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Vintage Asylum Classic gear from yesteryear; vintage audio standing the test of time. |
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In Reply to: Transistor replacement and some audio circuit understanding posted by jimkarl on July 31, 2014 at 19:17:51:
The diode test, as I understand it, is as follows:
For NPN transistor, place pos lead on base. Then you should see around 0.7 to 0.9V when the neg lead is placed on either the emitter or the collector. If the neg lead is placed on the base, the meter should read "open" when the pos lead is placed on collector or emitter.
For PNP transistor, the results should be exactly opposite.
It's not clear to me that you did the test correctly, but maybe you did.
Have you consulted a manual to determine whether 2N2869 and the 30203 are truly equivalent? Even if they are slightly different, you could verify your hypothesis by going ahead with installation of the 2N2869; if the bad channel is restored, you're on the right track. In fact, you could be done. As a source, try James Electronics in California. They have a good supply of "vintage" transistors. But your chances of fixing this thing for less than $9 are small.
As to the question of the balance control, why not just take it out of the circuit entirely? That will tell you right away whether it is a cause of problems.
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Follow Ups
- RE: Transistor replacement and some audio circuit understanding - Lew 07:08:26 08/01/14 (1)
- RE: Transistor replacement and some audio circuit understanding - jimkarl 13:37:25 08/01/14 (0)
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