JVC CD4-50 Demodulator Aquired

[ghalteman]

Hi,
I've been fortunate to aquire a JVC CD4-50 CD-4 Demodulator. If anyone is familiar with this unit, it has both a lower carrier adjustment similar to all other demodulators and also an Upper high end (Delay is the name of the control adjustment) adjustment to separate the upper frequencies.
My current problem is that my AT-20SS with a brand new stylus won't separate the upper level frequencies properly and my lesser quality AT-14S=Pro does nothing in this range. Has anyone found a CD-4 cartridge that still works well? They do deteriorate internally. Supposedly the internal mounting goes bad.
I use a BIC 1000 Belt drive turntable specifically designed for CD-4 and use 1 ft long Gold Ends cables from 70's. They work BETTER than the original Low cap. CD-4 cables that came with the table from new.

Cartridge suggestions? I tried the Ed Sauders CD-4 cartridge once and hated it, but I hadn't installed a headshell weight either (it is a lighter cartridge than the vintage metal CD-4 cartridges).

ANY CARTRIDGE SUGGESTIONS?

 

[Lucanu]

Welcome ghalteman.
A few questions....
Is your JVC working properly?
Are you in the possibility to try it with another setup (that is working properly)?
I ask you this because despite of a cartridge the demod must work (yes, maybe you hear sandpaper).

 

[Cai Campbell]

The CD4-50 requires a special setup record to properly adjust the delay settings. Do you have the CD4-50 setup record? If not, it doesn't matter which cartridge you use with the unit.

Also, it is my understanding that the delay is only relevant with "fussy" cartridges (i.e. those that were not specifically designed with CD-4 in mind). With a good CD-4 cartridge, the delay control will have little, if any, effect. Setting it "by ear" is more than likely sufficient.

What kind of CD-4 performance are you getting? If it sounds great, I wouldn't obsess over the delay control. I have a CD4-50 and I don't have the setup record. The delay control in my system has virtually no effect and I get awesome CD-4 performance.

 

[ghalteman]

Thanks for the replies. I have the JVC setup record with all the test tones in perfect condition. The ideal cartridge for this unit is supposed to be the JVC X1 or X2, but they are gastly expensive if ordered from Japan. Again, the delay is supposed to fine tune the upper frequency separation. My results using my Audio Technica AT-20SS with a new stylus have been pretty good, but I can only get the separation set on the right channel at present. I'm having a tech do a capitance and lead check. I'm using 1 ft. Gold Ends. Nothing lower than those.

Glenn

 

[rustyandi]

Hi,
I've been fortunate to aquire a JVC CD4-50 CD-4 Demodulator. If anyone is familiar with this unit, it has both a lower carrier adjustment similar to all other demodulators and also an Upper high end (Delay is the name of the control adjustment) adjustment to separate the upper frequencies.
My current problem is that my AT-20SS with a brand new stylus won't separate the upper level frequencies properly and my lesser quality AT-14S=Pro does nothing in this range. Has anyone found a CD-4 cartridge that still works well? They do deteriorate internally. Supposedly the internal mounting goes bad.
I use a BIC 1000 Belt drive turntable specifically designed for CD-4 and use 1 ft long Gold Ends cables from 70's. They work BETTER than the original Low cap. CD-4 cables that came with the table from new.

Cartridge suggestions? I tried the Ed Sauders CD-4 cartridge once and hated it, but I hadn't installed a headshell weight either (it is a lighter cartridge than the vintage metal CD-4 cartridges).

ANY CARTRIDGE SUGGESTIONS?

Do you have the instruction book that goes with it
If not I have one I can copy and send it
Ron
Australia

 

[ghalteman]

I've just got the CD4-50 demodulator back from a local technician. The diagnosis is the Audio Technica AT-20SS cartridge and wiring are fine, but the demodulator needs an adjustment on the left channels which no one I know can do. My friend Nick Perugini has the technical service manual, but he says it is all in Japanese. This demodulator used to belong to Gary Thilgen from Saranac, Michigan, an old quad buff,collector,and technician himself. He probably tweeked it back in the late 70's, but like all equipment, things age. Capacitors start to leak etc, so I guess it needs a little TLC from someone that knows what they're doing. I've also tried a JVC CD4-1000 that was repaired and had poor results because of it's age. Again, one channel decoded better than the other. I've also heard a similar story from a gentleman in Germany that owns a custom tweeked Technics SH-400. For now, I seem to get my best results from my Marantz CD-400. It clips on the right channels sometimes, but I get no raspyness which I sometime hear on the JVC CD4-50. I've sworn for a long time that the Marantz CD-400 with the manual carrier lock is a fine unit that seems to hold up well over time. Marantz always used parts that were tested to high tolerances.

