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Old transistor ID help

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texaslonghorn

New Member
Hi all. I have a set of old TO-3 transistors pulled from an old HarmanKardon stereo unit. They are labeled SDT-9261 and - what I assume is the date code of 6741. Best I can tell from my measurements, these appear to be NPN with gain ranging from 7 - 17. The HK unit was a low power receiver/turntable combo unit. The manufacturer marking is a capital "S" in a vertical rectangle (STMicroelectronics maybe??) There are also 2 other TO-3's that are fairly pitted on the outside and are hard to read, but I think they are labeled 86 5043 2, then below that VFS2745K. No manufacturer marking is apparent. Any ideas? Thanks.
 

hotwaterwizard

Active Member
What is the Harmon Kardon Model number?
I have a few Schematics
 
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texaslonghorn

New Member
I don't know. I salvaged the thing for parts a couple months ago. Now I am trying to clean out my stash of "stuff". I did contact Solitron and all they said is that the part has been obsolete for over 20 years and they have no info on it.
 

texaslonghorn

New Member
I contacted Solitron (perhaps the current name for Solidev??) and they indicated it was their part but has been obsolete for more than 20 years and had no information about it at all.
 

Mr RB

Well-Known Member
TO-3 rarely have a critical spec, provided you replace them with a modern device that has at least enough Vce and Ice spec so it won't blow. Usually the gain etc is controlled by smaller driver transistors and feedback etc so you can slot in just about any NPN.

If they are in the output amp I would throw in some 3055's, if they are in some PSU regulator maybe a MJ or something rated for lots of amps.
 

mneary

New Member
Are these GOOD 50-(+)-year-old parts that you're trying to find a use for?

Since they were made when gold was only $35 an ounce, their best next use might be in a smelter. Sorry, not in its electronics, but in the hopper.
 

texaslonghorn

New Member
I don't need them for anything, nor am I replacing them. These are pulls from a receiver that I pulled a bunch of stuff from earlier this summer. I was just curious if these are worth doing something with other than throwing away.
 

shimniok

Member
If they work they are probably worth something to a person with one of these receiver/tt combos that blew up the output transistors. Not that I would know anythign about blowing up output transistors... :D

Of course finding that person might be tough even listing on ebay for a whole 7 days. :D

Michael

Michael
 
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