Top Ten Worst Transistors - noisy, failure-prone, whatever... and replacements

I have not done a lot of refurbishing but have encountered 2SC458 two or three times. In my case they were in Akai tape recorders but I understand they were widely used by the industry in general.

Something I noticed though was that transistors designated 2SC458 could be either a square package with a sloped top or cylindrical with a flat front. It confounded me at first because oddly, their pin outs were mirror images of each other.
 
They indeed come in (at least) two versions;

nYfWWoa.jpg


sTngyWJ.jpg
 
I'm just curious . As someone who is somewhat less initiated in SS gear , how would one know what the designations with same # transistors that exist with different pinouts?
 
I'm just curious . As someone who is somewhat less initiated in SS gear , how would one know what the designations with same # transistors that exist with different pinouts?
Your meter is your friend. Takes about 15 seconds to determine which lead is the base. I always check as a sanity check when replacing transistors.
Background - when the Korean KSA733 and KSC945 with center base leads first appeared in the late 70's (Scott, Goldstar, Samsung and others) they looked just like 2SC945 and2SA733 (Center lead collector) and caused lots of headaches until people figured out what was happening.
 
Meter in diode test ohms. NPN + lead on one lead conducts to the negative lead on either of the other leads - that lead is the base. Reverse it for PNP.
 
Meter in diode test ohms. NPN + lead on one lead conducts to the negative lead on either of the other leads - that lead is the base. Reverse it for PNP.

And if you test transistors often, a $20 transistor/component tester makes it easy. Like http://m.banggood.com/search/transistor-tester.html

EDIT: There is a larger thread covering the different kinds of transistor testers here: https://www.audiokarma.org/forums/i...-transistor-testers-and-curve-tracers.916897/
 
Last edited:
And if you test transistors often, a $20 transistor/component tester makes it easy. Like http://m.banggood.com/search/transistor-tester.html
I have a couple of LCR-T4 12864LCD ESR SCR Meter Transistor Tester, and they last a year, so I decided to buy a couple more like a 2 weeks ago, from a US seller on ebay... What a pice of junk DOA and bad assembly. So I decided to make the effort a get a proper Peak semiconductor tester unit. Can't be more happier, is fast, accurate, reliable. No more hiccups and weird readings.
 
Last edited:
So I decided to make the effort a get a proper Peak semiconductor tester unit. Can't be more happier, if fast, accurate, reliable. No more hiccups and weird readings.

I agree: if you can afford the higher price, the Atlas Peak DCA75 Pro does an awesome job on transistors. It doesn't do all the resistor, capacitor and inductor readings like the cheap testers, but it is really, really nice for transistors.
 
Oh and don get me wrong, i really like the cheapos, but sometimes some works great, other not... the have not and standard, is like if you are lucky the will work, and when they work are great.
 
I wonder if anyone had experience in replacing power transistors BD 245B, and BD 246B with 2SA1695 and 2SC4468?
Comparing their characteristics 2SA1695 is stronger, 100W, comparing to BD246B 80W, but collector current is the same 10A, and 2SA1695 can withstand higher voltage 140V, comparing to 80V of BD transistor.
Their case is different, TO-3P (2SA1695), TO-218 (BD 246B).
I know TIP33B, and TIP34B would be direct replacement, but I have ones that I wrote, intended to repair some completely other thing, and crossed my mind, would it work?
 
Yes you get the real TEXTOOL ehhhh TFXTDOL zif socket. (as on the picture) buying devices like that.

Mine is "more or less rectangular and flat" and almost as good as a worn out Textool socket.;)
 
I've been using a Duoyi transistor tester for the last few years, and it has been great. Kinda thinking about springing for a Peak Atlas DCA Pro.
http://www.peakelec.co.uk/acatalog/dca75-dca-pro.html

BTW 2SC1318 isn't a faulty or bad device per se, it's actually a pretty good one. It just tends to end up in places where a bigger device should have been used in the first place. Like Pioneer power supplies.
 
Back
Top Bottom