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Sansui 9090 Complete Restoration

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Plimpington2

Super Member
I'm going to document my complete restoration of a Sansui 9090. I taught myself how to repair, rehab and even scratch build tube equipment a few years ago (with the help from the good folks here AND Uncle Doug on YouTube). Over the last 6 months or so I have been working my way through solid state stuff as well. I have several units under my belt (a few Luxman units, several Sansui, a few Pioneers, a few McIntosh) and just recently completed a repair on a 9090 for a friend. That unit BLEW me away in terms how it sounded and it's overall build quality. I also did a G-9000 over the weekend. So, I am going to dive into this disaster. Fundamentally it's all there (I think, save for the tape monitor switch, which I will source), but I want to strip it to the bones and build it back up, making this as nice a unit as possible. Here she is as she sits. BTW, Sansui is without question my favorite brand.



. IMG_3279.JPEGIMG_3281.JPEGIMG_3282.JPEGIMG_3283.JPEG
 
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Look forward to your rebuild on this fine model...! :thumbsup:

After waiting for the final parts on my 717's F-2663 board I finished it yesterday...
Some things take time...
 
Warren-Oates said:
review the service bulletin.

keeping the old driver board or going with the new version?
Click to expand...
I am DEF going with the new one. The board on the repair I just did was damaged beyond repair, and I wasted many hours trying to salvage it before I threw in the towel and bought the blank board from Ebay. I stuffed it myself after my Mouser delivery, and it looked and performed flawlessly first time in. I can whole heartedly endorse this product. $25 for the board and another $30 for the parts, and you are good to go in about 90 minutes of building.
 
I recently did some work on an 8080 for a friend & after listening to it I want one (or a 9090). I now "get it", lol.
I love that the tuner section can be lifted out of the unit.....sooo much easier for service.
 
PF Sound said:
I recently did some work on an 8080 for a friend & after listening to it I want one (or a 9090). I now "get it", lol.
I love that the tuner section can be lifted out of the unit.....sooo much easier for service.
Click to expand...
Yeah, I was blown away by the 9090 I did. I have this 9090 that I am rehabbing now and I also have a 9090db and two 8080's waiting for service. But this one I am doing a full teardown and rebuild for my own collection. I have even ordered what the seller CLAIMS to be 2SA116's "pulled" from another unit (actually, pulled from SOMETHING). It's an Ebay seller located in Miami, Fl. $14 each. IF they are genuine "pulls" that test OK, this will be a GREAT unit! He was able to fulfill an order of 10, which is suspicious in and of itself. Otherwise, I will have wasted some money but will resort to the current productive bog standard MJ units.
 
My 8080DB runs MJ’s and I’ve got a bunch of 747 and 116 pulls in the drawer that I’ve accumulated over the years.

The MJ’s sound great to me. Good enough that I’ve got a couple spare sets of each ready to go…just in case.
 
I'd just go with a new set of MJ's. Fortunately, they are a pretty good match for the original 2SC1116A's, they'll be real, &, even if the ebay ones are authentic, they won't have 50 years of use on them......@ about half the price.
 
PF Sound said:
I'd just go with a new set of MJ's. Fortunately, they are a pretty good match for the original 2SC1116A's, they'll be real, &, even if the ebay ones are authentic, they won't have 50 years of use on them......@ about half the price.
Click to expand...
Yeah, I may have wasted my money on those OPT's. But the repair unit I did had the original 1116's in it, and it sounded so good, I wanted to do everything I could to recapitulate that. If it doesn't work out, I will spring for MJ's.
 
PF Sound said:
I'd just go with a new set of MJ's. Fortunately, they are a pretty good match for the original 2SC1116A's, they'll be real, &, even if the ebay ones are authentic, they won't have 50 years of use on them......@ about half the price.
Click to expand...
And you won't have your heart in your mouth every time you have a cranking session :rockon: - because replacements are cheap and (at the moment) readily available.
 
The 9090 is a great unit. I have repaired/restored several including the DB's. The unit is straight forward and really has no real "genetic" issues. I found three areas that need to be given close attention. The power supply board F-2546 has a couple of variants involving a trace cut and insertion of a cemet resister over the cut. Also that board gets a lot of attention in the aforementioned service bulletin which applies only to units that:

"THIS MODIFICATION HAS BEEN DONE IN PRODUCTION, FOR 8080 AND 9090 SINCE APRIL 1976. This would preclude serial numbers xx604xxxx and include units thereafter."

