Found shorted diode bridge in power supply section . After replacement unit starts working . New diode bridge rectifier installed from power supply of Toshiba 60″ plasma TV.
Nice simple receiver , not overbuild. Easy schematic , good FM signal , not so many capacitors in signal path. Interesting detail – we found personal mark of production worker or repair person before us. Now it is piece of history.
One more detail – this unit very sensitive to DC OFFSET and BIAS adjustments. If your unit running extremely hot after 5-15 minutes , that is indication of your unit out of adjustment. Adjustments of this unit could be a big problem for not experience person. We try to show simplest way as possible for this specific model, this will work in case if you have all original parts in output section , not replacements. Ok, lets go . All work will be performed on output section of your unit , that is a section with output transistors and heat sink on it.
Grab you meter and put it to DC voltage measurement, no matter polarity , unplug all speakers , connect meter leads to speaker terminal on the back , unplug all input signals, turn on and measure DC voltage on your speaker terminals , we need 0.19 volt or less , close as possible to 0 volt for perfect case. Make it for left and right channel . Turn it off . Let it cool down and go to Bias adjustment – measure resistance of trimmer with black plastic top ( you have 2 of them) and adjust it to 120-125 Ohm for this specific model. Make it for left and right channel.
Turn it on again and check DC OFFSET one more time. Now , you heat sink should be warm only . Refer to our picture.
You have 2 couples of trimmers for 2 channels , left and right.
