AU-717 restoration

[elara]

I love the vintage audio but I am a beginner restoring them, so I apologize in advance for any fool sentence or question. (And for my poor english too)

Some few months ago, my dear Sansui AU-717 began with a audio problem by enhancing the midtones in the left channel and yesterday, the audio in the right channel began to be distortioned and almost not sound.

I am a lover of these machines, but I live in Chile at the end of the world, where there are no quality components and I dont want to risk a repair of poor quality, so I'm taking courage to attempt repair / restoration by myself with valuable help of all who want support me.

My amp has never failed before, I think it is best to do a restore, starting to change all components which are tipically degraded by the years.

As a first step in this challenging project, I plan to build a list in Excel that contains all the information needed to order the parts and that will be useful for other people who want to do their own restoration projects in the future.

I already have both the AU-717 service manual and the Sansui CPL, even so, I cannot find the specs (and part number) for a lot of parts, as such as the electrolytic Capacitors (E.C), several resistors, etc.

If would possible, Could you please explain me, how to find out (in these service Sansui manuals or wherever), the specs and part number for example for the C606 capacitor or the R15 resistor?

(Without looking that part installed in PCB, because in many cases, the amp could have installed a not genuine part, that was changed before you received it)

Here I left the Excel that I am making.

Thanks a lot.

 

[Sir.Byrd]

This model is victim to the corrosive glue problem, check out the power supply boards and the amp boards specifically for glue that has corroded components (usually adjacent to large capacitors) and add them to your parts list.

 

[skippy124]

Hi and Welcome to Audio Karma

I will have completed a full recap of a 717 within a couple of days, and will be able to provide a cpmplete electrolytic cap list. Note that there are a couple of differences between the schematic/parts list and what is actually fitted on the power supply board. I have the equaliser F-2723 and tone board F2720 to complete, once these are done I can confirm the capacitor list, and also advise what components are likely to be affected by the glue (as Sir.Byrd has pointed out).

Cheers

John

 

[elara]

Hi Mr. Bird and Job, I am really glad to know you and thanks for support me.

Let me tell, some minutes ago I took off the top and bottom amp´s covers and took a first look inside and I must admit I panicked a little .

From the outside (without removing the boards), I could see that both drivers cards as well as the power supply card have just a little of glue spilled around the capacitors and it appears that only a couple elements have been touched by the "sticky monster". (Hopefully, perhaps because the amp has very few hours of use, I dont know)

Well, anyway, we'll know it when we can take out those plates in there without breaking something in the process...

By the way, Could any of you please tell me what order should I follow removing screws, cables, everything and finally the boards?

Thanks again.

 

[Sir.Byrd]

Try this:
http://www.cdkands.com/AU717-1.html

You don't have to be as thorough as this guy.
I like to replace the filter caps with 15000uF 63V caps, I use Nichicon Gold Tune. This makes getting the PS board out a lot easier, but still tricky.
Make sure you take pictures before you take it apart, for your reference.
Also, don't forget the capacitors on the board for the pre/main connections on the back, there are four 10uF 25V caps hiding there.

 

[elara]

Hello friends, Could you please explain me, how can I identify using the service manual, which components are in signal path (audio) and which not are?
Thanks a lot.

PD:
I continue moving forward building a restoration spreadsheet for AU-717. I hope to upload the first beta version soon with a little help from my friends.

 

[pete_mac]

Don't forget to replace the fuse resistors too... Very important!

 

[Kico]

Sansui AU-717 Capacitor List

I love the vintage audio but I am a beginner restoring them, so I apologize in advance for any fool sentence or question. (And for my poor english too)

Some few months ago, my dear Sansui AU-717 began with a audio problem by enhancing the midtones in the left channel and yesterday, the audio in the right channel began to be distortioned and almost not sound.

I am a lover of these machines, but I live in Chile at the end of the world, where there are no quality components and I dont want to risk a repair of poor quality, so I'm taking courage to attempt repair / restoration by myself with valuable help of all who want support me.

My amp has never failed before, I think it is best to do a restore, starting to change all components which are tipically degraded by the years.

As a first step in this challenging project, I plan to build a list in Excel that contains all the information needed to order the parts and that will be useful for other people who want to do their own restoration projects in the future.

I already have both the AU-717 service manual and the Sansui CPL, even so, I cannot find the specs (and part number) for a lot of parts, as such as the electrolytic Capacitors (E.C), several resistors, etc.

If would possible, Could you please explain me, how to find out (in these service Sansui manuals or wherever), the specs and part number for example for the C606 capacitor or the R15 resistor?

(Without looking that part installed in PCB, because in many cases, the amp could have installed a not genuine part, that was changed before you received it)

Here I left the Excel that I am making.

Thanks a lot.

Rebuilt mine in January of this year attached is a complete cap list. Make sure you replace all of the fuse resistors!

 

[qpagoda]

Hello friends, Could you please explain me, how can I identify using the service manual, which components are in signal path (audio) and which not are?
Thanks a lot.

PD:
I continue moving forward building a restoration spreadsheet for AU-717. I hope to upload the first beta version soon with a little help from my friends.

The information is in the service manual. For each circuit board (starting on page 4 in my copy) there is a table that lists parts. Each part has a Part No., Stock No., Description, and Position. An example from page 5.

