Sansui 5000a Won’t Power On

[760t1988]

This is my first post, so I will do my best...
I have a Vietnam era Sansui 5000A receiver. I wanted this thing so badly. Purchased it from the original owner with all the manuals about 8 months ago. It sounds great. I love it and have had no issues with it. I don’t get to listen to it very often. I have used it maybe 10 times since I bought it. I let my 4 year old get some dance practice in with it last week and it sounded great...fast forward to tonight. I decided to switch it from a small table to a stereo cabinet. Moved it maybe 3 feet. Tried to be gentle. I have moved it once before with no issues. Went to turn her on and nothing. I press the power button and nothing happens. I thought the switch used to stick in place when I pushed it in (?) now it doesn’t, but I could be wrong, maybe I am remembering wrong? I don’t know if moving it had anything to do with it or not. I don’t see why it would. I am in Georgia and we have been having lots of thunderstorms and it is cold and damp in the house. I am running a dehumidifier to try and dry the house out a bit. Any ideas? Did my switch crap out on me maybe or could it be something more serious? I am a female and not the most electronic savvy, but probably quite a bit more than the average chic. I grew up with an audiophile dad, so a little is in my blood. Give it to me straight.

 

[dave9]

If you're remembering right and the switch action has changed, it definitely could have failed and is now the problem. You'd need a multimeter to measure whether the switch is closing the circuit when in the on position. This does not require the unit to have power, just to make a continuity (then resistance would be good if there is continuity) between the switch pins when it should be on.

If the switch works then you have the rest of the receive to look at for where the power stops. I take it there are lights that light up and those don't light? That would indicate a more simple problem like the power switch or a burnt fuse. Moving something shouldn't blow a fuse but possibly a fuse this old was in a delicate state and moving it was enough. You can take the fuse out and test it the same as you would the switch, for continuity with a multimeter.

 

[760t1988]

Thank you so much for responding! I will test the switch with a multimeter. I checked the two fuses in the back and neither looked blown. (I have not been so bold as to remove the wood case just yet, I think there may be another fuse inside?) I am not getting any power at all...no lights or anything. It is stone dead. In it’s normal state it lights when in tuner mode and no lights when in phono, aux, etc.
I really appreciate your response. I am so intimidated by this thing.

 

[Ylli]

I found the schematic here: https://elektrotanya.com/sansui_5000a_sch.pdf/download.html . There appears to be two aux outlets on the unit - one unswitched and the other switched. With the unit plugged in, check to see if the unswitched outlet has power. Then plug something in to the switched outlet and see if comes on and goes off with the receiver on-off switch.

If that all works properly, check that 5 Amp fuse (F001?) with an ohmmeter - sometimes just looking is not enough. Beyond that, there really is not much to fail between the power plug and the first set of dial lights.

 

[760t1988]

Thank you I will try that with my turntable.
Thanks for the diagram. I have the manuals for it, but I packed them away for safe keeping and need to dig them out.

 

[760t1988]

I just went to check the outlets. (I couldn’t check anything with a multimeter yet because my husband took it to work with him) When I went to plug the turntable in I realized there was a third fuse next the power plug. I removed it to take a look at it. (It looked ok... but I thought well, I will test with multimeter when I test the switch and other fuses) I screwed it back in. Tried the power for chits n giggles and I GOT POWER!
Thank you guys so much!
Now, I am not fooling myself, I know I am going to have more issues in the future. I am going to save the schematic. Do you all have any service suggestions? I didn’t get the opportunity to talk to the original owner about when (if) it had been serviced. What would you all suggest I do to keep her well maintained?
And thank you again! EP is awesome!

 

[760t1988]

Well my little girl heard the stereo on and jumped out of the bed, threw on a tutu and ran out to dance. She got through two songs and it died. I unplugged it again then removed the fuse next to the power plug and reinstalled it and it came on again. ???? It’s going a little wacky.

 

[760t1988]

And I was wrong about the switch, it doesn’t stay clicked in, but it does make a noise when I press it. Like an amplified thump.

 

[(*steve*)]

It definitely sounds like a switch related issue.

I would confirm by checking the switched outlet, but I suspect it may be beneficial to spray the switch with some contact cleaner.

Hopefully there are some openings in the switch that you can spray into.

I think the problem is probably more on the mechanical side, but contact cleaner should be sufficient to clean out any dust and muck that is preventing correct mechanical operation.

 

[760t1988]

I think I have some Deoxit I will try that.

 

[Ylli]

After it quits, if you turn if off and just leave it for a while and then try again does it work? Wondering about a thermal issue.

Could also just try a new fuse.

Might want to access the voltage selector. Unplug it, check for any corrosion, and plug it back in.

 

[760t1988]

When it quit last night it started right back without incident after I reinstalled the fuse. I turned her back on today and played for 45 mins or so without incident.
I was going to try deoxit, new fuses and multimeter checks. I will check the voltage selector too. Thank you for that suggestion.
One weird thing I noticed that may or may not be related...I live in an older house (late 1930s) and some of the plaster walls were recovered with wall board (before I moved in) and for some strange reason the outlet I am using was moved from the baseboard (the old and unsafe way they had outlets pre 1940 or so, some of my outlets are still in the baseboard) to the wall and they used GF outlets. I made sure to trip the outlet first thing to rule that out. It is very humid and damp in my state I assumed that had something to do with that type of outlet being installed there? Could that cause a voltage issue?

 

[dave9]

Ground fault outlets shouldn't cause a voltage issue by themselves, should either behave just like a regular outlet or trip.

I could ask whether the receiver has a ground pin on the cord, or if it had its metal chassis touching something earth grounded, but it doesn't really matter if you did not have to reset the ground fault breaker to get the amp to work for (however long).

If in doubt you could just plug a lamp into that outlet to see if the bulb burns at acceptable brightness (I mean an incandescent 60W or higher bulb would be "close enough" to the load the amp would have at moderate volume, while a mere ~9W LED bulb wouldn't tell you if there is something in your mains wiring limiting current and thus dropping voltage (would would also be a fire hazard, but forget I wrote that if the bulb stays bright).

While it is not something I would normally tell people to do unless they are familiar with working on mains voltage AC equipment, it is easy enough to measure whether the voltage is around 110VAC where it enters the amp.

The impression I'm getting is that this is not the problem, and that deoxit won't hurt, but that it seemed like your switch has a mechanical failure, because you have now twice mentioned that including "it doesn't stay clicked in" which I assume it previously used to do?