Sansui 500 restore

[bfrohwein]

Merry Christmas!

I'm pretty new to the Forum as a member, but I've been lurking around here for a while as a guest.

I've had this Sansui 500 kicking around for a while. I've decided to spend my Christmas vacation recapping / restoring it.

I've been lurking around here all month, reading up on this and that. I've got all my caps now, replacement tubes, etc. I've got a couple of questions for the experts.

going over the under belly of the chassis and perusing the schematic, I came across a selenium rectifier/diode (the little red capped balloon below the PS and marked "D" on the schematic in the 25V section). I was just going to swap it out with an silicon one but I started to wonder. If they used 2 other silicon diodes in the power circuit, is there a particular reason they would have used a selenium one in this particular place? I Was wondering if anyone knew of a reason I should not replace it with say a 1n4007?

Also. The Sprague PS coupling caps have been in there for a good 20 years, I believe. is it okay to leave them in there? I think polyester has a long life, the previous owner couldn't remember when he put them in. Sorry the schematic is a little blurry. the 11x17 schematic in the service manual didn't want to fit quite right on my scanner.

any input would be greatly appreciated. I have to say, I've enjoyed reading about the sansui enthusiasts around here.

 

[Bstable]

Interested in the results. My oldest brothers first stereo (1970 or so) consisted of that receiver. My Dad came back from Viet Nam with a brand new Sansui 5000A so the 500 became a hand me down. It stopped working one day in the later 70s, and a certain part was supposedly unobtainable. Of course those were the days well before the internet. I'll bet it could have been fixed.

Please post more pics as you move forward. :thmbsp:

BTW...welcome to AK.

 

[bfrohwein]

Thanks BStable. Looking forward to hearing it the first time.

I'll tell you what was next to impossible to find. That square tuning eye tube! I think just about anything else in there would be able to be found in some form or another.

it did work when I first got it. but the power tubes were pretty dead. and those oil caps are terribly leaky. a few leak physically!

the transformers are good, and the coils I've tested. so we're off to a very good start.

 

[larryderouin]

The diode is for the bias circuit. You can sub the selenium with a 1n4004.
If the resulting voltage is too high, put a bourns 10K .5w pot in and adjust to suit.

Once you get the power supply voltages in line the tuning tube may come back . Cross your fingers.

The spragues should be OK. The Elna's are pretty much shot. And as for the leaking SUZUKI's I'm surprised one hasn't gone "BOOM" yet. They love to self destruct!

Larry

 

[audiobee]

I have repaired and recapped a number of these 500 receiver...

I have not seen any of the 'red" diode failed on those , I would leave them a lone.

a few had the silicon rect, diode blown and it was caused by shorted power supply can capacitors and the small oil decoupling capacitor acrosse those diodes...

1- All of the oils and can power capacitors must go.. they are all dried up and about to be shorted out by now..
2- I would not touch any of the diode if they are OK.
3- leave all the resistors alone.

-- see the dual power black resistor 500 ohm + 700 ohm on the left side of your first picture !!!..

if the can power capacitors shorted out. it will take out that resistor plus the rect. diode.

- get rid of the replaced Sprague caps while you are in there... don't try to nickel and dime it...

don't touch the tuning eye until you have completed the recap.. they might come back..

nice little receiver... not much out put power those...

 

[bfrohwein]

Larry and Audiobee:

Thank you for your advice.

I was only thinking about replacing the selenium as a good measure. my curiosity about it was if there was a reason they choose it when they chose silicon elsewhere. now that you warned me of the SD's, I do have a pile of N5408's in my arsenal. As far as the eye tube goes, it works, but it's pretty worn/washed out. I haven't powered it up since I picked it up. the previous owner wanted me to see that it worked. I did cringe though when he turned it on, expecting fireworks..

I did manage to find a couple of eye tubes for it, JIC. I'll take any excuse to go tube hunting/shopping.

the power resistors tested good. as did the PS and the output transformers and the coils I tested.

as for caps. FWIW

I have some elna simlic II's, Nichicon UPW's and UKZ's. I also have some JJ can caps both regular and multisections I could use in here. was thinking about the JJ's most because they're exactly the same size as the elna's there now. as for the multisections, only to prevent the look of a cluster of nichicons "blooming" on the top of the chassis (although it will be covered). the upw's won't all fit in the multisection cans there now. plus, I'm not a big fan of re stuffing. I mean, doing the work, they look nice otherwise.

as for the films caps. I ordered up some illinois MPW's. I have a ton of film caps for my other projects, but I wasn't sure how "audio grade" they were. there are two 716p's I ordered for the 2 .015 caps I couldn't find in stock in the Illinois ones.

regarding the PS series coupling caps, no problem replacing them. I'm not really looking to cut corners, just wasn't sure if they should stay or go. I bought plenty of the illinois MPW's, they weren't expensive. I assume they will get it running. Not sure how more exotic type caps would sound here.



