Urei LA-22 component layout?

[jeffbro]

The service manual online does not contain a parts layout and half of the main PCB is obscured by the metering daughter board so the reference designators are not visible. Can anyone point me to a parts layout?

The unit I'm working on has one channel that goes into max gain reduction when the RATIO knob is turned fully CCW to turn on the AUTO function. MANUAL mode works fine, and I don't believe the AUTO switch is at fault. I'm trying to trace signals on the foil side of the board but don't know which IC is which.

 

[pvision]

LA-22 is incredibly tight inside. Might not be relevant to your situation, but the first one I bought had lots of problems, all traced to broken solder joints between the pots & PCB. I think it had been dropped in transit and landed on the knobs. Might be worth reflowing all the solder joints for the pots...

 

[jeffbro]

Right on! Reflowing many cracked joints at solder pads has fixed numerous faults with this unit but not this issue with the AUTO function.

The space between the main board and display board is so tight I can't even get my dental mirror in there deep enough to read the designators. Very frustrating.

 

[salomonander]

https://archive.org/details/studio_UREI-LA22_manual/page/n43/mode/2up
Go to page 42. The unit i once had, also needed lots of resoldering. All pots and switches should be resoldered. Be aware of bipolar electrolytics. Good luck.