AU-D9 for restoration

[Hyperion]

A small allen key?

No, 'push fit' - like all the other knobs.

Here's something weird, I was just looking at the volume knob for this one, and found 2 large black screws stuffed into one of the recesses in the back of the knob!

Another odd thing, someone had smeared some kind of black grease (graphited grease?) all over the sliding MM/MC switch rods, and around the selector switch bushes in the front panel.

 

[AUD101]

The black grease in those locations are factory - usually just in the area where the MM/MC switch rods meet the plastic standoff's and around the selector switch bushes as you have noticed - guessing to reduce wear and friction at those points

 

[P. Hageman]

John, I think you mean this black smear Its also on my D9 (see pic) I finally got the volume knob off, it had a 1,5 mm allen head screw. and no two large black screws So now I have the front face off and hope to reach into the balance potentiometer with some deoxit, because it screaches (is that an English word?) when I turn it.

 

[EngineerNate]

Yes, that's it - quality bipolars didn't seem to exist back then, or at least were more expensive that 2 standard ones back-to-back. But now, a purpose made audio grade bipolar is far better than 2 back to back.

I noticed it in the feedback loop of the MCS I rebuilt recently. I replaced with two bipolars of equal value instead of jumping because I'd already ordered them. I went with Nichicon Muse bipolars everywhere in the signal path that didn't specifically need a low leakage or was too large for a poly cap.

If I remember right, you halve the value when you replace with one bipolar?

 

[Hyperion]

because it screaches

'screeches'

Your picture - exactly like this one.

Funny about your volume knob, mine is definitely a 'splined' shaft volume control with a push fit volume knob.

 

[Hyperion]

If I remember right, you halve the value when you replace with one bipolar?

Yes. correct, in theory you should also add the voltage ratings - so Peter was right in his thinking when he asked about 100V (50+50), but in practise using the same voltage as the 'singles' is almost always OK.

So 2 x 10µF @50V to form a bipolar of 5µF @100V rating - replaced with one Nichicon ES 4.7µF @50V rating.

 

[Declivita]

Driver Board

Completed with its new components
View attachment 1577272

Parts replaced:-
16 Electrolytic capacitors. (2 replaced with film capacitors).
4 Trimmers.
4 Zener diodes.

I added thermal compound between the 'horseshoe' multi junction diodes and the tabs of the driver transistors, you can just see this in the picture.

Noticed the output driver capacitors original's are rated at 470 uF 100 volt and the replacements put in are only rated at 680 uF and 80 volt's... isn't it normal and diligent to go up an voltage increment rather than down one..?

 

[Hyperion]

Noticed the output driver capacitors original's are rated at 470 uF 100 volt and the replacements put in are only rated at 680 uF and 80 volt's... isn't it normal and diligent to go up an voltage increment rather than down one..?

I wondered if someone would notice that.

The main smoothing capacitors for the AU-D9 are rated at 71V, the service manual indication for the expected main rail voltage is +/- 62.2V, this example shows roughly that voltage at the relevant points. So I decided to increase the value of those local filtering capacitors, and at the same time in view of the above I also decided to reduce the voltage rating a little. It is a little odd that Sansui decided to use 100V capacitors in those locations, and those capacitors are even listed in the Service Manual as 470µF, 100V. - Sansui probably bought enough capacitors for the whole production run of AU-D9's in one go, so component availability issue at the time perhaps? - I don't know.

 

[Declivita]

I put in 5,000 hour life rated Panasonic 470 uF 100v FC series electrolytic , with a ripple rating of 1.92 amps and with a low ESR of 47 milli ohm's...! was disappointed with them so boosted them with another 47 uF in parallel on the underside of the MB ....but keep thinking I should have perhaps gone with the Nippon chemi-con GPA series that were similar looking to the originals..! the GPA series have a ripple rating of a bigger 2.5 amps... but didn't go for them, as they also had a higher ESR rating of 1.3 ohm's...

