Sansui 2000X Problem

[Lil Beav]

Greetings,

I am new here and have been browsing through archives trying to learn a little and maybe fix my 2000X. I bought it new in 1972 while in the Army in South Korea. I have a second 2000X that I bought on eBay a few years ago that is working OK.

So the problem is that there is no output to speakers or headphones on any input. Lights come on and radio signal indicator acts normal. The fuses look good and have output. I swapped the amp card from the other unit and nothing changed. The amp card from the bad unit worked fine in the other unit and the good unit card did not change anything the bad unit. I have a manual, schematic, and funky RadioShack multi-meter. I have been trying to follow signal flow but don’t really know what I am doing and what to expect. And I really don’t want to screw things up. I have cleaned and inspected very carefully and the only thing I see is that the amp card slot on the bad unit looks dirtier than the good unit. I have worked all the switches and buttons 30 to 50 times each with no change. I don’t yet have Deoxit but will be getting that soon.

Should I do anything else before cleaning the switches and button?

Measuring voltage on all the input/output connections on the bottom of the amp card connector looked the same on the bad unit as on the good unit. Does this mean anything? Does measuring this voltage mean anything and is it potentially harmful?

I am thinking that the problem is probably before the Amp card someplace in the switches and buttons. But could it be in the driver amp section and how could I test it?

I am having a good time reading in the archives and trying to figure it out. But I think it is time that I started participating in the forum. I need to get my Baby back in business and really appreciate any suggestions or comments you have.

Also, maybe not the time for this, but would like your take on the 2000X upgrades by Conrad. Has anyone done this and do you see a big difference?

Thanks,
Jeff

 

[Robisme]

Welcome to AK.

Use the preamp out of one receiver to feed the amp in of the other.

Then vice versa. This will tell you if it's the amp or preamp section of the bad 2000X.

Rob

 

[Lil Beav]

Thanks Rob,

I am not sure what the preamp is. The manual calls them "Driver Amp" and "Power Amp". I have already switched the Driver Amps (the one you can pull from the slot and swap without much trouble). There was no change. Is this the preamp or is there something else?
Jeff

 

[Robisme]

Look on the back of the receiver. There are preamp/amp in jacks with jumpers in them. If you pull the jumpers, it separates the preamp from the amp.

Use a patch cable to connect the preout jacks of the first receiver to amp in (or main in) on the second receiver.

The first receiver will be the preamp and the second will be the amp.

If you use the bad 2000X for the preamp receiver and you get no sound from the amp receiver, the preamp section is likely the problem. Could be a power supply issue.

If you do get sound, swap the cable around to use the bad 2000X as the amp.

Always have the speakers connected to the one you are using as the amp.

Rob

 

[Lil Beav]

Hi Rob,

I get dead silence both ways. I have checked it several times but not a peep.

Any thoughts?

Jeff

 

[super98lsc]

If both the pre-amp section and amp section test dead then I would strongly suggest a power supply issue as Robisme mentioned above. Checking the rectifier diodes, filter caps, fuses, transformer would be up next.

Just confirming your test and results:

• Pre out from good 2000x to bad 2000x MAIN IN = no sound?
• Pre out from bad 2000x to good 2000x MAIN IN = no sound?

If the above is true then both the amp and pre-amp section are dead which means the lights and FM pack are getting power but the rest of the system is not.

Check the negative rail voltage to the output transistors it should be around 30v on one transistor then double that on the next. So 30/60/30/60 or vice versa... Ill check mine tonight when I get home. Unless Rob already knows. Checking voltages stepping back towards the ripple filter/rectifier would be my next move depending on what you find at the rails.

Silly question but the power cord is in good shape and the internal voltage selector 120/240 you might try cleaning and re-seating it.

 

[Robisme]

Hi Rob,

I get dead silence both ways. I have checked it several times but not a peep.

Any thoughts?

Jeff

You had the speakers connected to the unit you had in the amp position? Then used the controls on the unit in the pramp position?

