SA-9500 II Cap & Transistor Lists

[markthefixer]

oooohhhh, BAD on ME, 9500ii, not D7000!!! I guess I AM really tired.....

I apologize....

Long long ago in a galaxy REALLY REALLY close, I sweated bullets on the substitutions for these NSA amps.
Use the 3800,3900, d5000 and d7000 lists (when they can be found) for NSA amplifier guidance.

as a side note I don't usually recommend those on-semi parts, except for in power supplies. They have slightly different characteristics that upset the Pioneer idle current circuits for the non-NSA amplifiers, but in places where the Vbe drop doesn't matter (power supplies etc) they are superior replacements.

 

[the architect]

oooohhhh, BAD on ME, 9500ii, not D7000!!! I guess I AM really tired.....

I apologize....

Long long ago in a galaxy REALLY REALLY close, I sweated bullets on the substitutions for these NSA amps.
Use the 3800,3900, d5000 and d7000 lists (when they can be found) for NSA amplifier guidance.

as a side note I don't usually recommend those on-semi parts, except for in power supplies. They have slightly different characteristics that upset the Pioneer idle current circuits for the non-NSA amplifiers, but in places where the Vbe drop doesn't matter (power supplies etc) they are superior replacements.

I made my Mouser order last night before your post. So the On-Semi's are a go or a no-go?

 

[markthefixer]

a go, for the power supply. that is the only place a B596 would be with it's current and speed ratings.

there COULD be a speed problem (too fast, oscillates if not properly compensated) which is why I usually stuck/stick with 2073's

 

[the architect]

Here's the Diode and Transistor readings:

D9
(+)Anode (-)Cathode 0.539v
(-)Anode (+)Cathode OL

D10
(+)Anode (-)Cathode 0.507v
(-)Anode (+)Cathode OL

D11
(+)Anode (-)Cathode 0.523v
(-)Anode (+)Cathode OL

D12
(+)Anode (-)Cathode 0.286v
(-)Anode (+)Cathode 0.306v

These were taken with the Diode removed from the board. D12 being the only bad one. All were replaced with 1N4004's since I already had them out.

Preliminary in-circuit Transistor readings:

Q8 NPN
0.497v (+)Base (-)Collector
0.517v (+)Base (-)Emitter
0.837v (+)Collector (-)Emitter
0.878v (-)Base (+)Collector
OL (-)Base (+)Emitter
OL (-)Collector (+)Emitter

Q9 PNP
0.879v (+)Base (-)Collector
OL (+)Base (-)Emitter
OL (+)Collector (-)Emitter
0.485v (-)Base (+)Collector
0.510v (-)Base (+)Emitter
0.516v (-)Collector (+)Emitter

Should get my Mouser order Tuesday. Wednesday at the latest.

 

[mattsd]

The transistors look okay, but I would take them out of circuit and test them again just to make sure, as being in circuit can hide a transistor that is open or create false readings like this on Q9 "0.516v (-)Collector (+)Emitter", you should be reading OL there. In reply to your PM, there isn't anything else that would cause the fuse to blow other then a shorted (or in this case an almost shorted) rectifier or one of those transistors being shorted, but just to be on the safe side I would check Q10 and Q11, they are the drivers for Q8 and Q9.

 

[the architect]

Q8-Q11 test good out of circuit. Kept the originals in. No replacements. New thermal grease on the 220's. New fuse. It's looking like all systems go for power up..

Dim Bulb Test was good. Bright then dimmed all the way down. Should I give it juice?

 

[mattsd]

Yes, as long as the bias is still holding, go ahead and test her out!

 

[the architect]

I am cautiously optimistic. How long before I know for sure everything will be ok ara:

 

[mattsd]

For now, the only way to know is to run it and see what it does, you've done just about everything you can to make sure it runs well. I doubt you will have any more problems, but if you do, they can be fixed!

 

[the architect]

I just want to give you and Mark a huge THANK YOU

It's been a while since I "successfully" upgraded an amp. Lots of setbacks and learning lessons in between but with the help of you guys and everyone on this site, just about anything is possible. :thmbsp: