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Sansui AU717 restoration


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Hi,

I am in the middle of restoring an AU717 that I acquired earlier this year, and I thought That this may be of interest to some SNA members.

The AU717 is the at the high end of the AU"X"17 series. The series starts with the AU117, and goes through to the AU517, and then finally the AU717. The AU717 shares much of its design with the AU517 (for example Dual mono power supplies). It is rated at 85W per channel, 20hz to 20khz with no more than 0.025% THD, and weighs in just a tad under 18kg.

The unit was acquired as not working, and without a base plate. It was in need of some TLC, as the faceplate and internals will attest.

AU717NFront1bc.jpg

AU717NFront2bc.jpg

Top cover was removed, and I think there must have been a half a kilo of dust all over the internals (tone control and equalizer covers also removed)

AU717Ntop1bc.jpg

Close up of one of the main amp modules

AU717Ntop2bc.jpg

Close up of a corner of the Power Supply PCA

AU717Ntop3bc.jpg

The amp suffered some damage during transport, the chassis has been bent slightly where the transformers mount, however that will be takan care of during the restoration

AU717Ntop7bc.jpg

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Love your work skippy ...amazing stuff

nice work John Is this one a keeper?

I admire your skills, great work! If only I had the ability to do this kind of work I would have saved a fortune in repairs and restorations over the yeas. Well done again, another classic Sansui back

First thing to do was give the entire unit a basic clean with a small paint brush and vacuum cleaner, and then remove the two main amp modules for a check over, full clean and recap. The 717, like the 417 and 517 have easily removable main amp modules.

AU717Noutputmodule1bc.jpg

The first thing to check are the fuse resistors, as I have indicated in previous threads on Sansui Amps, many have fuse resistors that give problems and should be replaced as a matter of course. Each main amp module has two 150 ohm fuse resistors, and they checked out as follows -

AU717NFuseRes1bc.jpg

AU717NFuseRes2bc.jpg

Definitely in need of replacement!!!!

As I was planning to do a full recap and also maintenance work such as removing the glue that was used to secure the larger PCA mounted caps, the amp modules were first stripped down for a clean.

Boards separated from the heat sinks

AU717Noutputmodule3bc.jpg

AU717Noutputmodule2bc.jpg

The output transistors were removed, and the then the transistor mounting bases also removed which allowed the heatsink to be fully separated from the PCA's (with the rear of the PCA's having been cleaned during the process.

AU717NoutputmodulePCArem1bc.jpg

Note the heatsink compound, somewhat dry and in need of replacement

AU717Noutputmodulethermalcompoundbc.jpg

The heatsink was then stripped of the mounting brackets, and all everything was given a good clean

AU717Nheatsinkcleaning1.jpg

Edited by skippy124
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The PCA's were also given an good clean, and them the modules were re-assembled

Output transistor sockets remounted

AU717Noutputmodule1ac.jpg

Output transistors placed in position (not yet ready for final assembly, I wanted to check them before putting them back in with new mica insulators and thermal compound

AU717Noutputmodule2ac.jpg

Outputs installed after all tested OK

AU717Noutputmodulefinishedbfa.jpg

Next was replacing the fuse resistors,

Existing fuse resistors

AU717NFuseRes1ac.jpg

New ones in place (taken after the caps were also replaced)

AU717NFuseRes2ac.jpg

Next on the list of things..... remove caps, remove glue and any affected components and replace caps

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Great reading keep it up...

Love your work skippy ...amazing stuff :thumb:

I admire your skills, great work! If only I had the ability to do this kind of work I would have saved a fortune in repairs and restorations over the yeas. Well done again, another classic Sansui back from the grave!

Thanks for your efforts in posting rebuilds, they are great reading :-)

Great work, I'd love to have that level of skill and knowledge. Thanks for sharing

Thanks for the comments, much appreciated

nice work John :thumb:

Is this one a keeper?

Hi Mark,

Yes, this one is going into the collection when finished, now looking for an AU217 and an AU117II and Pete and I will have the complete series.

Cheers

John

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The glue used to secure the large caps tends to go hard over time and will affect components that it comes into contact with, fortunately the glue hadn’t damaged any components on the main amp boards

AU717Noutputmoduleglue1.jpg

AU717Noutputmoduleglue2.jpg

Glue removed

AU717Noutputmodulegluegone.jpg

The electrolytic caps were replaced with a mixture of Nichicon HE, Panasonic FC and Panasonic stacked films were used for the 1uf caps.

