VintageKustom.com - RDF feed
http://www.vintagekustom.com/FUDforum/index.php
Transistors?
http://www.vintagekustom.com/FUDforum/index.phpindex.php?t=rview&goto=24985&th=4285#msg_24985
Now, on Q205, that's a 2n5088, right?
Are there any transistors on these boards that are not EBC pinout? Someone before me put a black mark on what I am guessing is the Emitter, but I can't be 100% sure...]]>Shaun_Musings2016-05-16T02:16:20-00:00Re: Transistors?
http://www.vintagekustom.com/FUDforum/index.phpindex.php?t=rview&goto=24986&th=4285#msg_24986
Have replaced all of the electrolytic caps on both boards ?]]>stevem2016-05-16T16:04:39-00:00Re: Transistors?
http://www.vintagekustom.com/FUDforum/index.phpindex.php?t=rview&goto=24987&th=4285#msg_24987
Yes, as Steve points out, the 2n4249 is a PNP transistor that is part of the low frequency oscillator. You need to use another PNP transistor there.
All of the original transistors use the E-B-C pinout. You can figure out which lead goes where by looking at the schematic and comparing the pc board connections with the schematic connections.]]>chicagobill2016-05-16T17:02:27-00:00Re: Transistors?
http://www.vintagekustom.com/FUDforum/index.phpindex.php?t=rview&goto=24990&th=4285#msg_24990
A4 - MKI - "Alice"
A4 - MKII - "Beth"
A4 - MKIII - "Cindi"
Which was in poor taste because the real A4, the first one, was the V-2 prototype. Blame Bud for the letter and number designations =)
So the first one I am working on is Cindi. Power amp section is fine, but when I activated the trem/vib, I could hear the trem/vib working, or at least, it was doing whatever it does to the signal, but the speed and intensity were doing nothing. I changed out the 2n4249 transistor (Q309) with a 2n3906. It was only then I realized I had removed the black mylar cap to clean around the speed pot (C316) and forgot to put it back.
Ahh... It's working, but with a catch: there's a tick in the speed knob, which I hear is not as rare as I thought. What should be the next step? I'm thinking of following the crazy signal path and remelting and soldering all the joints to make sure that all connections are good (which is always a good idea anyway), but are there any 'easy fixes' that you gentlemen are aware of that fixes this?
The other amp whose trem/vib isn't working is 'Alice' - the circuit breaker head. All I did with that head was replace a few transistors that were snapped off and recapped it. I'm not focusing on it right now; one amp at a time.
Finally seeing the end of the road here... I started fiddling with Beth back in December, working on it for three months before picking up Alice off CL for $100. Beth is still waiting for me to swap out the power section of an A-5 donor head kindly shipped to me by Terry =)
SDC]]>Shaun_Musings2016-05-16T20:13:44-00:00Re: Transistors?
http://www.vintagekustom.com/FUDforum/index.phpindex.php?t=rview&goto=24995&th=4285#msg_24995
stevem2016-05-17T10:21:01-00:00Re: Transistors?
http://www.vintagekustom.com/FUDforum/index.phpindex.php?t=rview&goto=24996&th=4285#msg_24996
I put the red lead on the resistor, transistor, etc., and the black lead on the chassis, correct? Set it for voltage, correct?
The amp itself sounds great, so I really haven't done much else to it, but one thing I did notice was that when I tested the big filter caps yesterday, I got a +40vdc, and the other one read -.01 and then zeroed out. That doesn't sound right, but the amp itself sounds so amazing that I'm reluctant to mess with the power supplies.]]>Shaun_Musings2016-05-17T11:43:59-00:00Re: Transistors?
http://www.vintagekustom.com/FUDforum/index.phpindex.php?t=rview&goto=24998&th=4285#msg_24998
stevem2016-05-17T14:26:44-00:00