TIP31A a good sub for a 2sc931

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#4
Its a Tip31c, which I think is OK.
I found a D1266 - which I am looking for its datasheet.
I'll dig through more of my crap through the day. If I dont find better match, I am thinking I'll put that TIP31C in it tonight.

Thanks.
Srinath.
 
#6
The 2sc931 is a to202 package, with the print facing you the pins will be E B C and the tip31 B C E . The only issue I take with using the TIP31 as a replacement is lower HFE and Ft. If this is in an amp as driver or output with the pnp complement to the 2sc931, it may cause an offset issue or worst case oscillation. I take this item was made late 60's early 70's to be using these old style types. Some details about what your working on may help someone to give you a better solution.
 
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#7
pics attached.

Pics of the circuit here. Its an akai aa 6600.
 

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#8
I would say that for the transistor to fail in that position/circuit is unusual if I didn't already know those old style 2sc458 are known to become leaky and/or noisy(square looking package). I would test voltages around the 2sc458 with the 2sc931 removed before putting another transistor in. Perhaps check after using a hair dryer on them to warm them up a bit to be sure. Also check C603 2200/16V cap for short, this part should have been a 35V in my opinion, and R608/100 ohm for correct value. Honestly I would just replace all of the 2sc458 with 2sc1815.
 
#10
Jerlwoo: I pulled the other channel C931 and put it in the location the dead one came out of, It worked fine. This was blown up by a speaker with an iffy 1/4" cable. My friend decided that since it has 1/4" output jacks, it was the amp to test my altec 1202's. Then it dies, and we conclude that the speaker had a short. I opened it up and chekced, found nothing and the speaker then worked fine with a different amp (without a 1/4" jack LOL) ... then I tested that cable he had, and found a spot where it had kinked and had a short.

Wg_ski: Thanks.

Thank both of you guys, I'll put it in and post back.

Cool.
Srinath.
 
#12
LOL, yes.

BTW The one and only amp I smoked on my watch with my stupidity - and not while working on it BTW, I smoked it being drunk and dead tired and seeing blue - hungry, and contorted into where the speaker was sitting @ 9 pm one saturday this summer - was a KR3200 and I smoked it by switching speakers - and these had a metal cabinet, and I carelessly contacted the cabinet. It burnt the pre drivers and many resistors but the power transistors were fine. In fact it burnt parts of the power supply too.

I'm yet to fix it. I may just fish parts out of it an toss it. Not worth fixing it - of course as a learning tool its priceless.

Cool.
Srinath.
 
#13
OK I got these other transistors sitting around -
D1226 from a DOA cassette deck, KSC2690AYS, ksa1220AYS, 2sc3902S, 2sa1507s, ksa1381ESTU, ksc3503dstu all new from mouser as part of my marantz 2325 repair.
Any of these works better than the TIP31c ?

I also have TIP35C and TIP36C's a plenty
Thanks.
Srinath.
 
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#14
TIP31C is in and works. I saw that the heat sink was shorted to the collector. So I basically just pushed the center pin down to contact the heat sink, and the other 2 well, there wasn't any crossing required.

Thanks jerlwoo and wg_ski.
Cool.
Srinath.
 
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