 

[ghalteman]

:banana:

I've just got the CD4-50 demodulator back from a local technician. The diagnosis is the Audio Technica AT-20SS cartridge and wiring are fine, but the demodulator needs an adjustment on the left channels which no one I know can do. My friend Nick Perugini has the technical service manual, but he says it is all in Japanese. This demodulator used to belong to Gary Thilgen from Saranac, Michigan, an old quad buff,collector,and technician himself. He probably tweeked it back in the late 70's, but like all equipment, things age. Capacitors start to leak etc, so I guess it needs a little TLC from someone that knows what they're doing. I've also tried a JVC CD4-1000 that was repaired and had poor results because of it's age. Again, one channel decoded better than the other. I've also heard a similar story from a gentleman in Germany that owns a custom tweeked Technics SH-400. For now, I seem to get my best results from my Marantz CD-400. It clips on the right channels sometimes, but I get no raspyness which I sometime hear on the JVC CD4-50. I've sworn for a long time that the Marantz CD-400 with the manual carrier lock is a fine unit that seems to hold up well over time. Marantz always used parts that were tested to high tolerances.

 

[ghalteman]

Does anyone have a copy of the Schematic for the JVC CD4-50 Demodulator? If so, I'd really appreciate a copy of one.

Glenn Halteman Reading, PA

 

[ghalteman]

At long last (7 = years to be exact), my JVC CD4-50 Demodulator was shipped back from Quadbob. Out of the blue Thurs. May 2 he offered to return it along with my paying the balance of what he said was part of the original deal. So long ago, I forgot. Anyway, the unit came back in worse shape functionally than when it left. He recapped it and supposedly replaced a CD-4 chip. The unit uses the CD4-392 chip. The same chip as several other demodulators including Sansui QRX-8001, 9001, 999, Fisher 634, Grundig's demodulator, and a few other units. Anyway, after spending another $180 to get it back, I will at some future point be placing this rare unit for sale on Ebay. I'll annouce the auction here on the forum when I do.

 

[JonUrban]

I remember Gerhard Thilgen. Wow, that name goes way back. A very big quad guy, and a heck of a nice guy as well.

Glad to hear you got your unit back Glenn.

 

[ghalteman]

Yes Jon, this was Gary Thilgen's demodulator that he bought from the JVC CD-4 Cutting Center way back. He is no longer into quad, but I spoke to him when I was trying to locate a schematic for the CD4-50. Unfortunately I never turned one up.

 

[ghalteman]

JVC CD4-50 CD-4 Demodulator FOR SALE On EBay Beginning Fri. May 24 Ending Mon.June 1
I will be posting my JVC CD4-50 CD-4 Demodulator for sale and for repair on Ebay beginning Friday May 24, 2013 at 11 PM Eastern time and ending Monday June 1 2013 at 11 PM Eastern time. Please direct any questions regarding the unit to the Ebay posting. That is where I will answer any questions. I will be making the unit available in the US and Internationally. Thanks. I am posting the unit with my best guess as to the problem with the left channels.

EBAY LINK: http://www.ebay.com/itm/JVC-MODEL-C...tronics_R2&hash=item27d323408b#ht_2448wt_1142

 

[Eggplant]

I used to correspond with Gary Thilgen in the late 70’s and early 80’s when I lived in San Diego and he lived up the coast some, telling me “You ain’t that far.” Always strikes me as odd to hear of someone no longer into quad, because ... well, I don’t know any. My situation went in an out of quad-friendly over the decades, but it does seem to take up permanent residence in a collectors’ life. Some may not becwilling to make the transition to 21st-century technology — I’m currently struggling with that a bit myself. Storing and playing records and tapes just won’t cut it for me, no matter how sexy it looks in the Hollywood Hills on Bosch. Guessing Gary hit the exit right about the time I was entering, as I recall his add for a complete set of 330 or so US CD-4 releases for sale. He should have waited a few years for eBay