Sony Ps-x75 Important notice re Main MicroProcessor MB8841-2

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charlesvasi5455
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by charlesvasi5455 » 05 Jun 2016 05:21

sterzi wrote:Hi,
found this in my workshop.
Probably 20 years in stock :shock:
If it's useful for somebody, contact me

Markus

http://fs2.directupload.net/images/150505/a87m3b3b.jpg
http://fs2.directupload.net/images/150505/8hcniu5n.jpg
Do you still have this IC ? What was this originally from and why was it in your workshop? Do you work with or diagnose circuit boards? Where might I find another one, has there been a recent replacement for this IC ?

brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 15 Feb 2018 19:58

PS-x75 layout.jpg
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[album][/album]Sony PS-x75 Turntable. Removal of cam/coil holder 1-867-113-00 to allow arm lifter to operate freely, and to stop
Arm related issues such as the arm swinging wildly before setting down.
1…unsolder all coil termination wires
2…unsolder cartridge wiring
3…unscrew and lift head wiring shield cover over cartridge wiring.
3a…remove the 2 x top yoke plates
4…unscrew PCB board position detection sensor. 1-601-927-00
5…unscrew shutter and remove 4-867-111-00 from coil holder x-4867-102-0
6…unscrew 2 x grub screws on the x-4867-102-0 M3 x 4 with suitable size Alan key
7….before removing the grub screws, mark with texta pen, the arm tube and coil holder (above) and try to use the same idents where the existing screws have touched the shaft.
8…. Remove coil holder.
9….remove 2 x brass mounting posts
10..Remove 2 x magnet assembly. ( Yoke 4-867-108 ) identify the marking as they are to be fitted as taken off. ( lift vertically as ferrite magnetism is strong)
11…Remove the surclip on the shaft.
12…Ease the coil holder/cam 4-867-113-00 from the shaft.
13..Gently with coil wires still attached place upside down to expose Sony Grease ……remove all old grease from bearing
14..REMOVE all Sony Grease from shaft.
15.. Use white grease such as MOLYKOTE on bearing surface and on lifter ident.
16..When refitting the shutter make sure its centralised in the housing[album][album][album][album][album][album][/album][/album][/album][/album][/album][/album]
Attachments
fatigue cracks in the cam radiating down from the bearing insert.jpg
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magnet assemblies.jpg
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Top coil holder fastened with 2 x alan grub screws.jpg
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The start and finish setup.jpg
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brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 15 Feb 2018 20:07

Additional photos
Attachments
Sony Grease gone hard.jpg
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The Shaft with Molykote.jpg
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close up of hardened Sony grease.jpg
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surclip exposed.jpg
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brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 15 Feb 2018 20:21

Sony Arm Components
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Sony Arm Components.jpg
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brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 15 Feb 2018 22:16

Additional Info.....
Between steps 4 and 5 remove the top 2 x yoke plates....
Use good JIS screwdrivers on this job.......for removing the brass supports use a good flat blade ideally this would not be tapered
I used cotton thread to bunch the coil wires together as these rotate with the cam/coil holder
Check the continuity of the 3 switches, Deoxit if necessary
Keep magnet assembly together and aligned
Put a smear of white grease on the cam/coil holder where the switches make contact
Note regarding the cracks on the coil holder /Cam ; it would appear every that every PSx-75 will have suffered fatigue cracks from the bearing, I don't consider this to be an issue at this time,In the future I may re-enforce the bearing surround plastic.

This Arm not dropping fault explained here is one of two main issues effecting the Sony PS-x75. the other being the failure of the MB8841-209 4bit Micro replaced with the MB8841-327

These two issues were expounded by the inactivity of the PS-x75 for many years.

One point I noticed that only after 2 or 3 years from new the PS-x75 would take longer and longer to drop to the record........it was worse in the cold weather, when the grease got harder

brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 15 Feb 2018 22:21

White Molykote Grease
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WHITE MOLYKOTE GREASE.jpg
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brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 15 Feb 2018 22:57

Shutter alignment to be centralised

Coil wiring tied off with cotton thread on Main Cam / Coil plate
Attachments
Shutter will be aligned with top coil plate.jpg
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Coil wiring is very fragile .jpg
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brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 16 Feb 2018 21:48

A note for purchasers of the MB8841.... Fujitsu Micro and that is ;

The numbers following MB8841...............such as 327 are the encoded Sony proprietary gate sequence for the MB8841 Fujitsu Micro

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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 18 Feb 2018 23:55

Finally.....an adjustment of the arm drop point may be necessary.
(Check the lead in track on your worst record.)
Attachments
Sony PS-x75 now working beautifully.jpg
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brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 21 Feb 2018 22:30

Faults due to the hardened grease issue....

Erratic Arm movement with out dropping to record

Arm slow to drop or not dropping at all

These issues apply also to the PS-x65 as they are basically the same setup ....

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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 02 Mar 2018 23:07

Original XL25A Cartridge Setup for the PS-x75

same as XL15
Attachments
Sony SH165 cartridge setup for the PS-x75.jpg
Sony Sh 165. XL25A. cartridge Setup for the PS-x75
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brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 03 Mar 2018 20:57

The Original Sony Stylus ND25E (for the XL25A) was on Ebay recently also perfectly suitable for XL15, XL25A,

XL35, XL45 MM cartridges and it was top of the range, elliptical stylus…..only the best OEM for your PS-x75 and

PS-x65


Enjoy your music
Attachments
Sony ND25E Box copy.jpg
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Sony ND25E .jpg
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brinsmeads
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 24 Mar 2018 00:07

The SH165 headshell was supplied as OEM with the PS-x75 which has a slight gold tinge to its colour.

The SH155 headshell was supplied with the XL45A MM cartridge installed as a complete unit and is silver in colour.

Both identical except for Colour
Attachments
SH165. (left) and SH155 (right).jpg
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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 27 Mar 2018 20:00

Delayed or Muting issues on the PS-x75 can be caused by the hardened grease on the coil/cam.

Also check S512 the muting switch for continuity ,which is one of the three switches that are controlled by the rotation of the cam/coil assembly

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Re: Sony Ps-x75 Important notice re Main MicroProcessor MB88

Post by brinsmeads » 07 Apr 2018 01:48

The Sony (Silver) SH155 was available as a packaged shell and is 11.5g weight with standard Sony interconnects.
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SH155......11.5g with cartridge wiring.jpg
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Sony SH155. Shell .JPG
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