Sansui solid state 7000 repair, recap, and restore

I hope this gets a conclusion at some point. I have a problematic unit of the same make and am learning a lot from all this.
Cheers and keep it up!
 
I jumped over here from.another thread where the 7000 was getting some discussion. I'll be interested to hear the OP's assessment of the unit after it is done. In looking at the pictures in this thread so far I see almost nothing in common (circuit boards or sub assemblies) in common with the 5000.

I'm now inclined to say that the 7000 is [almost?] an entirely different series versus the 2000/4000/5000 even if the amp topology is the same. I was expecting some parts in common, but that appears not to be the case. I don't own any of the six/seven/eight series that were produced concurrently, so have no frame of reference to compare the 7000 to those in terms of parts in common.

At any rate, this thread is a very good read, and I appreciate the thoroughness and attention to detail to documenting the rebuild so far. Looking forward to more as progress is made.
 
...I'm now inclined to say that the 7000 is [almost? said:
an entirely different series versus the 2000/4000/5000 even if the amp topology is the same. I was expecting some parts in common, but that appears not to be the case. I don't own any of the six/seven/eight series that were produced concurrently, so have no frame of reference to compare the 7000 to those in terms of parts in common....

interesting - could this be the discovery of a lost species of sansui !
 
I don"t want to derail this thread, so won"t post further on the relation (or lack of same,, it appears) between the 5000 and 7000. Just a theory I was hashing out in another thread when a link to this one was posted. Glad it was brought to my attention as it has been an interesting read on it's own right, and has answered a few questions I had on where the 7000 fit in.
 
I'm now inclined to say that the 7000 is [almost?] an entirely different series versus the 2000/4000/5000 even if the amp topology is the same. I was expecting some parts in common, but that appears not to be the case. I don't own any of the six/seven/eight series that were produced concurrently, so have no frame of reference to compare the 7000 to those in terms of parts in common.

At any rate, this thread is a very good read, and I appreciate the thoroughness and attention to detail to documenting the rebuild so far. Looking forward to more as progress is made.

This thread has links to many that discuss the Eight vs the 7000: http://www.audiokarma.org/forums/index.php?threads/the-master-sansui-7000-thread-link-thread.443893/

This particular thread is especially good for the Eight vs. 7000 questions: http://www.audiokarma.org/forums/index.php?threads/sansui-7000.212054/
 
Ok, I finally got things back into gear on the 7000. Here is some of what has transpired recently.

The big caps are a power reservoir / filter cap, the two output-coupling caps, and a smaller power supply cap. All of these are "so big" they need collars and this huge section dedicated to them.

C811,C812 2200 uF 80V
C005 3300 uF 100V
C004 1000 uF 50V​

C811 and C812 are the audio signal path caps that couple the power amp board's output transistors to the speakers. It is critical to keep the same capacitance value as this forms a filter on the output and any larger value would increase the bass emphasis. So, these get Nichicon KG 2200 uF 80V caps with snap-in leads.

C005 is the primary power reservoir and filter, so increasing its capacitance will smooth the rectified DC more and provide additional dynamic range. If you're in the camp that believes that. So, this one 4700 uF 100V Nichicon LS series. No fancy marketing hype, just more capacity.

C004 is a plain old power supply cap, so the Nichicon PW series is fine here.

The big deal with these caps is the originals are huge by comparison and are expected to be held in place with vertical collars. The new caps are tiny, especially in diameter, so you need something to firmly wedge the caps in the collars.

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I've used foam tape and even insulation as a wedge between the collar and the cap in other units and never really been satisfied with that.

So, since this is a restore for a good friend and I'm working on a unit for myself as well, this is a good time to up my game and experiment with a better solution.

What I did was locate some wood discs of the right diameter, affix the caps the to the discs, then use the collars to firmly hold the disc+cap assembly. A little drilling to allow the leads through and we're set.

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I did extend the snap-in leads with station wire so they could reach the existing wiring.

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The two tuner boards and the multiplex boards were next. They just get a recap for now. While these boards are not hanging in space like my KR-6160, they are wired on the backside and kinda Frankenstein-ish.


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The ground straps were a bit much:

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New caps:

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I've used foam tape and even insulation as a wedge between the collar and the cap in other units and never really been satisfied with that.
I usually opt to just restuff the old caps in this situation, but its nice to see the new caps after, I like!!
 
Great work!

Thanks, Nate. It is hard to get motivated these days and I feel kinda embarrassed that this Sansui solid state 7000 has taken me so long. I will be so happy when I finish it and get to hear how amazing 80 wpc with cap-coupled output sounds.
 
Isn't that a pretty good amount of power for a cap coupled amp?

Yep, it is. I don't know of another unit that does 80 wpc and is cap-coupled. I'm sure there are units like that, but I haven't run into any before. That was part of why I bought one of these.
 
Just to comment, I really like the wood disc mounting solution for the big filter caps. Care to say where you picked those up? I may end up doing something like that on a couple of amps that need recapping. Great thread overall showing your work and documenting for others to benefit from down the road.
 
Just to comment, I really like the wood disc mounting solution for the big filter caps. Care to say where you picked those up? I may end up doing something like that on a couple of amps that need recapping. Great thread overall showing your work and documenting for others to benefit from down the road.

I looked at Michael's (arts and crafts) and AC Moore, but they didn't have the right sizes to fit snugly inside the collars. So, I looked on eBay and after switching to metric measurements and found the ones I needed.
 
Great post and thanks for introducing me to the 7000. I'll be keeping my eyes open for one of these. Like I need any more motivation to buy old Sansuis!?

I recognized the F-1315 driver boards. They are the same as the QS-800A quad rear amplifier I am working on. It looks like the amplifier sections are very similar, same driver boards, same output transistors. The 7000 has a higher voltage transformer and more power. The QS-800A is rated at 45WPC.
 
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