Power isn't much of an issue, I have other amps for that. this is more of a, "Sansui made nice sounding stuff, it has a tuning eye.. I should have that" kind of deal. plus the price was right. it will be a bedroom set. Although I will need speakers! I didn't think this would drive my electrostatics.. hehe..

before I get too far ahead of myself, I just need to get r runnin'

my other hobby, btw.. is restoring antique radios from the 30s to about 1946/47.


Merry Christmas!

Bret

 

[bfrohwein]

one last question for you audiobee..

as far as the can caps go.. the schematic calls for 20-20-40 on the 3 section, and 20-20-20-40 for the four section caps. however, I noted, while tracing things out. Sansui seems to have made 'on the fly' production changes on this unit. the ones that are in there are all 20's. I did see that CE makes 3 and 4 section all 20's. however, I don't know if this unit is high end enough to warrant such a high priced cap. Since you have experience with these and I do not, If you think I should go for something like that, I would. they are a bit on the "wow that's expensive" side though. that was my only hesitation.

 

[Bstable]

Thanks BStable. Looking forward to hearing it the first time.

I'll tell you what was next to impossible to find. That square tuning eye tube! I think just about anything else in there would be able to be found in some form or another.

it did work when I first got it. but the power tubes were pretty dead. and those oil caps are terribly leaky. a few leak physically!

the transformers are good, and the coils I've tested. so we're off to a very good start.

I asked my dad about that receiver at Christmas yesterday, and got a little history. He bought it in Okinawa in 1962, but a tube went bad in it at some point. He went back overseas to Viet Nam in 1968, and found that tube. Then in early 70s the tuning eye went out, and he tried to find a replacement when he went overseas again in 1977. He had no luck. Sad, but the whole unit probably went into the trash at that point. Sounds like that eye was what you had trouble with as well. I remember that tuning eye. For some reason it was a very cool thing to look at as a 8 year old.

Again good luck...and take pics. :thmbsp:

 

[bfrohwein]

In the trash for a tuning eye tube. so sad. but that's how we were in those days!

When I called the guy I get my European tubes from, for the 6BM8 tubes. I was telling him about the square eye tube and that I just couldn't find any information on them other than this one was made by Toyo. He said, "oh, I have a couple of those, they're pricy though." So I bought two. now I have three. the original one, which is pretty dim and washed out and two bright new ones. Also toyo, all the same markings. I'm starting to think they were the only ones who made them and I am also thinking that they only made them for a couple of years, if that.

I also restore/collect old tube radios. Lately I've gotten in to anything with an eye tube. In fact, this Sansui bumped a 1957 Grundig monstrosity off my to do list. As a side project, I'm building an eye-tube VU meter as well.

 

[Bstable]

That is ironic that you said they were made by Toyo. This same brother was into 8-tracks (nobody else in the entire family ever was) anyway, at some point in the early 70's my dad bought him an 8-track recorder. I don't know why I remember the brand but I do...it was Toyo. I am going to check to see if I can find one.

That is incredible that this guy has TWO of those tubes. At 50 years old they had to have sat on a shelf somewhere. The color of that eye (pea green IIRC) matched all our carpet and appliances at that time. :yes:

 

[audiobee]

one last question for you audiobee..

as far as the can caps go.. the schematic calls for 20-20-40 on the 3 section, and 20-20-20-40 for the four section caps. however, I noted, while tracing things out. Sansui seems to have made 'on the fly' production changes on this unit. the ones that are in there are all 20's. I did see that CE makes 3 and 4 section all 20's. however, I don't know if this unit is high end enough to warrant such a high priced cap. Since you have experience with these and I do not, If you think I should go for something like that, I would. they are a bit on the "wow that's expensive" side though. that was my only hesitation.

replace with the same value of what ever it is in your unit....

since you are "restore" the unit, you will want to preserve the "look" and 'functions" of the unit...

