Sansui Model 250

Tube Sound

Super Member
I picked up this little guy a couple days ago. The seller indicated it had probably not been in use since 1979 but he had "plugged it in and it lit up". I took it home, brushed it off and cleaned the pots. I debated on taking it to a tech before firing it up, not having a variac, but........ in a moment of weakness, I threw all caution to the wind. Plugged it in and connected some Minimus 11's. Set it on FM Stereo and....... voila, we have sweet tube music. Dead silent, no hum, no static. All controls working beautifully. Long live tubes and Sansui!!
 

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Be CAREFUL! Be REAL CAREFUL with a Tube Sansui that has not been refurbished or you don't know the history on and it was "Plugged in and it lit up". You're asking for all kinds of trouble.

Open it up underneath and look for GRAY ELNA Electrolytics and Gray SUZUKI PIO CAPs. If you find any, REPLACE THEM NOW! They will blow, and it's not a "if they blow" but "WHEN THEY BLOW" scenario, and they will blow sooner than later. Replace with like value and increase the voltages on them one or two steps.

I do see some what looks to me, non standard (at least not stock) wiring to the Left Hand power resistor. It's possible that there has been some work done, but if it's been since '79, I'd still replace all the caps in it.

They are good little receivers when running right (Sansui overengineered them to an extent) but the parts (mainly caps and some resistors) are generally considered to be sub-par today. When refurbished/restored they are VERY GOOD.

Larry
 
Thanks for the concern, Larry. Yes, I was living dangerously, dodging bullets like a character in Person of Interest. No long term play here, just wanted to see if I had music. I'll be taking it in for a check up. Here's the underside.
 

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The only caps I don't recognize as original are the two output coupling caps (YELLOW and BLUE) in the upper left corner, but they very well could be. Everything else looks original. If it sounded 1/2 way decent under test, it should sound pretty good when refurbished.
 
Thanks Larry. I will follow your recommendations. I would say it sounded better than decent and was surprised how quiet it was. I'll look forward to listening when done. Appreciate your thoughts.
 
Basically replace all the PIO's (paper in oil) with Films (your choice of which one's), and all of the electrolytics. Most of them are axials. You CAN use a radial (sometimes at substantial savings to wallet.) in most cases. The 4 section CAN Cap can be gutted and restuffed with "pencil type" caps. I'd use 27uf 400V here. In the Single Can cap, use a 100uf 250Vcap. WV= working voltage which is the normal voltage it will handle during operation. SV = Surge voltage which is start up surge voltage upon switchon and will go down to operating voltage as the tubes start conducting. With tube units I uprate the caps working voltage to the old surge voltage or slightly higher due to the higher operating wall voltages of today. Your choice of brands, but stay with a known brand name, ie: Nichicon or Panasonic. Using Audio caps in this won't do anything other than empty your wallet a little faster. I use UPW or UHE(low impedance) Nichicon's in P.S. (non signal path) area's. Otherwise I use Nichicon UKL (Low Leakage or Low Noise) for signal path caps. If you have to use an axial, Nichicon's only series I know of is the TVX Series. Good general cap.

You can use Orange Drops, but I find the Cornell Dublier DME or DMT series of Film caps sound pretty much the same, and they are quite a bit smaller, plus they cost less. K40Y-9 Russian PIO's, are good for the output coupling caps or K42's. As the cases are metal, a heatshrink sleeve is recommended.

Along with cleaning everything it's a straightforward rehab.
Service manual is available at www.hifiengine.com
 
Those main filter can caps have been replaced at sometime. Notice the brackets, and the originals were wrapped in grey plastic. At least the ones I did were. As you play it, check those caps for self heating, that's a bad thing, but I bet you're ok on those. Follow Larry's good advice.
 
Larry and Jay, thank you both for taking the time to give me specifics on the restore. This is my last piece of Sansui gear and I want to bring it back right. I haven't listened to it since the first test, afraid of possible shrapnel wounds! You guys are great and I appreciate it.

Dan
 
I have one of these , I replaced the caps with orange drops and the electrolytic s - and power supply . Did this 24 years ago and still sounds great . Daily player . Have many hundreds of hours on it All tubes original ...except the 6AQ8 in the amp section ,,, subbed it with another brand .. just sounded better to my ear even though the tub tested good . Great set... that eye tube though is a tough one to get. I just unplugged mine to save it . Has no effect on anything disconnected . Enjoy it !
 
Measure resistance on it (lift one end from circuit.) It's a power resistor, probably 10 or more watts. R52 or R53. But it could also be R134 or R135 which are 20W. You'll have to suss it out from comparing the schematic and the layout internally. If one is bad (those ceramics from Sansui are historically multi-section) you replace both sections. 3.5KΩ may be hard to find for R52/53. and 1.7KΩ might also. Get them with in 5% and you should be ok. The metal cased chassis mount types would be ideal for this.
 
Can't recall where I bought it.
ohmite1403.jpg
 
Thanks for this helpful 250 thread. I have one that’s been restored (2 coupling caps replaced, tube sockets cleaned, tubes tested ok, bias adjusted, FM aligned, pots and switches cleaned…). It sounds wonderful. The only issue is the volume pot is tracking poorly and I’m always fussing with the channel imbalance. I know it’s a can of worms, but does anyone know of a suitable replacement pot? I appreciate any assist.
 
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Remember also that these were not made to operate on todays voltages which can be close to 125. A Bucking transformer is always your gears friend here. I use it on all my gear or they don't get plugged in.
 
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