Need help trubleshooting the Quantum Leap Diamond

[Havaden]

So a friend of mine came over with a broken diamond in hope that i could fix it. (because the store takes over 100$ an hour)
He really loved the pedal and used it in lots of gigs, but plugged in 48V instead of 9v in his last gig.
There is a frequent popping noise when i plug in 9V, even if i turn it off (true bypass)
The LEDs blink when i plug in the power, but thats it.
No burning marks on the circuitboard, no heat either. 

Im asuming its a dead pedal, but he is a good friend that i have played a lot with.
I will give it a try, but any help would be good.

[mth5044]

Do you have a picture of the PCB or a schematic or anything? A demo video won't help to debug! Find where the power comes into the PCB and trace where it goes to. Perhaps there was some kind of protection set up - a diode or something. Is it SMD or through hole components?

[Havaden]

Its all SMD, but i was thinking about some protection like that.
I got a few SMD pardts so i should be able to fix it.
Ive been looking for a circuit online but i can't find any.
Here is my debugging report so far:
LED blinks 2-3 times when power is plugged in.
No guitar signal in true bypass when power is plugged in, signal is fine when power is off
A frequent pulse is coming into the output signal with and without true bypass.
50Hz noise is coming when i touch the negative battery pole wire, therefore it is not connected to chassis or negative jack.
Mix knob is adjusting amount of noise when pedal is on.

There is no delay, chorus or flanger in any settings.


I would be happy if anyone know where to find the circuit 

[Ice-9]

Well first of all, with the correct psu see if the correct voltages are getting to where they should be. From the picture of the front of the pedal I expect there to be a PIC or ATMEL uC in there which probs runs through a 3.3v or 5v reg, check for this. I haven't seen inside this pedal before but it might also be DSP based which again will use a regulator for the DSP and again possibly 3.3v  

Get your voltages checked out and if this is all correct and good you need to audio probe the signals, then see where in the chain of events it is not working, also what make you think it is true bypass ? From the fault description it would sound that 48v has killed some circuitry in there. If it ha killed any digital programmable chips then you won't be able to fix it without the code to flash to the chip.

48volts seems a strange number for power, could that have been -48v phantom power in some way ?

Some detailed pictures of the PCB are the only way we may be able to help.

Fix any PSU problems first and see where you are fom there.

[Havaden]

You are right, there is a PIC24F J128 on the circuitboard
Here are the pictures:
Top

Power connection

Note the Pic on the right


I have a feeling the pic is fried, because no modes are active.
Knobs and switches have no effect at all (exept the mix for mixing in the effect to clean signal)


He used it for synth, i don't know if it could be the phantom -48V, but il ask him when i get the chance

[Ice-9]

After having a look over the PCB it looks like there is a voltage regulator (near the red toggle switch). This reg may be for the lower voltage for the PIC chip and other digital parts, my first checks would be for the correct voltage going in and out of that. There are also a couple of large diodes in the same area so check these as well.

[Havaden]

Youre right about the regulator ice
Its a 14CH N01A (adjustable regulator down to 1,2v) 
But then i don't really know if it should give out 3,3 or 5v 
I will post the readings when i get my tools back

[Havaden]

Voltages starting from the top pin on the picture:
Pin1: 9,22V
Pin2: 9,22V
Pin3: 8,72V

This looks rather weird if you ask me

[Ice-9]

I had a look at the data sheet for the PIC24F J128 and it's core voltage runs at 2.5v but the chip can be powered from either 3.3v or 2.5v as it has its own internal reg to drop it to 2.5v. So lets assume the regulator on the main PCB is in fact for the PIC chip then it really should only put out 3.3v max. I haven't found the data sheet for the 14CH N01A but I would say there is a definite problem around there as you should not be getting appx 9v on all pins.

[Havaden]

Thanks for all the help ice 
But it looks like this will be a donor body for another effect