Need Help Guys! Vintage Fisher Transistors

BrassTeacher

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I need help, if anyone can provide. My usually successful digging around the internet has turned up nothing so far.

I have a Fisher 500T receiver on the bench with distortion issues. The necessary repair is simple enough, except for one thing: ALL the transistors are marked with a Motorola logo, and an "in-house" Fisher part number. I was sure I'd have spares from the working (but cosmetically destroyed) Fisher 440T receiver I had. Unfortunately, the transistor part numbers are different, even though the main driver boards appear to be identical.

Does anyone have any access to old Fisher service info, especially if it is specific to the 500T, that can help me identify these transistors, and hopefully come up with modern equivalents?

Thanks!!!!
 
Don,
I have a pdf manual for the 500Tx which is applicable also to the 800T so I think it would work for you. It also has the house numbers for reference unfortunately. If you're interested, pm me.
Sparky
 
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Just for grins: On some of the small-signal transistors that are known to be good, what's the voltage drop between emitter and base? If its close to 0.6v, you're dealing with silicon. One or more of them on that old a piece my still be germanium?

That will make things more fun. I do know that NTE _used_ to carry germanium replacements but haven't checked in years.

There were times, as an old bench tech, when I had to reverse-engineer amp stages for problems like you're experiencing - no specific transistor specs to reference. Makes it quite a challenge and I couldn't charge more for the extra work, either.

Cheers,

David
 
OK, good for our OP...and apologies for stirring the pot with too much worry.

Cheers,

David
 
Well, the plot thickens, but I'm no better off. I have a friend that stripped a Fisher 500T a few years ago, and he put all the amp board transistors in a bag. I was ready to jump for joy when he showed me, but my hopes were quickly dashed.

All of THESE transistors had real RCA part numbers on them! :(. Still, should be easy to identify, right? Wrong. All the case styles for the small signal transistors are totally different (earlier) types. At least I can take my diode checker and figure out which driver transistors are NPN/PNP, and start plugging those in, and I have a spare set of outputs just in case, but any help on the small signal types greatly appreciated!
 
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