Recapping Sansui 881

wicked1 · 9th December 2009, 09:41 PM

I'm recapping an old sansui 881 for my dad. It was his first big stereo purchase. He gave it to me back in the 80's and I abused it through the 90's. It's been stored away in my basement for over 10 years now and my dad tells me he wants an amp to use w/ his MP3 player.. Perfect solution! He was unbelievebly excited when I mentioned it to him.

So, it's full of electrolytics. I definitely need to replace the power supply caps (buzz), and I think I'll probably just recap the entire thing so he can use it trouble free for the next 20 years...

I blew a fuse in it when I was a kid, and stuffed aluminum foil in its place. When I took the amp apart the other day I noticed some resistors on one channel on the driver board are completely burned up. Somehow the amp still works and both channels sound the same! Looks like I'll be replacing some resistors too.

I've got one question.. There are some low value electro's in here, 1uf and below, in the audio path. Any reason to put electro's back there, or should I use film in their place?

ticknpop · 9th December 2009, 10:29 PM

Yes small caps below 1uf can be replaced with plastic film - polyester and even beter- The new small Wima polypropelenes

sakis · 10th December 2009, 07:36 AM

often a wise choise is to use again good quality electrolytics but bypass them with filpm polyester polypropylene or even better smd styroflex which is hard to find but work very good and also are very easy to instal ....

then again there is a few other things you can do and some info may be found here ....

vintage amplifier repair/upgrade manual

wicked1 · 10th December 2009, 05:43 PM

I've got a question about the main power supply caps.. they are 500v 10kuf, 40mm. I want to replace them w/ 40mm caps, so they fit in the clamps.

I can't find anything of similar specs! (well, I was hoping to order everything from digikey, but I don't have to). All I can find at digikey in that size are 60 to 100v capacitors. The B+ (or whatever its called for solid state (im used to tubes)) is only 32 volts.

So, can I go with caps that much lower in voltage rating? Or, can someone suggest a place to purchase some large (about 1.5" wide x 4" tall) capacitors?

Thanks

wicked1 · 10th December 2009, 08:26 PM

So yeah, they're 50v caps.. the schematic im looking at has a typo....

wicked1 · 10th December 2009, 09:01 PM

Found some more! schematic labeled 4.7uf, and there's a 47uf on the pcb! (and this is the official sansui repair manual)

jaycee · 11th December 2009, 07:59 AM

To be sure about the power supply rails, disconnect the transformer and measure the AC output of the secondary windings - from that, AC * 1.42 = rail voltages. The old capacitors could be sufficiently dried out that they are loading down the supply.

I had a quick Google for the 881 and noticed there seems to be a few different versions judging by the pictures I've seen. That could explain why your service manual doesn't match up.

9th December 2009, 09:41 PM	#1
wicked1 diyAudio Member Join Date: Jan 2008	Recapping Sansui 881 I'm recapping an old sansui 881 for my dad. It was his first big stereo purchase. He gave it to me back in the 80's and I abused it through the 90's. It's been stored away in my basement for over 10 years now and my dad tells me he wants an amp to use w/ his MP3 player.. Perfect solution! He was unbelievebly excited when I mentioned it to him. So, it's full of electrolytics. I definitely need to replace the power supply caps (buzz), and I think I'll probably just recap the entire thing so he can use it trouble free for the next 20 years... I blew a fuse in it when I was a kid, and stuffed aluminum foil in its place. When I took the amp apart the other day I noticed some resistors on one channel on the driver board are completely burned up. Somehow the amp still works and both channels sound the same! Looks like I'll be replacing some resistors too. I've got one question.. There are some low value electro's in here, 1uf and below, in the audio path. Any reason to put electro's back there, or should I use film in their place?

10th December 2009, 07:36 AM	#3
sakis diyAudio Member Join Date: Jan 2006 Location: nea makri athens greece	often a wise choise is to use again good quality electrolytics but bypass them with filpm polyester polypropylene or even better smd styroflex which is hard to find but work very good and also are very easy to instal .... then again there is a few other things you can do and some info may be found here .... vintage amplifier repair/upgrade manual __________________ SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr

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9th December 2009, 10:29 PM	#2
ticknpop diyAudio Member Join Date: May 2005 Location: toronto	Yes small caps below 1uf can be replaced with plastic film - polyester and even beter- The new small Wima polypropelenes

10th December 2009, 05:43 PM	#4
wicked1 diyAudio Member Join Date: Jan 2008	I've got a question about the main power supply caps.. they are 500v 10kuf, 40mm. I want to replace them w/ 40mm caps, so they fit in the clamps. I can't find anything of similar specs! (well, I was hoping to order everything from digikey, but I don't have to). All I can find at digikey in that size are 60 to 100v capacitors. The B+ (or whatever its called for solid state (im used to tubes)) is only 32 volts. So, can I go with caps that much lower in voltage rating? Or, can someone suggest a place to purchase some large (about 1.5" wide x 4" tall) capacitors? Thanks

10th December 2009, 08:26 PM	#5
wicked1 diyAudio Member Join Date: Jan 2008	So yeah, they're 50v caps.. the schematic im looking at has a typo....

10th December 2009, 09:01 PM	#6
wicked1 diyAudio Member Join Date: Jan 2008	Found some more! schematic labeled 4.7uf, and there's a 47uf on the pcb! (and this is the official sansui repair manual)

11th December 2009, 07:59 AM	#7
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	To be sure about the power supply rails, disconnect the transformer and measure the AC output of the secondary windings - from that, AC * 1.42 = rail voltages. The old capacitors could be sufficiently dried out that they are loading down the supply. I had a quick Google for the 881 and noticed there seems to be a few different versions judging by the pictures I've seen. That could explain why your service manual doesn't match up.