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Transistor replacement options

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Posted on July 12, 2017 at 18:32:47
spindoctor
Audiophile

Posts: 1663
Location: Virginia
Joined: December 31, 2002
 I will likely need to replace a group of transistors in the Baldwin C-1 rebuild. The originals are RCA 36512 power transistors which I believe are germanium. If I replace these with modern transistors what are my options? I'm far more comfortable in the vacuum tube world so I appreciate the help here. This is a sentimental rebuild.

Sim

 

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RE: Transistor replacement options, posted on July 13, 2017 at 14:45:47
fredtr
Audiophile

Posts: 1987
Location: Phoenix
Joined: January 4, 2005
 Is 36512 stamped on the transistor? Are there any other numbers on the transistor? And just curious, has the transistor failed?

 

RE: Transistor replacement options, posted on July 13, 2017 at 16:30:37
spindoctor
Audiophile

Posts: 1663
Location: Virginia
Joined: December 31, 2002
 The 36512 is stamped on the transistor along with RCA. Other markings include FL and what appears to be 6? I suspect these are germanium. I also need to go back and check the rest of the circuit. More to follow. Thanks for helping.

Sim

 

RE: Transistor replacement options, posted on July 13, 2017 at 17:41:45
fredtr
Audiophile

Posts: 1987
Location: Phoenix
Joined: January 4, 2005
 Sorry I tried looking the number up in old cross references and OEM books and haven't been able to find it. I also found this RCA data book, didn't see it, but you should take a look:

https://archive.org/stream/RcaPowerDevicesDataBook1978#page/n5/mode/2up

Do you have a manual for the C-1? It is possible they had RCA select from a base device which may be explained in the manual. And it may be directly out of their application guide:

https://archive.org/details/RcaPowerTransistorApplicationsManual

There is an audio section. You could see if there is a match to the circuit.

And here is a simplified RCA guide:

http://n4trb.com/AmateurRadio/SemiconductorHistory/RCA_Semiconductor_Product_Guide_1963.pdf

They never offered that many audio devices, it could be a general purpose device, but I'm just not finding it, sorry.

 

RE: Transistor replacement options, posted on July 13, 2017 at 19:26:22
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 Also cross post this in the Tweak/DIY forum.

 

RE: Transistor replacement options, posted on July 14, 2017 at 03:46:00
spindoctor
Audiophile

Posts: 1663
Location: Virginia
Joined: December 31, 2002
 First, thank you so much for taking the time to do the research. I'm going to go back and recheck the circuits again and leave the power transistors to the end. I may ultimately need to replace them and rebuild the circuit around the new transistors. Thanks for taking the time to help.

Sim

 

Try the NTE help line, posted on July 14, 2017 at 06:48:29
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 http://www.sourceresearch.com/StoreWork/CrossList.cfm

Email them and sometimes they can help if the NTE search engine can't fine the parts cross reference

 

RE: Try the NTE help line, posted on July 14, 2017 at 07:10:16
spindoctor
Audiophile

Posts: 1663
Location: Virginia
Joined: December 31, 2002
 I emailed them and will let you know the result. Thank you for helping me.

Sim

 

Why do you want to replace them? Are they bad?, posted on July 14, 2017 at 12:20:21
Ralph
Manufacturer

Posts: 4778
Location: Minnesota
Joined: April 24, 2002
 -And if you think they are bad, why?

Are they the old doorknob style or the TO-3 case?

 

RE: Why do you want to replace them? Are they bad?, posted on July 14, 2017 at 12:42:43
spindoctor
Audiophile

Posts: 1663
Location: Virginia
Joined: December 31, 2002
 Thanks for responding. These are the round "door knob" types. But I've jumped the gun on this and need to do more testing. Tx.

Sim

 

You'll need a diode test functionality on your DVM, posted on July 14, 2017 at 14:22:35
Ralph
Manufacturer

Posts: 4778
Location: Minnesota
Joined: April 24, 2002
 Germanium transistors tend to show a bit of leakage when testing from emitter to collector. So don't reject them on that account unless they show a dead short or the same (and high) leakage in both directions.

If you do run into actually bad parts, I have a bin of old doorknob devices. For audio outputs they usually are not all that critical so its possible I have something on hand that will work.

 

I just have to say that I really appreciate the help from all y'all, posted on July 14, 2017 at 14:35:57
spindoctor
Audiophile

Posts: 1663
Location: Virginia
Joined: December 31, 2002
 I try to contribute where I have knowledge. I also know that I can post here and that even if it's a dumb question I'll get a good response!!! Thank you. I'll keep you informed as this project progresses. Actually I'm getting excited about this. P.S. This is the amp that Willy Nelson uses.


Sim

 

RE: Transistor replacement options, posted on July 16, 2017 at 20:06:24
spindoctor
Audiophile

Posts: 1663
Location: Virginia
Joined: December 31, 2002
 Replacements are ordered from Russia and they're germanium!!! ... more to follow.

Sim

 

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