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SA-1000 Transistor list

Bad news, the friend who offered to fix mine felt the job was more than he could handle skills-wise so informed me a couple days ago that the amp is coming back to me unfixed. But AKer w1jim has now stepped up to the plate and offered to recap it for me. I will hand it off to him at the AK fest in Clinton Mass next month.
 
I know, I'm picking up an old thread, but there seems to be one transistor, which may not be a correct replacement.
Q9 2SC984 is supposed to be replaced with KSC2383YTA, but Ic value for 2383 is three times higher than 984. This transistor is used in the biasing circuit. My 984 was burned out. I replaced it with 2383 and cannot set the bias current now. I am going to buy 2N2222A from digikey and report back, as it's a much closer transistor in terms of specs.
 
Just to confirm - everything works with 2N2222A in place of 2SC984. Need to figure out how to attach this TO-18 package transistor to the heatsink, as the leads on 2SC984 were much longer than on 2N2222A.
 
you can extend the leads a bit I would think
yeah the Vbe bias generator values play with the bjt parameters, so not always one size fits all.
You can try to make your own heatsink flange out of copper or aluminum or buy a small heatsink for that to-18 package, search mouser yet, i know they make to-92 heatsinks, 567-292-AB, no stock, but something like that, I see 532-575200B00
2n2219 comes in a to-5, might find a more suitable heatsink that is available
long list of possibilities
http://ca.mouser.com/Thermal-Management/Heat-Sinks/_/N-5gg0?P=1yzvl03Z1yzvkzhZ1yzvkzkZ1yztmve
 
rcs16 said:
you can extend the leads a bit I would think
yeah the Vbe bias generator values play with the bjt parameters, so not always one size fits all.
You can try to make your own heatsink flange out of copper or aluminum or buy a small heatsink for that to-18 package, search mouser yet, i know they make to-92 heatsinks, 567-292-AB, no stock, but something like that, I see 532-575200B00
2n2219 comes in a to-5, might find a more suitable heatsink that is available
long list of possibilities
http://ca.mouser.com/Thermal-Management/Heat-Sinks/_/N-5gg0?P=1yzvl03Z1yzvkzhZ1yzvkzkZ1yztmve
Click to expand...

I just ordered this one: https://www.digikey.ca/product-detail/en/aavid-thermalloy/322400B00000G/HS100-ND/5826 for TO-18. Just need to make some kind of locking flange to connect the TO-18 heatsink to the main heatsink. I'll be working on this SA-1000 for a while still, so I have time to figure it out. The main problem is solved, now I need to recap the power supply (speakers buzz very slightly with no input connected), replace power cord, which is frayed, etc.

Regarding extending leads - that transistor is stuck in such a hard spot - between leads for two big transistors, and behind large resistors. Just too hard to get in there. It sucks that the standard leads are ~5mm too short.
I seriously remember ordering some military 2222A ~10 years ago for the space station component we were designing, and they came with long leads option (JANTXV2N2222AL).
 
ViperZ said:
(JANTXV2N2222AL).
Click to expand...
Special case for sure, expensive too.

Glad to see you investigated more options, I suggested the to-92 flanged type as the flange looks easier to attach to a heatsink.
post a pic so we can see what you are up against.
 
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