The power supply board F-2546 does have one hard to find transistor 2SD-315 [TO-66] so keep the OEM if it is good.

The next board that can be a challenge is F-2541 The "Equalizer" PCB. The main issues on this board are the rotary switches that control functions. These switches are almost always tarnished [the contacts are silver plated] and can be cleaned up. Several posts on that process. If your unit has had the misfortune of having the 8 volt backlight [fuse type] bulbs replaced with 12 v then the contact controlling the backlight will most likely burned up and not repairable. The bypass procedure to get the "always on" feature for the tuner scale backlight can fix that. If the switch is OK and turns off the tuner backlight I always leave it as that is one of the OEM quirks of the 9090. It's a personal call. The 9090 is an analogue icon of the era.
 
aldena007 said:
The 9090 is a great unit. I have repaired/restored several including the DB's. The unit is straight forward and really has no real "genetic" issues. I found three areas that need to be given close attention. The power supply board F-2546 has a couple of variants involving a trace cut and insertion of a cemet resister over the cut. Also that board gets a lot of attention in the aforementioned service bulletin which applies only to units that:

"THIS MODIFICATION HAS BEEN DONE IN PRODUCTION, FOR 8080 AND 9090 SINCE APRIL 1976. This would preclude serial numbers xx604xxxx and include units thereafter."

The power supply board F-2546 does have one hard to find transistor 2SD-315 [TO-66] so keep the OEM if it is good.

The next board that can be a challenge is F-2541 The "Equalizer" PCB. The main issues on this board are the rotary switches that control functions. These switches are almost always tarnished [the contacts are silver plated] and can be cleaned up. Several posts on that process. If your unit has had the misfortune of having the 8 volt backlight [fuse type] bulbs replaced with 12 v then the contact controlling the backlight will most likely burned up and not repairable. The bypass procedure to get the "always on" feature for the tuner scale backlight can fix that. If the switch is OK and turns off the tuner backlight I always leave it as that is one of the OEM quirks of the 9090. It's a personal call. The 9090 is an analogue icon of the era.
Click to expand...
Thank you for this. I will look out for the update on the PSU board. I intend to move the under-mounted capacitors to the top since newer units will be smaller and will fit next to the emmitter resistors. I’ll switch over to polarized ones in that event. I do intend to do the “always on” mod. It’s odd that the 9090db and 8080db had “always on” from the factory (so I’m told). I have seen the switches in any event. They could use some attention for sure. Also, you can probably see I am missing the tape monitor switch. So, I have to locate one of those or lift from another unit.
 
Do you need just the switch button or the switch itself. PM me so I can have an idea what to look for in my "stach".
 
Be aware if you do the new driver boards the protection and negative feedback (4 wires) are disconnected and not used.
 
bobgroger said:
Be aware if you do the new driver boards the protection and negative feedback (4 wires) are disconnected and not used.
Click to expand...
I’m afraid I don’t know what you mean. The feedback loop is contained entirely on the new board. There is nothing to disconnect as far as I know. And the protection circuit samples the output. You cannot disconnect these wires. What do you mean?

In any event, I just finished a 9090 about 3 weeks ago and I built one of those new boards. It slotted in and functioned brilliantly without modification to the unit.
 
Anybody know more on the 4 wires being removed?? I know some are moved in the service bulletin. Seem to recall if you don't move them you get no sound with the new board. That's just on the units that need the SB though?
 
Did it come as a "box o parts" like that, or are the pix after your teardown?
The reason I ask is that I need to follow closely as I just purchased a 990 [non db]
which is the black face version of the 9090 [non db].
 
Sounds2good said:
Did it come as a "box o parts" like that, or are the pix after your teardown?
The reason I ask is that I need to follow closely as I just purchased a 990 [non db]
which is the black face version of the 9090 [non db].
Click to expand...
No, it came largely intact. I am going to tear it down. I got side tracked because I had to move on short notice. I hope to get back into it next week.
 
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