Sony PS-X800 repair and full calibration

[lsorrentino]

Hello all, some time ago I aquired two Sony PS-X800 turntables, both are faulty, and I would like to share with you the entire job of fixing and calibrating.
First one I'm tryng to restore arrived to me from Rome, I bought it completely dead, in acceptable cosmetic conditions but without cover or headshell, fortunately was well packed and comes with no further damage.

Symptoms: no signs of life.

I begin investigating with just a multimeter and easily realize that the +15V was not present and as a consequence looking at the schematic not even 5V that feeds the microprocessor...

Few seconds later I knew that R617 was opened, ok probably a weak fuse resistor, replace and will work again I naively thought...


I was optimist but careful , pulled out my variac and slowly turning up ac power I understand that rail was overloaded, it doesn't want to go up, like -15...

Idea! I will disconnect main motor! YEESS, now I have +15V and the table seems to revive, microprocessor at least try to make something, the tonearm try to do the balance procedure.


OK I though, I have the motor board that drains excessive current from +15V! I will disconnect that single wire and check again (with the variac of course). No, it does not work. Maybe an intricated ground loop? Yes, exactly, disconnecting the ground wire from the motor connector I haven't any overload.
In short I follow the ground, from the main motor board to the relay board and disconnect one at a time each wire (just the ground ones) the last was the gulty one, the UI panel one, it was pinched below the main control board! Loosen the main control board, passing the ground wire on the top, soldering back again and YESSS the turntable brings back to life!


Leaving upside down position, turning on the power, without variac at last, I can see the balance routine completes blinking and turning off the led and if a press start the platter starts to turn locking the PLL and stops immediately after because I need a new set of belts, but this will be the next chapter... I go to sleep.
To be continued...


In the above pictures some little anticipations, the stand I made to work with.

 

[Mr Boochie]

Congrats on tackling this monster. I opened a friend's dead unit, then put it back together and returned it as is. Well beyond my expertise.

Good luck with the fix!

 

[MRL_Audio]

Isorrentino I saw you post this elsewhere. Good luck on your journey. Put it on my watch list.

 

[lsorrentino]

Hi guys,
in the the past two months the the turntable was fully fixed and calibrated as per service manual, and now it's in my living room, let's see how.
First of all new set of belts, it's not easy to fit new ones but absolutely feasible if you have a little time, patience, some tweezers, a little hook and a screwdriver.
Old belts left some residue on the pulleys, not solid, something like oil, so I've completely removed forward motor and the epicycloidal coupler that needs cleaning and new grease.



Pay attention to the magnetic trace on the motor wheels, don't use magnets or magnetic screwdrivers in the nearest.

New belts on and... It works! Maybe...

OK I have the table connected to a pre and an headphone so I can play some records and test for further defects that will not be long in coming out .

A comforting new is that the tonearm seems do a rather good headshell weight compensation, and a very bad one is that after a couple of hour the arm begins to emit some buzz noise and makes little jumps in the vertical plane. Seems like an intermittent connection in the linear motor coils or something related with that.



Other very bad behaviour is in the tactile switches that are not responding well at all. I've first dismounted all and cleand in isopropyl alcohol, they improved a lot but not still perfects... This button are not the type you can open and clean internally, I've just unsoldered from the pcb and immerse in alcohol helping the cleaning action with a syringe.



Defects in summary:
1) After some random minutes the tonarm begins jumping / bouncing in the vertical axe, both in rest place that in play mode, half an hour, a hour and a half, a few minutes...
2) Button switches gives a bad feeling, I have to push a lot to make them works
3) Not mentioned yet, when I touch the arm during play I can hear hum, easy to check that is not grounded anymore

I leave as usual with a little anticipation, in that picture there is the solution to the dancing arm!


It's late, to be continued..

 

[ebk231]

Great Work. Im following

 

[lsorrentino]

Go on, I have done a nice stand, I have the schematic and a modern oscilloscope. Observing the arm behavior I can see it vibrates in the vertical axis, when it occurs, sometimes happens after two LP sides, sometimes after few minutes, it's very randomic.
It happens both in the rest position with the table stopped that in play mode with obvious disturbing effects.
Service manual tells me that there are two separate linear motors (coils) which operates in that direction, one apply weight compensation and tracking force, the other for UP / DOWN movements and BIOTRACER damping compensation.


Looking at the schematic I can see two nice transconductance amplifiers with a shunt resistor referred to ground each so I can directly measure the current that flows in the coils, power of modern scopes...

Below screenshot is with the arm in up position, there are pulses in the MFB driving coil, this pulses tends to increase the current, good new is not a wire interrupted in which case I would have seen a current drop.


Some screenshot with the arm lowered to the platter.


I can see that IC120-1 output varies on its own, then because of BIOTRACER closed loop, IC120-7 tries to correct bad behavior of the other opamp, below the faulty opamp.
I little freezing spray definitely killed the limping IC.


Now is the time to overcome my laziness, to change IC120 I have to disconnect all the JSTs of the big system control board, fortunately all marked with it's own number.


This is a generic opamp, I had at home a 4559 instead of 4558, is the same in this application, go!

Bouncing tonearm defect was solved, very intriguing to me, I am not a repair technician so it was the first time I saw an opamp behave like this. Very interesting.
Other thing I noticed with interest was a relatively big amount of patches below the system control board, that are not reported in the service manual. It was a tough project, also for Sony, this turntable.

As usual, I will continue soon.

Bye!

 

[Mr Boochie]

Good job! You did much more than I would ever tackle. Hopefully no more issues. What cartridge are you going to use? My friend's Sony had the Shure V15vmr. Sounded pretty good for the few songs I heard until the thing started acting crazy.

 

[lsorrentino]

Good job! You did much more than I would ever tackle. Hopefully no more issues. What cartridge are you going to use? My friend's Sony had the Shure V15vmr. Sounded pretty good for the few songs I heard until the thing started acting crazy.

View attachment 2408873

Actually I'm using it with an Acutex 420 STR that I've already adapted to my other PS-555ES. Overhang is the same and equals seems to be the spacers I had to add to make the arm stay parallel to the record.
To me sounds fantastic, I had the same cartridge I bought NOS a few years ago on a Thorens TD160 with SME 3009 II improved, this is very high compliance type, and the Sony is incomparable better, regardless in the SME I had the fluid damper: less distortion, less sibilances, cleanest bass, no coloration at all.
Sometimes it doesn't even sounds like a turntable, when records permits.

Bye,
Luca

 

[Mr Boochie]

Sometimes it doesn't even sounds like a turntable, when records permits.

Bye,
Luca

That's the goal! Live ambience quality, even in studio recordings.

 

[lsorrentino]

Live ambience quality

Not exactly in my opinion, more like to be in studio listening to the master. No audible coloration or distortion at all.

Luca

 

[Mi Li]

Hi guys,
in the the past two months the the turntable was fully fixed and calibrated as per service manual, and now it's in my living room, let's see how.
First of all new set of belts, it's not easy to fit new ones but absolutely feasible if you have a little time, patience, some tweezers, a little hook and a screwdriver.

Could you please share with me size of the belts?

 

[flavio81]

Hello all, some time ago I aquired two Sony PS-X800 turntables, both are faulty, and I would like to share with you the entire job of fixing and calibrating..

Hi,

Perhaps you would like to contribute or add information to this thread:

https://audiokarma.org/forums/index...rive-bsl-motor-works-troubleshooting.1021427/

It covers specifically these kind of Sony motors and their calibration.

 

[mcemsi]

Impressive job. Isorrentino do you have an idea why the toneram acts like that?: