I could boil a pot of water on my Sansui 5000A

[GlenMartin]

I have to say I am very grateful and humbled to have recently obtained this great sounding receiver along with a pair of Sansui SP2000 speakers, a pair of Pioneer CS-88A speakers, a TEAC 4010S reel to reel tape deck, a Sansui RA-500 Reverberation Amplifier and a Dual 1019 turntable all in mint condition. Included in the mix is an Onkyo TX-DS989 monster receiver and a newer JVC home theater receiver both working awesome. The owner recently passed and his wife, a friend of mine, knew I loved vintage audio and passed it all down to me completely gratis. Blew my mind. I rebuilt the crossovers on all speakers, refurbished the tape deck and the turntable. The owner was a Vietnam Veteran and bought all of this while he was in service. I want to honor his service by taking care of it, enjoying it as he did and keeping it all alive and together as it should be.

So onto my subject line. When I powered up the the 5000A, I was so impressed with the sound quality I tried all kinds of my favorite music on it for about a half hour. I've read so many great things about it and the one not so great thing. The pesky driver boards. I found a repair receipt from 1972 showing the boards were replaced from the F-1040's to the F-6013's due to the infamous overheating. What is puzzling, is the receiver still runs so hot with the replacement boards, it's almost a stove top burner after a while. I can't even touch the metal case without the risk of being burned. Turned it off real quick and blew cool air on it.

What could be going on? I found a rebuild kit on Ebay for the F-6013's here: https://www.ebay.com/itm/Sansui-F-6...r-Recap-Kit-for-5000X-5000-5000A/113905996150, but I am not sure if this will solve the problem. I was about to bring the receiver out to my car last night to bring it to a repair shop but thought I better come here first and ask and was wondering if this rebuild kit might be the fix I need before I shell out $400 to fix it. My repair guy charges me $400 for everything. Makes me crazy but he is good. I am not a trained electronics technician but I do know how to identify, solder and replace components, and read schematics. My weakness is diagnostics. I did a visual inspection of all caps and boards and all looked perfectly fine. No burns, corrosion or bad wiring.

Any clues as to where I am with this old girl right now? She still sounded sweet even in her heated moment.

Thanks for any ideas, suggestions or history you can share.

 

[elnaldo]

Hello. If you are not skilled to trace a fail, adjust the bias current, or work with the electronics inside the amp, your only move is to take it to a tech you trust.

I wouldn't buy any upgrade kit from eBay. I'd diagnose and fix the problem.

If you want to do a first try, please identify which board you feel overheating, and check the service manual to measure-adjust the bias current. That's usually the cause of hot heat sinks.

 

[rickb119]

Just wanted to say congrats on the 5000A. I have one and it is a very sweet sounding receiver. Hope you get it in good running order.

 

[maxhifi]

Sounds like runaway bias in the output stage. This is the same issue that one of the original F-1040 boards had in my 5000A, and in that case it was as simple as changing a few diodes. The thing is, you could either change everything and hope for the best, or take it to a tech who knows Sansuis and just fixes it properly.

 

[GlenMartin]

Hey guys.. thanks very much for your responses. Can you walk me through how to set the bias in the output stage or should I just take it to the tech.

 

[spark1]

You can get the service manual at hifiengine.com. Free. It will have instructions. There are two methods; I believe the manual describes how to measure/adjust bias current...which will require use of the ammeter function of a multimeter. Be sure meter is working correctly.

Before attempting adjustment, make sure the trimmers (the variable resistors) are in good working order. Do you know how to test them?

The first thing I would do is measure existing bias, to verify it is a problem.

 

[ifearbanjos]

One thing to consider is actual load on the amp. I do not know the architecture on the 5000A but the Later G series could not handle long sessions at party output at the lower 2 ohm to 4 ohm speaker loads many quad setups put on the amp. Set a turntable on top and its time to hear something go nova. Their DC drive did best at the 8 to 16 ohm actual loading.

 

[Lavane]

I had a 80wpc integrated amp I used for 15 years. It ran crazy hot. You couldn't keep your hand on the metal cover. Bias and DC offset were always right where they should be. It just ran damn hot for some reason. It lasted a few more years after giving it to one of my sons.