9090db F2624 TR017 2SA733 substitute?

Linehand

Active Member
Can anyone recommend an available replacement for this transistor? I've crossed it to several others, none a direct match, and not sure what measurements to prioritize for this application. Center collector configuration seems to make this one a little difficult...

Thanks

Paul
 
KSA733C make sure it's the 'C' suffix version (collector in the middle).
You may wanna use this:

ONDGjFH.jpg
 
So KSA733CGBU should be good, I was looking at all the data sheets for those and saw 1emitter 2base 3collector config, now I see where it says "C" suffix indicates center collector-

Thanks again guys
 
KSA733C make sure it's the 'C' suffix version (collector in the middle).
You may wanna use this:

This image would have saved about 4 hours of my life! haha I'm getting an education though

I have in my cart 863-MJE15030G and 863-MJE15031G for TR11-TR14, would MJE15032G and STV-3HY be a better match? Do value changes at any specific transistor necessitate value adjustments at the others?

Thanks

Paul
 
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Tom, what would you use as 2SC984 sub?
It's the single bottle neck transistor on the entire driver board. No real good replacement other than NOS Hitachi 2SC984 or newer versions that needs to have their case (body) isolated by, for example, encasing them in JBWeld or wrapping them in shrink. The newer versions have one of the pins (I think it's base) connected to the case. This will short with the driver transistor heat sink if not isolated.
would MJE15032G and STV-3HY be a better match?
yes, and no. MJE15032G (NPN) and the complementary MJE15033G (PNP) have higher voltage (VCEO/VCBO) ratings. The STV-3H(Y) thermistor diode replaced the 2SC984 temp/co transistor in a later revision of the bias circuit on the F2624 driver amp PCB. You can't just swap the transistor for a diode.
 
It's the single bottle neck transistor on the entire driver board. No real good replacement other than NOS Hitachi 2SC984 or newer versions that needs to have their case (body) isolated by, for example, encasing them in JBWeld or wrapping them in shrink. The newer versions have one of the pins (I think it's base) connected to the case. This will short with the driver transistor heat sink if not isolated.
yes, and no. MJE15032G (NPN) and the complementary MJE15033G (PNP) have higher voltage (VCEO/VCBO) ratings. The STV-3H(Y) thermistor diode replaced the 2SC984 temp/co transistor in a later revision of the bias circuit on the F2624 driver amp PCB. You can't just swap the transistor for a diode.


My mistake, I meant the to say MJE15032-33G vs MJE15030-31G rather than STV-H.

I'll go with what you have indicated (32-33G)
 
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The newer versions have one of the pins (I think it's base) connected to the case. This will short with the driver transistor heat sink if not isolated.
I believe you'll find it's the collector. :(

I think the safest/best solution is to use a plastic case (TO-92) replacement, and modify the method of securing the device to the heatsink, i.e. use the 'flat' of the TO-92 to the heatsink.
 
I believe you'll find it's the collector. :(

I think the safest/best solution is to use a plastic case (TO-92) replacement, and modify the method of securing the device to the heatsink, i.e. use the 'flat' of the TO-92 to the heatsink.

I subbed KSC2383 for 2SC984 and I could only get 1-6mA max across F04 . Swapped orig 2SC984 from other side, problem solved.

My best guess is Collector/Base voltage is too high on that one. Emitter/Base is close to original and you would think that would be the only real factor...
 
It's the single bottle neck transistor on the entire driver board. No real good replacement other than NOS Hitachi 2SC984 or newer versions that needs to have their case (body) isolated by, for example, encasing them in JBWeld or wrapping them in shrink. The newer versions have one of the pins (I think it's base) connected to the case. This will short with the driver transistor heat sink if not isolated.
yes, and no. MJE15032G (NPN) and the complementary MJE15033G (PNP) have higher voltage (VCEO/VCBO) ratings. The STV-3H(Y) thermistor diode replaced the 2SC984 temp/co transistor in a later revision of the bias circuit on the F2624 driver amp PCB. You can't just swap the transistor for a diode.


Here's what I did for 2SC984. I'm not certain how this will turn out.

I used KSC1845 and the design is based on Tnsilver suggestion (which after a two week crash course, I now understand haha) not sure its what you had in mind, but if its out there I haven't seen it...

Disclaimer: My stereo won't be pushed too hard

Been running thirty min since that pic and its ranging 27.10-27.81mA


IMG_1800.jpg

Resistor lead is close to transistor leg...

IMG_1801.jpg

IMG_1804.jpg
IMG_1805.jpg

Encased in JB Weld

IMG_1807.jpg

IMG_1808.jpg

IMG_1809.jpg
 
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Nice!!! Keep monitoring and let us know. I might do the same for my 9090 F2436 driver amp bias circuit, as the stock 2SC984 are starting to act up funny.
 
Nice!!! Keep monitoring and let us know. I might do the same for my 9090 F2436 driver amp bias circuit, as the stock 2SC984 are starting to act up funny.

So, I set bias at 30 +/- 1mA following the procedure you outlined - thanks for writing that up btw.

Ran at low/medium listening volume, transient peaks tapping just above 1w on the meters for 25 min

Results:

Right Channel (KSC1845)
Bias 1 min after shutdown: 37.5mA
Bias after 20 min: 31.77mA

Left Channel (2SC984)
Bias 1 min after shutdown: 35.4mA
Bias after 20 min: 30.30mA

So its easy to get OCD on this measurement and if you do, its best to set late night when voltage at the meter is most stable. The bias dropped then rose up 5 mA when the AC kicked on...

Also, meant to thank Hyperion for the TO-92 suggestion
 
Good! Looks like it's working. Should be stabilized after 20 minutes, but bias drops real fast on shutdown. Could the post shutdown reading be a meter memory thing (min/max)?

So the way I wrote that data is a little confusing. What I meant to say was I played the stereo until nice and warm, then shut it down, waited 1 min, then switched it back on. The '1 min after shutdown' reading is where the meter topped out before beginning to drop back down. I wanted to see how TR09 and TR10 interact warm vs cold.

I ran more specific timed tests and they are pretty close. This was from a dead cold start on different nights. AC was on and off which makes this a "real world test", at least for me anyway...

Left (2SC984):

43.00 mA @ 01 min
36.60 mA @ 05 min
28.55 mA @ 10 min
31.42 mA @ 15 min
36.98 mA @ 30 min

Right (KSC1845)

40.48 @ 01 min
35.43 @ 05 min
35.70 @ 10 min
29.80 @ 15 min
38.50 @ 30 min

I'm actually pretty stoked at how close they are. The only issue I see now is how it will react if pushed hard. Do we know how critical the thermal interaction is between TR09-10 and TR13-14 is? Is TR09-10 meant to react differently with temp increase?

My Spendors are such and easy load this beast doesn't even feel it...
 
Resistor lead is close to transistor leg...
could you tell me more details involving the resistor?? What value and where it was soldered ?? I'm guessing the resistor was only temporary acting as a heat sink for soldering possibly???
 
The resistor lead was similar in size to the transistor legs and worked well as a template to make the tight wraps in the new transistor legs. The resistor is not required in any other way.
 
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