :/

 

[PJS]

It might be worth grounding pin 13 to activate the internal programs of the FV-1 and see if you get sound then. That would eliminate the EEPROM as an issue

 

[MarX Halvick]

It might be worth grounding pin 13 to activate the internal programs of the FV-1 and see if you get sound then. That would eliminate the EEPROM as an issue

I Did try this earlier, did not work either

Thanks again

 

[PJS]

Just to be sure, measure the voltages at the middle pin of the chorus and reverb bots as you turn the pots. You have marked them as 3.3v. They should vary from 3.3v to 0 as they are turned.