Victor CD4-10 "Studio" Mods

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jwb474

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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.
I do Wima caps when I can physically fit them in. Most of the electrolytic caps I replace are not in the signal path. I use a good general purpose cap that measures a low ESR and a capacitance value within a 5%. I have found that today's caps are really close to published values. I have considered using a higher grade of Audio rated caps, but frankly for this level of designs, I believe we are already on the point of diminishing returns. For real high end stuff, like doing mods to Vacuum Tube pre-amps and Power-amps, where folks spend larger amounts of money on grid coupling caps you may be able to get a real audible improvement.
 

jwb474

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This installment completes the Phono Pre-Amp by including the RIAA H.F. Roll-Off portion of the EQ. None of the mods for the Studio version of the CD4-10 are included in this assembly. Just upgraded some caps, general re-capping and replacing the pots with good sealed multi-turn types. Plus a good cleaning.
 

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jwb474

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This Portion of the project is where all but one mods are done for the studio conversion. As with the other assemblies, I verified and made any corrections on this assembly's schematic. I will post the Top assembly next. I will be looking for parts and figuring out how to do the more complex mods. One thing popped up during this is I now have reason that the "Note 5" mods may have discrepancies or I may have interpreted them wrong and I believe that "Notes 3 & 4" may come in to play. I will know this as soon as I receive pictures from a known CD4-10S.
 

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jwb474

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This is where it all comes together. The only change at this level is the chassis mount capacitor that is replaced. All switches were cleaned with Deoxit D5 and the pots were cleaned with Deoxit F5. With this entry we now have a actuate and complete schematic of a stock CD4-10. As as I progressed thru the assemblies, it came very apparent that the CD4-10 has a lot in common with the JVC 4DD-5 and Marantz CD400. I will probably raid parts from one of my 4DD-5s to do the mods.
The next challenge is when I do the Mods on the Carrier Recovery assembly is to figure out an alignment procedure using what instruments I have.
 

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jwb474

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OK, attached are the 1st of many photos coming from a working CD4-10s
Preliminary looking at the photos reveal that there are undocumented mods made and that "notes 3 & 4" are indeed implemented along with the mods outlined in "note 5".
The owner of the CD4-10s is taking measurements as needed to verify values and actual rework.
More later as I update my documents and then I will post all of the revisions to my earlier posts.
 

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jwb474

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OK, Here is the revised mods on the 2nd Stage Phono Pre-Amp since getting info from a working CD4-10s. Quite a lot of difference from the original mod. Some mods weren't even documented anywhere.
 

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jwb474

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This assembly was the most extensive in the mod process. JVC put a lot of effort on the recovery of the signal and the A.R,N.S. accuracy.
 

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jwb474

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This is the completed documentation of a CD4-10 Studio.
Up next, from the measurements I am getting, I will provide a method to calibrate a CD4-10s. More details to follow. Since Winter is coming to my area I will be switching to my Tube hobby for a while. I will continue to provide updates to the CD4-10s project as time allows.
 

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ArmyOfQuad

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Any further updates on the CD4-10S project? I have a CD4-10 that I'd love to get modified if possible.
 

quad4all

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As can be seen, the "Direct Phono Output" function has been completely removed. The phono input now goes directly to the 1st stage Phono Pre-Amp assembly.
Does this mean the 10s has no working direct phono output ,or is it just a modification you made?
I do have a 10s and yes my direct phono output is not working. What is the benefit of disabling it? Sorry I'm not good in electronics.
 

jwb474

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Just a couple of days ago I noticed a reply to the CD4-4s mod thread. A member was asking a question about the direct phono wiring. I went away for a while as I pondered my response. When today I went to respond I cannot find the thread. I certainly hope that I am just somehow doing something wrong in my search for the thread. I would not be able to re-create the entirety of the thread.
 

jwb474

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Does this mean the 10s has no working direct phono output ,or is it just a modification you made?
I do have a 10s and yes my direct phono output is not working. What is the benefit of disabling it? Sorry I'm not good in electronics.
Yes the 10s has no direct phono output. The phono input goes directly to the phono pre-amp assembly, bypassing the switch assembly. This is done to reduce the capacitance with the wiring. The switch and addition cabling does add capacitance to the overall input and capacitance in this case is an enemy of the 30KHZ carrier and addition frequencies to 50KHZ. This is why it is so important to have low capacitance cables from the turntable to the demodulator input. The JVC engineers wanted to maximize the performance of the 10s over the stock 10.
 

ArmyOfQuad

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So I threw more money at the money pit that is the rack of stereo equipment, and as usual, I get to watch it go *poof* without any quad bliss to show for it....

I have the cartridge, I have demodulators, I have quad amps.....but the turntable situation still needed to be addressed. I was quite disappointed to find my luxman was no longer up to the task of being a functioning record player, and attempts to have it repaired were chased away. This resulted in the purchase of an NAD C588 turntable. Which, unfortunately, doesn't accommodate multiple cartridges without having to do a complete recalibration every time you change it, which is a pain in the neck. At least with swappable headshells, all that's needed is an adjustment of the counterweight - but I suppose a swappable headshell offers another contact point in the chain.

Anyways, I made sure I put in a shelf wide enough for a 2nd turntable, and after doing research, found that I once again came up with the NAD being the best option when considering all things. I had considered perhaps going with something vintage to stay in the quad time period.....but I'm so sick and tired of all the things that come with that! No one services these things, and I'm not getting any closer to being anywhere near competent enough at electronics to realistically service any of this stuff myself - but that seems to be what it comes down to. You want it fixed, learn how. No one ever wants to repair anything, or I've not found the right place. Even when I take a nice luxman turntable to a stereo repair shop, it's chased away in favor of replacing it, so now it sits in my basement to rot.

So, the new turntable has arrived, and I set it up, put on the signet cartridge, aligned it, and got out my demodulators - the Marantz CD400, and the Victor CD4-10. Did a quick setup of the CD4-10 to see how it performs as is - sandpaper city! More money that was thrown on the pit - with no payoff since no one will work on it for me! And I've tried!

Ok - onto the marantz. Well - it's become problematic. Which I've known for years, but stay in denial about. As anyone knows that has heard my CD4 conversions, every now and then if the planets align, it can produce some quad bliss to be captured. But - it's a pain in the ass. Right channels like to crap out at times requiring wiggling wires.

And my quad amp - a marantz 4060. A rather budget model of the marantz amps. I do have a 4400 in the basement - no sound from the pre-amp. Another piece of equipment I bought under the delusion that I could find someone to repair it, more money thrown at the pit. Well, the 4060 is a crackly mess if you touch anything, and lately doesn't like to settle down into working - the right channel likes to pop out, resulting in needing to wiggle the volume knob and maybe play with the tape monitor button to turn it into a crackly mess and hope it settles into working. Lather, rinse, repeat.

So.....another purchase that will probably sit unused due to the frustrations it takes to get anything useful out of it.


Which brings us back to the topic at hand.........could anyone do the modifications documented in this post on my CD4-10 for money?
 

Mark Anderson

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I feel your pain. Had a reel deck worked on a few years ago and wasted $400. Came back with a hum in the right rear. Trying to find someone with the knowledge and desire to fix these gems is getting harder. Maybe a thread of repair gurus could help other folks in the future but I cannot add to that, I did find a reel to reel enthusiast in Phoenix Arizona but he specializes in very high end decks.
I hope you can find some relief somewhere as we always appreciate your time in doing conversions
 
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