altec 1210 powered mixer

[ansteyred]

Hi i need some help trying to find out whats wrong with this unit. it comes on fine but has some humming, then it dies after about 10 minutes. i have the skematics for it and have checked the following: (1) the power outputs from transformer check good, even when it dies.(2) I removed all the boards and inspected them looking for anything burnt, or loose, and cleaned all the pots.(3) I installed a grounded cord and checked all the wiring for anything loose or corrorded. (4) cleaned all the 1/4" input and output jacks. I have found nothing major wrong but I dont know where to go next!!! i suspect it is a solid state component on the pre amp board. It gets very muddy sounding and fades outs before it dies. Anyboby out there got any suggestions??? Please help.

thanks

[cclark65]

I am only a hobby elecronic repair person, so I don't know a lot about it, but I would start first with some of the capacitors, especially since it's an older unit. Those old caps made from cardboard dried out and changed values, or just plain don't work anymore. Since you said there is a humming sound also, usually a filter capacitor somewhere is going bad.
I have a few Altec 9440-A amps, and went through them and replaced all the caps on the control board and driver boards. It made quite a difference in the sound.