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Looking for circuit schematic for a Teac AG-7D. There's no visible burning on the board, no blown fuses, the power light comes on, it just won't make a noise any more.

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This unit has detected a problem in the output section and the protection circuit is preventing the output relay from turning on. In most cases this is due to shorted output transistors which will need to be replaced. If you have a multimeter, set it to read DC volts and measure the voltage on the three legs of one of the output transistors. You should read .6V, 40V or so and 0.0. I suspect that you will read 40V on two fo the three legs. If so, that is your problem. Please note that the actual reading for the higher voltage may be something other than 40. I don't have the service manual for this model, so I don't know the exact voltage. It will be anywhere from 35V-75V depending upon the actual design and output transistors.

I am not aware of the availability of schematics for this unit, but any shop that works on audio gear should be able to repair this without them.


Posted on Mar 09, 2009

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