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Sansui 500A

Overundr1

Overundr1

AK Subscriber
Subscriber
Picked up a Sansui 500A green dial freebee over the weekend from a little old lady who said it had been stored away since the Vietnam era. Absolutely perfect condition, dare I say brand new in appearance. Sat it on my workbench, pulled the covers which showed no signs of anyone ever having been inside the unit. Toyed with the idea of plugging it in however common sense prevailed and looked through the forums for guidance. Read about cap explosions, fires and other assorted mayhem with old tube gear, and being a transistor kind of guy I thought I had better ask first. What is the safe way to bring this unit online? Oh, btw she also had in a folder containing the original operator's and service manual along with set up sheets, warranty cards etc.
-Lee
 
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Thanks for the link, glad I did not just power up to see what would happen. Any suggestions as to a variac for the bench? Been meaning to get one for a while now and at a loss as to amperage needed.
-Lee
 
wow! what a score!!, if it has been stored away for decades like most of the tube gear i get, you will need to bring it up slowly on a variac! if you dont have one most electronic, tv repair places still have variacs in the shop, if you go in and offer $10 to power up your sansui im shure they wont mind, if it is as nice as you say, it probubly wont need anything else immediatly exept for caps, and if it hasnt had much use you can probubly get away with not changing them right away, also u are gunna need some electronic cleaner spray, (de-oxit), cause im shure the controls are gunna be very noisey. id love to see some pics!!
 
I will put up pics probably tomorrow night, (band practice tonight) and called one of my in town contacts who has a variac he will let me borrow for free :) Really is a pretty piece, I can't believe the point to point wiring in this reciever. Already cruising the service manual and diggin for caps.
-Lee
 
Over the course of several hours I brought the 500a up on a variac yesterday. When I finally got to line voltage levels I placed the output tubes in their sockets and crossed my fingers. Lights came on, tubes all started glowing and she came online. Hooked up a set of test speakers and gave a listen. FM reception was amazing, far better than the Kenwood tuner I usually use. Controls were very scratchy so apart she came again for the full de-oxit/faderlube bath. Even without digging into cap replacement the sound was very very good. I see why folks like tube gear.
-Lee
 

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While I do not have a 500A (wish I did), I do have a 1000A that I have replaced all of the capacitors. Please don't stretch your luck and play it for any extended period of time. You may loose the output tubes or even worse, the output transformers. If you see any red plates on the output tubes, it is time to remove the power until you have at least replaced the coupling capacitors to the output tubes (all four of them!). If the 500A has ELNA or Suzuki gray capacitors (they look like electrolytic... they aren't) they are very, very suspect. They are paper caps.

Nice receiver. You should be proud!
 
+1 what KVFLYER said. I too have a 1000A that I replaced all the caps on. I see a lot of Suzuki caps in there. And I thought EroFoils in my FISHER's were bad. The Suzuki paper in OIL have to be the absolutely worse caps there are. Run it up to test and plan on replacing everyone of those axial Suzuki's. With the values they are, orange drops, axial poly's, Russian PIO's (some guys swear by them- I'm on the sidelines about them, besides being cheap) are a good choice for it. If you want to tailor your sound, you can mix, match, and get boutique caps. But 1st get a baseline sound you like. then experiment if you so desire.

Like kvflyer said the 500A is a real nice receiver. And your copy is just flat out delicious.

Larry
 
Thanks for the comments, this is going to be a fun restore. With the pots all cleaned and lubed I ran her for about fifteen minutes. What an amazing sound. I guess what I am hearing is timbre, just like the overtones I get with my tube fender twin vrs a transistor practice amp using a BigBadVoodoDaddy cd I had in the shop as a source. Sweet. I took heed from the posts above, did not run the volume way up the scale and shut her down. I can only imagine what early Sansui gear sounds like after a set of new caps. BTW, if anyone ever needs a copy of the owners or service manual I have the originals in pristine shape and would be glad to make a copy since I see this unit is not in the AK database.
-Lee
 
From working on my 1000A, a few observations.

Leads on components are much thinner than USA made parts. So, they may break if too much wiggling etc. is done. The terminal strips are "J" shaped a lot of the time instead of just being a lug with a hole in the middle. You can often carefully unwrap the old component (read: NASTY gray capacitor ;) ) if you try. I used a solder sucker first to remove almost all of the solder. Tube sockets are much like USA manufacture so no big difference.

Resistors are fragile and the ends come off easily. But there are usually no unusual values. The auction site has resistors by the kit, with most values and in 1% from vendors in the Far East. I have found them to be reliable and usually spot on value. So if you damage one, just sit back, take a swig of your favorit adult beverage and call it a night. Tomorrow is another day as the song goes.

