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BA-F1 restore

That left channel has a nice variety of parts thrown at it. Looks like the drivers were replaced at least. What outputs are in it?

Edit: oops. Right channel I meant.
 
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The left channel is relatively untouched, and has the original outputs (NMA/NMC1012) attached, it was one of these that was showing that 10Ω short. Something nasty must have happened to the right as I see an assortment of replaced semiconductors and different resistor types - I'll be rationalising that in due course. ;) This channel also has the replacement OP transistors MJ15024G/MJ15025G, which are some of the best currently available power transistors you can get in a TO-3 style metal case these days for our purposes, along with MJ2119X pairs.
 
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ManyMoonsAudio said:
You going to stick with those outputs?
Click to expand...

I would like to get an original set (2+2) for the channel with modern replacements if found reasonably quickly and not too expensive. Or I might change the replaced set for MJ21193G/94G (or 95G/96G) - however these seem to be getting a bit more difficult to get easily. (short stock - long lead times etc). I don't think there is much likelihood of changing all for TO-3P replacements as it stands at the moment.

I need to discuss this with the owner - as he'll be paying for any replacements. :)
 
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Hope your customer lets you do what you think is best. With this caliber of amplifier, I wouldn't give them the choice.
 
We have decided that we will fit a full set of TO-3P replacements, and remove the (as yet) undamaged originals.
 
Hyperion said:
you guys with all that popcorn
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Lets see those TO3P
 
Interesting direction. Why though? You have a good set of originals in one channel, the 2SA1117 and 2SC2608 are absolutely perfect replacements for the other channel. Once you take care of those black mica caps, the amp is stable.

Don't take this wrong. I am very curious to see how you mate a flat pin in a round hole, so here's my popcorn:

:lurk:
 
Yes indeed, Z doing another nice job there.

What it boils down to, IMO, is that 2SA1117 and 2SC2608 are rather standard devices (too poor for this Sansui) with limited bandwidth (fT),poor beta-drop and much higher Cob.

2SA2223A & 2SC6145A are so-called high-fT devices, with low Cob, and of top of that a very linear Beta-Ic curve, making them VERY good output devices for which this Sansui was designed around.
 
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