Sansui AU 3900 recap

ALL212

This one is "done" also. In order to get them all I'd have to unmount all of the front controls (except volume, mic and power) and unsolder at least one set of wires to the board in the front. No fun and way too risky - this one does work.

Driver board all recapped except for 2 that are NP (non-polarized) caps that weren't marked in the schematic or parts list as such.

Power diodes removed and new heat sink grease applied. Rebiased to factory spec. Front panel cleaned up nicely. And it's breaking in.

tonyb

How she sound ? Good lookin' piece, be happy to break it in for ya.

mhardy6647

That little rogues' gallery line up of victims doesn't look all that daunting in number compared to some of the 1970s soiled state stuff of my ken

What're your preferred brands/types of electrolytics for a rehab like this one?


Just curious, you know?


DSC_0328 by Mark Hardy, on Flickr

ALL212

tonyb wrote: »

How she sound ? Good lookin' piece, be happy to break it in for ya.

I'll send it! I think I can get this other board recapped without removing it...look to N. central IL for smoke tonight...

At the moment the 222 sounds better - 3900 is still a bit bright to me but it's not broke in yet either.

mhardy6647 wrote: »

That little rogues' gallery line up of victims doesn't look all that daunting in number compared to some of the 1970s soiled state stuff of my ken

What're your preferred brands/types of electrolytics for a rehab like this one?

You waiting for the zombie apocalypse!! I love Sansui gear...maybe it shows...

I like Nichicon Muse, Fine Gold or those newer blue ones. But this time I also bought some Elna Silmic II's. I overbuy big time. If I need 4 I'll order 10. Most of these were in the 30 cent or less range. This board had very small holes but I also have a very small file and a few of the holes are just a tad bigger than before so I can get the new caps in.

Schematics are darn near microscopic so it's really hard to figure out where to use premium and where to use standard so I use the best I've got everywhere.

agfrost

Like those Sansuis! Very pretty. Need to bust my TA-500 out of storage.

ALL212

No more Sansui gear. Winter is coming to an end so my projects begin to orientate outside. I do have a G6700 that I've done the main caps on but it needs a do over as well. Hmmm... I do have a Sansui tuner here that I should take the covers off of. There is a Yamaha receiver and a Marantz receiver laying around here somewhere...

Next big project is a tube pre/headphone that I'm waiting on a pair of transformers for.

I've come to the realization that I only have so much room in the house for this stuff. My wife doesn't like using speakers as a dining room table and the sound systems in the bathrooms might be a bit overkill. I also have found that as cool as this older stuff looks it breaks and is a PITA to fix. So I've rotated a few pieces out that I probably should have kept.

Jimbo18

that will make a heck of a nice karma....Just sayin'

tonyb

In with 69....

mhardy6647

agfrost wrote: »

Like those Sansuis! Very pretty. Need to bust my TA-500 out of storage.

heh -- there's one of those here, someplace, too

mhardy6647

tonyb wrote: »

In with 69....

aren't we all? (ahem)

cortico

Good job! I find this really exiting, I’ll try to do a follow up on my 1060 rebuilt,

Already have the caps, transistors and resistors for an almost full rebuilt!

ALL212

Really bugged me that I didn't replace the caps on the tone control board but getting it dismounted would be problematic at best. Did you know you don't have to mount the caps on the same side they originally were?!



Also replaced a couple of lower quality caps that I used because lead size of what I wanted to put in wasn't right. Corrected that with my pointy file.



Only two caps left to replace and those are NP caps I don't have in stock.

I think this thing sounds much better now that I did the tone control board.

The bad boy lineup:


Organize those caps! uf on the left, volts on the right.

ALL212

Thanks! Electrolytic caps aren't that expensive at the values in this amp. The "big" 3300's were under $3.50 each. Most of them fell under .50 each. I doubt the executives at Digikey are getting bonus's on me!

Jimbo18 wrote: »

that will make a heck of a nice karma....Just sayin'

Maybe before the rebuild...

