Looking For Info, Sansui G-5700 Volume Variation, Capacitors?

[PghAudioGuy]

My 1980 Sansui G-5700 has only one issue - the volume (both L&R speaker channels) fluctuates intermittently from two of 3 sources: FM Radio, Aux/CD Player, but not Phono (as far as I can tell). The volume occasionally rises a few decibels, then after staying at the higher level for a minute or two, returns to the lower level. I'm wondering (a) what the problem is, has anyone experienced this problem and found the fix, and (b) if it's an e-cap, where do I start looking? I have very little experience with electronics, although I do have a friend who's advising me and does this sort of thing, says he'll help me fix the problem if I get the parts - but I don't know what parts I need!

I've been inside this machine, cleaned up 40 yrs worth of dust and found one cap with a bulging/swollen top (picture) and identified 11 others that could be suspicious, based on what my (much more knowledgeable) friend has told me. I DON'T want to have him recap the entire receiver, I just want to find the one (or ones) that is responsible for the volume fluctuation issue. Does anyone have any feedback, suggestions, instructions on where to start in fixing this problem?

Also, a bill of materials for this receiver would be helpful, according to my friend.... Anybody?

 

[djwhy60]

I have copies of the service manual and corrections....will upload to AK documents...may have to check back tomorrow to see if they posted it.

 

[djwhy60]

Tried an upload by Email....the file is too large...will try to ZIP it.

EDIT: Will not let me zip it to a smaller file. Follow this link to HIFI Engine, sign up and you can download the files.
https://www.hifiengine.com/manual_library/sansui/g-5700.shtml

 

[PghAudioGuy]

Tried an upload by Email....the file is too large...will try to ZIP it.

EDIT: Will not let me zip it to a smaller file. Follow this link to HIFI Engine, sign up and you can download the files.
https://www.hifiengine.com/manual_library/sansui/g-5700.shtml

Thanks, but don't worry about it - I've got those also, I get all that stuff off HiFiEngine. And yes, that service manual is 37.5mb, it's quite a large file. I tried to attach it to email for my buddy, it wouldn't go thru Comcast's servers.... I clean up/refurbish & resell receivers, so I'm always on HiFi Engine looking for specs, brochures, manuals - it's a great site. But this Sansui is my own machine here in my home system, I've owned it for 40 years and except for a few lights that needed replaced when it was about 10 yrs old, this is the 1st problem I've ever had with it....

SOOOOOO, I have all the #s from the schematic diagram (1000µF 63V E.C. for example) that's what I need to buy new ones?
Thanks again for responding to my request for info, I really appreciate it.

 

[djwhy60]

No problem.....I like doing research for manuals.

I think your best move would be to have this post moved to the "Sansui" thread. Most people who post in this area are just looking for manuals. The Sansui thread has LOTS of techs helping, and a lot of them are well versed with problems Sansuis' have. I would imagine you could ask a moderator to move it. I will ask them too!

 

[PghAudioGuy]

No problem.....I like doing research for manuals.

I think your best move would be to have this post moved to the "Sansui" thread. Most people who post in this area are just looking for manuals. The Sansui thread has LOTS of techs helping, and a lot of them are well versed with problems Sansuis' have. I would imagine you could ask a moderator to move it. I will ask them too!

Thanks, djwhy..... OMG, I had no idea I was posting in this category/thread! I'm just a "newbie" but even I know that this is NOT where this request belongs - thanks so much for pointing that out. I need to put it in a different category or two!

Sooner or later, I'll figger it out..... Promise. Thanks again - so much!

 

[djwhy60]

Thanks, djwhy..... OMG, I had no idea I was posting in this category/thread! I'm just a "newbie" but even I know that this is NOT where this request belongs - thanks so much for pointing that out. I need to put it in a different category or two!

Sooner or later, I'll figger it out..... Promise. Thanks again - so much!

I see the Mods moved it.....no problem..we are all new here at one time! Hope you get the help you need.

 

[PghAudioGuy]

I see the Mods moved it.....no problem..we are all new here at one time! Hope you get the help you need.