AU717Noutputmodulefinishedbfa.jpg

Next job was to get the power supply board out for inspection

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The power supply board was removed and once again the dreaded Sansui glue was evident, and there were quite a few components that had been damaged by contact with the glue

AU717Npowersupply1ac.jpg

AU717Npowersupply1Glue.jpg

AU717Npowersupply2Glue.jpg

The electrolytic caps were removed, and this revealed the full extent of the problems

AU717Npowersupply3Glue.jpg

AU717Npowersupply4Glue.jpg

The glue had also run down the board in a couple of places, again causing problems with some components it came into contact with

AU717NPSUDiodegluedamage1.jpg

This is the diode pair that was removed in the photo above – note the corrosion

AU717NPSUDiodegluedamage.jpg

The glue had also run down and around/under one of the fuse clips

AU717NpowersupplyGluefuseclip.jpg

AU717NpowersupplyGluefuseclip1.jpg

Once these components are cleaned they will be re-installed, plus 10 resistors will need to be replaced and all remnants of glue removed. Once this is complete new caps will be installed….. watch this space for more photos once this is done

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Amazing work mate. :thumb:

Cheers!!

Some further progress has been made, the glue has been completely removed (needed to remove another set of fuse clips on the opposite of the board as the glue had run under these as well)

Diode bridge has had the corrosion removed and a cot of clear protective laquer applied.

AU717NPSUDiodegluedamagefixed.jpg

And the glue around the fuse clips removed

AU717NpowersupplyGluefuseclip2.jpg

And to show the importance of removing any glue affected components - this rectifier diode is one of several that are spaced off the board with small ceramic tubes, this is what was hidden by one of these spacers and shows the effect the glue can have over time -

AU717NPSUDiodegluedamage2.jpg

The PSU board finally ready for caps to be fitted (there are still two bi-polar caps on the board, I don't have replacements for those at the moment, but a couple are one the way

AU717NPSUreadyforcaps.jpg

And the finished result

AU717Npowersupply1newcaps.jpg

AU717Npowersupply3newcaps.jpg

AU717Npowersupply2newcaps.jpg

More instalments to follow....

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Great stuff Skip..............that amp looked near death at the start!

That glue is certainly evil stuff!

What solvent do you use to remove it?

Or is it mechanical?

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Thanks LP

I use a mechanical process to remove the glue, a strip of FR4 circuit board about 10mm wide with the end filed to a chisel shape, and this is used to scrape the glue off carefully. Then a final clean with isopropyl alchohol. Most solvents that will soften the glue will also take off the silk sceeening. The dried out dark brown glue usually comes off relatively easily, but the light brown glue that has not yet "gone off" can be time consuming to remove.

Cheers

John

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I recall working on a Sansui AU 414 several years ago- superbly built, but that rotten glue was really annoying. I used Shellite to help get the gunk off, but it seemed to take an age!

I replaced all the electro caps bar the main two big P.S. ones -then Shock, Horror!- modded the main power amp boards to improve the subjective sound quality! Needless to say, my customer who asked me to do just that, was stunned at the improvement!

Another happy customer! But boy, what a Wagnerian effort is was to get it there- dunno if I would want to do another in a hurry!

So hats off to Skip for tackling the job- I think your work looks a little neater than my effort was.

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Thanks for the comments!!

I think it might have been a 417 that you worked on tagstrip - very similar to the 717, a little less watts out and a single power supply rather than the dual mono that the 517 and 717 features.

A little more progress.......

I am waiting on a couple of caps to finish off the power supply board before I can start to put her back together, so tonight I had a go at the front panel....

Just a reminder of what it originally looked like

AU717NFront1bc.jpg

AU717NFront2bc.jpg

Well it wasn't much cleaner behind the front panel either.....

AU717NbehindFrontpanel.jpg

A clean of the panel and the knobs and lever switch covers, and she is back together again

AU717NFront1ac.jpg

AU717NFront2ac.jpg

AU717NFront3ac.jpg

I hope to have her back together again over the weekend, and will hopefully post up some final pics and some performance test results.

Cheers

John

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Ah yes, John you were right- it was a 417 I worked on a while back. I must be getting all lysdexic in my old age as eye carnott rumembah numbizz!

When you look at the great build quality of this series Sansui's it makes you wonder "What wuz they thinking wiv all that gloo everywhere!"

Talk about spoiling the ship (although very slowly) for a harp'orth of tar!

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Skippy,

I have an apology to make, I accidentally rated this topic with 4 stars instead of 5 due to fumbling fingers pressing the wrong spot on the IPod!

