KTC transistors

[Mars Amp Repair]

Hello folks,
I'm repairing a Marantz SR6008 receiver with blown output stage (yeah I know, not guitar amp) and wonder if anyone has any experience sourcing these 'KTC' type transistors. I was hoping it would be like some of the other companies who just put their prefix in place of the standard prefix e.g. 2SC, 2SA, 2SK, etc. but no luck there. I could go through & try to match them all by spec, but I'm trying to save time as just not wanting to play guess-match parts as it's for another employer & time is an issue. Here is an example of a needed xistor: KTC3964 specifically listed as a temp tracker for output bias...not a 2sc3964. any ideas always appreciated. Thanx, glen

[Mars Amp Repair]

Say, I may be wrong about the KTA, KTC not being 2SA & 2SC (tho the specs seemed to ring that out). I found a supplier that all many find helpful: Audio Lab of Georgia (audiolabGA.com). They have subbed some of these KTA, KTC transistors to the 2SC, 2SA counterparts. They also have some of the actual KTA, KTC versions. I'll update as I discover more...thanx, glen

[J M Fahey]

Cool

In general, when house numbers are involved I straight play the parameter match game, or "what it´s suppossed to do".

Contrary to tubes or ICs, transistors are widely compatible, and in obsolete stuff (think 50s to early 70s) main problem often is weird obsolete casing and pinout.
Just last week, not sure it was here or at DIY Audio, somebody was repairing an old receiver , and needed transistor could be replaced by a BD139 or MJE340 case type transistor, don´t remember its TO case code, BUT instead of a metallic back, collector was connected to a coat hanger hook shaped (interrogation mark shaped) strip of metal leaving the middle of its plastic body AND its pinout was EBC instead of typical BCE or ECB.
Which forced Tech to get a dubious $18 "replacement" instead of a 50 cent modern one, which to boot beats it in all aspects.

Oh well.

[olddawg]

Cool

In general, when house numbers are involved I straight play the parameter match game, or "what it´s suppossed to do".

Contrary to tubes or ICs, transistors are widely compatible, and in obsolete stuff (think 50s to early 70s) main problem often is weird obsolete casing and pinout.
Just last week, not sure it was here or at DIY Audio, somebody was repairing an old receiver , and needed transistor could be replaced by a BD139 or MJE340 case type transistor, don´t remember its TO case code, BUT instead of a metallic back, collector was connected to a coat hanger hook shaped (interrogation mark shaped) strip of metal leaving the middle of its plastic body AND its pinout was EBC instead of typical BCE or ECB.
Which forced Tech to get a dubious $18 "replacement" instead of a 50 cent modern one, which to boot beats it in all aspects.

Oh well.

I used to “flywire” a lot of that stuff upside down... but it can be tricky when heat sinks are involved.

[nosaj]

Say, I may be wrong about the KTA, KTC not being 2SA & 2SC (tho the specs seemed to ring that out). I found a supplier that all many find helpful: Audio Lab of Georgia (audiolabGA.com). They have subbed some of these KTA, KTC transistors to the 2SC, 2SA counterparts. They also have some of the actual KTA, KTC versions. I'll update as I discover more...thanx, glen

Got 'em listed here and you might find some others in here that are good too. If you see something not there add it to here https://music-electronics-forum.com/...ad.php?t=49178
nosaj

[doctor]

In addition to prefixes that meet known standards (JEDEC, JIS, Pro-Electron), many manufacturers use their own prefixes. Components that differ only in prefix are often identical, but not necessary. Therefore, I would recommend referring to datasheets that consist all needed information.