Yeah, and major THANKS to you again! This is where it should have been, "Exclusively Sansui". Great!

Thanks once again for all your help..... mw

 

[whoaru99]

That one capacitor isn't necessarily "bulging". There is a plastic disk on top and those can warp, giving the appearance of bulging. That's most likely the case. It can be a little stiff but usually you can press it down to confirm it's just warped plastic cover or something else.

 

[Hyperion]

Does anyone have any feedback, suggestions, instructions on where to start in fixing this problem?

When addressing a problem like this first make sure all the switches and controls are clean, that's the contacts 'in' and 'on' all of the switches - use DeOxit D5, and for the controls use DeOxit FaderLube F5 - and I recommend you read the thread about how to use DeOxit first.

Here:
https://audiokarma.org/forums/index.php?threads/the-idiots-guide-to-using-deoxit-revisited.207005/

There is talk about changing capacitors, don't change anything until you have understood more about how this fault behaves, maybe making voltage measurements of power supply voltages within the receiver while it is in fault mode and then compare these with a set of readings NOT in fault mode.

Good luck.

 

[PghAudioGuy]

When addressing a problem like this first make sure all the switches and controls are clean, that's the contacts 'in' and 'on' all of the switches - use DeOxit D5, and for the controls use DeOxit FaderLube F5 - and I recommend you read the thread about how to use DeOxit first.

Here:
https://audiokarma.org/forums/index.php?threads/the-idiots-guide-to-using-deoxit-revisited.207005/

There is talk about changing capacitors, don't change anything until you have understood more about how this fault behaves, maybe making voltage measurements of power supply voltages within the receiver while it is in fault mode and then compare these with a set of readings NOT in fault mode.

Good luck.

Thanks, and thanks to all for your advice! I have DeoxIT D5 and DeoxIT Gold G5, I've used them both. And I use them on every receiver I clean up and refurbish, it's one of the first things I do, clean all the switches and pots, the buttons too. I've always had good results, it gets rid of all the fuzziness and any cracking, popping - and I've had some miraculous results on a couple switches I thought were bad/needed replaced, some have "come back from the dead" - not often, but sometimes. I've never used FaderLube.

As for the capacitors, I'm of the (humble, uneducated newbie) opinion that, at 40 yrs of age, the major e-caps on these machines are all due for replacement - and for the $$ it's not a huge outlay of cash for the caps. I can't solder my way out of a ball of speaker wire, I can just get by - but it ain't pretty. And I have a buddy who does ALOT of this, he helps me out. This major and one other new minor (yes, there are now two) issue could be related to lots of things, but replacing the e-caps as a start (and recognizing other problems along the way, like the corrosive adhesive Sansui used on these boards back in the 70's & early 80's) seems like a logical place to start.

And the 2nd problem? I've noticed the past couple years that the receiver puts out more sound thru the right speaker channel than the left, and it just became more obvious in the past 2-3 days after powering the machine up after a few weeks of inactivity. And it's NOT the balance control knob, I even de-oxed it a 2nd time to make sure. This issue alone tells me that the left channel has either (a) an e-cap gone haywire or (b) bad connections to the board due to corrosive adhesive or a questionable solder connection. Keeping in mind that this is a 40 yr-old machine that has performed flawlessly up until bout 2 yrs ago when the volume up/down issue came up.

But I really appreciate the advice, and I'll keep looking into this until I solve this mystery (electronics and electricity are a mystery to me), then I'm going to sell the G-5700 when I have it back to peak performance level, I already bought a replacement that's in place and working fine - a Pioneer SX-850 I got from a guy in Canada. I also have a Kenwood KR-4070 & KR-2300, Pioneer SX-434 and SX-727 and Technics SA-5160 sitting around if I need back-up.

I'll figger it out - eventually.....

 

[PghAudioGuy]

That one capacitor isn't necessarily "bulging". There is a plastic disk on top and those can warp, giving the appearance of bulging. That's most likely the case. It can be a little stiff but usually you can press it down to confirm it's just warped plastic cover or something else.

Thanks for that piece of advice - I did not know that. I'll try pushing it down to see if it's really swollen or just "popped" like you said....