Sansui 5000A Recap

[two.dogs]

Just picked up a very nice 5000a. It was mounted in a custom stereo console, so beautifully preserved but no case. I was surprised to find that it has the F-6013 boards already installed. A few lights are out but still working perfectly with 40 year old caps. I think this survivor deserves a new custom case, new caps, and selected new transistors. Anyone have a cap list?

 

[ric27]

Very Clean

Man that 5000 looks very clean inside. Is that the way it came? I have the X series 5000 an I really like it a lot. I will be watching to see what you do with yours as far as recaping. Mine works great except after it has been playing for a few hrs it sometimes has a break up of the out put the will clear up if I cycle the power switch off then back on. It will go on playing fine for a few more hrs.

 

[two.dogs]

Sparkling clean inside is the way I bought it. It had been installed vertically in a console and protected from dust. It'll take me a while to make the parts list if I cant find one. I've scanned the service manual and there are some transistors that are known to fail (2SC458 for example). This might well be causing your problems.

 

[two.dogs]

F1042 Board (diode stack)
Replaced SW-1-02 diodes with 1N5404

 

[two.dogs]

F1137 Board (Ripple)

C014 100 50 UPW1H101MPD
C015 330 16 UPW1E331MPD
C016 1000 10 UPW1C102MPD
D001 SW-05-02 1N4004
D002 SW-05-02 1N4004
D003 SW-05-02 1N4004
ZD001 ZB1-27 1N4750A
ZD002 ZB1-13 1N4743A

Voltages seem nice and solid. 80V to the driver boards, 24V and 12V to the tuner section.

 

[two.dogs]

F6013 (Driver)

C802 100 25 UPW1H101MPD
C804 220 6.3 220/25 UPW1E221MPD
C805 4.7 50 MKS2B044701K00KC00
C806 3.3 25 3.3/50 MKS2B043301H00JSSD
C807 100 50 UPW1H101MPD
C809 470 6.3 UPW1E471MPD
VR801 100K 3352H-1-104LF
VR802 1K 3352H-1-102LF
TR801 2SC1000 KSC1845
TR803 2SC984 KSC1845
TR804 2SC680 2SA1930
TR805 2SA566 2SC5171
6237BG heatsink
6237BG

 

[two.dogs]

Finished the rebuild but still some issues to diagnose.

First, there is a faint buzz from both speakers that is not affected by the volume or balance controls. Hum is identical regardless of source selector. I'm guessing a grounding problem? It could also be the power supply but I rebuilt it with all new caps and diodes.

Second, there is a buzz in FM associated with the stereo indicator light. It is not affected by the volume or balance controls so it seems to be sneaking in somewhere downstream of the preamp. I wonder if these two buzzes are related?

 

[larryderouin]

Nice so far. What about the Equalizer board (F-1136), Muting Board (F-1120), the tone control board (F-1029), Protector bd, (F-1041). All of these boards have at least 1 2sc458 and caps that can / will contribute to the noise you are hearing.

FM Multiplex is always noisier than FM Mono due to it's having an AM carrier for the MPX signals. Plus it needs approx 50% more signal strength to equal FM mono in clarity and SQ. If the FM MONO has a quiet background, and FM stereo has a background his on a relatively average station strength I would consider this normal. If you have a close in , very strong signal, and you still have the same amount of hiss, then you're MPX should be aligned by a shop. DO NOT try to attempt this by yourself. They are very labor intensive, require special tools, equipment, and procedures

 

[two.dogs]

I did the equalizer and tone boards with parts below. My protector board was disconnected long ago when the F6013 boards were installed so I left that alone. I think I might have missed the muting board though. I'll throw some new parts on it and see if that improves things.


F1036 Equalizer
C601 1.5 10 2.2/50 ECQ-V1H225JL
C602 1.5 10 2.2/50 ECQ-V1H225JL
C605 220 6.3 220/25 UPW1E221MPD
C606 220 6.3 220/25 UPW1E221MPD
C607 10 10 10/35 UPW1V100MDD
C608 10 10 10/35 UPW1V100MDD
C611 10 25 10/35 UPW1V100MDD
C612 10 25 10/35 UPW1V100MDD
TR601 2SC458LG KSC1845
TR602 3SC458LG KSC1845

F1029 Tone
C701 0.2 50 2.2
C702 0.2 50 2.2
C705 30 15 33/25 UPW1E330MDD
C706 30 15 33/25 UPW1E330MDD
C707 30 15 33/25 UPW1E330MDD
C708 30 15 33/25 UPW1E330MDD
C709 3 25 3.3/50 UKL1H3R3KDDANA
C710 3 25 3.3/50 UKL1H3R3KDDANA
C714 1500pF 1000pF QYX2A102KTP1FD
C715 1500pF 1000pF QYX2A102KTP1FD
C717 3 25 3.3/50 UKL1H3R3KDDANA
C718 3 25 3.3/50 UKL1H3R3KDDANA
C721 30 15 33/25 UPW1E330MDD
C722 30 15 33/25 UPW1E330MDD
C723 1 50 1/50 ECQ-V1H105JL
C724 1 50 1/50 ECQ-V1H105JL
C725 0.47 25 .56/63 ECQ-V1J564JM
C726 220 25 220/25 UPW1E221MPD
R701 1K 1/4W OF102JE
R702 1K 1/4W OF102JE
TR701 2SC693F KSC945
TR702 2SC693F KSC945
TR703 2SC536 KSC945
TR704 2SC536 KSC945
TR705 2SC871D 2N4401
TR706 2SC871D 2N4401

