Good evening all
I’m working on a Sony TA-F60 with shorted outputs so I went down the circuit to see it anything else was bad and found these two transistors that are measuring a diode junctions half of the time on my Peak Atlas meter, so they’re obviously toast. In the pic that is attached they are Q109 and Q112 and part numbers are 2SA1026 and 2SC1634.
I’m really hoping to use something that I have on hand. I read somewhere that a KSC1815 would work well enough for the NPN. Of course I don’t have any, I have several KSC1845. I’m hoping someone might be able to list a few suitable replacements for both and hope that I have something. I could even go with something in a bigger package as long as it works electronically.
Dan
I’m working on a Sony TA-F60 with shorted outputs so I went down the circuit to see it anything else was bad and found these two transistors that are measuring a diode junctions half of the time on my Peak Atlas meter, so they’re obviously toast. In the pic that is attached they are Q109 and Q112 and part numbers are 2SA1026 and 2SC1634.
I’m really hoping to use something that I have on hand. I read somewhere that a KSC1815 would work well enough for the NPN. Of course I don’t have any, I have several KSC1845. I’m hoping someone might be able to list a few suitable replacements for both and hope that I have something. I could even go with something in a bigger package as long as it works electronically.
Dan
Attachments
Collector current on KSC1845 only 50mA vs 200mA for the 2SC1845. So I'm not sure it will be okay. KSC1815 is 150mA.
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Thank you, I appreciate your input. What do you think about the KSC2383YTA? If anything it might be a bit overkill. I’m not skilled in comparing and finding good transistor replacements so there very well may be something I’m glancing over.
Dan
I didn’t see this response, I’ll check my stock, I have a lot. I will certainly make sure that pins are oriented correctly.
Dan
Yeah my bad, I was just going off of min hFE from the data sheet. I pulled the 2sc1634 from the good channel and it’s measuring in the mid 500s while the 2383s I have are in the low 200s.
Dan
From memory 2n3904 don't have a very high gain either, you may need to find a different replacement [emoji848]
What about the ZTX696B? It has a slightly lower Veb at 5v vs 6v. Everything else is overkill. Although gain might be slightly high, I don’t know. Looks like I can find a couple that measure right at 800. I have several so I might be able to find slightly lower.
Dan
Additional gain should be okay, negative feedback should take care of it.
If it's similar to ZTX694B then it should be absolutely fine, that's what I just found and was going to suggest. Overkill, maybe, but if you have them already then what does it matter ¯\_(ツ)_/¯
If it's similar to ZTX694B then it should be absolutely fine, that's what I just found and was going to suggest. Overkill, maybe, but if you have them already then what does it matter ¯\_(ツ)_/¯
Excellent! You’ve been an excellent help. Now to see if I have something similar for the 2SA1026...
Dan
Looks like the closest I have would be a BC556B which has an Ic max of 100mA vs the 200mA of the 2SA1026.
Maybe I should order the complement of the ZTX696B...
I’d go to the local electrolytics store, but they only carry NTE lol.
Dan
Maybe I should order the complement of the ZTX696B...
I’d go to the local electrolytics store, but they only carry NTE lol.
Dan
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Measure the Vce of Q109 & Q112 then multiply that by 50mA. Calculate the power dissipation and figure out what your comfort level is as to how hot the chosen device will be running continuously.
Okay I certainly can. Won’t I have to wait until I have good parts to put in place of Q109 and Q112 before I can measure?
Dan
These transistors normally don't do much of anything, with Vce <1 V - they're just for current limiting. I'd say a little medium power job with Vceo (preferably) at least 50 V like 2SC1815 / 2SA1015 or similar would work fine. Not much beta required. BC639/640 should also work - even BD139/140 if need be. Preferably Japanese (ECB) pinout in any case. If you're up for some leg twisting, you could even throw in some BC337/327 or 2N2222A/2N2907A. ZTX parts are also EBC, btw.