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Sony PS8750 / TTS8000 oscillator replacement proposal with modern CMOS

Harolda

Harolda

Well-Known Member
I am working on a TTS8000 which has very similar electronics to the PS8750 speed control. I am also now in the process of designing an alternative solution for the OKI MSM5576 oscillator that delivers the 240Hz, 480Hz and 960Hz signal. This is the same in both the TTS8000 and the PS8750!

It involves a CD4060BC counter IC, a 3.932160Mhz xtal (same as in the TTS8000 and PS8750), 2 resistors and maybe 2 caps. This will supply the 240Hz, 480Hz and 960Hz square wave signals. I now integrate this solution (after testing a small proto) to a complete new servo board PCB for the TTS8000 due to a lot of issues with bad pad's on the original PCB.

The CD4060BC has the following output that can be used to divide the xtal frequency of 3.932160Mhz:

Pin3: Q12: divider 2^12=4096 --> output frequency is 3932160/4096=960Hz
Pin2: Q13: divider 2^13=8092 --> output frequency is 3932160/8092=480Hz
Pin1: Q14: divider 2^14=16384 --> output frequency is 3932160/16384=240Hz

Voltage input is the same as for the MSM5576. rerouting of the signals is required since the pin connections are different and because the CD4060 is a 16pin IC. 8 connections are used vs the 7 used on the MSM5576

I am thinking that a small PCB that can be installed in a 14pin dip socket can be a solution for both the PS8750 and TTS8000.

So the change would look like
1) desolder OKI MSM5576 IC
2) mount 14pin dip socket
3) mount custom adapter PCB on the 14pin dip socket that contains:
a) the CD4060BC IC
b) the required resistors
c) the rerouting of the signals to the correct MSM5576 positions
4) Maybe an update of the oscillator coupling caps.

I am not yet sure if this can be done with maintaining the old xtal or that a new xtal has to be installed on the adapter PCB. The xtal is coupled to the CD4060 ic using a series and parallel resistor

This is an example for a 1Khz output. In our case we would use output 1,2 & 3:

Accurate-1-kHz-Crystal-Oscillator-Circuit-Diagram-1khz-1-kilohertz-cd4060.jpg

This is not much different than the MSM5576 except the additional ground connection for pin 12 (reset)


In the PS8750 the speed control board is a seperate PCB, in the TTS8000 everything is integrated on one PCB.

This gives us also the option to design a modern PCB for the PS8750 with little effort that takes care of:
- A failing MSM5576 IC with the solution i described above
- The through board connections with a modern 2-layer PCB design
- All new components since all other IC's are available

What do you think?
 
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Well it works, i just put in a cd4060BE with the proper resistors and caps and i get a nice 240Hz, 480Hz and 960Hz and very stable!!
I measure:
239.9977Hz for 240Hz,
479.9954Hz for 480Hz
959.9907Hz for 960Hz

So no need anymore to look out for a OKI MSM5576 IC to repair a Sony TTS8000 or PS8750.

I made a complete new PCB for my TTS8000 also to get rid of the issues with the via´s on the old PCB. The new one is very clean and uses modern via techniques.
I will post some pictures of the new PCB

Next step is to add the other IC´s and to see if everything measures according to spec!
 
Oke some pictures of the new PCB. The 5.5V and 13V power supply have been installed and work according specs. The start-stop circuit is installed and works according specs. In the right bottom of the PCB you can see the new installed IC with a new xtal and the caps and resistors:

IMG_2625.JPG IMG_2628.JPG
 
Glad to see you have had success with the board, I am a bit of a fan of the TTS-8000.

Curios if yours is a 100v unit or even if they were ever really marketed outside Japan with other voltages.
My early TTS-2251 drive has a multi-voltage transformer.
 
I read somewhere that is has been exported to the UK as well. Mine is 100V. I have a good quality step down transformer from Airlink which i also use for my Sony PS-B80
 
Hi Harolda,

As a TTS-8000 owner and massive Sony collector and restorer, I am really thrilled by your project here !!!
Excellent job !!

Although my TTS-8000 is still spinning just fine, I may want to buy a board of you in case you would go sell them.

Coincidentally, a good audio electronics buddy of me in France has just finished the development of a new PCB for the PS-8750, based on the same 4060 IC.
His prototype boards will come in soon.

I equally got a PS-B80 from Japan :)
 
Hi Oilmaster,

nice to hear that you are enthousiastic about this thread. It took a while to get some replies on this thread. I already was under the impression that everyone sold their PS-8750 ;)
I would also be interested in how the PCB for the PS-8750 would look like. it would be an easier job than for the TTS8000. The PS 8750 uses different PCB's. In the TTS8000 everything is integrated into one large PCB.

