Ibanez AD-9 problem

[Bernardduur]

Hey all!

I got this Ibanez AD-9 from a guy who said it didn't work; he wanted to throw it away

So I tried it........ and it does this weird thing

- On low delay times the delays are still good and crisp
- If I turn the delay time up the delays get distorted to a point the real sound is not noticeable

I thought it was a simple case of adjusting the bias trimpot of the unit but I can't find a place in which she sounds OK; turning the bias pot does make the delays cut out on some max settings, but no clean delays can be heard.

Any ideas?

Some info:
- supply voltage = 8.93V
- voltage over MN3205 = 7.71V

Delay trimpot (2k) is set to 1.20k
Feedback trimpot (20k) is set to 9.62k
Balance trimpot (20k) is set to to the middle position (both sides 11.6k)

[zachomega]

My starting place is to measure the pins of the 4558 chip.  What are the voltages? 

-Zach

[Bernardduur]

Quite OK

I probed the circuit and I lose the signal after the BBD chip

Before it I have good quality

So it has to be somewhere around that stage