Sansui AU-317 MK2 Repair/Restoration.

[Sh1mmy]

I've had this amp which I bought at the tip shop for just $10 collecting dust for the last 4 years.
Twice in that time I pulled it out, pulled the covers off, had a look and put it in the "too hard basket" after remembering why I put it away the previous time.

It was labeled as "not working" but was hopeful it'd be a simple fix, especially when lifting the cover and seeing the date and bias voltage on the shield dating to just a year prior.

But alas, it had many problems, a simple fuse was not one.
I posted up on an existing AU-317 restoration thread, where I had attempted to diagnose the issues but quickly found I was getting in too deep for my knowledge and confidence.

I also considered sending it off for repairs, which I never really followed through with.

 

This time however, I'm wanting to actually get this amp going and wanting to do the work myself, and put in some time to learn the hows and whys, for most of my electrical knowledge is with much simpler workings and most of that I've forgotten.

I'm hoping it'll take the place of my Monarch Series 8 Model 88 amp which is in the middle of a Rega RP1 with a Nagaoka MP110 and a pair of Acoustic Research TSW 210 speakers.

 

I've also found a service manual and several pages of others restoring/repairing this particular amp which so far has proven helpful, I'm also hoping to lean on the knowledge of a few on this forum who know their stuff to help get me by.

 

So far I've concluded that the left channel has the most issues and failures while the right has so far only a few. 

I've found 3 dead output transistors, 2 of which are clones,

2 dead driver transistors,

Several faulty, burnt or out of spec resistors.

And a few out of spec capacitors.

It also had a fair bit of dodgy looking solder joints, original and from it's previous service.

 

During the service before my ownership it seems a few capacitors were replaced with those sold at DSE, brand of Hitano and another brand that I've yet to identify (havn't removed them from circuit, tested fine in-circuit).

I'd like to replace as many as I can while I'm at it anyway.

I'm only looking at the power amp at the moment too, haven't looked at the other boards yet.

 

A couple of questions for now though.
Is it worth checking every transistor, resistor and diode, I'm assuming it would be but curious if there are any known problematic ones?

If so, is it worth buying the jaycar in circuit transistor tester? I don't see how it would function any differently to a diode test on a multimeter is all.

I can't test the ceramic or film capacitors as my multimeter doesn't seem to go low enough, and my old meter, a cheap digitech doesn't seem to be accurate.

Replacement output transistors, 2SC2261 with MJ21193G and 2SA981 with MJ21194G OR 2SA981 with 2SB554 and 2SC2261 with 2SD424.

Would there be any audible difference between them?

Where is a reliable place to buy them?

Also where is a reliable place to buy new capacitors and driver transistors?

 

 

And because no thread is worth anything without pics, here are some old (when I got it) and new pics (crappy phone pics for now).

 

Edited August 30, 2017 by Sh1mmy

[sloper]

Goodaye

 

Have done 2 AU101 an AU505 now, apart from a  couple of dumb mistakes got them done easily.

 

The first 101 l got original transistors off ebay from England, used Panasonic and Nichon caps from RS.

It had a bad tranny on the tone board, replaced all and it came good, then did the caps.

Then modded it.

 

The second 101 has A Fairchild replacement transistors  on the tone board

Had a bad tranny on the power board, found that by tapping it, matched 2 transitors as replacement.

Also replaced 2 power transistors as they were mismatched.

Then capped it and modded it.

They sound  a little different now, took the panasonic coupling cap modds off and used the Jaycar crossover caps, sounds much better got some Jantzen coming some may try those.

l 'll admit l put one leg of the power cap in a support hole.

 

The 505 has fairchild transistors in the tone board as one was making the left channel scratchy.

(note spec sheets for the replacement was top view original bottom view, yes l did put them in the wrong way around )

Fitted and modded he caps.

 

Eviel bay will get you original transistors, they will cost  a little more and l would avoid buying from China.