Your rebuilds definitely rate the full 5 stars!!!!!

Regards,

SS

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Ah yes, John you were right- it was a 417 I worked on a while back. I must be getting all lysdexic in my old age as eye carnott rumembah numbizz! When you look at the great build quality of this series Sansui's it makes you wonder "What wuz they thinking wiv all that gloo everywhere!" Talk about spoiling the ship (although very slowly) for a harp'orth of tar!

I know what you mean about eyes and old age!!

I wonder if they thought back in the 70's when these were being made that they would still be around 35-40 years later, and stiil be going strong (apart from the dreaded glue......)

wow John, that has come up a treat. Lovely work and thanks for sharing :)
Skippy, I have an apology to make, I accidentally rated this topic with 4 stars instead of 5 due to fumbling fingers pressing the wrong spot on the IPod! Your rebuilds definitely rate the full 5 stars!!!!! Regards, SS

Thanks Mark and SS, much appreciated

Well, the major part of the rebuild is complete, and she is up and running!!!

Pete dropped in the two bipolar caps that I needed to finish off the power supply board recap, and these were installed and the power supply board refitted to the chassis. I also checked the fuse resistors on the Tone control and Equaliser boards (four 82 ohm fuse resistors on each board), and these were either high in value or open circuit so all were replaced.

Two of the tone control board fuse resistors

AU717NFuseRestone.jpg

Once the power supply board was refitted, the two main amp modules were also put back in and the amp connected via a dim bulb tester to the mains, and power applied. The amp behaved perfectly…. It came out of protection, and preliminary bias and offset checks were done. Bias was a little high on one channel (not surprising given that the amp modules had lots of handling during the restoration and it only takes a slight movement of the adjustment pot to make a big difference in the bias current. The offset was just about perfect. A check of all control showed the balance pot was a little noisy and this was attended to. All other controls were fine. The dim bulb tester was then dispensed with, and final bias and offset checks were made……. It was then time to put the amp through its paces with a test CD that Pete burnt for me with a range of different genres, just perfect for this as I know each track pretty well by now…..

Some shots of the final result (pics aren’t particularly good….. black is hard to photograph, particularly indoors with flash.

Before the internal covers were put pack on

AU717Ntop2ac.jpg

AU717Ntop1ac.jpg

AU717Ntop3ac.jpg

Internal covers fitted

AU717Ntop2accovers.jpg

AU717Ntop1accovers.jpg

AU717NFront4acwithcovers.jpg

Next on the list of things to do before the restoration is completed is to order four new filter caps, and do a drawing of the base plate in order to get a new one manufactured. Once the filter caps are replaced, and the new bottom cover fitted, I may go through the tone control and equaliser boards and recap those as well. In any case I will continue to update this thread as further progress is made, and thanks again to all those who have posted in this thread.

Cheers

John

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Thanks LP

I use a mechanical process to remove the glue, a strip of FR4 circuit board about 10mm wide with the end filed to a chisel shape, and this is used to scrape the glue off carefully. Then a final clean with isopropyl alchohol. Most solvents that will soften the glue will also take off the silk sceeening. The dried out dark brown glue usually comes off relatively easily, but the light brown glue that has not yet "gone off" can be time consuming to remove.

Cheers

John

I use this stuff all the time to remove heatsink compounds in computers.

Best thing I've tried for it........saved me heaps of time over the years.

Oomph_Glue_Remover.jpg

Orange based.............and rarely causes side effects...........smells nice too!

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  • 1 month later...

Time for a little update!!

I have recently received a little something from Canada in the post

AU717NFilterCaps.jpg

These will be fitted shortly, along with the 10 turn Bias pots.

And today, I received something that I had been waiting for for a while now, but it was worth the wait

AU717Nbaseplate.jpg

A brand new baseplate to replace the one that was missing when I acquired the amp. Very happy with the way it turned out!!!!

Looking forward to getting these last items fitted and then having some serious listening time.

Cheers

John

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Oooooh... Now I'm excited!!

That custom baseplate turned out brilliantly. I'm speechless!

Time for a little update!!

I have recently received a little something from Canada in the post

AU717NFilterCaps.jpg

These will be fitted shortly, along with the 10 turn Bias pots.

And today, I received something that I had been waiting for for a while now, but it was worth the wait

AU717Nbaseplate.jpg

A brand new baseplate to replace the one that was missing when I acquired the amp. Very happy with the way it turned out!!!!

Looking forward to getting these last items fitted and then having some serious listening time.

