Fixed Sony PS-X75 with an Arduino Mega Board

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MKB1

  • Jr. Member
  • Posts: 3
Fixed Sony PS-X75 with an Arduino Mega Board
« on: 30 Jun 2022, 07:48 am »
Fixed a SONY PS-X75 Record Player (1980's) with a blown MB8841-209L microchip. Fixed it with a Arduino Mega2560 Board and the fabulous Embrio Software.

A long, long time ago in 1980’s Sony produced one of the best automatic record players the Sony PS-X75.

The only problem was the main Microprocessor (IC) was prone to breaking. Our Sony had a broken IC and no one manufactures these anymore and you can't buy secondhand chips either.

We searched the galaxy for a replacement and couldn't find one.

I reversed engineered the chip using Sony PS-X75 Service Manual and programmed a £30 Arduino Mega board to replace all the functions of the main IC chip.

The linked video below for some could be a bit boring but the heart surgery to replace the main chip with an Arduino Mega board WORKED !

All functions thanks to Embrio are now FULLY Restored using an Arduino Mega Board.

All the following works:
Auto Play
Record Size Detection
Auto drop
Auto Stop
Button start / stop
Button up/down
Buttons forward and backwards
Repeat
Speed selection
No record detection
Home arm detection
Stylus force and bias
All lights and buttons
Auto arm up and home on startup, auto play and stop.
New External USB fitted to upload config changed to Arduino.
New light sensor board made for record size detection as main board one was randomly working.
New LED light fitted.
Added a 9v transformer to power the Arduino when the Sony is turned on.

Enjoy

Youtube with all links to what I did to fix this vintage machine :)
https://www.youtube.com/watch?v=31ILr8oTtt4





Norman Tracy

Re: Fixed Sony PS-X75 with an Arduino Mega Board
« Reply #1 on: 30 Jun 2022, 03:14 pm »
Bravo!

 :thumb:

Norman Tracy

Re: Fixed Sony PS-X75 with an Arduino Mega Board
« Reply #2 on: 30 Jun 2022, 06:04 pm »
MKB1 I am curious about a very unique feature of the PS-X75, servo damping. Like some Denon turntables from the 1980s (DP-51L, DP-57L, DP-67L, et.al.) the PS-X75 uses electronic damping of the tonarm/cartridge ~11 Hz resonance frequency. This same system allowing the adjust while playing electronic stylus force feature. Are the feedback loops controlling the tonearm's damping digital or analog? That is did the Arduino and its code need to deal with the damping servo?

MKB1

  • Jr. Member
  • Posts: 3
Re: Fixed Sony PS-X75 with an Arduino Mega Board
« Reply #3 on: 1 Jul 2022, 01:28 pm »
Hi

This does have to be taken care of within the Arduino, it has a couple pin inputs that relate totally on where the tone arm is and if it's up or down and then from the signals/waveforms these are digital high or low into the Arduino.

Waveforms



Essentially I have to control the force, bias and balance depending on the state of three digital pins

The inputs coming in are:
  • is the Tone Arm up or down (pin 27 Down - pin 28 up)
  • Is the tone arm in zero balance (pin 29)

This then then lets me set the following outputs back to the board.
  • Arm Bias on or off Pin 23
  • Arm Balance on or off Pin 26
  • Stylus force on or off Pin 20

I've followed this principle from the Service Manual (great read) when to use force or not. Once playing the stylus force ant-skating dial kicks in and you can manually adjust the stylus force pressure.



I hope that helps, this was one the trickiest areas to try and get my head around and understand and if 0g to 3g of viable (dialled) stylus force should be applied - I hope I've applied it correctly :)

MKB1

  • Jr. Member
  • Posts: 3
Re: Fixed Sony PS-X75 with an Arduino Mega Board
« Reply #4 on: 14 Jul 2022, 01:52 pm »
This sounds absolutely amazing with the Goldring 1042 cartridge fitted - its OMG working/sounding so beautiful.

https://www.youtube.com/watch?v=7M-VY9lgjXk