SANSUI 719 - restoration thread

[Wakefield Turntables]

City link has just dropped off two huge parcels. One contains a au719 it's in a sorry state. I've just opened the box and it powers up so that's a start. Apparently right channel is faulty. I will post some picks tonight when. Get camera charged and the beast set up. Let the restoration begin...

[John]

Its a nice amp when up and running, the older amps are pretty special

[Wakefield Turntables]

ok, no output whatsoever to right channel any ideas what could be causingt this? Will be dismantling the amp tomorrow to check caps and resistors.

[istari_knight]

Do you have the service manual ? I can send it over if not...

First things to check would be to make sure the lesser used switches are clean, the fuses on the transformer secondaries aren't blown [each channels power supply appears to be fused separately.] If that lot checks out alright try measuring the DC offset & bias voltage to see if anythings obviously wrong.

[Wakefield Turntables]

James,

Service manual would be ace. I spent four last night cleaning the bloody thing. This thing looks like its been stored in a garage all it's life. Thanks for the advice, I'm hoping it's something simple like a fuse, but if not I will be lesson in pcb diagnostics! Do you want me to send you a Pm with my email address?

Ps If I get time I will pat some pics tonight.

[istari_knight]

James,

Service manual would be ace. I spent four last night cleaning the bloody thing. This thing looks like its been stored in a garage all it's life. Thanks for the advice, I'm hoping it's something simple like a fuse, but if not I will be lesson in pcb diagnostics! Do you want me to send you a Pm with my email address?

Ps If I get time I will pat some pics tonight.

Yeah if you PM me you email I'll forward it, its not the best quality but is legible... Certainly better than stabbing around in the dark.

If it was filthy we can hope the problem's dirty switches :goodluck:

[Wakefield Turntables]

Just a few pictures to start the thread off. 1024910250102511025210253 As you can see it came in a sorry old state with all sorts of grime on its front. It also looked like it had been stored in a garage for 30 years when the lid was lifted. As you can see if scrubbed up pretty well inside, and so has the faceplate. The case is knackered and at this moment is sitting in my garage waiting to be attacked with the wire wool and spray paint.

[Wakefield Turntables]

Several more pictures before I go! I think I may have found out why the right channel was out. 10256 two very knackered fuses, I'll be going to down to Maplin's tomorrow and replacing all of them just to be on the safe side. Surely I can't be this lucky? I will also be spraying the base plate tomorrow. As you can see from this 10255 it was very very dirty. This will be sprayed black on the inside and outside. The front of the amp looks a little bare without its faceplate 10257 but it should look very smart when its replaced and its handles replaced. Finally just another quick snap of the transformers just show you how dirty the thing was when it arrived 10254, errrr! More updates tomorrow.

[istari_knight]

Always nice to see an old amp given a new lease of life... Do update whether the replacement fuses blow or not.

[Wakefield Turntables]

Nope the replacement fuses didnt blow. I replaced all 5A fuses with new and kept the original 3.5A. Everything got a good clean with deoxit including the fuse holders. I now need to measure DC offset.

PS all switches have now been cleaned with deoxit. R channel still silent.

[Wakefield Turntables]

ok, measured the DC left channel bias and this measured more or less on spot on at 24mV, the range should be 23mv +/1 1mV. The Right channel measured a big fat ZERO!

[istari_knight]

I doubt its anything major if the new fuses didn't blow :thumbsup:

For setting DC offset [as per the SM.]

Connect your + DVM probe to the left channel speaker output + & your - DVM probe to the left channel speaker output -. Turn your DMV on [set to DC 200mv range if not auto.] Turn the amplifier on making sure that no inputs are connected, tone controls are set flat & speaker outputs are turned on. Adjust the variable resistor labelled "VR101" until you get 0mv or as close as you can get. Then switch your DVM probes to the right channel speaker output & adjust the other "VR101" until you get 0mv or as close as possible.

You may find the trim pots are dirty or corroded with age if they aren't sealed which will cause your readings to jump up & down, usually a squirt of cleaner & a few rotations does the trick... Don't do this with the bias trim pots [VR02]

[istari_knight]

You beat me to it, I was just getting to bias setting ! ...Hang on I'll have a look at the SM.

[istari_knight]

Okay, I highly doubt the output transistors are blown as that would cause your fuses to blow... Can you measure the DC voltage going into F-2926 & F-2927 driver boards ? Pins 10 [+] & 12 [-] They should be +63v & -63V for each pair of pins to ground.

