SOLVED help with d3lay troubleshoot

[Big_Other]

Hi!

So I just finished building the d3lay pedal. It was working perfectly, until I -somehow- accidentally turned the DC jack causing the +9V to touch the upper middle pot for a maximum of 30 seconds.

After fixing the DC jack properly this time, the LED turned on but now there is nothing but dry sound coming through - I suspect it must have fried an active component, but have no idea how to check this.

What component would be likely to be the culprit? Any tips on how to check this? I'd love to hear your takes...

 

[fig]

That would put 9vdc where 3.3vdc should be on the FV-1….

Does pin 8 of IC2 show ~ 3.3v?

 

[Big_Other]

Thanks for your super fast reply! I was indeed afraid of frying that FV-1...

There is no voltage on pin 8 of IC2

 

[Robert]

If you socketed IC2 remove it and measure the voltage on pin 8 of the empty socket.

 

[Big_Other]

If you socketed IC2 remove it and measure the voltage on pin 8 of the empty socket.

still nothing...

 

[Robert]

Measure on the outer pins (1 and 3) of IC4 (L78L33).

Just so I'm clear, are you saying the DC jack rotated and touched the metal housing of the pot, or the lugs/pins?

 

[Big_Other]

Ah, also no 3.3V on the voltage regulator. 9V is present on pin 3, but nothing on pin 1.

It indeed touched the metal housing of the pot, not the lugs.

 

[Robert]

Can you lift pin 1 of the regulator out of the PCB and measure the voltage on the floating pin itself?

 

[Big_Other]

Hmm, on the floating pin there is 3.3V present

 

[Robert]

Sounds like you have a short somewhere on the 3.3V line. It could be the FV-1 IC but I would rule out any other possibilities first.

Make sure nothing is making contact that shouldn't with any of these points in red.

 

[Big_Other]

Thanks a lot for your help! I am learning a lot through this.

It seems to be fixed! A pot was touching one of these points ever so slightly. Lesson learned: put isolation tape on the metal housing

Thanks again!

 

[giovanni]

Thanks a lot for your help! I am learning a lot through this.

It seems to be fixed! A pot was touching one of these points ever so slightly. Lesson learned: put isolation tape on the metal housing

Thanks again!

It sounds like you need “pot condoms” (I don’t like that name but it’s often used)!

 

[Robert]

Excellent! I couldn't quite wrap my head around how grounding the 9V supply would damage anything on the 3.3V line but stranger things have happened. Glad to hear that wasn't the case!

I'd slap some heat shrink tubing around those DC jack lugs as well.

 

[fig]

Excellent! I couldn't quite wrap my head around how grounding the 9V supply would damage anything on the 3.3V line but stranger things have happened. Glad to hear that wasn't the case!

Gotcha…I mistakenly assumed it made contact with a pin, not the housing.

 

[Robert]

Gotcha…I mistakenly assumed it made contact with a pin, not the housing.

I thought so too initially, but then I got to thinking "How long are the lugs on that DC jack??"

That would have probably had a more disappointing outcome.

 

[fig]

I thought so too initially, but then I got to thinking "How long are the lugs on that DC jack??"

That would have probably had a more disappointing outcome.

I did try to visualize, but all that came through was an episode of All My Circuits