 

[AUD101]

Like John - I also went with 80V cap's (470u) in these positions - Nippon Chemi-Con - KZE Series (18 x 20mm) - Voltage across them approx +/- 61.2V

 

[Hyperion]

EQ Board

Before (I did start at the bottom of the board and removed the two large electrolytics, and cleaned the glue, +five new capacitors fitted - that took well over an hour to do).


After


Well that was a lot of work, 45 capacitors removed, 39 replacements fitted, and 5 zener diodes changed, replacement trimmers are not fitted yet, I'll do that when the board is re-mounted in the chassis.

 

[Hyperion]

I received two more trimmers today, as the ones I bought for the EQ were never going to work the way I had initially thought - so I copied the trimmer solution from @P. Hageman (same as @AUD101 ) - and it works very well. I re-installed the EQ board and it dialled in perfectly. - and it sounds excellent !!!

I am on the home straight now, just a few more things to do and it will be finished.

 

[AUD101]

Any pic's to share of the PCB side trimmer install?

 

[Hyperion]

Any pic's to share of the PCB side trimmer install?

Yes of course, more pictures to follow.

 

[Hyperion]

The trimmer installation



A rare event happened in order to install these trimmers, I actually had to change my soldering iron bit ! - from a conical tip to a fine pencil tip - so I could solder the middle legs (hidden in this picture), of the top and bottom trimmers.

Additionally, although very difficult to see in this picture, I have placed fibre washers under the left hand heatsink screws (on the left, top and bottom) to prevent any chance of the screws shorting on the very close nearby track.

 

[AUD101]

With kind permission granted from John (so as not to hijack his thread)


Speaker A & B relay's replaced on Protector PCB F-3259



Parts acquired to replace the Speaker B relay - Omron G2Z-222P-US

Relay: Omron G2RL-2 - 24V DC (note the two inner pins need to be cut off as they are redundant)
Relay adapter PCB & Pins from Audioberg

 

[Hyperion]

And finally...



83 Capacitors
9 Zener diodes
8 Trimmers
4 Output Transistors (not shown)
2 Resistors
1 Relay

 

[EngineerNate]

Nice knoll job.

 

[KeyserSozee]

Nice job, very well done.... the 4x pots on the PSU / EQ board can be adjusted without removing the circuit board from its mounting location.
There are small holes through the circuit board to allow a (very small) screwdriver to be inserted from the back, adjusting the pot from its 'bottom'.

The Bournes (multiturn) pots are great for their fine adjustment... but I thought I'd just point this out for anyone servicing a AU-D9 in the future.

 

[RA Kowal]

Hello,

I am recently retired and am embarking upon audio restotration work as a hobby along with repairing vintage BMW airhead motorcycles ( a cliche of the 1960s old-guy in the garage tinkering...)

I am starting with some of my own personal gear which includes a Sansui AU-D9. I purchased this new back in the early 1980s. A few years ago the phono section developed problems. I took it to a reputable shop in Chicago who declined to work on it, saying it would be best to find a donor amp and replace the entire power supply board. Now I have decided to start my restoration with this board. The rest of the unit functions reasonably well although the DC offset on one channel is higher than I would like at 29 mv compared to 16 mv on the better channel.

I plan to replace all the electrolytic capacitors on the power supply board. Some have clearly leaked or swelled. I am having trouble however finding replacements for the tiny old polystyrene capacitors. I do not yet trust my schematic reading skill enough to determine the specs for these.

May I ask if you have a list of the capacitors and other components you replaced on your AU-D9 power supply board?

I am now equipping my bench starting with a nice Tektronix 2235 scope I found locally in Chattanooga and an SG-502 oscillator I just purchased on e-bay.

Thank you. Kind Regards, RK


Hafler P225
Hafler P125
Bryston 1B
Magnepan SMGA
Magnepan MG II
Kenwood KR-5600
ProAc D25
Sansui AU-D9
Sansui TU-517
Denon DP 61F
Denon DP 30LII