JVC CD-4 demodulator 4DD-10

[Sonik Wiz]

Good Morning all
I've joined the site to further my knowledge of the Quad scene, as I've been out of it for *gulp*, 50yrs!
I understand formats have come and gone since my days, and truthfully I don't understand the "mechanics" behind the working of 4 channel playback, but I know what I like.
Ive sent my Sanusi QXR 9001 to qxr restore for a full restoration, the Holy Grail, Cap upgrade and LED lighting. Probably spending way too much, but cry once and then enjoy is my motto. I also have a Marantz 6300 that has served me well and after using some DeoxIT D5 all functions are working

So my question to the experts, in 2024 what is the goto stylus for 4 channel playback that would work with my 6300
I use to use Shure products back in the 70's and ofcourse were inexpensive compared to todays market
So please share your opinions, as Iam still a few months from getting my ole girl back, which Iam patiently awaiting

The topic of CD-4 cartridges has been discussed to death on QQ. The search tool is your friend. Check this out:

https://www.quadraphonicquad.com/forums/search/187438/?q=CD-4+cartridge&c[title_only]=1&o=relevance

There is no single "go to" cartridge since there is no one making one specifically for CD-4 anymore. Member recommendations are many & varied becuase of this. I get quite good results using an AT 440 MLB. But Qudradisc is really low on my priorities so I don't usually have a CD-4 demodulator in my set up. Of course for you it will be right there inside the Sansui.

 

[Bruce00]

The topic of CD-4 cartridges has been discussed to death on QQ. The search tool is your friend. Check this out:

https://www.quadraphonicquad.com/forums/search/187438/?q=CD-4+cartridge&c[title_only]=1&o=relevance

There is no single "go to" cartridge since there is no one making one specifically for CD-4 anymore. Member recommendations are many & varied becuase of this. I get quite good results using an AT 440 MLB. But Qudradisc is really low on my priorities so I don't usually have a CD-4 demodulator in my set up. Of course for you it will be right there inside the Sansui.

Thank You.........Yes I did do a search and came up with the results you listed. But unfortunately , most every time the discussion comes up, it is so far over my head, it might as well be in a different language
I always had good results with 4 channel separation with the Shure I had been using, but I starting over thinking, **my usual problems** that there were better solutions for stylus
I started thinking it was the Sanusi taking what ever signal it received and turning it into the quad.
So that's why I just figured it was better to ask, what the experts would use

Hope my ramble makes sense
Now if you are building a 2 valve or 4 valve Harley motor or welding, I can help you out

 

[Michaelteg24]

I have the QSI-5022 CD-4 decoder IC application note scanned, I can email it to you if you give me your email (via the conversation option).

The schematic of the JVC 4DD-5 is online (somewhere, haven't found it yet) and should be useful to reverse engineer ANRS.

An all software CD-4 decoder was developed about 5 years ago (there could be some useful info in the thread):
https://www.quadraphonicquad.com/forums/threads/working-cd-4-software-demodulator.24900/


Kirk Bayne

Thanks for the link to the thread.
I have downloaded copies of All You've Ever Wanted to Know about the CD-4 Disc Sytem and the service manual for the JVC CD-4 4DD-5 ; That I bought last month and has a problem with it.
It had been serviced in 1978 by some repair place.
They used a Sylvania ECG123A to replace a 2SC458LGC.
I have bought some original Hitachi 2SC458LGC's I found on eBay. Hopefully they are still good. I have seen posts that report failure issues with them.
They are being delivered today.
I am going to find out if it makes a difference before going further with troubleshooting the problem.
I will send you my email address after while.

 

[kfbkfb]

Also, Louis Dorren was designing a new CD-4 decoder, I think only a prototype was built, here's the thread about it and Lou answers a lot of questions about CD-4 decoding, the info may be useful in designing a CD-4 encoder:
https://www.quadraphonicquad.com/forums/threads/lou-dorren-a-new-cd-4-demodulator-archive.9035/


Kirk Bayne

 

[furui_suterioo]

I'm in the process of building a CD4 Modulator.
It will feed proper left-right signals with a FM modulated 30 kilohertz carrier to a demodulator to be able to test it without a turntable.
The CD4 test records have very short test tracks that force you to play it over and over again to make measurements of the signals as it progresses through the system and make adjustments to the systems controls.
I like a good long steady
signal to allow me to troubleshoot a demodulator with problems!
So far I have I designed the Sum and difference circuitry and the RIAA pre emphasis and de emphasis circuitry, easy breezy!
The PLL for modulation is next on the list and will not be difficult ether.
When completed I will upload a schematic and parts list.
At any rate it's keeping me off the streets and out of trouble !

Sounds like a great project. There is definitely an audience here interested in a project like that so feel free to post updates when you get started.
I bought a pair of qsi chips with the intent of building a demodulator (when i find the time). They are supposed to have everything contained in the chips for demodulating except the preamp. Good luck!

 

[Michaelteg24]

Thanks for the link to the thread.
I have downloaded copies of All You've Ever Wanted to Know about the CD-4 Disc Sytem and the service manual for the JVC CD-4 4DD-5 ; That I bought last month and has a problem with it.
It had been serviced in 1978 by some repair place.
They used a Sylvania ECG123A to replace a 2SC458LGC.
I have bought some original Hitachi 2SC458LGC's I found on eBay. Hopefully they are still good. I have seen posts that report failure issues with them.
They are being delivered today.
I am going to find out if it makes a difference before going further with troubleshooting the problem.
I will send you my email address after while.

