[Solved] TSI361R - Identify obscure/old blown transistors

[zifk]

I got my hands on a fairly old and obscure frequency counter, the Apti-Meter 361R from transistor specialties inc.
It's a beautiful piece of kit with a great nixie display.


From the little information I can find about it (1), it's from the 1960s and is filled with Ge PNP transistors.

It has a few issues that I'm trying to work through, and so far I've identified two transistors which are shorted.
However, I can't find any information about the transistors themselves, as I believe they were custom, given the "TS" labeling on them. See highlighted cans on attached images. Both are labelled TS-1172, one additionally with 202 the other 208.


Does anyone know how I can go about replacing these?


(1) http://madrona.ca/e/edte/TSI361/index.html

[floobydust]

Tung-Sol Electric TS-1172 I did a dig and have no data.
I would consider generic PNP Si 2N2905, 2N2907 can (if heat diss. is important) or generic PNP Si plastic, or Ge if the circuit is critical about V_BE for 0.25V
Some people find Ge transistors short due to tin whiskers (inside) and blow them out using a power supply.

APTI Meters Instruction Book Models 361,361R, 371, 371R schematic, BoM etc.

[coppercone2]

can you like treat those ge transistors somehow to cure them, maybe temperature ?

[floobydust]

They zap the junctions to blow out tin whiskers, the germanium worshipers working on guitar effects pedals. Even pin-to-case.
For OP, I'd just evaluate the circuit if it must be Ge or not, and prefer to put in Si replacements which beat them in most regards.
Unless they want it all original.

[coppercone2]

but maybe you can annel them or something like that to stabilize the wiskers formation

[floobydust]

Annealing tin seems pretty hot 230-300°C? and where does it go? Fall inside I guess.
More pics here: NASA Anecdote: Tin Whiskers Inside of AF114 Transistors
They recommend tapping on the top, yeah beat up that transistor's whiskers lol

[fzabkar]

Some historical stuff here:

http://semiconductormuseum.com/PhotoGallery/Photogallery_Tung-Sol_Historic_Germanium_Computer_Transistors.pdf

Tung-Sol Computer Transistor Data Sheet:

Shown above is the data sheet for the 2N1313. This type of documentation was typical of that supplied by transistor manufacturers to customers in large Handbooks or Data Books. This device was documented with an 8 MC cut-off frequency, or switching speed, which is quite slow compared to competing computer transistors from this timeframe, and this factor may account for the low sales volume for the product. After Tung-Sol exited the transistor business in the mid-1960s, the 2N1313 was second sourced by ETCO, General Instrument, Industro and Western Transistor Corp.

[zifk]

Thanks for all the info! Flood especially, I'm amazed you found that book, I searched long and hard for something like that. I have some nice reading ahead of me.

I'm fairly certain I toasted these two transistors. Luckily I'm fairly certain they don't play any critical black magic roles. The instrument was mostly working fine and counting beautifully until I went poking inside trying to figure out why the front reset button wasn't working . Otherwise, most of the transistors seem to be functioning just fine, so I doubt it's an age thing.

As best as I can tell, these two simply switch the ~-9V level used for the transistor logic, so I'll probably try some Si replacements after analyzing the schematic a bit more.

[coppercone2]

Annealing tin seems pretty hot 230-300°C? and where does it go? Fall inside I guess.
More pics here: NASA Anecdote: Tin Whiskers Inside of AF114 Transistors
They recommend tapping on the top, yeah beat up that transistor's whiskers lol

I was thinking more along the lines of maybe some how treating it to prevent future regrowth, after their vaporized. maybe you can relax the material some how

like with carbon comp you can bake them to regain their performance. that is much simpler system but the concept is the same

[zifk]

Well after swapping out the two suspected failures with some 2N4403 Si PNPs, everything is back up and running! Thanks for all the help and advice.