Down TonyB! Down boy! Someone says karma and all forms of composure just disappear!

Engineer degree not required for this. Finding a schematic and service manual before starting isn't necessary but it does help just in case a cap falls out and you have NO idea which side goes where. If you can figure out which end of a soldering iron gets hot 9 out of 10 times you can do this. Get a decent de-soldering tool. Mines just a bulb sucker but it works.

Clipdat

Ever do one of these? Onkyo Integra A-8067

ALL212

Nope...too new! The 222 has no IC's and the 3900's fanciest component is the 5 legged dual transistor. Easy Peasy!!

Skill level will depend on what it looks like once the cover is off. Sometimes boards just come out easy. Sometimes...not.

Clipdat

A-8067 hooked up to a pair of Snell Acoustics bookshelf speakers was my father's stereo when I was a kid. I've had a desire to replicate it lately.

mhardy6647

Dang that Onkyo amp is nice looking!
(Not to denigrate the Sansui, of course... but... dang)

Clipdat

If you look up the specs, it's nothing special hahah.

That's why I need to figure out if it actually sounds good like it did as I remember it when I was a kid.

mhardy6647 wrote: »

Dang that Onkyo amp is nice looking!
(Not to denigrate the Sansui, of course... but... dang)

mhardy6647

I'm not a big "specs" guy any more when it comes to hifi

Clipdat

Keep your eyes open for a nice condition one (or one of it's later variants) for me, would you please?

mhardy6647 wrote: »

I'm not a big "specs" guy any more when it comes to hifi

tonyb

Aaron,

I heard tell on some vintage forums, in particular relating to Sansui's, that if the caps or resisters are still performing to spec, or close to it, that they should be left alone when redoing these pieces.

Reasoning was, the older Japanese made caps and resisters were of better quality than you can buy today. I'm not a DIY guy, so true or not, I dunno man.

I think todays parts might give a better more detailed sound signature to these older pieces, but may lose some of that vintage sound we all fell in love with to begin with. If that makes any sense.

mhardy6647

Reasoning was, the older Japanese made caps and resisters were of better quality than you can buy today. I'm not a DIY guy, so true or not, I dunno man.

Generally not true of most kinds of capacitors. There are exceptions -- e.g., vintage Western Electric "oilers" chock-full of PCBs No kidding around, phenomenal crossover capacitors -- but priced are outrageous.

The 1960s (in particular) and 1970s Japanese capacitors (particularly paper-in-oil caps, generally used as coupling caps in vacuum tube hifi from Nippon) weren't great -- and, at this late date, they're abysmal

By and large*, electrolytics of today are way better than they were in the 1960s or 1970s.

The vintage gee-tar amp crowd are enamored of vintage capacitors of various kinds (e.g., Sprague bumblebees) -- but those guys are nuts and take lots of drugs.

The only place I'd be (really) careful in a rehab is, if doing a receiver or tuner -- don't muck with the tuner section unless you really know what you're doing or if there's really nothing to lose.

As a rule of thumb, if it is in the signal path and if its an electrolytic and if it is decades old -- change it

As far as resistors -- yeah, there's good things to be said, sonically, for carbon comp resistors, but old carbon comps a) drift in value over time and b) get noisy. Modern, decent quality carbon films are OK for most purposes. Metal oxide resistors are fine in power supplies.

Just my hardly-humble and at least partially empirical opinions, of course!
___________________
* And remember, all generalizations are false, including this one.

ALL212

tonyb wrote: »

Aaron,

I heard tell on some vintage forums, in particular relating to Sansui's, that if the caps or resisters are still performing to spec, or close to it, that they should be left alone when redoing these pieces.

Reasoning was, the older Japanese made caps and resisters were of better quality than you can buy today. I'm not a DIY guy, so true or not, I dunno man.

I think todays parts might give a better more detailed sound signature to these older pieces, but may lose some of that vintage sound we all fell in love with to begin with. If that makes any sense.

