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Realistic STA-2100D Amp Board issue

J

Joe1980

New Member
I purchased a Realistic STA-2100D which had 3 blown TO Transistors and other driver transistors burnt out.

I've replaced the following parts:

TR 507B-508B
TR 503-504B
Protection Relay
all new Caps
VR 501 and VR 502

My issue is that im getting 53 volts at the output on Channel B.

Channel B does not pass the protection unless i unplug the output pin 13 wire.

Channel A works fine and I had swapped many parts into Channel A to test what the issue is. I can no recreate this. Any part swaps did not affect channel A.

I can not figure this out.

Any help would be appreciated.
 
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Did you test the output emitter resistors? (R529 through R532) Sometimes when an output transistor(s) fail they will take the emitter resistors out as well.
And the same holds true for the driver(s) (R523 & R524)

The amp boards have a couple of sometimes troublesome VD1221 dual (blob) diodes. Check those.

Double check the replacement parts TR507 & TR508 and TR503 & TR504 are installed with the correct pinout.

Under a nice bright light look very closely at the solder pads on any component you have replaced for cracks or breaks where the trace meets the pad.

Is it safe to assume you are using a DBT?
 
mrk229 said:
Did you test the output emitter resistors? (R529 through R532) Sometimes when an output transistor(s) fail they will take the emitter resistors out as well.
And the same holds true for the driver(s) (R523 & R524)

The amp boards have a couple of sometimes troublesome VD1221 dual (blob) diodes. Check those.

Double check the replacement parts TR507 & TR508 and TR503 & TR504 are installed with the correct pinout.

Under a nice bright light look very closely at the solder pads on any component you have replaced for cracks or breaks where the trace meets the pad.

Is it safe to assume you are using a DBT?
Click to expand...
I did test the output emitter resistors and they tested good. Ive checked all the diodes as well. All Transistors are installed correctly. All traces look good, I am using a DBT
 
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