Modern transistors and caps l used RS.

 

Do it all in stages and test it.

 

And l need to thank a certain member, he knows who he is.

 

regards Bruce

[blakey72]

@skippy124 or @pete_mac

[Sh1mmy]

@sloper

 

Nice, since actually diving into it proper, I've come to realise it's really not that difficult or daunting (well it might be a bit daunting when it comes time to turn the power on, haha), it's just a process and a trial of elimination.

 

I did find "original" output transistors on ebay that "seemed" original with the font and thickness and all, also from the UK I think, but still wasn't 100% sure.

I found Mouser who seems to sell individually, I've yet to have a proper look though.

Need to make a list of all the bits I'll need too, are Panasonic and Nichion the main go-to brands for caps?

 

I just had another look at it now, pulled all the transistors on the power board and tested, they all check out fine (aside from the previously mentioned driver and output transistors).

One had been replaced though, TR11 with a C3245 where a 2SC 1951 is supposed to be.  

Looking around, to my eyes it doesn't seem to be an appropriate replacement and a better one could be put in it's place.
Anything I replace on one channel I'd like to replace on the other too, to keep them as close as possible to each other, although I'm not sure how much difference if any a single transistor would make, I'd still know, haha.

 

Next I guess I'll check the diodes, pull a leg out and test.

Then finish off checking the rest of the resistors, and try and properly identify a couple that I can't quite make sense of yet.

[pete_mac]

13 hours ago, Sh1mmy said:

@sloper

 

Nice, since actually diving into it proper, I've come to realise it's really not that difficult or daunting (well it might be a bit daunting when it comes time to turn the power on, haha), it's just a process and a trial of elimination.

 

I did find "original" output transistors on ebay that "seemed" original with the font and thickness and all, also from the UK I think, but still wasn't 100% sure.

I found Mouser who seems to sell individually, I've yet to have a proper look though.

Need to make a list of all the bits I'll need too, are Panasonic and Nichion the main go-to brands for caps?

 

I just had another look at it now, pulled all the transistors on the power board and tested, they all check out fine (aside from the previously mentioned driver and output transistors).

One had been replaced though, TR11 with a C3245 where a 2SC 1951 is supposed to be.  

Looking around, to my eyes it doesn't seem to be an appropriate replacement and a better one could be put in it's place.
Anything I replace on one channel I'd like to replace on the other too, to keep them as close as possible to each other, although I'm not sure how much difference if any a single transistor would make, I'd still know, haha.

 

Next I guess I'll check the diodes, pull a leg out and test.

Then finish off checking the rest of the resistors, and try and properly identify a couple that I can't quite make sense of yet.

 

 

Element 14 or RS Components are your local choices for capacitors, transistors, resistors, diodes etc. Mouser or Digikey are your main overseas. Avoid ebay... too many fakes.

 

Definitely look at using Panasonic FC/FM/FR or Nichicon PW/HE series caps if possible, or even United Chemicon. They are cheap when purchased from the above sources.

 

You also have the opportunity to replace any of the smaller signal path coupling caps with film caps while you're in there. WIMA and Panasonic make compact stacked-film caps that will fit.

[Sh1mmy]

Thanks @pete_mac, I found a combination of of Panasonic FR and Nichicon PW/HE caps to replace all of the electrolytics from both Element 14 and RS Components, I tried to keep them all one brand and series but easier said than done it seems, at least keeping the same capacitance and voltage anyway.
Aside from the 2x 10000uf 56v filter caps, not sure what to replace those with, in circuit they tested around 8300uf each, have no way of testing resistance.

 

I'm also replacing the following transistors.

2SB 527 with MJE 15031G

2SD 357 with MJE 15028G

2SC 2261 with MJ 21194G (or MJ 15015G ?)

2SA 981 with MJ 21193G (or MJ 15016G ?)

2SC 1951 with ZTX 694B

 

Any idea if they will be suitable replacements?

