Im just going to remeasure the listed transistors.
Red to base, Black to collector Red to base Black to emitter Red to collector Black to emitter then reverse
2385 reconnect PS00 to P400 pin question
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Red to base, Black to collector Red to base Black to emitter Red to collector Black to emitter then reverse
Ok I will remove them tomorrow, I do have a transistor tester. I'm also thinking I should replace the resistors listed , that way there is no question of their condition
I tested the transistors and findings are as per photos, number on the photo is transistor number without the Q
Also you can see a photo behind the board, the circled part was like that before the transistor was removed, not sure but i believe that needs to be jumped or that transistor can not work properly. That number is Q717
Even with the heat down to 320 c it is hard not to affect board, when i replace the transistors i will make sure all legs connect to trace.
Lastly if as i believe all of the transistors are good should i replace them with new ones. ?
Also you can see a photo behind the board, the circled part was like that before the transistor was removed, not sure but i believe that needs to be jumped or that transistor can not work properly. That number is Q717
Even with the heat down to 320 c it is hard not to affect board, when i replace the transistors i will make sure all legs connect to trace.
Lastly if as i believe all of the transistors are good should i replace them with new ones. ?
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OK, here is what I found.
- You tested Q717 and found an NPN transistor with leads 1=B, 2=C, 3=E with a gain of 118.
- The PL shows this is a 2SC1568 (datasheet attached)
- The pinout of the 2SC1568 is a NPN with leads 1=E, 2=C, 3=B, reverse of what you measured
- What is the PN of what you pulled out of Q717 and why are the leads in reverse order?
- Is it the same PN as Q718 for the other channel and mounted the same way?
- Was the part mounted on the board backward or is it a bad part?
- Let me know what you find.
Reading always from From left to right on how they are on the board Q713= ECB Q717 ECB Q721=BCE Q719=ECB
Photo of Q717 attached
When i test i always start from Base no matter which way it is installed , my readings reflect that
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Yes, it matches the board, but when you tested the part in the transistor tester it reads 123=BCE, not ECB. Backward from the datasheet and your board layout.
There is something wrong with that transistor or your tester.
Your tester doesn't care which test lead is connected to which transistor lead. It determines that at tells you on the display. So in this case lead 1 = base, not emitter.
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If I put the transistor into the tester the other way it reverses the order . I will send a photo each way. It may just be the way I tested
Transistor tested both ways attached
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If you don't mind me asking ,Does it look like the transistors are good or should I replace them,
Transistors seem to be OK, but they don't match the other channel. You can put them back in and take voltage measurements of EBC voltages for all transistors and compare against the schematic. Maybe that will provide a clue.
When you tested the transistors before in post #1024, were they in circuit or out of circuit?
When you tested the transistors before in post #1024, were they in circuit or out of circuit?
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They were in circuit