The ONLY parts I'm replacing are electrolytic caps. Those are known to "dry out" and their original value become so far out of spec they are a hazard to the remaining life of the other components.

The big caps I took out of the 222 were 1500's. My meter max's at 2000 and they measure at or past that - 33% or more from original value. The channel imbalance was restored 90% because one cap had opened up completely. It's still off a bit but that's what that balance knob is for...right?

Once the 222 was done and this 3900 by only doing the electrolytic caps at original value (in some cases a slightly higher voltage rating) the sound went from grainy and brittle to, in the 222's case, very tube like. The 3900 sounds more solid state but wow... it's listenable now. Before you just wanted to turn it off after a few minutes.

So for a couple hours of work and less than $50 these might not be back to original but they don't hurt the ears anymore.

Where the heck do you live? You were here so you must be fairly close. I'll "rent" one to you to try out. Maybe both? NO karma. No Tony...no Karma. But if you really fall in love with one we could work something out!

[Deleted User]

Another area to consider are the resistors and capacitors used in the cartridge loading section and any feedback circuits, especially the RIAA feedback. Here the value tolerance is important especially between the two channels. I have found .1% bulk metal foil resistors can be worth the extra expense as well as using matched polystyrene capacitors.

cortico

tonyb wrote: »

Aaron,

I heard tell on some vintage forums, in particular relating to Sansui's, that if the caps or resisters are still performing to spec, or close to it, that they should be left alone when redoing these pieces.

Reasoning was, the older Japanese made caps and resisters were of better quality than you can buy today. I'm not a DIY guy, so true or not, I dunno man.

I think todays parts might give a better more detailed sound signature to these older pieces, but may lose some of that vintage sound we all fell in love with to begin with. If that makes any sense.

Many people dislike the sound after restoration. It happened to me when I replaced original film caps with on an old receiver. I am sure the old parts add some Mojo, but it's like Russian roulette!

I am really curious to finish my project and compare a stock Marantz 1060 with the restored one. I have to say that I absolutely adore the way the stock unit sounds.

http://forum.polkaudio.com/discussion/180594/in-love-with-capacitor-coupled-output-sound#latest

Although It's a pretty much common sense that electrolytic caps on old units should be replaced, also resistors should be checked.

The picture below shows some signs of discoloration by the old caps legs, this could have been caused by heating or oxidation... it was on a countdown to disaster.

ALL212

I'm following that rebuild you're doing - nicely done!!

Film caps vs. Electrolytic's.... tough one to call when doing a fix/refurb. I'm under the opinion that film caps have a definitive sound signature in the signal path and can do magic in a power supply (assuming you can fit the darn things anywhere close to where the originals came from!).

I'm certain that electrolytics have a sound signature also but I'm not sure if I'd be able to tell the difference between the higher ended ones. Possibly between the lower (cheaper) versions vs. the higher (expensive) versions.

Another thing you get caught in is you need to come close to matching the specified farad value - in most cases you can hit that dead on. What is sometimes difficult is finding your favorite electrolytic in that value AND the voltage value. Going higher in the volt value doesn't hurt anything but it increases the size of the cap and the leads. Sometimes that just doesn't work and you'll need to move into a different brand/series.

One thing I would not change out from these older units unless it's blown would be the transformer. Sansui in particular was supposed to have excellent transformers.

cortico

Thanks Aaron, likewise!
Some values are difficult, it should be ok staying within 20% tolerance for the caps... some resistor locations have smaller tolerance, though.

ALL212

Last two caps done. Had a pair of NP's (Bi-polar, no polar, not polarized etc...) in there. Could use film caps or other types but space is at a premium in there so got the Nichicon BP's, the shiny green things.

Going to stick a fork in this one. Done!



Found these laying around the house. The Marantz looks fairly easy and service manual is a dream. The Yamaha's manual...not so good. I'll start a new thread on these.

cortico

Those Nichicon look cool! I cracked a Parasound cd player and had a few, it's great that Parasound uses such great parts into their equipment...