Electrolytic capacitors most likely should be replaced. If they get warm, they MUST be replaced. Keep in mind that often a warm electrolytic cap may be getting heated by tubes very near by. I don't know about the 500A, but the electrolytic filters are usually 500 WVDC. So, the usual 450 WVDC that are plentiful are not good enough.

Tubes will most likely be OK. They are usually the last to go. The only exception may be the outputs. But don't throw them away. And whatever tube is in front of the outputs, 6AN8, 12AX7, whatever, even if it measures way low, it will still work just fine. Japanese tubes are not junk. They are very good, usually made by Toshiba, Matsushita etc.

Take your time, don't rush it. You have a museum piece in your hands. When done properly, you will be rewarded with hundreds of hours (yes hundreds) of trouble free use. BTW, a fan may help. these guys get very hot and heat is an enemy.

Another whole thread can go on about lowering the input voltage if yours is high.

Enjoy, keep us posted, and pictures would be nice. Also, I am sure that the Sansui database would really benefit from a scan of the manual. Even though I don't have a 500A, I may some day. I do have also a 1000 (in addition to the 1000A). That is a strange bird. Still in queue for restoration. Only a few caps replaced so far. Check them out and look at the output tubes. They are European TV Horizontal Output Tubes...
 
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I'd go for "reforming" the main caps with a high-voltage power supply - put like a 10k resistor in series, and if you can charge them up (remove the + side from circuitry to be sure it doens't pull current) slowly to full voltage and after a half hour or so if they don't pull more than a couple of mA (measured by a current meter, or a few volts across that resistor), it's been reformed and is good.

You said you ran it for 15 minutes, the main power supply caps are likely reformed now, or something bad would have happened ...
 
Wow!

What a beauty! A true time capsule.

Personally, I'd replace everything electrolytic in it, and all the oil caps too of course. Yeah, the PS caps won't blow an output if they fail, and most likely you'd start to hear a nice hum before they went completely.

But, if you're going to roll up your sleeves and tackle that rats nest, why not do everything, and then not have to potentially go back in sooner than later???
 
Sorry to revive this old thread (not sure if that is looked down upon on these boards since I'm a noob (1st post :music: ))

I just saw a Sansui 500A on Ebay and the description says this:

This unit has been in storage for over thirty years. It belonged to a friend and he didn't want to spend any money on it. It turned on and it sounded really great, then the sound gradually deteriorated. It works but needs restoration.
Click to expand...

It sounds like he just threw it into a wall socket and flipped the switch after it sat for 30 years. What do you think will now have to be replaced/restored to bring this back to pristine audio quality?
 
all the electrolytic capacitors need to be replace..
a deep cleaning of all the controls.. chassis, face place....

labor intensive...
 
I sent the 500a off to Nosirrah (Casey) as a freebie soon after the initial post for his Sansui collection. Perhaps he might chime in with an update.
-Lee
 
Thanks for the info, what would you say is a good price for a 500A that just had the switch thrown on and needs all caps replaced?


I'm trying to enter tube audio (I'm an Electrical Engineering student in my Jr year) and I'd really like to find a good piece that may need a decent amount of work, but has extremely good potential when restored. However I will also need to find some good vintage speakers, although all of my speakers are 89dB+, most being 90-92.

I have mainly Polk Audio Monitor Series speakers (Monitor 30s and 45B) and a Definitive Technology 2002 C/L/R. So obviously none of these are great for a vintage tube receiver.


I really want something that needs some work like the one I mentioned does, I don't want a restored receiver that is plug and play. If anyone had something they wanted to get off their hands I would definitely be interested and would obviously pay shipping :)

If I wanted to make a thread sort of getting this across what would be the best section for me to do so in order to get the best info and maybe even possibly an offer for equipment that needs a decent amount of work that they have had just sitting collecting dust that they would consider parting with.
 
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the one you mentioned and it is on the Bay right now is not a good candidate for restoring..

the chassis is rusted very bad.. look at the area near the power transformer and can capacitors !!!.

there is no way to fix bad chassis that rusted like that.
 
Well unless I wanted to replace the sheet metal that is. I have a lot of experience with modding guitar amp chassis and I think that wouldn't be a big deal to cut out a section of that after un-mounting it all. However with the point to point wiring underneath, that would not be an easy job and definitely not worth the $120 bid it is sitting at right now. This is why I was kind of asking a general info question about which section of the forums I could post what I basically said above in.
 
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