Op Sun, 06 May 2007 14:01:06 +0100, schreef N Cook:

Richard Rasker wrote in message
news
Hi all,

I've got a rather old beastie here, a LAB Series L5 amplifier, apparently
capable of some 150 watts of output power, with a shorted end stage
transistor.

The transistor is an RCA type, with the following markings:

254 002C
RCA
CW 7923

The last number no doubt indicates the production year and week of the
transistor, but I can't find anything about this 254 002C type number.

could it be 40254 , Ge, PNP, TO3, 32V, 5A

Case style and .2V or .5V for VBE and NPN/PNP of any isolated/pulled working
ones would be useful

Thanks for your reply but no, it's definitely a silicon NPN tansistor:
VBE=0.79V, VBC = 0.77V. (And I wouldn't expect germanium transitors to be
used in amps from 1979.)
And my apologies for omitting important data; it's indeed a TO3 case;

Closer inspection of the end stage reveals that there's eight (not ten) of
these, in two groups of four, each group driven by an RCA410 transistor.
The '254 transistor emitter resistors have a surprisingly high value:
3.9 ohms each, at approximately 3 watts.
The power supply is some +/-55 volts, which would indeed produce around
150 watts maximum power in an 8 ohms load.


Richard Rasker

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