I found most of those suggestions on other forums.
Can't remember where I found the 2nd option for the outputs, but looking at the spec sheet, they didn't seem too far off ?

 

Is it worth replacing the bias pots?

If so, what could I replace them with?

 

[Sh1mmy]

I also have to replace TR09 and TR10.

2SC1313 with KSC1845FTA.
From the info I've read so far, the KSC1845FTA has opposite pin layout, the 2SC1313 mounts in place where the flats on them are on the heatsink with paste.

The replacements won't, will they still be ok for this use?

 

I've now checked half the resistors and 18 of them are out of spec or faulty.

About to get started on the rest of it.

 

 

Edited September 2, 2017 by Sh1mmy

[Asteroid]

My AU217 had the transformer primary go open circuit. ☹

[Sh1mmy]

That would have been annoying, were you able to replace it?

 

I'm pretty certain the majority of the issues on mine is limited to the power amp board.

It'll near be a new amp by the time I'm done, only a few original bits will be left in it.

 

I've got 42 resistors to replace.
Only 6 of them aren't really needed but I'm replacing them anyway as they look crispy and to replace the same bits on both channels at the same time.

 

About to get started on checking the diodes.

I'm up to $95 in parts as it is now.

14 transistors, 42 resistors, 22 capacitors (not including any film, ceramics or the filter caps).

 

The 1/2w resistors I'm going to have to substitute to 1w items, as I couldn't find non-flammable 1/2w versions.
Hopefully there'll be enough space but by my understanding, I think it'll help with some of the heat issues.

[Asteroid]

A full rebuild!

I sent mine to the "maybe later" pile, replaced it with a new Rega Brio.

 

The only sensible choice seemed to be having it rewound but even if it worked but would still be completely original and need servicing. Maybe one day.

 

 

 

[sloper]

Goodaye

 

how are you testing resistors?

Seems a lot of faulty ones.

 

regards Bruce

[Zaphod Beeblebrox]

On 9/2/2017 at 6:54 PM, Asteroid said:

My AU217 had the transformer primary go open circuit. ☹

 

Most likely a thermal fuse. With some dedication and care, you can often replace it. 

 

I have not done an AU-217, though I have done many others, including many Sansuis.

[Sh1mmy]

2 hours ago, Asteroid said:

A full rebuild!

I sent mine to the "maybe later" pile, replaced it with a new Rega Brio.

 

The only sensible choice seemed to be having it rewound but even if it worked but would still be completely original and need servicing. Maybe one day.

 

 

 

 

Yeah, it's quite a list so far, haha.
I had put it aside a couple of times now and after seeing some prices of these on ebay and such, and how good a rep they get for what they are I figured it'd be worth saving if I can.

Half the issue with not doing it before was I just couldn't be bothered too.

 

I do have concerns with replacing so much, as how much of the original amp sound and quality will remain.

 

1 hour ago, sloper said:

Goodaye

 

how are you testing resistors?

Seems a lot of faulty ones.

 

regards Bruce

 

These I'm testing in circuit with my multimeter.
Quite a few are visually faulty, burnt, crusty, discoloured etc.

A fair few look ok but measure all over the place.

There's a good few that still seem alright, along with a few that had been replaced before.

 

I do remember powering it up once and it had a resistor or two that instantly turned red, so at a guess I'd say it's had a lot of heat damage and over voltage or current.

I cut the power plug off it after this, as a reminder to not plug it in again.

I've got a feeling it may have been some sort of cascading failure to cause so much damage.

And I think the previous service may have had something to do with it, I'm not too certain, there was some poorly fitted components, poor soldering and it seems they did the bare minimum and cheapest way to get it going again.

The fuse resistors had been replaced, and measure fine, but I'd like to replace them anyway so I know what's in it. They are 5%, no idea on thermal coefficient.

 

I'm also really hoping that the dual-fet IC chips are fine, as it seems there are no real modern equivalent option.