SX-727 restoration question

[TomSc]

I'm finishing up a recap on a 727. I've replaced all the electrolytics on the PS, protect, and all audio boards. I also replaced the usual problem transistors while I was in there. I did not replace Q1 and Q3 (2SD313D) on the PS board - AWR-010. I don't have anything on hand to sub for those. The board doesn't look like it's been running too hot. Only a very slight discoloration under R9. The previous owner must have treated it well and not shoved in a cabinet.

Would you go back in and replace the the two 2SD313e and/or R9 (330/2W)? The KSC2073 has been used in the past - and they're only $1.00/each

 

[larryderouin]

I'd replace the 2sd313's. R9 could stand to be lifted off the board a bit. If the leads aren't long enough to do so (1/4" or so) get a 3W and put a kink in the leads so it sits up from the board like R1 (the one with the fiberglass cover on it and it's leads) or R8. Heatshrink the leads on the new resistor.

 

[TomSc]

Thanks Larry! Your advice is much appreciated. I have a few 313's in my Mouser cart along with a few 300/3Ws.

 

[pa_200]

You may lift up the new R9 and bend away from the transistor like this.

 

[TomSc]

Excellent idea. That's exactly what I'll do that once the parts arrive. And why didn't they do that in the first place? They had to know that resistor was going to generate some heat. In their defense, I'm sure the engineers never imagined these receivers would still be in use 50 years later.