It would also be handy to measure the voltage readings on the F-3098 board... Pins 19 [+] & 21 [-] and Pins 20 [+] & 22 [-] They should be +32v & -32V for each pair of pins to ground.

[Wakefield Turntables]

James, thats quite a bit of homework to do. Leave it with me and I'll do all said measurements.

[reddish75]

Original sansui parts, http://www.sansui-parts-shop.com/index.php

[pete_mac]

Bugger, I completely missed this thread as I've been a bit quiet on AOS over the past few months!

How did you get on with your repairs?

The 719 is a formidable amp when operating in tip-top condition. I have a fully restored 719 as one of my regular amps.

[Wakefield Turntables]

Pete,

You will be pleased to know that the 719 is now working. I've still to pick it up. The diagnostic work was a little beyond my skills but it did get some attention from a very well known AOS'er! It's been cleaned up and needs some respray work but it looks a hell of a lot better than it did when I first purchased. You will also be glad to know that I rescued a SE=7 and that is in 9/10 condition, just a little mark which can be rectified with some spray paint :eyebrows: I've not done anything internally yet, but thats maybe something for the future. I will post some pics but it will probably be at the end of the month.

A

[pete_mac]

Brilliant! Glad to hear it. :)

[Wakefield Turntables]

The Sansui is now plumbed back into the listening room and sounds very good, it dosen't quite come upto the standards of my other kit but I've only tried it on some tannoy 15" MG's!! The amp needs some cosmetic work and maybe the speaker binding posts replacing but that can be done at some point in the future. I have noticed some scratches on the painwork and also the cardboard fascia plate has faded to a dark grey colour this could do with a respray, ok this is very minor but it's bugging the hell out of me! The amp case needs a complete restrip and respray but again something which can be done at any time. I will post some more pics later!

[istari_knight]

Glad to hear you managed to get the old girl working again :thumbsup: ... I just hope you've bought some new 'clip on' test leads for your dvm ? :)

[Wakefield Turntables]

Glad to hear you managed to get the old girl working again :thumbsup: ... I just hope you've bought some new 'clip on' test leads for your dvm ? :)

Nope I've not bought any clip on leads yet, you'd think I'd learn by now! The old girl just needs a little more TLC, she could do with the caps replacing but again it's a job for later, I'm just concentrating on enjoying her and slowly doing the TLC as time and money permit. She's my 3rd AMP now in the listening room :eek:

[Wakefield Turntables]

Now screened power lead added, some cosmetic work done to front fascia to remove scratches and bottom plate cleaned up and resprayed. I'm not looking forward to installing the gold plated speaker plugs :eek:

[Wakefield Turntables]

I thought I'd better include some new pics. 1085710858108591086010861

As you can see that AU719 has a nice beefy uprated power cord in the guise of an old Isotek Elite power cable that I had kicking around. Ive installed a silver plated plug with silver fuse. The casework of the amp was pretty shoddy. The underside has been resprayed with a gloss black finish, all the rust was polished out. The protective upper casing is probably going to be completely stripped and repainted, I think the scratches are too deep to get away with a quick spray of paint over them. The speaker binding posts are not great in this amp. As you can see with have some nice shiny gold plated thingy bobbies which were sitting in my tool case gathering dust. I'm making some new covers for the feet tonight and experimenting on what I can use to removed the paint from the casing.

[Wakefield Turntables]

Casing should be finished next week. Speaker binding posts are the next job. Look like a new mounting board will be needed, just so happens I have some nice homocopolymer at work to make one. The journey continues. More photo's later.

[pete_mac]

Nice work! :)


Casing should be finished next week. Speaker binding posts are the next job. Look like a new mounting board will be needed, just so happens I have some nice homocopolymer at work to make one. The journey continues. More photo's later.

Indeed, aftermarket binding posts will need to be installed on a custom mounting board. I've used acrylic/plexiglass for this exact purpose on my AU-719.

Here's the first one that I did (a bit nasty looking, but effective)

http://i535.photobucket.com/albums/ee359/petemacozfoz/AU719newspeakerterms.jpg

http://i535.photobucket.com/albums/ee359/petemacozfoz/AU719newspeakertermsrear.jpg


The same technique was used on these two 719s. The top one is my own personal amp which I converted to single binding posts only, with the speaker switch removed from the circuit, and replaced with wire directly from the PCB). The bottom amp was restored for a friend.

http://i535.photobucket.com/albums/ee359/petemacozfoz/au719rearcomparison.jpg

[Wakefield Turntables]

I think this thread needs to be restarted. This project got lost in the sands of time. I'll update some photo's later!

