Sansui 2000x MPX board versions

ConradH

AK Subscriber
Subscriber
The 2000x manual and schematic show the F-1190 MPX stereo board to have filter modules (FP38A). I think I've seen one like that. The rest that have crossed my bench have discrete parts and I think the board is F-1190-2. The layout and schematic are slightly different. Does anybody have a schematic and board image for the latter version? Obviously I muddle along with mark-ups and notes, but it would be nice to see the Sansui docs on the matter. I've checked the other similar models, but they also show the module type board.
 
Conrad; Both my A and X have the 90-2 board. And the scats both show the F-1190 board. I think Sansui screwed the pooch big time on these. My "A" has more boards from the "X" model than the "A" model. About the only thing that is are "A" modules are the Power supply boards and the amplifiers. Everything else is from the "X" line. Real PITA to have to go between 2 manuals. My 1st "A" also had more in common with an "X" than an "A" too.
 
They did tend to mix and match boards from various models and time periods. No biggie as with a large enough collection of manuals you can usually find something close. Right now I've got an F-1190-2 MPX board that's dedicating its existence to proving I'm an idiot. I can't get the control chain to turn on and enable the 38 kHz amp, but looking at the schematic I don't see how it would ever work to begin with. Next step will be to open up a working unit and record each and every voltage.
 
Whew, fixed it! For a while it wasn't clear who was going to win the fight, but I didn't have to resort to opening another unit. There are a couple 0.02 ceramic caps associated with the "noise eraser" transistor. It turned out C418 was slightly leaky, having a resistance of about 6-10 kohms. While pulling transistors to test them, I measured resistance to the various nodes. The end of C418 should have shown no resistance to ground, so the minute I got a reading I knew the answer was near. New cap, touched up the alignment, perfect! I wouldn't wish that kind of problem on my worst enemy because everything looks about normal on the scope, but it doesn't work. Small high value ceramic disks do sometimes degrade as they get older, so that's one more thing to add to the check-list for 2000 series "no stereo" complaints.

(edit- added the MPX info to my 2000x page)
 
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The 2000x manual and schematic show the F-1190 MPX stereo board to have filter modules (FP38A). I think I've seen one like that. The rest that have crossed my bench have discrete parts and I think the board is F-1190-2. The layout and schematic are slightly different. Does anybody have a schematic and board image for the latter version? Obviously I muddle along with mark-ups and notes, but it would be nice to see the Sansui docs on the matter. I've checked the other similar models, but they also show the module type board.
In the style of dynaco fm3 modification of the outputs using the PEC modules, will build the FP38A filter modules using polypropylene capacitors. The schematic to the FP38A modules is published by Sansui for the 5000 model. However I will use such for the Sansui 200 receiver to obtain the best possible sound. I suspect that the modules are too old and likely ceramic capacitors
 
Damn. I didn't think about other models of the era! More digging to do.
 
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