[Heathkit] SB-650 repair and restoration

[Bwana Bob]

Happy New Year; so far, so good.


I use an SB-650 digital display  with my HW-100.  If I had an SB-101, I 
wouldn't bother with a digital display, but with the 5 kHz resolution of 
the HW-100 dial, it definitely benefits from a digital display.

However, every time I use the   SB-650 digital display  it acts flaky.   
I usually have to open it up and reseat a bunch of chips or swap some 
around.  As it warms up it may get better or worse.

I think part of the problem is oxidation of the IC sockets. I've tried 
Deoxit on the IC pins, but it only gives temporary results. I'm thinking 
that this could be fixed by plugging Gold-plate socket headers between 
the chips and the sockets on the PC board. I am not going to desolder 
and replace the existing  sockets; that would destroy the board.

The other cause of malfunction is excessive heat.  I read somewhere that 
the 7400 series TTL chips can be replaced with 74LS  Low Power Schottky 
equivalents (if one can still get them).

Does anyone have experience with improving the reliability of the 
SB-650?   (I bet the redoubtable Mike Bryce, WB8VGE has some ideas).

The other option is to give up on the SB-650 and get something like 
this:  http://www.electronicspecialtyproducts.com/dd103.html but I do 
like the classic looks of the SB-650.

Thanks, and 73,

Bob WB2VUF