Acoustic Amplification AG60 Guitar Amp - Schematic Needed

buck1107

Member
2015-05-27 10:39 pm
Good Afternoon,
I'm troubleshooting my Acoustic AG60 guitar amp and am needing a schematic. Upon contacting the company, they said that they don't supply them, so I'm wonding if the schematic and/or service manual are on the net somewhere? After endless Googling, I came up with nothing.

Thanks very much for any leads!
buck
 

buck1107

Member
2015-05-27 10:39 pm
Thanks
It's making a hum that's not affected by the volume controls.

No input sounds make it to the speakers, and none of the controls have any effect on the hum.

There are two input channels, and the 'peak' LED for the input of channel two is always illuminated.

I haven't tried the line outputs yet to see if it's only the speaker path, etc.
 

buck1107

Member
2015-05-27 10:39 pm
Thanks.
It's taken some time to get back to it, but I ordered and installed a replacement amp chip (3886). Upon testing it, the amp is still making the same hum, exactly as before. The 'peak' LED is still illuminated (channel 2).

I used an audio probe and traced the input sound through the first level potentiometer in channel 2. Do pots ever go bad?
Thanks for any ideas.
buck
 

buck1107

Member
2015-05-27 10:39 pm
I'm continuing to test this, and so I decided to start by testing the transformer.
I disconnected all primary and secondary connections from the board and did a continuity test. There are 3 secondaries on the transformer and each of the three tested with 100% continuity between each of the secondaries' leads. The thing I wonder about is that one of the secondaries also tested continuity with another set of secondaries.
More specifically there is a pair of yellow wires, a pair of orange wires, and three wires consisting of two reds and a green and the middle. The three wires tested continuity with the orange wires.
Could this be in the design, or is this a flaw or damage?

Thanks
 

buck1107

Member
2015-05-27 10:39 pm
Here's a photo, showing the power board (top center), with the secondaries (the orange, yellow, red/green).
 

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