Sansui AU-317 caps

[JackieJoe]

Hi folks!!!
I recently bought a Sansui AU-317 and after a quick look under the cover i noticed some capacitors, 6, have been replaced by axial caps brand ITT 100v 330mF. If i'm not wrong original ones on this model were ELNA 50v 470mF. Can that somehow wrong recap cause any problem? The amp, for now, seems to work perfectly and i'm very happy with the sound. Your opinion on this would be greatly appreciated. Thanks.

 

[CrSens]

The caps are bellow spec, but no harm will come to the amp. I would be more worried what other creative substitutions were made in the amp (meaning grab something from the shelf, whatever you can improvise). These 6 by themselves are not reason for concern (other than potentially affect the sound at higher volumes).

 

[JackieJoe]

no harm will come to the amp

That's good to know, thanks. I'll have them replaced with the right ones soon.
I'll post a few more pics, if you can spot anything wrong I'll be grateful.

 

[JackieJoe]

More pics

 

[pete_mac]

Aside from those axial caps, she's stock-as-a-rock.

 

[DEFTECHY]

Regardless of if those caps wont cause any damage, I would want to change them out for correct spec better brand caps ASAP. Whoever changed them clearly didnt know what they were doing besides being able to solder them in (post a pic of the solder side of that board) they used wrong spec and type of caps & didnt even remove the brown glue!

When you replace the caps, take some time to clean the glue off the board with acetone, wet a couple small pieces of cotton rag and let them sit on the glue for about 5 minutes, that will soften the glue to be scraped off with a plastic or wood tool or small flat blade screwdriver very gently. Replace or clean & test any part it touched too, that glue can become corrosive & conductive causing all kinds of problems.

 

[JackieJoe]

post a pic of the solder side of that board)

I will certainly do as soon as tear down the amp to replace caps. Thanks for your advice. Any suggestion on what brand type model should I get as replacement ?

 

[CrSens]

Be very careful and note the polarity as installed, there might be a PCB silkscreen error on position of one of the caps (+and - reversed).

 

[Mike_S]

Most likely that is what the person just had laying around, so they were used.
You should also pull all the fuses, after clean all the holders and fuses, they are nasty.

 

[Jefft91]

You sould replace those axial caps with any reputable brand (as sold on Mouser, DigiKey if in U.S.) of radial style low ESR electrolytic capacitor (Nichicon UPW, for example). Use 50V (or 63V), at least 470uF, but a little higher is okay, within reason.

As to cleaning off the glue, I recommend you not use anything metal, as it can scratch the PC board and silk screen. I use wooden sticks (so-called orange stick used for manicures or a large chip stick cut into a point). Hard plastic scrapers work as well.

Good luck!

 

[JackieJoe]

Thank you all for the advice. I'm a bit scared of making some damage to the amp as it is working great right now and it's my first recap (I have some soldering skill though) but i understand it has to be done. Quick question I'm going to change the 4 150 ohm resistors as well. what should i buy? I read they are fusible resistors so i guess a normal resistor will not do. Advices are greatly appreciated. Thanks.

 

[Jefft91]

Replace fusibles with same wattage (usually half watt, IIRC) metal film resistors. Try to space them off the board for cooling. I always measure the resistance of those I pull. I use it as a measure of how much stress the amp has seen in its life. If the resistances are close (less than 25% above, say) to their spec value, it tells me the amp hasn't seen a lot of heavy use. If they're kOhms or MOhms, it says I should replace everything that is prone to wear out without exception.

 

[Mike_S]

Thank you all for the advice. I'm a bit scared of making some damage to the amp as it is working great right now and it's my first recap (I have some soldering skill though) but i understand it has to be done. Quick question I'm going to change the 4 150 ohm resistors as well. what should i buy? I read they are fusible resistors so i guess a normal resistor will not do. Advices are greatly appreciated. Thanks.

Always use metal film to replace fusable. Never have any of them been in spec. They also help change the sound for the better. Think it's due to being in spec, metal film have less noise/distortion over the fusable.

 

[JackieJoe]

Guys, could you tell me what should i do whit those 2 caps in the pic as they look like leaking on the board. there are 4 of those all leaking. They look different from normal caps, what are them?

 

[JackieJoe]

Also this component needs to be replaced. I looks like the glue has compromised it. is it a cap? Sorry i'm not very good at reading schematics

 

[pete_mac]

Guys, could you tell me what should i do whit those 2 caps in the pic as they look like leaking on the board. there are 4 of those all leaking. They look different from normal caps, what are them?

They are polystyrene caps - they contain no electrolyte and cannot leak.

 

[pete_mac]

Also this component needs to be replaced. I looks like the glue has compromised it. is it a cap? Sorry i'm not very good at reading schematics

It's a ceramic capacitor. The glue can be removed from around the capacitor and the legs inspected for corrosion before worrying about replacing it.

 

[Sui-Yogi]

Guys, could you tell me what should i do whit those 2 caps in the pic as they look like leaking on the board. there are 4 of those all leaking. They look different from normal caps, what are them?

Indeed , those are polystyrene cap , they don’t leak but they are heat sensitive, so if you removed them or work around them with components in the same track and close to the particular cap then you need to be careful, fast with your soldering iron or even better attach a heat-sink at their leads .

The leaking material on the PCB is probably some Bacardi rum drops back from a party in 1985 when a person was “resting” their glass on the top of the amp and chit-chat …. Wellcome to the vintage restoration world and to AK “Exclusively Sansui forum “ …..

 

[Hyperion]

The brown stuff looks like clumsy glue trails, from the original application of the stuff used for the larger capacitors when the boards were built. The glue also needs to be removed from under the larger electrolytics - same process.

And to remove the glue it is best to carefully remove the (polystyrene) capacitors (as said, they are very sensitive to heat), and scrape the glue off the board, also make sure the poly cap leads are cleaned of it.

 

[JackieJoe]

they contain no electrolyte and cannot leak

That's good to know(excuse my ignorance ). Stains under each of them must be related then to insulators which are missing in my amp and instead i've seen in others au-317 pics. Maybe them went damaged and removed???