Rob

 

[larryderouin]

Rob; In the original post the OP stated that he swapped the driver card (amp board) and it worked in the other 2000X. If he's not getting anything hooked up to the other 2000X via jumper RCA's, then his Power Supply cards (F1197 and F1195) need work.

Lil Beav. Set your meter to DC Volts (200V range or AutoRange). BLACK PROBE TO CHASSIS FRAME. With the RED Probe and the unit turned on, Probe the power supply boards (the two horizontal boards in front of the amp board connector.).

Insulate all but the extreme tip of the probe to minimize or prevent slips, sparks and AW SH**'s. We've all done it, but it helps with the nerves.

Take the readings on the boards as shown in the pic. List them on your post.

 

[Lil Beav]

Rob,

I used headphones and made sure I was getting sound out of the good unit. I used the jumpers in and out of the good one and had sound. I tried both combinations and made sure that the headphones were in the unit taking the main input. my source was an ipod going into the Aux jacks and I made sure it was in the output unit and that it was playing. I was confused that I got nothing, so I checked and repeated everything several times.

super98lsc,

I am new to this. The rail I think is an good ground point on the plate holding the boards. I have been using the points that have multiple wires soldered to them. Do I have this right? I am not sure where to check on the output transistors. I think these are the 4 large transistors on the heat sink. Could you give me an idea about there to test these? Any leg or one specific?

Larry,

I checked the points on the two cards. On 1197, the Rectifier block, the voltage was as you suggested it should be. On 1195, the Ripple Filter block, the point you indicate for 14 Volts was reading about 12V. The other point however read zero. I have tried several times and and am pretty sure that there is no voltage. Appreciate your tips about the probe and the good graphics.

All,

Thanks for your feedback. Any suggestions from here?

Jeff

 

[Robisme]

Rob; In the original post the OP stated that he swapped the driver card (amp board) and it worked in the other 2000X. If he's not getting anything hooked up to the other 2000X via jumper RCA's, then his Power Supply cards (F1197 and F1195) need work.

As I mentioned in my second post. Just making sure his testing was accurate.:yes:

I have had to repair a few similar Sansui powers supplies lately.

Rob

 

[larryderouin]

Beav; Set your meter to ohms and read across R011 (probe on each end of the resistor. Should read 220ohms +/-5% if ok. If it reads O/L or whatever your meter reads for an open circuit (same as holding a probe in each hand and not touching them) the resistor is shot.

In any event you're gonna need the ripple board rebuilt, plus the Rectifier board to bring them both up to spec. Caps, out of spec resistors, Zener Diodes, and possibly transistors. The Zener's might be hard to find @ Mouser, so digikey would be a good choice to locate them. I might still have the envelopes for them with the mouser part numbers on them.

Download the manual from www.hifiengine.com

 

[Lil Beav]

Hi Larry,

Yes, R011 reads open, no reading when I connect from one side to the other. Sooo.. How do I proceed. Should I de-solder all the wires coming into the boards or can they be worked in place? The manual has a list of components for each board. Should I plan to replace everything or test each component first?

I have a Service Manual with 31 pages. Is there another different manual at the site you mention?

Thanks much,
Jeff

 

[147JK]

The Zener's might be hard to find @ Mouser, so digikey would be a good choice to locate them. I might still have the envelopes for them with the mouser part numbers on them.[/url]

Larry I was just working on a 2000X. I did not replace the Zener Diodes in mine. I only see 2 in the unit - both on F-1195 (Ripple Filter). Should these be replaced?

 

[larryderouin]

147jk. I habitually replace them. They can get noisy. But then I don't just repair them to get them working, I do comprehensive overhauls on them which would consitute a restoration in most cases. I do this on all my receivers. 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 They are faster, soft recovery and quieter in switching. Having a clean reliable power supply is paramount to stable and quiet operation of the 2000X. Between a minimal Ripple, Conrad H's board improvements http://conradhoffman.com/Sansui2000x_mods.htm and good quiet transistors (no 2sc458's), the 2000 series can be as quiet as a tomb @ midnight.

