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5000x Refurbish & Troubleshoot

TheScrounger

TheScrounger

New Member
I am pretty new to AK and this is my first post in the Sansui group. I have recently been bitten by the Sansui bug and now I am hooked. It started with a 1000x and I just acquired a 5000x. I have been reading the posts on refurbishing the 5000x and want to first say thank you to everybody for sharing all your knowledge.

The system works very nicely and is pretty clean on the inside. I plan to recap it at some point in the near future. I've checked the bias and it is spot on. My 5000x is a later model so it has the F-6013 boards.

I have an issue that I haven't seen discussed any posts. The selector switch doesn't change the display correctly when switching inputs. The Tuner Dial, Phono 1, Aux, and FM Stereo lights all remain illuminated in all settings except Phono 2. When Phono 2 is selected, the FM Stereo and Phono 2 lights will illuminate and all other lights turn off.

Has anybody seen this before? Thanks in advance.
 
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Something similar, maybe, I have a 5000 that the stereo light is always on, all selector positions. I got into the MPX board, tested the switching transistors, all good. Keep us posted if you find the problem with yours. Did you look for the schematic on this site? In the DYI forum there is a link to the database.
 
tom3 said:
Something similar, maybe, I have a 5000 that the stereo light is always on, all selector positions. I got into the MPX board, tested the switching transistors, all good. Keep us posted if you find the problem with yours. Did you look for the schematic on this site? In the DYI forum there is a link to the database.
Click to expand...

Instructions are for a 5000-x,a or 5000 as VR401 is the same on all of the F-1006 MPX boards.

Usually that is an adjustment that is out of spec that causes the stereo light to remain on even when a stereo signal is not present. The adjustment is on the Multiplexer board F-1006-2 and is VR-401 its a 200k pot with a flat-head screwdriver slot in it. Right in the top center of the board.

Find a dead spot on the dial with nothing but hiss, then adjust until the FM Stereo light just goes off, then tune to a good station and adjust slowly until the FM-Stereo light comes on and remains locked in. If the FM is "bouncing to mono-stereo but sounds clean and devoid of hiss then adjust it a tad more until stable. What you want is it should stay in MONO until a solid stereo carrier signal is picked up.
 
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tom3 said:
Something similar, maybe, I have a 5000 that the stereo light is always on, all selector positions. I got into the MPX board, tested the switching transistors, all good. Keep us posted if you find the problem with yours. Did you look for the schematic on this site? In the DYI forum there is a link to the database.
Click to expand...

Thanks Tom. I did find the schematic on that's AK database. They are much better quality than the one I had. Should make reading much easier.
 
super98lsc said:
Instructions are for a 5000-x,a or 5000 as VR401 is the same on all of the F-1006 ...
Click to expand...

Super98lsc, fantastic information! I will give this a try.

Hopefully I will be able to determine why the other lights stay on. It doesn't really seem to be affecting anything, but it prefer for the radio dial to turn off when using the phono inputs.
 
So your dial remains lit when the selector is changed to phono, aux etc? Sounds like someone modified the unit. I have read of people doing that so they can "look at the green radio dial" when using other modes. Point of it turning off was lower drain on the power supply aka more rail voltage/current reserve for the amplifier output. I will scan over the schematic and report back. I have rebuilt a few 5000a,x and my 2000x. The 5000x I rebuilt everything tuner, did alignments on it, the works even had to replace the IC Amps (little flying saucers) on the FM IF board.
 
super98lsc said:
So your dial remains lit when the selector is changed to phono, aux etc?
Click to expand...

I ran across some posts where people were trying to figure out how to mod some units to get the back light to stay on for the tuner. I don't think that is the case for mine, but it could be. I have not studied the schematic, so forgive my ignorance. I have seen some posts where people have discussed "leaking" transistors causing lights to stay on. If there are transistors being used for switching lights on, I suspect that this could be my issue. My reason for thinking this is that when I switch to Phono 2 the tuner display lights turn off. In all other modes (Phono 1, AM, FM, FM Stereo, and Aux) the tuner back light is on. Additionally, along with the tuner back light, the Aux, Phono 1, and FM Stereo lights are lit in all modes excluding Phono 2.

