Sansui 5000A - Dim bulb tester stays bright - Please help

[TubeJunkie]

Hi. I have a Sansui 5000a that has a power issue. When powered on through my dim bulb tester, the light bulb stays bright, indicating problems. But when I remove the two speaker fuses, and power on with dim bulb tester, the Sansui powers on, and DBT, bulb dims, which is good. So I’ve went over the Ripple board, all good there. Pulled output transistors, they test good. Check diodes. So, I now will look at the Driver boards. Am I going in the right direction?

This 5000a has the notorious F-1040 driver boards. Ugh... lol.

Also, two of the big 2200uf filter caps measure more than double spec. Each Like 4800uf. That measurement taken with caps connect in circuit . The other two measure fairly close to spec.

 

[Ylli]

I don't see any speaker fuses on the schematic I found. There are two 4A fuses in the power supply, F002, and F003. These feed power to the left and right amplifiers respectively. First thing to do is to determine whether removing F002 or F003 improves the behavior of the DBT. That will tell you if the problem is in the right or left channel (or both).

Also, two of the big 2200uf filter caps measure more than double spec. Each Like 4800uf. That measurement taken with caps connect in circuit . The other two measure fairly close to spec.

The schematic I have show these as 1500 uF. They are electrically in parallel and therefore will measure 2X in circuit.

 

[tom3]

One way I've tested the amps is to use a night light as a dim bulb tester for each of the amps. Hook the light up to replace the R or L fuse. If the 7 watt bulb glows pretty bright you probably have a short in there. The circuit sees 80v DC so the bulb will glow some with a high current flow. Usually if there actually is a problem you'll see a blown fuse though.

 

[slimecity]

You will get more help posting this in the Sansui section

 

[TubeJunkie]

I removed just the left 4a fuse and dbt is still bright. I replaced the left fuse, and removed the right fuse, dbt dims and receiver powers up. So, I’m assuming this tells me the problem is in the right amp? Looking at the receiver from the front, is the right amp board (F-1040-1) on the right?

 

[Hyperion]

Looking at the receiver from the front, is the right amp board (F-1040-1) on the right?

People who can answer that question 'off the top of their heads' mostly reside in the 'Exclusively Sansui' sub forum here on AK.

Report your own first post (using the 'Report' link on the bottom left) - and request that this thread be moved there.

You'll get more frequent responses there, and anyone else who has this problem, and is looking in the right place i.e. the Exclusively Sansui sub forum, will see how it is solved.

 

[TubeJunkie]

I’ve reported the request to move it to Sansui only section. Thanks

 

[TubeJunkie]

I removed just the left 4a fuse and dbt is still bright. I replaced the left fuse, and removed the right fuse, dbt dims and receiver powers up. So, I’m assuming this tells me the problem is in the right amp? Looking at the receiver from the front, is the right amp board (F-1040-1) on the right?

 

[Hyperion]

Darn it - I thought the 5000 series experts would be swarming around - however nothing but ...... tumbleweed.......

Bump!

 

[TubeJunkie]

Me too. I need some expert advice. I’ve been all over this thing and can’t find a bad component anywhere.

 

[s-petersen]

Not really a Sansui or solid state guy, but I would remove the output transistors on the bad side, and see if it powers up, possibly a bad cap is throwing the bias off.
If it still has a high current problem with those removed, try removing the drivers.

 

[blhagstrom]

The 5000A F1040 boards are known problematic.

There is a thread around here, either the 5000 or the 5000A that details a nice rebuild of the board.

Find that thread.
Study it.
Pull the F1040 and rebuild them according to the info.
Reinstall, test, adjust.

Enjoy.

 

[TubeJunkie]

Well, I just realized that this 5000A has the F-1040-1 driver boards instead of F-1040 boards. Didn't know until now! Now I need to find a service manual for the F-1040-1 board. No wonder I'm having a hard time with this receiver. LOL

 

[TubeJunkie]

Anybody out there? I started a thread in Digital Docs requesting the F-1040-1 board schematic or service manual for this Sansui 5000A

 

[Sansuiman]

I don't think there is a schematic in existence for the F-1040-1 driver board. The service manual shows the original 1040, and Sansui almost never updated a service manual after the original publishing (periodically a sticker that could be applied over an erroneous portion of a page wassupplied, but required the shop to actually put it on).

There were a couple of tech bulletins issued for the 5000/A/X regarding stabilizing the original driver board, and another detailing their replacement with the F-6013 board.

Sansui service manuals are notorious for errors anyway, and thus it is recommended that one work back from the actual board to compile a parts list for rebuilding rather than using the service manual schematic or parts list. If you have questions on modern part substitutions for those that are now obsolete, post them here and one of the experts will chime in.

 

[TubeJunkie]

Thanks Sansuiman for chiming in, and sharing that info. I’d love to find some F-6013boards. I read another member has the F-1040-1 SM. I sent him a message. I may put this one on the back burner for now , or until I get thst info

 

[Sansuiman]

Ok, I'd add that the F-1040 (and presumably 1040-1) can be made stable by some minor modifications. I don't have them scanned, but somewhere I have old copies of the tech bulletins on the subject and modded my own years ago. I've since put reproduction 6013 boards in both my A and X models as each had subsequently blown a channel and I decided to replace rather than rebuild the original drivers again. Kept the old ones just in case I decided to go back.

While having the 6013 boards is nice, it isn't really necessary as if you do the factory approved mods, the originals can be made to work reliably. And, I think there is something to be said for maintaining originality where possible.

 

[grindfix]

Thanks Sansuiman for chiming in, and sharing that info. I’d love to find some F-6013boards. I read another member has the F-1040-1 SM. I sent him a message. I may put this one on the back burner for now , or until I get thst info

Did you find SM for 1040-1 version?

 

[avionic]

https://www.audiokarma.org/forums/index.php?threads/sansui-frequently-asked-and-more.144580/page-9

 

[grindfix]

I figured out all but C804. Is it supposed to be 1uf or SM has error and it is 10uf?

jpdylon been out of forum since last year. I wish I could ask him. I hope he’s alright.