I will post all my progress here so other can use this tyo their advantage. I hope you also do this with the PS8750 PCB. I also would be interested on the values for the additional resistors and caps for the IC and Xtal your tech used!

I will finish the project and i have one spare PCB left. Maybe i will sell it in the future.

What arm do you use on the TTS8000?

Did you do any mods to the PS-B80?
 
I'll PM you about my buddy working on the PS-8750 board; I am not involved with his project but he shares the fun with me (a PS-8750 is one of the few Sony items for me left to get)

I bought the TTS-8000 in a TB-1000 plinth, which had a Grace G-940 tonearm and headshell with a Shure MM M44G cartridge, while living in japan.......otherwise the delivery would never ever have been possible without damage.....I took the whole thing apart nevertheless when I moved back to Europe.

So, in order to build up a decent Sony assembly, I purchased a PUA-1500S and PUA-1600S tonearm separately before leaving Japan, and via Axel of TVK I got some nice NOS XL-33 and XL-44L cartridges. The thing is....I haven't had the time to mount any tonearm back in, the table is standing in a corner for some time now. I could use some help with that, since I am not an expert in tonearm setup and alignment (still have to purchase the gear for that as well).

The PS-B80 arrived half a year ago, it did survive the voyage very well. I unpacked it, but again had no time to install a cartridge.
My intention is to recap it anyway before first power up. This week or weekend I may have time for a first peek inside.
So... two major TT on the floor, lots of vinyl, but unable to play it....:(
Too busy with multiple amplifier rebuild projects :oops:
 
I'm the french guy who's working on the new PCB of the PS8750.
I have just finished the routing and I'll send the gerber files to a PCB manufacturer in the next days.
I have replaced the OKI circuit by the same CD4060 and I have also replaced the 5V discret voltage regulator by the very common 7805.
The rest of the schema is the same as the original.
As soon I receceived the PCB, I'll post some pictures of it. For the moment, here is a 3d view from my CAD software.
 

Attachments

This sounds very interesting. Anyone who can future proof these Sony masterpieces gets my vote. I have a TTS-8000, a UK model with a Resinamic plinth. I am using a Technics EPA-501H tonearm with a Cartridgeman Music Maker 3.
 
Thanks for the reply.

@Oilmaster, you should really start listening at the PS-B80. I have been doing nothing else last 2 weeks, in combination with a XL55 and a fresh restored TAE88 it really sings!!! If you have a Sony cartridge integrated in the shell, like a Xl55pro, there should not be a lot of work setting up the PS-B80.

@pat: Thanks for sharing the pictures. At first i also wanted to use a LM7805 for the power supply of the IC's even bringing the complete power supply into an external enclosure. Maybe something for later. I would be interested in the resistors and caps you plan to use on the 4060. I used a 1M & 1K for the resistors and 2x22pf for the caps. I also installed a new xtal.
Do you also replace the other ic's with (modern) equivalents?
 
Hi Harolda,
I have checked the CD4060 on a breaboard with 1 Mohm + 2,2 Kohm and with 22 pF + 100 pF and it seems to work with a new xtal.
The logic circuits have to be N or LS version. I tried HCT with no succes, maybe the 22pF caps and the 10k feedback resistor are not adapted.
I order one prototype PCB today. I hope I will have it at the end of the next week.
I will post some pictures of it as soon as I receved it.

By the way, I have also made a set of 3 new PCB for the SONY ST-A7. This tuner suffers the same deseases as the PS8750-TTS8000 PCBs.
 
Thx pat, looking forward to see your work. I will check the new IC's i used. I also did not change the 10k resistors and 22pf caps.

At the moment I have some delay since I decided to get the Ps B80 back on my desk. Now I did a complete job on all caps and through pcb connections. Cleaned all connectors and I am currently in the process of adjusting everything. This is learning by doing, the sm is not clear on all adjustments. But I am almost there, the adjustments need a few iterations and I also changed some trimpots for most accurate adjustment.

After that back to work on the tts8000
 
Hello,

Some pictures of the new PCB.


Xtal1.jpg Xtal 2.JPG

The oscillator is working fine.
The signal for the neon bulb stroboscope is also OK.
The 4060 is an HCT version, but the other TTL IC involved in the clok dividers must be the old N version because of a special design of the circuit. I tried a 74HCT00 for IC105 and I obtained a nice 100 MHz oscillator but not a divider by 2 as expected.
 
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Looking good! Did you have some certain issue with your ps-8750 or do you just wanted to make a new pcb?
 
Yes, I had issues with my own PS 8750 and I also repaired some others for my friends.
The majors problems were in the bad solder joints on the Xtal board so I decided to make that new PCB.
 
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