Any thought would be greatly appreciated.
 
Sounds like someone shorted the power coming off the selector switch to all of the bulbs except Phono-2. Now it could be that the selector switch goofed up causing it but they are really robust and well made. I mean most of these are older than me and still work great with a simple cleaning. (find me an LG appliance that lasts like that now) What I would inspect is the leads coming off that selector and see if there is evidence of tampering or (all them braided or soldered together). On the diagrams I have included the dial lamps (back-lighting only) are on when in positions 3,4,5 (Circled in Red) which would be AM, FM, FM-Stereo (FM-Auto on a 2000 series) The FM Stereo lamp is driven by a transistor that switches it located on the underside of the chassis. So my guess is a person worked on it and either "fixed-it" or tried to modify the lamps to always be on not realizing only a portion of them were the dial lamps vs the input indicators. Dial Lights vs inputs.jpg Lighting Pilot Lamps.JPG
 
super98lsc said:
Sounds like someone shorted the power coming off the selector switch to all of the bulbs except Phono-2.
Click to expand...
Super98lsc, thank you so much for taking the time to research and reply to me on the switch layout. I had started reading the schematic the other night and saw the portion you included. I was beginning to suspect that the issue must be at the switch. Your post confirms that I was reading the schematic correctly. Hopefully I will have some time this weekend to investigate further.

Thank you again for sharing your knowledge.
 
I finally had some time to look for the cause of the tuner light staying on regardless of the input selected. I started with the selector switch, but it did not appear to have been tampered with. Next I began looking at the F-1065 accessory board. I noticed two jumpers that didn't look right that were bridging several of the selection lights. The solder joints didn't look original and there was some insulation burnt off of a near by wire. I heated up the soldering iron and removed the jumpers. Problem solved!

The FM Stereo light is still on in all modes. I haven't tried the fix recommended by super98lsc yet.

The red wires are the jumpers I removed.
 

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super98lsc said:
Usually that is an adjustment that is out of spec that causes the stereo light to remain on even when a stereo signal is not present. The adjustment is on the Multiplexer board F-1006-2 and is VR-401 its a 200k pot with a flat-head screwdriver slot in it. Right in the top center of the board.
Click to expand...

I tried adjusting the VR-401 pot and unfortunately that did not resolve the issue with the FM Stereo light staying on. I did notice that adjusting the pot did cause the light to get slightly brighter, but that was the only change. On the copy of the schematic that I have the F-1006-2 is located at the intersection of the 4 separate pages, which makes following the circuit extremely difficult. Does anybody have a better image of the F-1006-2 schematic? Or any ideas on other issues that could be causing the FM Stereo light to stay on?
 
I believe that I have tracked down the issue with the FM Stereo light always on to transistor TR409 on the F-1006-2 board. The schematic shows that this transistor should be a 2SC708 however the part I pulled from the board is a 2SC971. It seems much easier to find an equivalent for the 2SC708 than the 2SC971. Would it be safe to use a 2SC708 equivalent? Or should I continue to look for a 2SC971 replacement?
 
After replacing TR409, I did the FM Stereo light sensitivity adjustment that super98lsc recommended. These steps are also found in the troubleshooting section of the service manual.

super98lsc said:
Usually that is an adjustment that is out of spec that causes the stereo light to remain on even when a stereo signal is not present. The adjustment is on the Multiplexer board F-1006-2 and is VR-401 its a 200k pot with a flat-head screwdriver slot in it. Right in the top center of the board.

Find a dead spot on the dial with nothing but hiss, then adjust until the FM Stereo light just goes off, then tune to a good station and adjust slowly until the FM-Stereo light comes on and remains locked in. If the FM is "bouncing to mono-stereo but sounds clean and devoid of hiss then adjust it a tad more until stable. What you want is it should stay in MONO until a solid stereo carrier signal is picked up.
Click to expand...
 
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