Sansui XR Q7 Restoration

[Sci525]

Hi All, A couple months ago I purchased a Sansui XR Q-7 with issues. It was a bit of an impulse buy, but it came with a couple arms and cartridges and worked as a manual. I plan to slowly restore it to like new condition. I’m and experienced tinkerer, but not with turntables, so input is welcome.

The plan:
1) Fix the tonearm automation. There is no tone arm lift or movement.

Edit: New plan, recap first and see if that solves the sync issue before breaking into the motor.
2) Clean and lubricate the main motor. The speed is dead on, the quartz lock is fine, wow and flutter are lower than I can measure, and I can’t feel any rumble in either the table or tonearm, BUT the sync light flashes indicating a problem.

3) Recap. If I can get it working well enough to want to keep for a long time it makes sense to replace those electrolytics.

4) Restore the physical appearance. If I manage to recap it without burning up an irreplaceable IC I will deal with the vinyl wrap, corroded metal, dirty buttons, and brutalized dust cover.

Step 1, what’s wrong with the tonearm control? In short, both the micro switches and micro motor in the assembly were broken. The previous owner told me it was a bad sensor, but all the sensors check out, even the much-maligned TPS605. The original micro motor was a HMR2628-2 and I’ve found a NOS HMR2628 locally after about 15 sec of Googling. It was posted on the bay, and I got it the next day. I will have to buy a lottery ticket this week. The new motor is working well, and the micro switches were replaced with Omron SS-3GP which were direct replacements. The mechanism also got a decent cleaning and lubrication, but I only disassembled enough to get to the areas needing grease according to the manual. At first the movement was a bit jerky, but after a few operations its looking smooth enough.

The starting point.

And the guts pre restoration with today's task, the tone arm mechanism in the top right.

Broken micro motor and micro switches.

Fixed, cleaned, and re installed.

Time to move it into the office and align a cart. It came with a Pickering XV-15 and I got a Swiss nude for it. I’ll try to get some quality time with it this week before I take apart the DD motor next weekend. I don’t see any guidance on that in the manual…

Cheers,
Joe

 

[jqp]

In the service manual there is an adjustment mentioned for the synchrotor circuit via a potentiometer and it is quite simple. Wonderful table, love mine. I have not considered motor disassembly and lube as it looks like a difficult task. Have you put a new belt on the tonearm motor?

 

[Sci525]

In the service manual there is an adjustment mentioned for the synchrotor circuit via a potentiometer and it is quite simple. Wonderful table, love mine. I have not considered motor disassembly and lube as it looks like a difficult task. Have you put a new belt on the tonearm motor?View attachment 2840933

Yes, new tonearm belt. When I first got the table, I went through the motor adjustments in the service manual but wasn't able to nail the values. That's why I decided it probably needs a recap with new trim pots. I will go through the motor adjustments again with extra patience, then recap before I think about motor disassembly. Thanks jqp.

 

[Sci525]

I've aligned the Pickering XV-15 and listened to a couple records on my office set up. The Pickering is a Pickering. I’ve had one in the past and it was a solid performer, so is this unit. It is neutral across the mids and highs, lows are controlled, but sound rolled off a tad. Nothing a bit of tone control can’t handle. Tracking is great. Dynamics/SNR aren’t so great in this setup which has a relatively noisy phono pre. Cart output is on the lower end and noise seems to swallow a bit of the dynamics. I will play with tracking weight, but the Pickering may also just need a clean phono stage.

The deck is good. I will need to use it on a cleaner sounding rig with a subwoofer to really see if it's effecting sonics, so right now I'm just looking at function. The only issue so far is that occasionally I have to push the Start button twice to get it to start.

 

[Sci525]

As jqp suggested, going through the adjustments to the motor control solved the silent sync issue. It required higher precision than I first assumed. “Set to 100 kOhms” means set to 100.0 kOhms. I’m glad there is no need to poke around inside the DD motor. We shall see how long it takes to drift out of spec.

Another issues has come up with it in daily use. A couple times after powering up, the auto functions don't work. I have to cycle the power, then everything is fine. Any idea what that's about?

