AMI R-94 loud hum, no sound

[dardie72]

I just picked up a AMI R-94. Everything seems to work except no sound. Only a very loud hum. Looks like they had a remote Volume control cable that has been cut, wire ends are not touching. Left ch overload indicator lamp is lit. If I unplug the 4pin speaker output from the amp the light goes out. If I reverse L/R speaker wire and plug in still same. L ch led overload lights up.  Any idea where to start for troubleshooting this. 

Thanks in advance,
Darryl

[Ron Rich]

Hi Darryl,
You need to get a copy of the amp schematic and trouble shoot-- Check the 4, 5, Amp (FAST Blow--I hope !) fuses, on the driver boards--If any are blown, replace the transistor that's associated with that fuse, and replace "Q-5" on the board. Check the board for any other out of spec. items--replace what's bad, set the bias as per the instructions on the schematic. If you don't have the skills needed check our FAQ's section for a list of repair people--also, when you get a second, please read and comply, with our "posting rules" as shown in our "User Introduction" section--- Thanks, Ron Rich

[dardie72]

So I have been going through testing the resistors on the driver boards. Found a couple that aren't matching up. But 1 in partiucular is the R29. On one board it is a .2ohm(2W) as per schematics. On the other board it is a .1ohm(2W). Looks like it came from factory like that. Would this become an issue. Its the board on the left. The resistor is the larger one just to the left of R32.

Thanks
Darryl

[Ron Rich]

Hi Darryl,
The one on the left is dis-colored, and bad. It started life as a .2 / 2w-- but some fool let some of the smoke outa-it, so, it's only a .1 now---
Ron Rich