Victor CD4-10 "Studio" Mods

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jwb474

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A while back I had mentioned that I some details on the Studio mods for the CD4-10.

They are not very clear as they were sent as JPG files and a text note.

Here is the Postimage link to the gallery containing the pictures: http://postimg.org/gallery/jnp8hin4/

As you will find it is going to be an uphill battle to figure it out. If anyone hear has a good PDF copy of the CD4-10 service manual or just the schematic, then it would be easier to figure out what is going on. My only other option is to reverse engineer my CD4-10, when I have the time that I really don't have.
 

Attachments

  • CD4-10S mods.txt
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Thank you for this information. I haven't come across the full schematic as yet. If I do, I will post here or add to quadraphonic.info. I am interested in trying to do this to my CD4-10. The supply in Japan seems to have dried up or I would have tried for a second, just in case....
 
Let me know how this turns out, I have a working Victor CD4-10 myself that I'd love to get modified sometime, but am not sure where to begin to find someone capable of such a project. As is, it does seem to work, but I've not been as happy with it as the marantz cd-400, so I'm thinking the modifications must be necessary to get top performance out of it.
 
Got around to study the mods. What I decided to do was to redraw the schematic in which the mods are affected then slowly make the changes. Attached document is what I finally came up with. The Ref Des and Values are the best I could decipher from the original mod instructions. There was a lot to guessing going on. My next step to verify the original Ref Des and Values against my unit. When that is done and verified and any corrections that need to be made are done, then move on the next step in resolving any questions on the mods themselves. If this works out, then I see no reason that these mods could not be applied ( with several extra mods ) to the JVC 4DD-5 or Mararntz CD400.
 

Attachments

  • CD4-10 Studio Mods.compressed.pdf
    555.3 KB · Views: 270
May I ask you all two questions:
1. Is this this the unit that has the thin metal model sticker over the original model number on the front that simply states CD4-10S ? Or does it actually say "Studio" somewhere (either on front or rear)?
2. Does the "Studio" model have balanced XLR's on the rear? Or just the same RCA Phono's as the CD4-10?
Thanks
 
May I ask you all two questions:
1. Is this this the unit that has the thin metal model sticker over the original model number on the front that simply states CD4-10S ? Or does it actually say "Studio" somewhere (either on front or rear)?
2. Does the "Studio" model have balanced XLR's on the rear? Or just the same RCA Phono's as the CD4-10?
Thanks

I really don't know. My unit of course is a regular CD4-10. I don't know if any "Production" CD4-10S were done. As for balanced XLR outputs, since the original mod instructions did not address the audio outputs by adding balanced buffers on the outputs, I would guess that only RCA outputs were used. That not to say that with a little extra work, that balanced outputs could be added. There is certainly plenty of room and there are many circuits designs already done that could be used.
 
I am starting the CD4-10S journey with the easiest part, the Power Supply. I am going PWB by PWB and going to clean them, draw out schematic, verify Ref Des and Values then do the mods. Will also do addition mods like re-capping.
 

Attachments

  • CD4-10 Power Supply, Back, Original.jpg
    CD4-10 Power Supply, Back, Original.jpg
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  • CD4-10 Power Supply, Back, Re-Capped.jpg
    CD4-10 Power Supply, Back, Re-Capped.jpg
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  • CD4-10 Power Supply, Top, Original.jpg
    CD4-10 Power Supply, Top, Original.jpg
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  • CD4-10 Power Supply, Top, Re-Capped.jpg
    CD4-10 Power Supply, Top, Re-Capped.jpg
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  • CD4-10 Power Supply.compressed.pdf
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That's quite the project jbw! Hope it all works out.

Is that a drawing typo on your graph paper pdf.... should the 'B5' connected to R504 on the left side read 'B2' ?

Yes, that is very much a typo, Thanks for catching that. This also why I am posting this project, so that I can get doubled check. By the way you typo my initials :).
 
Dumb question from electronics dunce, but are there proprietary chips in these devices, or is it something that could theoretically be copied and reproduced? Just thinking out loud here, but it seems like there would certainly be a market for a small run of a high quality CD-4 demodulator in the absence of Lou Dorren's project since his passing.
 
Dumb question from electronics dunce, but are there proprietary chips in these devices, or is it something that could theoretically be copied and reproduced? Just thinking out loud here, but it seems like there would certainly be a market for a small run of a high quality CD-4 demodulator in the absence of Lou Dorren's project since his passing.

Yes, a lot of the CD4 Demodulators use proprietary chips. For instance JVC teamed up with Signetics to develop the CD4-392 IC. Yes it could be reproduced given if the effort and expense could justify the sales, they would have to sell tons of them and probably at a fairly high cost per chip. Right now the best hope is going to come from the Involve folks for a new demodulator.
 
Moving on further in the project, this is the 2nd assembly to be reworked. The reason for the 1st stage title is because most all demodulators take the carrier tap off after the RIAA L.F. boost instead of after the full RIAA EQ. The 30KHZ carrier and it's modulation are so far down in amplitude after passing thru the H.F. roll-off portion of the RIAA EQ that a carrier lock is all but impossible. The CD4-392 IC overcame this issue.
 

Attachments

  • CD4-10 1st Stage Phono Pre-Amp, Revised 6-16-16.compressed.pdf
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  • CD4-10 1st Stage Phono Pre-Amp, Top, Original.jpg
    CD4-10 1st Stage Phono Pre-Amp, Top, Original.jpg
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  • CD4-10 1st Stage Phono Pre-Amp, Bottom, Original.jpg
    CD4-10 1st Stage Phono Pre-Amp, Bottom, Original.jpg
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  • CD4-10 1st Stage Phono Pre-Amp, Top, Modified.jpg
    CD4-10 1st Stage Phono Pre-Amp, Top, Modified.jpg
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  • CD4-10 1st Stage Phono Pre-Amp, Bottom, Modified.jpg
    CD4-10 1st Stage Phono Pre-Amp, Bottom, Modified.jpg
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Hello jwb. I do some recapping now instead of repairs, or in addition. It looks like you use Nichicon for the larger 'lytics? Have you ever considered their "audio" lines of caps? I have a Mac receiver to do and am choosing caps. Also, nice touch on the (poly? film/foil?) replacement of the smaller ones. What brands do you like for those? I've looked through audio forums where I'm not a member, and there is some extreme hype there. I've been using Nichicon for a long time, since some Panasonics leaked in the bag after about 10 years.
 
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