Welcome to Solid State Guitar Amp Forum | DIY Guitar Amplifiers. Please login or sign up.

April 30, 2024, 05:55:42 PM

Login with username, password and session length

Recent Posts

 

Marshall VS100R transistors

Started by markorock37, March 01, 2024, 12:34:07 AM

Previous topic - Next topic

g1

Yes it would seem T1 is bad as you verified R5 and D1.  But you also need to check their solder connections.
As T1 and T2 form a differential amplifier, it is best to replace them as a pair.

markorock37

I don't see 2SA872 on Mouser, is KSA992 a good sub?

g1

Quote from: markorock37 on April 13, 2024, 02:57:58 PMI don't see 2SA872 on Mouser, is KSA992 a good sub?
Yes, those should work.

markorock37

Well, I've replaced T1 and T2 as well as D1. Still reading pretty much the same voltages. At this point, all transistors have been replaced in the amplifier portion. I hate to deem this unit a loss but I am leaning that way as it was quite a mess with the traces from prior techs. Im 99% sure I have all the traces repaired correctly.

saturated

Hang in there bud  8)

Don't give up before the miracle  :P

If anybody can get your amp running these guys can.

Maybe post up some pics of the boards

 :)
I ask stupid questions
and make stupid mistakes

criticism, critique, derision, flaming, verbal abuse welcome

g1

Yes, pictures should help.  Especially of any trace repairs that have been done.
Also, e,b,c voltages for T3 and T5.