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Sansui 2000X Problem

Don't Rely on the schematic to be correct as to part #'s as the Zener Diodes have shown. Visually verify each and every part on the schematics/parts list against the actual unit and note changes. Download the 2000A manual and use it for comparison. I've seen / had an "A" model that was more "X" than "A". When you get done with the verification, mark up a version with all the corrections on itand save it as your specific manual for THAT UNIT.

I haven't looked at the specs for either, but if they are the correct value and voltage, they should work. Be careful of larger than normal leads on the zeners. If so just use a twist drill and drill out the holes by hand. Make the leads about 1/4" to 3/16" long and use heat-shrink to insulate them.
 
Hi Larry,
After removing the Rectifier and Ripple Filter cards I realized that my Rectifier card does not have Diodes D003 and D004 or Resistor R003. Also, there are no connections on points OF, OG, OJ, or OK. I checked and found that my other 2000X also does not have these parts. I have included a picture. I guess there was an engineering change at some point that eliminated them. Your point is well taken to check each item on the board and not just go by the schematic diagrams and lists in the manual.

Jeff
 

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Well THAT makes it easier. Sansui was infamous for making line changes that never made schematics. Replace the TWO caps on the right side of the board, and the 2 diodes on the left. 1n5406 for the diodes on the rectifier board.

What are the serial #'s on your 2000X's? We can tell within a month when built from that.
 
Dec 1971 amd April 72

First number of a 9 number serial is an unknown. 2nd number is plant #, 3 is year, 4&5 are the month, 6-7-8-9 are run #.
 
larryderouin said:
If your output voltages are with in 5% of nominal for that pin (25v +/- 1.25V and 14V +/- 0.7v) don't worry about it. I would replace the small rectifier diodes with UF4007's. And the large one's with UF5408's.
Click to expand...

Well I changed out the small and large rectifiers, but I'm getting 21.6 V and 13.2 V on pins 7 and 6 - both beyond the 5% tolerance. However with the poor reputation of the NTE Zener diodes, I'm wondering if I should just leave it as-is, or go ahead and change them out as well..?:scratch2:

Uh oh.. I see I've introduced a new problem.. now the display light have gone dim. They are about 1/2 as bright as they were before changing the diodes. Something's not right.

I checked the offset voltages.. I had them set at 30 V per Conrad's mod instructions. Now I see they are reading about 25 V.
 
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Attached is a pic of what came out of D001 and D002 on the rectifier block, as well as what I replaced them with (1n5404). The old ones look odd.. are these simply an older style of diode design?
 

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Wait wait wait.. may have found the problem.

I had left the unit on the dim bulb tester.

OK, it's Saturday, and I'm an idiot.:sigh:

Yes it checks out good after removing the dim bulb. However still slightly low on the voltages near the Zeners. Hmmm... change the Zeners out or not?
 
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147JK said:
Attached is a pic of what came out of D001 and D002 on the rectifier block, as well as what I replaced them with (1n5404). The old ones look odd.. are these simply an older style of diode design?
Click to expand...

The old style ones are called 'top hat' rectifiers for obvious reasons, a very dated style of rectifier.

You have formed and mounted the replacements very well. :thmbsp:

PS: you are allowed to make mistakes on your own time :D
 
Well, more than a year has gone by and I finally rebuilt my ripple filter and rectifier cards (1195 & 1197). And she is back to life! Thank You All!

But unfortunately there is a hum at low or no volume that I don't like. It goes away when I disconnect the Pre-output/Main-input jumpers in the back., so I think it is it is somewhere in the Pre-amp.
Any suggestion on how to troubleshoot?
Thanks,
Jeff
 
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