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Old 04-21-2015, 04:34 PM
rca2000's Avatar
rca2000 rca2000 is offline
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Join Date: Mar 2003
Location: cincinnati,ohio
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WHY do germanium transistors test so WEIRD ??

So I have this rock-ola juke box amp to re-cap. I have done this....no real problems. BUT...when I went to check on the ckt. resistance on the negativbe B- supply rail (for the output stage-which is PNP GERMANIUM transistors) ..it checked LOW_-about 50 ohms or so across it. (n ONE direction ONLY though.) SO i checked the output transistors--delco PNP germaniums and they checked LEAKY...or so I THOUGHT. From E to C--they checked around 50 ohms or so ONE way...BUT the other way--they did NOT do this..the fluke meter just flashed "ol"... crazily. on diode test they do NOT show right at ALL.

B-to E and B to C checked similarly weird one way MUCH worse than the other. All FOUR transistors showed this. So I figured I had bad trannies. But this amp was supposed to WORK--it just needed re-capped to make it "whole".

THEN...I recalle that germanium transistors DO check different than silicons. I went and stole a couple of them out of a Zenith amp that is supposed to be working...and they checked about the SAME way.. Somewhere about 125 ohms or so one way E-to C and high the other way.

WHY do they show like this Normal si trannies do NOT . Is this normal for them ?
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