Sansui AU-D9 – Power transistors not amplifying after restoration

[rayma]

I only have a small note to point out, I hear a slight preponderance on the medium frequencies, which in some scenarios is also slightly annoying; of course I also tried with other speakers (ESB 75LD), and although with less evidence, it always manages to have a bit of emphasis on the medium frequency;

Please give the amp a few weeks to break in to be sure. This is unlikely, perhaps the preamp section tone controls,
are they out of circuit? The room acoustics are much more likely to be a source of tone change than the power amp.

 

[Pioneer_Exclusive]

I read on some forum that Toshiba has changed the logo and you can still find something with the new logo, but I don't know if the quality is the same or they are fake copies;
I found some pairs in an online store in my country, where I bought Sanken (2SA1295/2SC3264) for this Sansui and they work great;
it's a store where several repair technicians buy, maybe the ones he sells are NOS?

The transistor in the photo is most likely cheap Chinese junk and a blatant fake. 💩
The logo looks authentic, but China has no problems with such things. You can buy 10 pairs of 2SC2238/2SA968 on eBay for $4.14...
If you install something like that, it might even work for a while. But the next time you get it, under greater load, you'll destroy your beautiful amplifier... Best regards to Xi Jinping.

Be careful with such transistors. If you absolutely want originals, look for used parts instead.

 

[thimios]

You can buy original.Here.

 

[tonyEE]

I wonder if he has the 2SA1106 and 2SC2581. Those are the OEM for my Sansui G7500 and the ones I'm running now took almost six months to find, used, from a guy "who knew a guy" who was parting one of those receivers.

It'd be nice to have a spare set just in case.

@GESMAN The widely available TO3 "replacements" for my G7500 are much slower and sound different. The sound of my G7500 is indeed more midrange forward. It has a "lighter" sound with a good extended treble and somewhat lighter bass, but still quite deep. It feels "fast on its feet".

That's the best way I can describe, it's the house sound for all of those High Slew Rate amps. I assume your amp is similar in that respect? My receiver was built around '79..

There is no sense in rebuilding one of these Sansui amps unless you have to OEM transistors, that was the whole thing about the sound of the amp. Otherwise, go get a Kenwood or Pioneer.

This is a snapshot of the schematic showing the driver board and notations for the G7500. .

 

[wg_ski]

That’s somebody that had a big batch of them, not a store trying to push fakes as new manufacture. They look EXACTLY like the pulls, don’t they?

Probably got them in the late 80’s or early 90’s originally.