 

[jqp]

It took about 40 years for the synch rotor circuit to drift about 1% on mine. I don't have a good answer regarding the power cycling issue you are having. What I would try is unplugging all the circuit board connectors and plugging them back in again. Sometimes it just takes a refresh of the connection to fix intermittent problems.

 

[Sci525]

There are at least two issues which cause the auto tone arm features to not function properly.

First is that there is too much friction somewhere in the assembly causing the belt to slip on the pulleys. I've identified where it gets stuck (the lifter cam depressing micro switches, or pressing on the cam spring), but just adjusting or cleaning those parts doesn't help. Maybe the grease I'm using is too thick? I suppose I need to fully disassemble the mechanism, clean, and relubricate. Any recommendations on lubricating plastic on metal assemblies for minimal friction? I'm wondering if I should just use a teflon spray? I usually think of grease as providing lubrication where you also need water protection, which is not an issue.


The second problem is that the tactile switches, especially the "Start/Stop" switch, appear to occasionally register twice with a press, effectively canceling out. Deoxit didn't help, but before I spend time thinking about this issue, I need to get the tone arm mechanism working properly.

Cheers,
Joseph

 

[jqp]

There are at least two issues which cause the auto tone arm features to not function properly.

First is that there is too much friction somewhere in the assembly causing the belt to slip on the pulleys. I've identified where it gets stuck (the lifter cam depressing micro switches, or pressing on the cam spring), but just adjusting or cleaning those parts doesn't help. Maybe the grease I'm using is too thick? I suppose I need to fully disassemble the mechanism, clean, and relubricate. Any recommendations on lubricating plastic on metal assemblies for minimal friction? I'm wondering if I should just use a teflon spray? I usually think of grease as providing lubrication where you also need water protection, which is not an issue.
View attachment 2845006

The second problem is that the tactile switches, especially the "Start/Stop" switch, appear to occasionally register twice with a press, effectively canceling out. Deoxit didn't help, but before I spend time thinking about this issue, I need to get the tone arm mechanism working properly.

Cheers,
Joseph

Super lube teflon grease is what I use for metal to plastic contact so Teflon spray would work also. I think you are right to pursue the tonearm stickiness issue. If there is no tonearm movement after pressing the start button the table will shut down which might be the problem you are having. Once the tonearm moves as it should and if it still shuts down, then there are further issues. There is also a tonearm height adjustment and it might be bottomed out causing problems...just a guess!

 

[Sci525]

I've got the tone arm assembly working without any slipping of the belt. Despite several iteration of cleaning and lubricating it turned out that most of the friction was on the reverse arm caused by the appropriately named friction disc and friction plates. A couple nuts hold a compression spring and I simply needed to loosen the nuts to regulate the friction applied by the plates. Took some calibration, but it runs well now.

I also think that the new belt I have is a bit too big. I was sold a 3.5 in (89 mm), but I noticed some sold for this deck are 85 mm. I image the 85 mm would handle a bit more friction, be a tad less finicky.

I'll put the table back into use for a couple weeks and see how the tone arm control and sync control hold up before deciding what to do with it next.

 

[Sci525]

After a couple weeks of operation, I had problems again with both the silent sync motor and the tonearm mechanisms. Both had simple solutions.

The tonearm belt was still slipping after repeated cleaning of the mechanism. I replaced the new tone arm belt with the old dry rotted one it came with. It's smaller and works well. A 3.5 in circumference belt is too large for this table, at least with 40+ years of wear. I buy a couple in smaller sizes and see what works best.

The silent sync light started blinking again after some use. I cleaned the bearing sleaves for both the silent sync and DD motor with a cotton swab, figure below.

They were VERY dirty. I gave each 3 drops of liquid bearings, and everything has been working well for several days now.

I've got it playing through the phono section of a Denon PRA 1500 now, this is the quietest/cleanest phono section I own and the difference between the Denon pre and the DIY mess I was testing with was immediately noticeable on the XR-Q7. I had a much harder time differentiating the two phono sections on my ProJect table, but to be fair it probably needs a new stylus. I'm looking forward testing more in my main system, but I'll resolve some cosmetic issues first.

