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Transistor Substitutions

rwwear said:
Sometimes one has to cross the legs of a transistor to match the original and insulate where shorting is possible. But most manufacturers make different pin outs for the same part. An Atlas DCA 75 will tell you what the actual pins are.
https://www.mouser.com/ProductDetail/STMicroelectronics/TIP112?qs=JV7lzlMm3yIGNlF3DEpFzw==&gclid=Cj0KCQjww7HsBRDkARIsAARsIT6zr_AJMuzwGh1uuFvSSIfVd8TUh5KGupxeEQFYPMz-D9vRoMzy3JIaApOUEALw_wcB
Click to expand...
I understand crossing the pins is sometimes necessary from experience. The data sheet for this transistor shows a different pinout than how the transistor is installed on my board. The transistor is an sa628a. There is also an sa628 transistor. The data sheets show them to have the same pinout. The sa628a transistors were installed at the factory and had been operating for many years with no problems. Something is not right. Btw the link posted just took me to an unrelated transistor on mouser’s site.

Thanks for responding!
 
Google listed it as a replacement for the sa628a. Sorry. Do you have a way to check the pin out? If they worked with no problems, they must have been right.
 
I have replacements. They have a different pinout. No I don’t know any other way to determine the pinout than consulting the data sheet.
 
Yes, I should get one of those. I have one of the cheaper ones and it quit working. It never returned the same information twice when it was working. It did give a pinout reading but...
 
Young46 said:
Yes, I should get one of those. I have one of the cheaper ones and it quit working. It never returned the same information twice when it was working. It did give a pinout reading but...
Click to expand...
The one I have works well but I don't believe they ever measure exactly the same every time. I think the transistors have a lot of fluctuations themselves. But I'm no expert. You can also connect it to your computer for more results.
 
Any idea how(where) can i get a substitution or original to replace these transistors on the power supply board of my Mcintosh C-26? The service book doesn't say more then NPN 132-095 and NPN 132-028 but this is just part #.
 

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ivo said:
Any idea how(where) can i get a substitution or original to replace these transistors on the power supply board of my Mcintosh C-26? The service book doesn't say more then NPN 132-095 and NPN 132-028 but this is just part #.
Click to expand...
According to this http://www.tubebooks.org/file_downloads/McIntosh/semiconductor_data.pdf the 132-026 = 2N3738 https://alltransistors.com/transistor.php?transistor=3539
and the 132-095 = GE/X32W6047 = 2N5550 https://www.mouser.com/Search/Refin...0J3DBWKx-6Qix7hyUwTHIYtlY2LRuPsAaApmgEALw_wcB

Also see https://www.antiqueradios.com/forums/viewtopic.php?f=19&t=287374
 
rwwear, Thanks a lot!! This is great information! I'm going to replace all devices on the power supply board on my Mac C-26. I'm missing the phono section there, but tape and tuner are working good.
Thanks again, man!!
 
Young46 said:
I understand crossing the pins is sometimes necessary from experience. The data sheet for this transistor shows a different pinout than how the transistor is installed on my board. The transistor is an sa628a. There is also an sa628 transistor. The data sheets show them to have the same pinout. The sa628a transistors were installed at the factory and had been operating for many years with no problems. Something is not right. Btw the link posted just took me to an unrelated transistor on mouser’s site.

Thanks for responding!
Click to expand...
The “A” is probably higher rated voltage. Aren’t they B-C-E for pinout looking at the flat, pins down.
 
TTA004B and TTC004B can also be used, though next delivery date is estimated 31-Mar-20 in case of TTA (PNP). Production seems still running, or they have a good surplus at factory.

160Vceo / Ic 1.5A / Pc 1.5W (t=25 *C) / fT 100MHz / hFE 80~280 / Cob 12pF (17pF)
 
For those of your with older NAD equipment (2100, 3100, 7100, others), I can confirm this substitution works:

2SD1238 --> 2SC3856
 
Mouser also has the TTA006B/TTC011B(soon) which are the old 2SA1837/2SC4793 in the smaller TO-126 package. It gives you 230v Vce to play with, but the package limits the SOA such that they are only slightly more robust than the TTA004B/TTC004B at higher Vce, and slightly less at low Vce.
 
KSA1220 / KSC2690 have higher Cob, where 2SA899 / 2SC1904 have impressively low ~3pF Cob.
In applications like VAS/predriver, KSA1381 / KSC3503 (also with low ~3pF Cob) will be superior to the 1220/2690 pair and the TTA/TTC004 pair.

The place the latter parts would be beneficial is where a higher Ic is needed (the originals are 0.05A, so not this particular application).
Those TTA/TTC parts are definitely nice though (with good "all round" numbers), will be useful to keep on hand for other substitutions.
 
zaibatsu said:
KSA1220 / KSC2690 have higher Cob, where 2SA899 / 2SC1904 have impressively low ~3pF Cob.
In applications like VAS/predriver, KSA1381 / KSC3503 (also with low ~3pF Cob) will be superior to the 1220/2690 pair and the TTA/TTC004 pair.

The place the latter parts would be beneficial is where a higher Ic is needed (the originals are 0.05A, so not this particular application).
Those TTA/TTC parts are definitely nice though (with good "all round" numbers), will be useful to keep on hand for other substitutions.
Click to expand...

Thanks for the tip. These will be used in a a predriver application.
 
great info and hoping to tap expertise for substitution suggestions for the transistors in the power supply of an marantz 1180dc:


SD313(D od E) Vceo 60; Ic 3A; Pc 1.75W; fT 4MHz; hFE D=60-120, E=100-200
- possible subs; KSC2334 Vceo 100; Ic 7A; Pc 1.5W; fT ?MHz; hFE Y=120-240 vs.
KSC2073 Vceo 150; Ic 3A; Pc 1.5W; fT ?MHz; hFE H1=40-80 H2 60-125 vs.
MJE15028/30/32 Vceo 120-250; Ic 8A; Pc 2(?)W; fT 30MHz; hFE(?)

2SC1509(Q) Vceo 80; Ic 1A; Pc 0.75W; fT 60MHz; hFE (no Q??) R=130-220; S=185-330
- possible subs; KSC2383 Vceo 160; Ic 1A; Pc 900mW; fT(min 20)-100MHz(?); hFE R=60-120; O=100-200; Y=160-320
KSC2690AYS Vceo 160; Ic 1A; Pc 1.2W; fT155MHz

- sorry for the "?" marks but not sure how to interpret the datasheets correctly for these values
- i would plan to replace the complements as well

thanks
 
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