When you can't power up a Sansui 210

[davstev]

Hi All,

I have inherited a 10 WPC Sansui 210. Cute little thing, seems to get pretty good reviews. It won't power on. I tested all the fuses inside the unit with my DMM, and they test fine. No fuses on the back. The former owner said that he heard a pop or something like that, and after, the unit wouldn't power on. All caps in view appear ok. Power switch is of the knob variety, not a push button and I tested it with a DMM and it seems good.

What are the first checks that you would do with this receiver to try to isolate the problem? Test the power transformer? Far from a tech here, but would like to give it a shot.

Thanks,
David

 

[Thierry]

A long time ago I had a Sansui 310 which certainly has a lot in common with the 210 below, and I still have its service manual.
There IS a power line fuse inside the receiver (A on picture below, 2A slo-blo) along with two quick acting fuses protecting the output stage transistors (B).

 

[davstev]

A long time ago I had a Sansui 310 which certainly has a lot in common with the 210 below, and I still have its service manual.
There IS a power line fuse inside the receiver (A on picture below, 2A slo-blo) along with two quick acting fuses protecting the output stage transistors (B).

View attachment 2482584

Thanks for he reply Thierry, but as I mentioned, I checked all he fuses and they're good.

 

[Catmanboo]

I'd start by checking continuity of everything in the power supply first, from the cord to the transformer, then check secondary voltages of power transformer & supply. Kinda sounds like a defect in this area which may have been caused by something failing downstream. do you have the means to do this? And how did you check fuses, with a VOM or DVM presumably?

 

[davstev]

I'd start by checking continuity of everything in the power supply first, from the cord to the transformer, then check secondary voltages of power transformer & supply. Kinda sounds like a defect in this area which may have been caused by something failing downstream. do you have the means to do this? And how did you check fuses, with a VOM or DVM presumably?

Thanks. Though I am a beginner, I think I do have the means to do this. Just reading up about the technique as I write this. testing transformer (electronicrepairguide.com). One theory offered by someone was that at least one of the diodes after the transformer had failed. Will look into that after testing the transformer. Also, I understand there can be a fuse in the transformer itself...

Yes, I checked the fuses with a continuity tester on the DMM.

 

[Catmanboo]

Thanks. Though I am a beginner, I think I do have the means to do this. Just reading up about the technique as I write this. testing transformer (electronicrepairguide.com). One theory offered by someone was that at least one of the diodes after the transformer had failed. Will look into that after testing the transformer. Also, I understand there can be a fuse in the transformer itself...

Yes, I checked the fuses with a continuity tester on the DMM.

I just re-read your first post, my bad for asking how you tested fuses- duh! The dial lights may be on a 6 volt or so AC feed right off the power transformer. You can check those for continuity also, to see if any are good. If they're all burned out, that will make it appear to be stone-dead when it's actually not. I've seen this myself. Keep us posted with your discoveries!

 

[davstev]

I just re-read your first post, my bad for asking how you tested fuses- duh! The dial lights may be on a 6 volt or so AC feed right off the power transformer. You can check those for continuity also, to see if any are good. If they're all burned out, that will make it appear to be stone-dead when it's actually not. I've seen this myself. Keep us posted with your discoveries!

Good thought about the dial lights. I did just power up, and though it wasn't the result I might have hoped for, there was something. When powered up, headphones in the jack, I get a hum on one side, and nothing on the other. No signal passing through at all- no FM/AM or aux. Checked the headphones on something else and they are functioning fine. Regardless of what setting I put it at on the selector knob- FM, AM, Aux, there's no change- just the hum in one ear. So it seems the unit is in fact powering up, but just not working at all. Hum in one ear is when the volume is completely down, and it does not increase with volume increase, stays the same.