Sansui QRX-3000 Driver Transistors

[Richard P]

I just finished repairing a QRX-3000 that had both front channels out - 2 outputs (2SD313), the output caps and the NPN drivers TR805 & TR806 (the schematic calls for 2SC634As but the original parts that were installed were 2SC1364s). Everything else tested good. I used 2SC1060s for the outputs. For the drivers, I found the recommendations for KSC945 for protection boards or KSC2690 for 'more demanding' applications. The 2SC1364 is rated for 200 mA so the KSC945 was out for a driver. The KSC2690 would be fine, but I have quite a few KSC2383s and KSA1013s that are my go-to for higher power applications using the TO-92 package. they are the taller version, but easily fit the original footprint - watch the pinout, of course. Dropped them in, cleaned up some questionable soldering, adjusted the power supply to 25V and the bias for each channel to 20 mA across the fuses and the receiver is singing once again. Now some Deoxit, general cleaning and a tuner alignment and it will go back into service. Hope this is helpful to someone . . .

Rich

 

[tcdriver]

Back in service. Do you use it in the quadraphonic mode?

 

[Richard P]

Yes - I have it hooked up to 4 speakers currently . All of the quad modes appear to work well and it sounds really good. . . . still scratching my head on the turner, though. Voltages aren't right. The drain on the dual gate fet is supposed to be 0.4V and I'm only getting 0.22. Maybe that's OK and i just need to do the alignment.