 

[two.dogs]

Figured I'd measure across the speaker outputs (with 8ohm dummy load connected) before making changes. Scale is 10mV per vertical division, 5ms per horizontal division. Its always a good rule not to do math in public, but...
We've got about one cycle every 2.5 divisions. At 5ms per division that's 12.5ms. Take the inverse and multiply by 1000 and its an 80Hz ripple.
Where would a +/-10mV, 80Hz ripple come from? Keep in mind that I'm an oscilloscope newbie so pilot error is always in play.

 

[two.dogs]

OK, Larry, I got excited when I looked again at the protection board. The wires were clipped from the amp drivers so it not longer protects the unit as I mentioned. However, the board still passes 25V to the tone board through a pair of 2SC458s. I changed these out for KSC1845 with high hopes but, alas, the problem remains.

 

[two.dogs]

I have another 5000A in good original condition that I just hooked up for comparison.

faint buzz at zero volume: recapped unit - yes; original unit - yes (identical)
louder buzz with stereo light: recapped unit - yes; original unit - no

So I wonder if I expect this receiver to be silent at zero volume? I'm sitting about 3' away from my Klipsch RB-5 bookshelf speakers with sensitivity of 96dB.

 

[larryderouin]

See if you can tell if the hum/buzz is 60Hz or 120Hz. 120Hz is almost always Power supply , 60Hz could be anywhere else. It's possible that another transistor is noisy. Problem is finding it.

Try the 5000A with a less sensitive pair of speakers. And listen at the same distance. It may be something you can live with. Sometimes finding a problem is almost an exercise in futility. As you have another 5000A you might consider swapping boards between them (one at a time to localize the problem.) Once you localize the problem, finding the offending part on a board can be problematic, due to finding a compatable replacement, especially transistors.

Double check all of your ground points for corrosion, loose joints, etc.

 

[Hyperion]

Where would a +/-10mV, 80Hz ripple come from? Keep in mind that I'm an oscilloscope newbie so pilot error is always in play.

More likely to be 60Hz, perhaps scope in use with 'fine' timebase control not at reference position, or possibly scope out of calibration?

 

[two.dogs]

Thanks Larry and John,

I'll have to look at my scope technique to see if I've mis-adjusted something. Would be nice to know the exact freq I'm looking to eliminate. I've made some forward progress though by removing the audio input to the F6013 driver board coming from the F1029 tone board, just on one channel. The hum disappeared and all I could hear was the faintest hiss with my ear right next to the speaker. So the driver boards, output transistors and main power supply are all good, which is a relief - lots of new parts and effort went into those. And I know the buzz isn't coming from anything before the tone board because I'm getting the hum at zero volume. So it has to be the tone board or the part of the power supply that drives it.

John

 

[two.dogs]

This one has me confused. I think my noise problem is related to the shielded wire carrying audio from the tone board to the amp drivers.

• Signal wire connected to tone board and amp board (with shield attached to amp board) - I get hum under all conditions - even when I touch the chassis
  
• Signal wire disconnected from tone board, but still connected to amp board - I get hum but it stops when I touch the chassis.
• Signal wire disconnected from amp board (shield still connected like in first pic) - no hum.

First pic shows where the signal wire connects to the amp driver board (two connections here - one for the signal and one to ground the shielding). I have the audio wire temporarily disconnected.

Second pic shows how the wires are routed from the tone board (bottom left) to the amp drivers upper right (audio passes through the hole near the cap that is vertical in this pic).

Third pic shows the connection to the tone board (blue wires with grey and blue shielding - the shielding terminates an inch from the tone board.

Fourth pic shows me touching the chassis, and thats where weirdness happens

Any suggestions are appreciated.

John

 

[avionic]

Looking good...

 

[two.dogs]

Looks good but I've got to get it working! Any idea why the hum might stop when I touch the chassis?

John
Ret USAF 1986-2007

 

[Tim64]

Hi John, Did you ever find out where that hum was coming from? I just got one of these and it has a faint hum with volume control at zero it's faint you don't hear it unless you are right at the speaker. Mine works but will be getting new caps the hum just might be inherent in the design. Your post will be a valuable reference for me thanks for posting it.

 

[thehof]

Hi John, Did you ever find out where that hum was coming from? I just got one of these and it has a faint hum with volume control at zero it's faint you don't hear it unless you are right at the speaker. Mine works but will be getting new caps the hum just might be inherent in the design. Your post will be a valuable reference for me thanks for posting it.

Same