Polishing the dust cover, making new hinge holders for it, removing corrosion from all the buttons and metal parts, then maybe... a real wood veneer. I think I'll clean up the vinyl wrap and consider a real wood veneer in a year or two if this table can take and hold the top spot.

 

[Sci525]

Progress.
New dustcover hinge holders.

And in position.

New feet. These are just Sorbathane hemispheres on 1/2” MDF pucks. The screws are fixed into the pucks so that the pucks can be rotated to help level the table.

And the feet doing feet things. They work great and I like how the table looks with the extra half inch of space under it.

The buttons were trouble. They are plastic with some metallic film over them.

The corrosion went all the way through the film in spots, and cleaning revealed the black plastic underneath. Maybe I'll make wooden replacement one day.

I couldn’t capture it with pictures, but after scrubbing with rubbing alcohol the table is a noticeable shade lighter.


Anyone have a printable protractor they like for this table? I'm having trouble with inner groove distortions.
Some measurements coming soon.

 

[Sci525]

Silent groove noise measurements as promised with comparison to a decent ProJect table I've been playing with. Phono stage is a Denon PRA 1500, measured at 1V output and adjusted for the different outputs of the cartridges. Sorry the figure isn't pretty. Still figuring it out.



Edit: I see there is a massive loss in resolution in this photo upload that makes the axis un-readable. You can probably figure everything out from the notes, and if anyone actually cares, let me know and I'll try to upload with better resolution.

 

[CrSens]

Do you usually don't have IGD issues with this particular Pickering? It could all be just the stylus issue. I don't see a connection between IGD and silent groove noise spectrum.

 

[Sci525]

Do you usually don't have IGD issues with this particular Pickering? It could all be just the stylus issue. I don't see a connection between IGD and silent groove noise spectrum.

I didn't mean to connect the IGD and silent groove noise, although I see now that's how it reads. I have mostly resolved the IGD with better alignment. It's still audible, but maybe inherent to the stylus/cartridge. I don't have a test record to measure it.

Separately, I made those noise measurements simply to compare the tables I have on hand and posted because the difference is pretty significant, as least from a numbers point of view.

 

[RemoWilliams]

Just purchased one of these and although the Seller showed the platter spinning when I got it home and plugged in all i have is power with the platter not spinning when I press the start button.


I did remove the bottom cover and was checking the tonearm motor belt, appears a bit loose but wondering if while checking I was turning the main gear the motor drives. Is it possible I might have put something out of alignment? I imagine there is an led involved to give indication of tonearm position.


Not terribly experienced but willing to go as far as I can with disassembly, cleaning etc.


I need to reglue the switch housings that are affixed to the metal function strip located at the front, the power switch button dropped inside so I could not turn it off. Obviously the glue used had dried with time.


The Seller had intended to use it but stored it for 4 years, the original owner he purchased it from had also stored it for a time and it was functioning then apparently.


I hope I can find the reason why the platter is not spinning, did notice in the video the seller had in the posting on marketplace that the synchro motor indicator was flashing.


Any help would be greatly appreciated!

 

[jqp]

If the table detects that the tonearm is not moving, it will shutdown, not power up/spin or power up briefly and then shutdown. A properly fitting tonearm belt is necessary to get the tonearm moving...the belt cannot be loose or slipping. I had the same problem with my XR-Q7 when it followed me home around 7 years ago. Dug into my bag of small belts until I found one that fit and that fixed the problem.

 

[RemoWilliams]

The belt is definitely on the loose side, most likely original as well. I will order a new one soon, have to reassemble the control panel and buttons in the meantime.

 

[Sci525]

Any help would be greatly appreciated!

If you manually move the tonearm over the platter, does the turntable spin? If so, then that motor is fine, which is expected. The spindle and spindle housing likely need to be cleaned and lubed, post 10.

As for the tonearm mechanism, it is complicated. It uses a combination of two switches and three LED/sensors to figure out where it is and move accordingly and there are a couple adjustment points to line everything up. The mechanism also can't be too tight, or the belt will slip, but too loose, and the gears won't engage properly. So, the bolt that holds the gearing mechanism together needs to be tightened correctly by trial and error, then glued so it doesn't get loose. On my table, the switches and motor were both bad, but replacing them was the easy part relative to getting all the other adjustments right after reassembly.