Cheers

John

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  • 5 months later...

How's this one going John? Did you get that base plate on and the large caps in? Those big filter caps look like thesame as went in the 1010....

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  • 11 months later...

I came across a much better physical specimen trolling on eBay at the right time, and managed to get it for a great price ($240)... It plays ok, but I know it can be better. Your post was an inspiration for me to get off my butt and start the work...

 

Just thought I'd put in 2 cents about another minor issue with these amps that causes a lot of grief..

 

If you're experiencing intermittent L/R volume output, first check the power/pre coupling switch in the rear...it can cause intermittent issues with L/R channel output (making you think its something to do with the volume control, etc)..I've read of many a poor SOB arduously replacing, drilling into the sealed case to get deoxit in there, spending huge sums on used replacements, etc... when a quick spray of contact cleaner (or replacing the switch) would have solved the problem...

 

 

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I came across a much better physical specimen trolling on eBay at the right time, and managed to get it for a great price ($240)... It plays ok, but I know it can be better. Your post was an inspiration for me to get off my butt and start the work...

 

Just thought I'd put in 2 cents about another minor issue with these amps that causes a lot of grief..

 

If you're experiencing intermittent L/R volume output, first check the power/pre coupling switch in the rear...it can cause intermittent issues with L/R channel output (making you think its something to do with the volume control, etc)..I've read of many a poor SOB arduously replacing, drilling into the sealed case to get deoxit in there, spending huge sums on used replacements, etc... when a quick spray of contact cleaner (or replacing the switch) would have solved the problem...

Indeed... The connected/separated switch is the very first port of call for each and every Sansui that has this switch fitted. It's probably the vey first thing that skippy and I clean when working on these amps.

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I came across a much better physical specimen trolling on eBay at the right time, and managed to get it for a great price ($240)... It plays ok, but I know it can be better. Your post was an inspiration for me to get off my butt and start the work...

 

Just thought I'd put in 2 cents about another minor issue with these amps that causes a lot of grief..

 

If you're experiencing intermittent L/R volume output, first check the power/pre coupling switch in the rear...it can cause intermittent issues with L/R channel output (making you think its something to do with the volume control, etc)..I've read of many a poor SOB arduously replacing, drilling into the sealed case to get deoxit in there, spending huge sums on used replacements, etc... when a quick spray of contact cleaner (or replacing the switch) would have solved the problem...

 

Nice informative first post Clinton, Welcome.

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  • 2 years later...

hi there. i am looking to buy a sansui amp that is really in bad shape inside. glue of death and bad caps everywhere. is there something i should be careful off. i mean, can this amp 100% be fixed with recap etc or is there something that cant be fixed, if broken, and i have to be aware of? the amp has the power cord cut, and in the photos i see no fuse on the back.

your experience in sansui is appreciated. thank you

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4 hours ago, porotikos said:

hi there. i am looking to buy a sansui amp that is really in bad shape inside. glue of death and bad caps everywhere. is there something i should be careful off. i mean, can this amp 100% be fixed with recap etc or is there something that cant be fixed, if broken, and i have to be aware of? the amp has the power cord cut, and in the photos i see no fuse on the back.

your experience in sansui is appreciated. thank you

 

Welcome!

 

Which model of amp is it?

 

 

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  • 2 years later...

Hi All, Skippy and Pete in particular who seem to be experts on this gear, I've come across a beautiful AU-717 and the matching SC-2110 tape deck. I'm using this thread, which is incredible, to help in my cleaning and tweaking. 

Just wondering if there is a local supplier of belts that can be recommended? I've found some in the US and EU, but nothing local yet. 

 

Here is a photo of the amp and deck.

 

Cheers!

 

Sansui au717_sc2110.jpg

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2 hours ago, jammyringo said:

Hi All, Skippy and Pete in particular who seem to be experts on this gear, I've come across a beautiful AU-717 and the matching SC-2110 tape deck. I'm using this thread, which is incredible, to help in my cleaning and tweaking. 

Just wondering if there is a local supplier of belts that can be recommended? I've found some in the US and EU, but nothing local yet. 

 

Here is a photo of the amp and deck.

 

Cheers!

 

Sansui au717_sc2110.jpg

 

Try Wagner / WES Components - they typically have an excellent assortment of belts!

 

 

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On 18/09/2012 at 11:19 AM, skippy124 said:

I don't think that will remove the glue, Iv'e tried orange oil electrical cleaner (concentrated orange oil), and it didn't work.

Cheers

John

Acetone is needed to do the job right.

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