Re: TM5xx/TMxxx Pass Transistors. SUBJECT CHANGE, WAS: DC-508 repair advice

 

Hi Michael,
There a lots of possible replacements provided the voltage, current, and power ratings are equivalent. The other thing to watch for is be sure the replacement pass transistor leads are in the same order as the originals. Tek changed the parts they used over the years and you must make sure your replacements have the same order for the E, B, and C pins. Beyond these 4 things the package outline is the only other detail that you need to match.

The rightmost slot of the TM504, TM506, and TM5006 are high power compartments so they probably have beefier pass transistors.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Mlynch001
Sent: Sunday, December 15, 2019 1:49 PM
Subject: Re: [TekScopes] TM5xx/TMxxx Pass Transistors. SUBJECT CHANGE, WAS: DC-508 repair advice

Dennis,

I was able to find the original specs for my particular unit and then found some replacements that I thought might work. It has 5 bays with the same NPN and PNP parts and the high power compartment used something different. I found some replacements and then used the curve tracer to match the old parts to the new parts as close as possible. I’m going to look at what you have written, to see how close I got by dead reckoning and using my Curve Tracer. I appreciate your guidance, I always learn something from the members of this group.

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Michael Lynch
Dardanelle, AR




--
Dennis Tillman W7PF
TekScopes Moderator

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