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John-Del[_2_] John-Del[_2_] is offline
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Default Resistor not the same as schematic

On Friday, November 29, 2019 at 7:13:38 AM UTC-5, wrote:
Its a Sansui 5050 receiver. The power amp works, the radio tuning meter
moves, so it seems that works. But the preamp board is dead. Not a
single transistor or any other component on that board has voltage.
There is 44vdc on a wire from the power supply. It goes to a resistor.
No voltage on other side of this resistor. Multimeter on ohm scale
confirms resistor is open.

The problem is that resistor is red red brown @ 5% (gold). Thats 220
ohms. Yet an online schematic shows R601 as 100K.

OK, I know that resistor is dead, but how can the actual color code be
so different from schematic? The resistor is not burnt, but may have
gotten warm. Yet the color code is plain to see, except the gold band is
kind of greenish.....

My plan is to clip in a resistor, but where do I start with such a
conflict of values....

Yes, I triple checked this is R601. Unless the schematic is labeled
wrong????

This appears to be the only voltage source to this board.....

Any ideas or suggestions?

Thanks


Schematic errors are very common. We expect them and are never surprised by them.

100K won't deliver enough current to run a pre-amp board. If it is the B+ feed to the preamp, then it's going to be a much lower value resistor. Does the schematic show any voltages on the transistors that the 44V source feeds?