Sansui QRX-7500 FM lamp stays on - Help Needed

Is the stereo lamp suppose to stay on all the time on this receiver? It never goes off in any function. (aux, Am, Fm, etc.). I put a new lamp in and it lights but never goes off. Anyone know what could be wrong if anything.

Anyone know?

If the FM receiver works normally otherwise, it's either shorted or the transistor that drives it is shorted.

- Pete

LBPete said:

If the FM receiver works normally otherwise, it's either shorted or the transistor that drives it is shorted.

- Pete

Click to expand...

OK. Thanks Pete. I am looking at the service manual and it says check TR16 or a 2SA562 (Y) on F-1479 board, except I can't find a F-1479 board. The board I see that looks like the F-1479 tuner board is a F-1517 on my receiver and is located top center looking down on the receiver. There is a TR16 transistor on the board but it is a 2SC1364. Is this the driver transistor?

Sorry, I don't know enough about this model to give you guidance. You should be able to trace the circuit back to the correct board. Where do the wires from the lamp go?

- Pete

LBPete said:

Sorry, I don't know enough about this model to give you guidance. You should be able to trace the circuit back to the correct board. Where do the wires from the lamp go?

- Pete

Click to expand...

That's OK. I am going to check the voltages on the F-1517 tuner board stereo IC03 pin 6. It should be 6v. I have a schematic for that board I found in my files. That's where the wires go to that board. I am getting some help from a local friend of mine who works with me and is pretty good at reading schematics and following traces. Going to check the voltages on the emitter and collector on the transistor 2SC562 or TR12 to see if it is getting 6V also. I think that is the driver transistor.

Thanks for your response and if we are able to find problem I will post and update.

Fixed!

Pulled the tuner board and checked the TR12 (2sa562) transistor and replaced it with 2sa733 and I now have stereo lamp. :thmbsp:

Update

This did not work like I thought. Had to change the diode D01 in the power supply and the capacitor next to it to bring the voltage up in the IC stereo decoder. Also the MPX red box or "red thing" was bad and needed to be changed as Fred Longworth "audio fanatic" referred to in in his post. I pulled one from a Sansui 881 I had for a parts unit.

http://www.audiokarma.org/forums/showthread.php?t=133252

Thanks Fred!