[agk]

Good man. I love these things and spend hours kicking myself for letting my 919 go for a song.

[Wakefield Turntables]

I'd have loved a 919 but ended up with this old girl. It started out with the right channel not working and it still hums a little. I'm starting to price up Caps. I don't want to spend silly money on this amp but enough to make sure that it lasts for a lifetime, this one is a keeper.

[DarrenHW]

Good luck Andy, I love my little AU-101, picked it up last year for £5, complete recap for £7 (following a thread which I believe was created by Pete Mac's son), total cost £12! It's the amp for my kitchen system (which also doubles as office) and I love it's old school sound, especially when connected to my DIY Valve DAC. I still have to finish it off with a rewire with switch bypass and I'll probably cut some new Mahogany cheeks.

Not sure if I want to follow this thread or not as it will inevitably lead to me moving up the Sui food chain, I could then move the 101 to the gym/shed though :eyebrows:

[Wakefield Turntables]

I've been thinking about how I would like to restore my 719. I've seen quite a few restoration threads that have replaced various caps with boutique parts and altered values from factory spec. This got me thinking about the Sansui Sound. I don't want to loose the Sansui sound and i dont want to get bogged down with trying numerous cap types so I have decided to stick to factory values but replace with excellent quality caps. Sansui in there wisdom failed to publish resistor values and the manual I own has some published values. I have decided to replace resistors where possible with better tolerance and spec. The biggest part of this restoration is the research into the parts. I shall be removing the caps and resistors from the both driver circuit boards. I'm afraid that the fabled Sansui Glue problem has also struck my PCB's so they shall need a good clean. I'll post some picks at some point. :)

[Wakefield Turntables]

Ok, caps, binding posts and some new internal ofc copper ordered! Decided to stay with original Nichicon and Elna caps and values. Better to play safe.

[awkwardbydesign]

It's funny how we all love different amps. These Japanese amps leave me cold, but it's fun to watch someone else restoring them. I prefer the left-field oddities myself.

[Wakefield Turntables]

It's funny how we all love different amps. These Japanese amps leave me cold, but it's fun to watch someone else restoring them. I prefer the left-field oddities myself.

Well I have fond memories of listening to a Sansui Amp in my mates bedroom as a Teenager so this is a journey back to childhood in some respects. It's not the best amp I've ever heard but it's still pretty good any functions as something to use when I dont want to fire up the valve or main systems.

[Wakefield Turntables]

Some photo's at long last!

Some goodies come through the post

http://i98.photobucket.com/albums/l247/WAKEFIELDAUDIO/goodies_zpskmcaufoe.jpg (http://s98.photobucket.com/user/WAKEFIELDAUDIO/media/goodies_zpskmcaufoe.jpg.html)
A bit of open heart surgery

http://i98.photobucket.com/albums/l247/WAKEFIELDAUDIO/openheartsurgery_zps0jbpbmwu.jpg (http://s98.photobucket.com/user/WAKEFIELDAUDIO/media/openheartsurgery_zps0jbpbmwu.jpg.html)


One of the driver boards removed before decapping, cleaning and the dreaded Sansui glue removed.

http://i98.photobucket.com/albums/l247/WAKEFIELDAUDIO/fullycapped_zpsrhxr4d6j.jpg (http://s98.photobucket.com/user/WAKEFIELDAUDIO/media/fullycapped_zpsrhxr4d6j.jpg.html)


Decapped, Cleaned and ready for recapping


http://i98.photobucket.com/albums/l247/WAKEFIELDAUDIO/DSCN1781_zpsjr4lddq2.jpg (http://s98.photobucket.com/user/WAKEFIELDAUDIO/media/DSCN1781_zpsjr4lddq2.jpg.html)

Some pure Cu speaker binding posts to replace the crappy Sansui versions

http://i98.photobucket.com/albums/l247/WAKEFIELDAUDIO/Cuspeaker_zps2mp8c5sz.jpg (http://s98.photobucket.com/user/WAKEFIELDAUDIO/media/Cuspeaker_zps2mp8c5sz.jpg.html)


More photo's when I get time.

[Wakefield Turntables]

Porgress is a little slow. The Sanui is built like a tank and needs a lot of dismantling. I'll be doing more recapping tonight and then I need to dismantle the phonostage card for recapping. Binding posts are probably the next job followed by a nice new earthing post. The project slowly moves on.....!