Boss ME-50 issue

[stevenrb718]

Boss ME-50, originally with no power. Found voltage rails but seemed to be missing the 3.3V. Replaced a couple blown capacitors, a blown transistor, and faulty voltage converter for the 3.3V rail. I now have proper voltage throughout. The board powers up, but the audio is a distorted mess. I traced the audio line into the AK4552 IC fine, but the L and R audio out of the IC was this distorted mess. I swapped the IC with one from a Boss pedal (that I suspect might also be bad, but thought maybe not in the same manner) and the signal is still distorted. I'm getting the proper 3.3V into the IC from the regulator, and proper paths go to ground. I'm not sure if the AK4552 is even at fault, but they're seemingly difficult to come by at a lower price. I don't believe I can just substitute with a different IC, but again not sure. Is there any other way I could verify the IC as faulty?

[Helmholtz]

Is there a schematic?

[Jazz P Bass]

The AK4552 is pretty much plug & play.
Proper clock & power supply and it should work.

[stevenrb718]

Any idea where I could source the AK4552? Would be rather surprising that 2 separate Boss units would have a faulty AK4552 in the same manner, but still possible.

[nosaj]

Google is your friend.
nosaj

[stevenrb718]

Google is your friend.
nosaj

I appreciate witty retorts as much as anybody, but that or any other search doesn't even produce a single AK4552.

[nosaj]

Is this not one? It was in the search
nosaj

[stevenrb718]

Is this not one? It was in the search
nosaj

No, that's a 4452 not 4552, plus that's a 32 pin square casing whereas the one I'm looking for is 14 pin rectangular casing.

[nosaj]

My apologies
nosaj

[stevenrb718]

All good, that's why I was hoping to verify my 2 chips are bad, as sourcing replacements is pretty difficult.

[nosaj]

This is all i could find
The product sellpoints well leave a lot to be desired.
Is this and old chip I can check at the parts warehouse i go to next time.

[nosaj]

All good, that's why I was hoping to verify my 2 chips are bad, as sourcing replacements is pretty difficult.

Have you checked the voltages to the socket with the chip out vs in? With a signal checker is the audio clean up to the socket with chip in /out?

nosaj

[g1]

You might have to look for some other junk unit that uses that same chip, like in that other pedal you have. Sometimes you can pick up working units pretty cheap, but not sure how much time & effort you want to put into this.
Some boss & roland stuff, some Line 6 stuff. google "AK4552" (in quotes) along with any of those brand names to find model #'s.

[stevenrb718]

Have you checked the voltages to the socket with the chip out vs in? With a signal checker is the audio clean up to the socket with chip in /out?

nosaj

Voltages on pins 4, 5, & 6 are all about 3.3V with or without the IC in place. Both channels of the audio coming into the IC are fine.

I managed to find a few more Boss pedals I have that don't work in various ways, which all have a 4552. I pulled the IC from one of them and dropped it in the ME-50... still no change. I can't imagine I came across 3 nonfunctional 4552s, but maybe? It might be a dumb question, but could something else be forcing the 4552 to create a distorted signal, like the clock?

[g1]

Yes, the clock and a few other inputs must be good. MCLK, LRCK, BCLK, SDTI. Have a look at all of them with the scope, sometimes you will see something real obvious, like very low level or distorted waveform.
Datasheet for AK4552 attached.