Beav. Replace the capacitors, resistors, rectifier diodes, and zeners. Chances are something else caused the R011 to open up. Check the transistors using Echowars 6-way testing procedure. If they pass use them. If not, they'll need to be x-referenced and replaced.

 

[147JK]

147jk. I habitually replace them. They can get noisy. But then I don't just repair them to get them working, I do comprehensive overhauls on them which would consitute a restoration in most cases. I do this on all my receivers. 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

Larry thank you.. I will open it back up and change out the diodes. One quick question.. I don't see anything called out for D003 or D004 on the rectifier block (see attached from the SM). Any idea what to use for these? Same as for D005, D006, and D007?

 

[Lil Beav]

Thanks Larry,

Do you have any suggestions for what type of capacitors are best? Any suggestions for the other components?

Jeff

 

[larryderouin]

Rectifier block. D001 and D002 use a 1n5404 (3A 400v prv)
D003 and 004 I use 1n4007 or UF 4007 (1A 1Kv) mainly because I have a pile of them. 1N4004's(1A 400V) will do good here.

In the Ripple Filter D005,006,007 Same thing. 1n4004

D003 and D004 were overlooked in the parts list on the 2k-X where the 2k-A shows them. See pic. Same board, same parts.

The Zener's are both 1W. At the time I bought them @ mouser these were the only one's available. Since they (mouser) has apparently stopped carrying NTE, I'll put the NTE numbers out there as BOTH MOUSER and DIGIKEY do NOT carry anything in 14V 1W and 25V 1W. NOTE that the NTE Zeners seem to be working ok.

ZD001 is 1W 25V Zener NTE5082A
ZD002 is 1W 14V Zener NTE144A

Suggest this. Recap and replace the rectifier diodes, and out of spec resistors. Then check your voltages. If within 5%, don't worry about the Zeners. Usually NTE is a LAST RESORT, Avoid at any and all costs by the more experienced members here. We generally don't recommend NTE. But in this case it may be warranted. Check them 1st and if ok leave them alone. Only replace if shorted, or the value is more than 5% out either high or low from nominal.

CAPACITORS.

Standard Nichicon Radials (UPW or UHE series for power supplies) are what i use in almost everything. I'll use UKL(Low leakage (read low noise)) in the signal path.
If the value is BELOW 2.2uf, use a Stacked Film cap. Panasonic ECQ caps are good for this. However they are at end of life cycle and will be discontinued by the manufacturer. But any mylar cap will do as long as the voltage is higher than the voltage spec'ed for the electrolytic. They are quieter, and don't dry out (read.....no more replacement!).

 

[Robisme]

Would a 1n5351 be too large to use as a replacement for ZD002?
Or a 1n5360bg for ZD001?

If they were needed.

Rob

 

[147JK]

Zener's are both 1W. At the time I bought them @ mouser these were the only one's available. Since they (mouser) has apparently stopped carrying NTE, I'll put the NTE numbers out there as BOTH MOUSER and DIGIKEY do NOT carry anything in 14V 1W and 25V 1W. NOTE that the NTE Zeners seem to be working ok.

ZD001 is 1W 25V Zener NTE5082A
ZD002 is 1W 14V Zener NTE144A

Thanks Larry - really appreciate the help.

On the Zener diodes.. there is another source near where I live that also appears to carry them. I think they would ship out as well. I'm not sure about the prices, but here is a link to them in case someone can use them:

http://www.vetco.net/catalog/product_info.php?products_id=2072
http://www.vetco.net/catalog/product_info.php?products_id=4039

 

[Lil Beav]

Thanks Larry,

I appreciate your advice. It will take me some time to get things together and start on this. It is more involved than anything I have done in the past and I hope that I am up to it. Any other thoughts/recommendations will be greatly appreciated.

Jeff