SOLVED Boonar Dawner Prince

[Haz]

Hi!
I have this pedal with an issue of dropping voltage. Is has multiple voltages inside, 3v, 9, 27 volts. 2 boards interconnected. When I separate the boards, lower one with powersupply holds voltage ok leds on bottom board are working.
When I connect upper board, voltage drops in 1-2 sec and pedal turns off so I think issue is in the top board with FV - 1 chips.
I check every cap is tests ok with LCR meter, no shorted resistors. Nothing get's hot on IR camera. FV-1 chips heat up equally.
I have a minor delay effect when pedal is on untill it shuts off.
Here are the guts
Any ideas?
Any input is appreciated

 

[Haz]

Can somebody tell where to look for a problem?

 

[Mcknib]

Sounds like it might potentially be a voltage regulator problem

Possibly shutting down automatically

Did you check the power circuit for components heating up or just the FV1 board

 

[Haz]

Voltage doesn't drop on lower board even if both boards are connected.
I get 50C degrees on LF33, It's outputting steady 3.3V so I guess it is normal operation. Otherwise no hot components.

 

[Mcknib]

What are you using to power the pedal

 

[Haz]

I've managed to get friends functional pedal and poking with a scope in both I've found out that one of the fets was shorted on mine.
Replacing that fixed the problem!

 

[utopcell]

This looks way more complicated than I thought it would be. What do all these circuits do ? Why does it need 27v ? Does it attempt to simulate tubes with some jfet circuit, like a Fetzer valve circuit or a 12ax7ws ? Why are there 2(!) FV-1 chips in it ?

 

[comradehoser]

Apparently, it's a Binson Echorec clone--multihead drum echo/delay.

I thought it was a delay for drums, it's a magnetic drum head instead of tape

Catalinbread also has an echorec pedal, btw.

Since this is a production pedal instead of a DIY project, though, most manufacturers will offer repairs or replacements for nonfunctional pedals--does Dawner Prince no longer exist?

 

[Haz]

Yes they exist but I've got 0 support for the used pedal. Nobody replied my emails. Lucky me it was a single component issue so fixing that got me a working pedal.

 

[Feral Feline]

This looks way more complicated than I thought it would be. What do all these circuits do ? Why does it need 27v ? Does it attempt to simulate tubes with some jfet circuit, like a Fetzer valve circuit or a 12ax7ws ? Why are there 2(!) FV-1 chips in it ?

27v is likely to provide some extra headroom so the signal doesn't distort. However, having said that there will be regulators to knock that down for the FV1 chips which operate at 3v3, IIRC.

As for why 2 x FV1, I'm guessing it's to have extra "heads" in the tape delay or in this case heads per spinning-drums delay emulations.