Sansui 7000 - a tale of two bothers

DCinDC

I'm here to fix it
WTH?

I started work on these two today. Look at the bottom pics attached.

The tone board is totally different and they have different filter and or protection boards.

SN 222110187 this is the newer one with the smaller tone board in the pics
has a tone board marked F-6010
has a power filter board marked F-6012
has a phono board marked F-6011
These numbers are not even in the board db and the number is so high you'd think it was either a service replacement or from a much newer unit!

SN 221030054 this is the 54th one made! and has the big board in the pics
has a tone board marked F-1316 this one has had lots of mods with cut traces and jumper wires.
has a power filter board marked F-1317
phono board preamp is incorporated into the tone board.

These numbers are not in the board db either.

These two receivers look identical from the top, but not the bottom! Both work, basically.

Does anyone have any clues? Does anyone have a schematic for the 7000 in electronic form they can send to me?

pics go old/new/old/new left to right below
 

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Got you didn't they?
Sansui did many mid-life changes to gear without updating the manuals.
If you need the switch labels for those member Spaceman had one, he found some decent replacements.:thmbsp:
 
another brother from a different mother....

This one is serial number 221030555 and it has the big (older) board.

This one was a cosmetic basket case with a broken dial glass but I got a new face on the net, and am slowly putting it right again! Under all the grime it has a nice wood cover and the face is nearly unmarked!

Any body have a clue on the newer boards?
 

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let us know when you get it all back together. are you going to do a recap? curious what you think of the sound quality
 
Sansui finally got tired of modding the boards on the older receivers and eventually, up-dated the boards. :dunno:
 
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another one....

221080147
larger (older) boards.

Found a shorted SCR and muting transistor on the protector board. Removed them.

I have schematics for these protection boards in the 7000 but don't really get it. It measures and integrates the output and at some point just shorts the input of the power amp. Because it uses an SCR, it latches and you have to power down to get sound back. Not what I'm used to seeing in a "protector" as far as what it does. is it a "Too Loud Protector"? :)
 

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Tonight I found another difference, apparently a running change.

The mic jack of a later unit had additional contacts which I assume were used to short out the output of the mic amp when no mic was inserted, I presume to lower the noise floor.
 
WTH?

SN 222110187 this is the newer one with the smaller tone board...

SN 221030054 this is the 54th one made! and has the big board

Good thread. Thanks for uncovering these production differences. These two receivers were built more than a year apart. The top one was number 187 off line 22 in November of 1972. The bottom one was number 54 off line 22 in March of 1971. Sansui sometimes built more than one model at at time on these production lines so being #54 does not necessarily mean it was the 54th 7000 built that month.

- Pete
 
oh I know about hifiengine. I haunt that place!

Lo and behold I got another 7000 out of storage and found the schematic in the pocket on the bottom!
 
These aren't G-7000s, the are the older 7000 model. At least 5 years older.

- Pete
 
Another one....

Serno 221061448

larger, older board

I wish I had a 1972 model to try and determine the cutoff.

pics below
 

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With the next gen, but identical looking Eight you see that toward the last production run in around '72 they got updated with a speaker protection relay - something never metioned in the sales brochures. Some Ak's who have had both says there is a difference in sound too, the later being less warm, but more musical.

Curious if the two brothers sounds more like cousins once restored to glory ?
 
Hey, just looked in here a minute & saw this. I still never put my decals on Casey, the 7000s been my main 'puter amp for quite awhile, & for now I'm running a pretty nice Pioneer PL-570 into it for records. :thmbsp: I probably should dust sometime, to see what my serial # is again at least. :D
 
I've got two Sansui solid state 7000 stereo receivers to rebuild. The first of them, serial number 221030511, has the larger tone board.

IMG_7105.JPG IMG_7106.JPG IMG_7107.JPG IMG_7108.JPG IMG_7114.JPG IMG_7126.JPG
 
The second Sansui 7000 is serial number 221072865 and also has the large tone board:

IMG_3823.JPG IMG_3824.JPG IMG_3827 (1).JPG IMG_3829.JPG
 
Mine is a SN 221090369. Smaller tone board. So that appears to be the first month of the newer design. I will have to follow the leads to see if there is a separate phono board. I assume there has to be.
 
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