If you want to save some money and still preserve the "look" of the unit some what...

here what you can do.

let's say for the 20-20-40 Can cap.. if you can only find a replacement Can Cap with the same diameter but only has two 20-20 section and it is reasonable price, then by all mean use that and the 3rd section you can use a small capacitor and put it right under neat and just tie the GND together and the + terminal to the + wire..

Do the same for the 4 sections..

don't do the ugly scheme like "cable tie" 4 exposed caps and wired them on top of the chassis....
the unit will look like it had been raped by some amateur "restores"..!!!





same for the 4 section cap....

 

[kvflyer]

...


don't do the ugly scheme like "cable tie" 4 exposed caps and wired them on top of the chassis....
the unit will look like it had been raped by some amateur "restores"..!!!





same for the 4 section cap....

Hear hear! "What he said".

 

[bfrohwein]

replace with the same value of what ever it is in your unit....

since you are "restore" the unit, you will want to preserve the "look" and 'functions" of the unit...

If you want to save some money and still preserve the "look" of the unit some what...

here what you can do.

let's say for the 20-20-40 Can cap.. if you can only find a replacement Can Cap with the same diameter but only has two 20-20 section and it is reasonable price, then by all mean use that and the 3rd section you can use a small capacitor and put it right under neat and just tie the GND together and the + terminal to the + wire..

Do the same for the 4 sections..

don't do the ugly scheme like "cable tie" 4 exposed caps and wired them on top of the chassis....
the unit will look like it had been raped by some amateur "restores"..!!!





same for the 4 section cap....

lol @ amateur rape restores....

None of that here! if there was room underneath for all of them, I'd have done that. I seem to only get that luxury on the 30's and 40's radios.

I've ordered the cans. I was having these horrible visuals of a terminal strip and 2" wide shrink wrap tubing. Although neither of those seems as gruesome as your description.

I had to go to storage today to pull out my old Klipsch 1.1's so I can test this when it gets done. While I was there I grabbed my SL1200MK3 turntable. I've missed my vinyl... except I couldn't find my records! :dammit:

Also, my CD player seems to be dead, and the left channel on my other tube amp is putting out far less volume than the right.. Looks like I'm going to keep my soldering iron busy till summer.

I'd better get back to work on this thing, I've spent 2 1/2 hours today fiddling with my VTA 70i. :thumbsdn:

I'll post some pics here maybe tonight or tomorrow. when I've made more progress.

 

[bfrohwein]

Happy New year!!

as I promised. here's an updated pic. I've finished recapping the underside. I'm still waiting on the multi section caps and clamps.

some of those little buggers were tedious. I nearly went cross-eyed staring at such close things for so long. :drool:

I still need to take out the PC board and recap that. Also I noted there's a crack in the board. looks like one of the stand offs was too short, whomever assembled it, tightened the screw down too far. and yes, there's a split in the in copper foil. looks like it's the perimeter ground though. but needs to be repaired none-the-less.

Also, I need to pull out the phono stage and recap that. good times!

most importantly though.. I dug through my storage and found my records

as long as those caps show up tomorrow. *fingers crossed* I should be able to fire this up on the variac by NYD!

 

[Roy Skinner]

nyd

It is New Years Day. I hope you are smiling about your 500.

 

[bfrohwein]

I wish! it's still sitting on the bench. the post office seems to have lost my last package of parts I was waiting on.

 

[bfrohwein]

I fired it up tonight. no am or fm. I have an amplifier though. aux worked.. for a while.

the switches (rumble, high filter, loudness) seem bad. I cleaned them, but it requires wiggling to get them to work, especially the rumble filter, where ch 1 and 2 will cut out completely. then while messing with switches something shorted, pegged my ammeter.. so I get to figure that out now. :dammit:

I do happen to have a spare switch that matches the ones in there, so I'll replace the rumble filter with that one.

kind of a bummer about the am/fm though.

for the 30 minutes it was running it sounded really nice. pretty impressed with the bass for such a low power amp. :thmbsp:

 

[bfrohwein]

found the short... oops.. solder blob...

 

[vigman]

Keep going.. doing GREAT~
Smaller amps like this are real crowd pleasers....

Mike

 

[bfrohwein]

waiting on parts sucks. I still need to troubleshoot the radio section. weird I have no AM or FM.. I suppose that should be a clue as to where to start looking.

so far, the biggest wow factor is when the eye tube pops on when I switch to the tuner. it does sound nice though.