Any info on a Sansui SM-320

chrisand4

Not cheap, just thrifty..
Hello all,

This SM-320 was posted on bartertown recently for a great price considering the condition. I’ve been looking for another tube/amp receiver lately and thought this one would be a challenge to restore.

The seller had already tested it out with a variac and had a video of it playing, so I knew it would work in some capacity. I unboxed it today, checked it with a dbt, and brought it up on the variac.

I didn’t know what to expect, but I was pleasantly surprised with how great this thing sounds even in its current condition...I mean it sounds as good if not better than some of the other gear I have around. I played it for around 10 minutes and everything seems to be working. The big resistor directly in the middle of most of the rust did get pretty warm, not surprisingly as I’m sure it has drawn in some water/moisture and cooked at some point. I’m done playing with it for now until after the rebuild, I still have an AU-717 waiting on a recap, but this one is next, and I can’t wait to start on it.

Anyway, the point of the thread. There doesn’t seem to be much, if any information out there on this model. Does anyone have knowledge to share or maybe a schematic? Any help is appreciated.

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I’ll check with my audio guy. He may have schematics if you’re interested.

Yeah if he can dig them up, they would probably help. Most of the work in this one will be disassembling it so I can work on the chassis. I’ll probably go for a sand and repaint. I might even be able to get it powdercoated, but I’m not sure I want to take it apart that far.

Thanks again for the sale, I couldn’t be more pleased. Great packing job too.
 
Yeah if he can dig them up, they would probably help. Most of the work in this one will be disassembling it so I can work on the chassis. I’ll probably go for a sand and repaint. I might even be able to get it powdercoated, but I’m not sure I want to take it apart that far.

Thanks again for the sale, I couldn’t be more pleased. Great packing job too.

I was most impressed with shipping. I missed the post office so I took it to UPS. I saw that was delivered at 9:30 or so. That’s 400 miles in about 14 hours.
Glad you’re satisfied. Really a nice piece that sounds good for its look.
 
Whoa. I was thinking the SM series were more of a radio than anything serious. That looks like serious equipment, pretty impressive. Dual tuners, serious iron, magic eye? Wonder how it got into that condition though, closet with a roof leak? That big resistor might be a speaker impedance corrector? Early solid state receivers had that. That would be a real worthwhile long term project. Keep us posted. Sansui fans want to know.......
 
Yeah if he can dig them up, they would probably help. Most of the work in this one will be disassembling it so I can work on the chassis. I’ll probably go for a sand and repaint. I might even be able to get it powdercoated, but I’m not sure I want to take it apart that far.

Thanks again for the sale, I couldn’t be more pleased. Great packing job too.

No go - on the schematics.
 
Whoa. I was thinking the SM series were more of a radio than anything serious. That looks like serious equipment, pretty impressive. Dual tuners, serious iron, magic eye? Wonder how it got into that condition though, closet with a roof leak? That big resistor might be a speaker impedance corrector? Early solid state receivers had that. That would be a real worthwhile long term project. Keep us posted. Sansui fans want to know.......

Dual tuners - the Audio Shop that I bring my stuff to explained to me that before FM multiplexing was around, one channel would tune to a certain freq on AM and the other channel would tune into a certain freq on FM, both broadcasting the same, giving you 'Stereo' effect. Never knew about that. There is a switch on there to allow AM and FM at the same time, I asked why in the world that was a feature.
 
FM/AM Simulcast was a short lived feature from 1959 to 1961 model years (for the most part). When the FCC ok'ed FM MPX in mid 1961, pretty much everyone rushed to FM multiplex Stereo to get on the bandwagon,so to speak. Back to FM/AM the AM side was tweaked like crazy to almost FM SQ standard so the AM on these should be very good once rebuilt and aligned. One more thing, it may have an external MPX (to mpx) jack on the top or even the back. If so you can connect to an external multiplexer and get FM MPX STEREO.

The big resistor is one of the power resistors off one of the can cap sections (probably for the FM Tuner section).
 
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