The Hitachi 2SC458LGC's I found on eBay arrived yesterday and I replaced the Sylvania ECG123A that was used to replace the X301 (JVC schematic reference number in the 4DD-5 Service Manual).
It brought it back to almost complete operation. I also found that C301 in the left channel and C302 in the Right channel were also bad! JVC used caps rated at 25 volts to block the 25 volt supply in the bias network and used the 4.7 uF value to set the time constant at the right value. You should always use a cap with a higher voltage rating than the voltage you are blocking. I replaced them with 35 volt caps with the correct 4.7 uF measured values. That bad is on JVC!
In this circuitry the values of the components are critical in order for the circuit to have the right pole-zero positions in s-plane for it to work right! It's all about poles and zeros!
Now the unit is working like brand new!

 

[Michaelteg24]

Sounds like a great project. There is definitely an audience here interested in a project like that so feel free to post updates when you get started.
I bought a pair of qsi chips with the intent of building a demodulator (when i find the time). They are supposed to have everything contained in the chips for demodulating except the preamp. Good luck!

Good luck with your project too! And most of all have fun doing it !
Thanks for the encouragement to continue to post updates.
The qsi chips sounds a lot like the CG477 chips that were made by Signetics back in the day! It is/was described as having the low noise preamp included.
Hindsight is 20/20...If I knew then, when I was working there, what I know now, I would have bought several hundred of them.
I still have the copy of the Phase locked loop manual that was given when I was introduced to the technology by my supervisor Peter Telfer and Les Hadley who had done extensive work helping with the development of the chips. I was given a blessing by Ira Zingmond when he hired me.
At the moment that he hired me I didn't know just what good fortune had befallen me!
I was given an education in electronics by the best people in Silicon Valley that few people have the opportunity to acquire.
The best part of it was that instead of having to enroll in the Universities and pay for an education, like almost everyone else, I was paid to acquire the knowledge that was given to me!
I got to work with the people who were the professors and educators at the Universities.
The downloaded manual and the section of the application book on PLLs published by Signetics do not cover the CD4 chips.
They are only covered in the version of the manual that I have a copy of.
So... with all that name dropping and self centered monologue out of the way...
Who made the qsi chips that you have?
Can you get more?

 

[Michaelteg24]

Sounds like a great project. There is definitely an audience here interested in a project like that so feel free to post updates when you get started.
I bought a pair of qsi chips with the intent of building a demodulator (when i find the time). They are supposed to have everything contained in the chips for demodulating except the preamp. Good luck!

 

[furui_suterioo]

Good luck with your project too! And most of all have fun doing it !
Thanks for the encouragement to continue to post updates.
The qsi chips sounds a lot like the CG477 chips that were made by Signetics back in the day! It is/was described as having the low noise preamp included.
Hindsight is 20/20...If I knew then, when I was working there, what I know now, I would have bought several hundred of them.
I still have the copy of the Phase locked loop manual that was given when I was introduced to the technology by my supervisor Peter Telfer and Les Hadley who had done extensive work helping with the development of the chips. I was given a blessing by Ira Zingmond when he hired me.
At the moment that he hired me I didn't know just what good fortune had befallen me!
I was given an education in electronics by the best people in Silicon Valley that few people have the opportunity to acquire.
The best part of it was that instead of having to enroll in the Universities and pay for an education, like almost everyone else, I was paid to acquire the knowledge that was given to me!
I got to work with the people who were the professors and educators at the Universities.
The downloaded manual and the section of the application book on PLLs published by Signetics do not cover the CD4 chips.
They are only covered in the version of the manual that I have a copy of.
So... with all that name dropping and self centered monologue out of the way...
Who made the qsi chips that you have?
Can you get more?

Interesting, thanks.
The QSI-5022 chips made by Quadracast Systems Inc. designed by Lou Dorren (one of the pioneers of CD-4 and discrete quad FM broacast). From what i have read, they were the final iteration of CD-4 IC chips offered in commercial demodulators like the Technics SH-400.

There is mich information on here sbout Lou Dorren, he had been working on a new production demodulator when he passed several years ago. There is a long thread for on here, although a bit sad since it wasn't ever finished.
I came across some on ebay from a saved search, they had two pairs so i bought 1 pair and left the other for someone else. Haven't seen anymore since.

This website has a design for a demodulator using the qsi chips.
https://www.sm5cbw.se/sm5cbw/rt/7504.htm

 

[Michaelteg24]

Interesting, thanks.
The QSI-5022 chips made by Quadracast Systems Inc. designed by Lou Dorren (one of the pioneers of CD-4 and discrete quad FM broacast). From what i have read, they were the final iteration of CD-4 IC chips offered in commercial demodulators like the Technics SH-400.

There is mich information on here sbout Lou Dorren, he had been working on a new production demodulator when he passed several years ago. There is a long thread for on here, although a bit sad since it wasn't ever finished.
I came across some on ebay from a saved search, they had two pairs so i bought 1 pair and left the other for someone else. Haven't seen anymore since.

This website has a design for a demodulator using the qsi chips.
https://www.sm5cbw.se/sm5cbw/rt/7504.htm

Thanks for the link.
It has 18 pages of information on the qsi chips.
With the revitalization of vinyl maybe one of the 3 billionaires can be encouraged to start making CD4 LPs again! Seeing as how they have the cash to throw around then they could throw some towards CD4 Quadraphonic LPs!

 

[kfbkfb]

https://www.worldradiohistory.com/A...0s/1974/Radio-Electronics-1974-06.pdf#page=38

(more about the QSI-5022)


Kirk Bayne