Franken Sansui AU-999 Build Up

This thread will detail the build up of my AU-999.

I bought it from someone who raped all the boards and some of the switches out of it when it broke. Thankfully, it was inexpensive. relatively...

It's a good lesson to teach people to sell broken stuff, complete and whole. Just because you can't fix it, doesn't mean that someone else can't. Often it will sell for pretty near what a working one does. So don't gut it without trying first. That said, it took someone parting one out for me to get the parts that I needed.

Cosmetically it's in excellent shape.

Every plug in board (two tone, one filter, one phono preamp, two amp drivers) and the wired in ones underneath (two ripple filter, one preamp power supply, protection HA!) were missing. So was the power switch, and another switch was broken off. The power transistors were pulled too.

I've managed to buy the two tone boards, the filter board, and some switches.

The power switch is pretty much unobtanium. I'll be building a soft start circuit with two power relays and using the regular switches which are low current.

I still don't have a phono preamp board for this one, so I'm gonna put a Rod Elliot P-06 phono preamp in it. With Sansui MC transformers.

I'm also going to install a loudness circuit, with an Alps pot with loudness taps. Still looking for that though.

I need to build a preamp power supply board too, but that won't be too hard. I don't need to replace/fabricate ripple filter boards because I am replacing the power amp in it's entirety.

I'll be installing a new TC7123 based relay protection circuit in this once the amp is installed and working.

The power amp is from China, a copy of the Destroyer X amp that's so popular on DIYAudio. It comes with Toshiba 2SA1943 2SC5200 output transistors, but I will be using OnSemi MJ21195G and MJ21196G. Because I already have them, and also to be T03s to mount on the AU-999 heatsinks.

If you want to see the amp modules search ebay on "DIYAudio "destroyer X" DXAMP Amplifier kit".

I'll also be recapping the preamp boards and replacing all the transistors with new Fairchilds. The main capacitor filters will be upgraded to about triple capacity with film bypass caps. I will install them in the chassis to preserve the classic under hood looks.

So, that's the plan. I'll post more as it gets done. The amp boards should be here within a month.

Wow the amps are here. 10 days from China!

No docs. Nuthin. Just parts in a bag. Not for the squeamish...

Sounds like a long term project....good luck with build.....

Some pics today
I'm gonna host them on photoucket to conserve AK space.
I won't embed them cuz they are huge.

This is the short URL for the whole pic folder.
http://photobucket.com/Franken99

Today I removed the chassis mounted driver transistor sockets and the driver board card sockets. I also removed the bias transitor holder from the TO3 sockets. I won't be using them, and they'd just be in the way.

Bottom pic of chassis with parts removed.

Top pic of chassis with parts removed.

One of the primary reasons i chose the ebay Destroyer X clone power amp is the card size will fit within the chassis of the Franken99, standing up like the original cards. The other reasons were cost, and reputation of the circuit.
Pic of amp card standing in front of the heat sinks.

I installed the replacement switch mechanical guts in my broken switches. Swapping over the lever assy is easier than unsoldering from the wafers, and safer.

As I was about to wire up the balance test switch I realized that I would never use that function, and I needed a switch for the loudness circuit I am going to add. So that's the one.

I also determined that I am going to reuse the tag board for the "mystery components" (Subsonic filter actually, see my other thread about that) to mount the loudness components. There's already shielded wiring going to it, and it's a handy size for the loudness circuit.

pic of original mystery components (Subsonic filter actually)

All the lamps will be replaced with LEDs. I'm going to reuse the original bridge rectifier for a new LED supply. I will add a much larger bridge rectifier for the main supply, along with much more capacitance.

I need to find that Alps pot with loudness taps now. Or maybe I'll just find one I can steal from a parts amp.

Cool project, that au-999 is one sharp looking piece of gear.

You might be interested in these (no affiliation)

http://cgi.ebay.com/ws/eBayISAPI.dl...02&ssPageName=ADME:B:SS:US:1123#ht_500wt_1156

Ha! Those are mine.

I don't need them anymore. The drivers I'll be using are on the new amplifier boards.

I received the volume pot with loudness taps from China.



It is an Alps copy, but it was the only thing with loudness taps and the right resistance, and physical measurements.

I've researched the components necessary to duplicate a loudness curve that I like. I looked at the Sansui 771, Eight, Eight Deluxe, Seven and Six. The Six, Seven, Eight Deluxe circuit wins. The Six schematic has a typo though, showing the 390pf cap as an 890 pf.

The components are:
390 p
22k
.022 cap