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In Reply to: RE: Thanks, but posted by M3 lover on December 09, 2016 at 14:09:00
However, your information about ability to drive difficult loads may mean my tech at the time didn't know what he was talking about.
Not necessarily that.Just sometimes even I thought loads were too difficult for some amps but the citation 12 was a great amp because it's a dual mono and I was looking at a modded schematic with FET outputs. Even the stock amp is a very good amp.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
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From the mid to late 1960s, there aren't too many ss amps worthy of that quote. Dynaco and Marantz were also decent, but the dual mono Cit 12 did prove itself rather well. Even today, a good example, simply rebuilt with upgraded caps and some resistors, is a pleasant surprise...
Resto highly recommended !
If it is a stock 12 it shares the main AC fuse. If that is not blown you do not have a dead short. You probably have at least one open emitter resistor and probably a shorted output, they had no current limiting.
I like real RCA 2N3773s for outputs. Some say you can use the 2N3055 but its Vce rating is too low. While most units can handle it, you are exceeding the limits. For drivers I remember a 2N3440 I think and its complementary of which I do not remember the number. Of course you could go ape shit and put MJ15024s in for outputs, which would probably melt the transformers before going bad. Not that bad an idea, they are like six bucks each at Digikey, and since they are a modern part you can probably get them all from the same lot number. Other places have them as well but I have had pretty good luck with Digikey.
None of this applies if it is a Nelson Pass modded unit. Everything is different. The only traces that remain are the power transformers, maybe the filters but I am not sure about that.
Ive been using the MJ15003 and MJ15004 in most SS amps. I have a lot of the 2N3055s still but use them for regulators.
The citation 12s I worked on have 2 fuses and it's been 3 years since I did the last one. They prolly had earlier versions with one.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Edits: 12/09/16
I stand corrected, it has been a long time since I worked on one. Now what the hell was I thinking about ? I distinctly remember working on a dual mono amp and saying "All they share is the AC fuse and power switch".
Still I would recommend a dim bulb tester after the fuse is replaced. Easy to build and saves alot of silicon. Those outputs are alot easier to get and to replace than the drivers. In fact now I remember it took a hammer and punch to get the originals off the heatsinks.
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