Line 6 lowdown studio 110

[Tonal1]

I wonder can anybody help me out with one of these that I was asked to take a look at.

It's just outputting noise, like pink noise and no signal at all.

Traced signal right from input into something called a ak 4556,signal looks ok on my scope going in but looks trash coming out but I'm not sure what I should be getting

I usually would run a mile from amps like this because I don't do digital and smd stuff, but it's for a friend

I'm unable to post a schematic at the moment but on it it says that if ak4556 is "stuffed " to replace some resistors and caps.

Anyone here worked on one of these and could give me some pointers

 

[Tarzan]

A schematic I found. Maybe of help.
Good luck with ...

 

[Tonal1]

Thanks Tarzan
I have that schematic already but I'm a bit lost on digital circuits and parts so small that I'm wary on putting a probe on it and shorting it out and damaging it.

 

[JMFahey]

something called a ak 4556,signal looks ok on my scope going in but looks trash coming out but I'm not sure what I should be getting

It´s a DSP or analog to digital converter or processor.
That said, the almost unreadable schematic seems to show 2 pins, 19 and 20?????????? , where apparently analog audio is restored, inject signaln at the input, follow it bup to chip analog input and then scomethose so called analog outputs.
If nothing out, it got lost in Digi-Land, junk the amp, guess an out of warranty "official" repair will cost more than current amp value.
If analog signal present, trace it to check where it stops.
Please show the full schematic, only preamp is shown.
If supply , speaker and power amp work, you *may* strip the Digital preamp and build a simple classic one on Veroboard or similar and make amp usable.

EDIT:

I'm unable to post a schematic at the moment but on it it says that .....

WHY?????
Is it a PDF? ... a GIF? .... just attach it here!!!!

 

[Tonal1]

I couldn't post a schematic because at the time of posting,it was only on my work laptop and I didn't send it to my home laptop but it's the same as the one Tarzan posted above.

Thanks for confirming my theory that because I'm getting signal into that chip and nothing out, means it kaput

As I stated already,because I don't deal with amps like that and I'm nervous probing on parts that I'm not familiar with.

Thanks

 

[JMFahey]

Cool.
Leave it alone, you don´t NEED to solve EVERY problem thrown at you.

It took me a lot to be comfortable with that.