On post 145, the common probe goes on the base, not the collector. The pin in the middle. You don't need drawings, a table with Q# with b-e forwards backwards then b-c forwards backwards readings. I have no idea how you associate your 6 drawings with the transistor they are reporting.
Reference post 160, diode readings from E to C are USELESS!!!!!!!!!!!!! As I said in post 157. You need to measure B-E. B is the left one looking from the long end.E is the right one looking from the long end. C is the case. There are apparently no backwards readings. Yes, 400 B to C on the bottom drawing looks out of the norm. 241 on the top drawing from left B to right E pin looks also defective.
Reference post 160, diode readings from E to C are USELESS!!!!!!!!!!!!! As I said in post 157. You need to measure B-E. B is the left one looking from the long end.E is the right one looking from the long end. C is the case. There are apparently no backwards readings. Yes, 400 B to C on the bottom drawing looks out of the norm. 241 on the top drawing from left B to right E pin looks also defective.
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The little metal lip on the can marks where the emitter is. The lead next to that, closest to it, is the base. So base is the middle one of the three leads. Then, follow indianajo's instructions, or these: https://vetco.net/blog/test-a-transistor-with-a-multimeter/2017-05-04-12-25-37-07
Are there any other numbers/letters on the small transistors?
Are there any other numbers/letters on the small transistors?
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thank you all for helping me until now. i dont want to continue with this because i see that is pointless it can't be fixed. btw i learned a lot of thing along the way so that also counts 😀
Sure it can be fixed. Take a break.
Then come back an reread the posts and try to extract the essence from them.
Work slowly and systematic. I'm sure you can do it.
Hugo
Then come back an reread the posts and try to extract the essence from them.
Work slowly and systematic. I'm sure you can do it.
Hugo
its pointless xdd i still dont know what transistors are bad, so i dont want to do this anymore, but for sure i will write here with new project sometime 😀 i always work on something i guess that this amp is damaged a lot.
at this point i can only change all transistors and those two resistors xdd rest of the resistors are ok so thats a option and those transistors are not expensive anyways.
no xd small ones dont have any marks on them , i can change 2n3055 but i dont know what are those small ones
For the small ones, at least you need to know if they are NPN or PNP. You can measure that using a diode tester, use the steps in the link I posted.
Then, replacements for the NPN could be BC141 and for PNP the BC161, if your supply voltage is not more than 60 volts (probably not). You can get those in Europe from Reichelt or TME, they are quite cheap, still produced in India.
Good Luck 🙂
Then, replacements for the NPN could be BC141 and for PNP the BC161, if your supply voltage is not more than 60 volts (probably not). You can get those in Europe from Reichelt or TME, they are quite cheap, still produced in India.
Good Luck 🙂
i will do exaclty that 😀 wil lreplace all transistors and two resistors and it may work 😀 maybe some of them work but they are old for sure and needs replacement anyways
That would indicate the transistor has a gain of 23, in your tester. Those multimeter transistor testers use a rather low base current, and if you look at the datasheet for a medium power transistor (like the ones you have), you will see it has low gain at low currents. So 23 makes sense. Now you can maybe see with this tester wich transistor is PNP. I think only one of your transistors, namely the bottom driver, will be PNP.
will remove rest of them and i will test them and i will post results here. first one only shows results in npn not in pnp section so its npn
i marked them 1 2 3 with black marker so i know xdd i only have to mark where leads go because it had more then 3 holes maybe its drilled by mistake xdd
I really cannot see the difficulty in locating the base pin. On 2n3055 (TO3) looking at bottom from the long end, base is the left. c is the case. On TO5, the small ones, the base is the pin in the middle. Diode measurements forwards and backwards are made from b to e and b to c. NOT E TO C!!!!!!!!!
2n5320 and 2n5322 are valid modern replacements for the small ones for voltages up to 80. In stock at digikey US. BC141 npn has Vceo of 100 from central semi, but Check open circuit voltage at the blue capacitor 60 or below before buying BC161 which has vceo of 60. Central BC441 pnp has Vceo of 70.
2n5320 and 2n5322 are valid modern replacements for the small ones for voltages up to 80. In stock at digikey US. BC141 npn has Vceo of 100 from central semi, but Check open circuit voltage at the blue capacitor 60 or below before buying BC161 which has vceo of 60. Central BC441 pnp has Vceo of 70.
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You check E to C for a short, that is all. This measurement is normally open for your transistors. Some transistors do have a diode across the emitter to collector, normally reverse biased in operation. Those would be horizontal outputs in TVs and power switching transistors.
i was measuring from c to e and b i did not know that is not right so i should not measure anything with c ? only e and b ?
and
After two weeks and 180 posts I want to ask you guys one thing, if it were you, what would be the first thing you would do to diagnose this amp?