F-2723 Equalizer Circuit Board

If you look below the diagram of the board, you see a Parts List. In the second section of the parts list (the middle one) at the top of the list you see

C01, 02 0602109 1.0uf 100V M.C. 1C, 2C

That translates to capacitor C01 and C02, and (obviously) 1.0 micofarad, 100 volt, M.C. = mylar capacitor.

When I recapped my AU-717, I used Quattro to create a cap list by going through each of those Parts Lists for each circuit board and recording the caps. I then took the amp apart and checked each cap to make sure it matched the list. There are a couple of differences, but I don't remember what. As I checked each cap on the circuit board, I marked the cap with a red marker so I could keep track of what I had already done.

 

[elara]

QPAGODA,

Thanks, but even I dont understand how to identify the components which are in the audio signal path. For example in the PS Board there are components dedicated to protection circuit which are not in the audio signal path I guess, nevertheless I cant find where to confirm that I guess. Thanks.

 

[elara]

Thanks a lot Niko, I will compare your valuable information with my Excel. Cheers.

 

[Sir.Byrd]

By the way, if you replace any transistors with KSA992s, make sure you check the pinout of each to make sure you have them in right. I put a bunch of them in backwards because I was doing them by physical orientation (flat side facing the same way) but the pins were ECB on one, and BCE on the other. You can just flip it 180° and it will work.

 

[qpagoda]

QPAGODA,

Thanks, but even I dont understand how to identify the components which are in the audio signal path. For example in the PS Board there are components dedicated to protection circuit which are not in the audio signal path I guess, nevertheless I cant find where to confirm that I guess. Thanks.

Oh. Sorry, I misunderstood what you were asking. The answer to your question is, I don't know, either. You should be able to get some idea by examining the amp itself. The orange caps are supposed to be low noise caps. When I ordered caps, I ordered low noise caps to replace those. I didn't worry about the others. I used good quality caps for the rest (mostly Panasonic FC, I think), but I did NOT order the most expensive caps I could get. Based on what I have read on AK, modern caps of good quality are better than good quality caps available when these amps were built. I wasn't trying to upgrade the sound compared to a new AU-717, just restore it.

 

[OverLoad]

By the way, if you replace any transistors with KSA992s, make sure you check the pinout of each to make sure you have them in right. I put a bunch of them in backwards because I was doing them by physical orientation (flat side facing the same way) but the pins were ECB on one, and BCE on the other. You can just flip it 180° and it will work.

If you replace transistors, make sure you check the pinout PERIOD

 

[Banong]

Rebuilt mine in January of this year attached is a complete cap list. Make sure you replace all of the fuse resistors!

Good job on the parts list. It will be a good reference and easier for newbie like me.I have one question, the list for F-2663 PS board, it says:

4 C08 > 220uf 63Volts

Does this means that there are four C08 on the board with 220uf / 63V ? or i need 4pcs. of 220uf / 63V to complete this board including C05, C06 & C07 ?:scratch2: thank......

 

[OverLoad]

You need 4x 220uF/63V (C05,06,07,08)

 

[Banong]

You need 4x 220uF/63V (C05,06,07,08)

Thanks for that info. I need one more list and I'm ready to order my parts. Anybody has the list for the fuse resistors?

Thank you expert guy's, you make this job easier and save some time for a newbie me.

 

[Hyperion]

Thanks for that info. I need one more list and I'm ready to order my parts. Anybody has the list for the fuse resistors?

Thank you expert guy's, you make this job easier and save some time for a newbie me.

AU-717 Fuse resistors

F-2723
R47, R49, R48, R50 all 82Ω

F-2720
R37, R39, R38, R40 all 82Ω

F-2721 / F2722
R23, R25 / R23, R25 all 150Ω

Just replace these with ½ or ¼ watt metal film resistors - you don't need to get fuse resistors for these positions.

 

[Ghog]

elara, something I did when I recapped my 717 was a BIG help upon reassembly. It was my first attempt at doing anything like this, and I was afraid I would never get all the pieces put back together correctly.
I took a piece of corrugated cardboard and kept it on my workbench. Every time I would remove a piece, whether it was a faceplate or one of the covers inside or a board or whatever, I made small holes close together on the cardboard with the tip of my screwdriver. I inserted the screws from that piece into the cardboard in a group, wrote beside them exactly what they held in place, and drew a circle around them. When I was done disassembling and recapping I had a piece of cardboard with maybe 50 or 60 screws in 15 or 18 groups, and as I reassembled it was a snap to get the right screws back in the right place. The cardboard provides enough grip to hold them in place, but allows them to be easily removed during reassembly.
I also made pages and pages of diagrams and notes. Every single thing I unhooked or took off was in the notes, along with diagrams of each board showing which wires went where and such. Each board element was listed and those lists were useful as CHECKLISTS for reassembly. I double checked everything by those lists, then triple checked.
End result? My first attempt at electronic repair was a complete success. Don't be afraid of doing it yourself. Just be very methodical and slow and patient.
And get the service manual and schematic. They can save your rear end if you run into a problem.
And read and read on this amp here at AK. There is a huge amount of vital info that you won't get anywhere else.

 

[Hyperion]

Really excellent advice Ghog :thmbsp: