Separate CD-4 demodulator

[gvl_guy]

I bought a new old stock JVC about a year ago. When I received it in the mail, it would not turn on. I gave it to a local stereo store to repair it. They recapped it and said it needed a few new relays. It really hasn't been right, I'm not getting great CD4 out of it. I used the one in my receiver now. So just be careful, New Old stock might not be the way to go. The shop told me you really need a unit that has been powered on a few times and it's lifetime.

 

[fredblue]

I bought a new old stock JVC about a year ago. When I received it in the mail, it would not turn on. I gave it to a local stereo store to repair it. They recapped it and said it needed a few new relays. It really hasn't been right, I'm not getting great CD4 out of it. I used the one in my receiver now. So just be careful, New Old stock might not be the way to go. The shop told me you really need a unit that has been powered on a few times and it's lifetime.

totally! this ol' stuff likes to be used! i noticed the "Blend" switch on the back of my Grundig demodulator has started leaking since i relegated it to the closet.. eek

also, gotta say i'm surprised to hear the Sansui outboard CD-4 unit is not just a 4DD-5 clone like almost all the others!

 

[Doug G.]

Years ago, now, I got both a Panasonic SE-405 and a Technics SH-400 and (I know I'm tempting fate) they have been perfect.
You should get the seller to guarantee the unit works and if he won't, don't buy it unless the seller will agree to pay for return shipping if it doesn't.

Demodulators are complex devices and it's difficult to correct problems in them beyond simple power supply cap. replacement. A CD-4 expert is needed and they are very rare, these days.

Doug

 

[MyCuff]

Well ,I'm travelling to Oregon this summer. The QRX restore shop is only like 30 minutes away from Corvallis. Too bad I can't take the QRX as a carry-on. Anybody ever send one with them as luggage? Seems like it would more dangerous than shipping.

The CD-4 demod seller specifically says he is unable to test, which I believe. No way will he guarantee it.

 

[Doug G.]

There is no way I would leave a piece of equipment in the hands of airline baggage handlers.

If the seller cannot guarantee function, he should agree to paying for return shipment if it doesn't work and you want to return it. There is no way you should be out any money, at all, if it's defective.

I have talked sellers into paying return for a defective product even when they state "buyer pays return shipping". Ethically, there is just no way the buyer should be out any money if something doesn't work, unless the seller specifically says the item is defective. Then, as a buyer, you take your own chance.

Doug

 

[gvl_guy]

Is it the demodulator in your receiver that's bad? The QRX Restore was really nice working with me and my Sansui, walking this non-techie guy through some things and, if needed, I could have just sent the demodulator board to them. Unfortunately, I blew out something else after I opened it up and had to send the entire unit back. (Turned out to be a fuse. ) But they fixed the demodulator (replacing some resistors) and I'm back in Quadradisc action!

 

[MyCuff]

Actually, As I recall, I sent them the demodulator board. Was it separate from the phono board? If so, I pulled out and sent both boards back in 2016-2107 time frame, and both boards tested good. They also did the full restore in 2015. I have faith in their work, but I think it's not the actual board but some sort of connection issue. I don't relish the idea of shipping the entire unit across country and back again. I greatly prefer the sound of the music hall phono preamp over the integrated phono preamp, for both stereo and quad, but that may be because there is just something not quite right about the phono section in general. If using the onboard phono, the right side is always weaker, and the VU meters objectively confirm what I subjectively hear. The demodulator does work. I can play CD-4 LPs and get 4 discrete channels, and I feel like I dialed it in correctly using the Sansui CD-4 test record. It just does not sound that good.

 

[jupp369]

I bought a new old stock JVC about a year ago. When I received it in the mail, it would not turn on. I gave it to a local stereo store to repair it. They recapped it and said it needed a few new relays. It really hasn't been right, I'm not getting great CD4 out of it. I used the one in my receiver now. So just be careful, New Old stock might not be the way to go. The shop told me you really need a unit that has been powered on a few times and it's lifetime.

The JVC 54x6 have only 1 Relay for the speakers: it get's dirty, has to be cleaned with fine sandpaper. And it get's weak, need a slight adjust. Changing is nearly impossible.
But all the capacitors from 50uF up needs to be changed except the both big power (>6800uF), without any problems, easy to reach. The are leaking, see the brown sauce at their bottoms. ... and change the lamps to LED.
Than you got a good working amplifier, like new!

You can also add a new In / Out just behind the RIAA for recording and playback CD4 from DVD. Works good and saves your vinyl.

 

[gvl_guy]

The JVC 54x6 have only 1 Relay for the speakers: it get's dirty, has to be cleaned with fine sandpaper. And it get's weak, need a slight adjust. Changing is nearly impossible.
But all the capacitors from 50uF up needs to be changed except the both big power (>6800uF), without any problems, easy to reach. The are leaking, see the brown sauce at their bottoms. ... and change the lamps to LED.
Than you got a good working amplifier, like new!

You can also add a new In / Out just behind the RIAA for recording and playback CD4 from DVD. Works good and saves your vinyl.

Actually, it was the JVC 4DD-5, so speakers shouldn't be any issue.

 

[Soundfield]

I saw a JVC CD4-1 Demodulator on eBay today and was struck by something I’d not noticed on a demodulator before. On the rear panel it has this switch and socket for the 4CH “RADAR” (Always thought that was a particularly stupid term, but anyway….)

What is it for? There are two possibilities I guess. 1 – it sends the signal to an external indicator rather than to the front panel lamp, or 2 – it displays the signal from another demodulator rather than its own. But either option seems entirely pointless.
I could only find the Japanese user manual and so its explanation is rather lost on me unfortunately. An accompanying diagram shows the socket connecting to a JVC 4AD-10 unit, but I can find no references to such a unit on line so I’m none the wiser.
Any ideas?

 

[Owen Smith]

Maybe it's a trigger output so the curtains close automatically when a CD-4 plays...

 

[Doug G.]

I was going to say the JVC unit is a huge display that reads, "And we have Radar at XX:XX Am/Pm" for those who really get into the radar coming on and aren't satisfied with just a little, puny, light.

Doug

 

[par4ken]

I saw a JVC CD4-1 Demodulator on eBay today and was struck by something I’d not noticed on a demodulator before. On the rear panel it has this switch and socket for the 4CH “RADAR” (Always thought that was a particularly stupid term, but anyway….)

View attachment 70221

What is it for? There are two possibilities I guess. 1 – it sends the signal to an external indicator rather than to the front panel lamp, or 2 – it displays the signal from another demodulator rather than its own. But either option seems entirely pointless.
I could only find the Japanese user manual and so its explanation is rather lost on me unfortunately. An accompanying diagram shows the socket connecting to a JVC 4AD-10 unit, but I can find no references to such a unit on line so I’m none the wiser.
Any ideas?

The Japanese always seem to love extra "bells and whistles" even if they are rather frivolous. I could see that possibly being used in a showroom to control a larger sign indicating CD-4 operation. If used commercially say in a bar or music man DJ operation you might want to likewise indicate CD-4 via a larger display (I don't think that CD-4 was stable enough for that usage though). It could also be possibly be used as a control signal to automatically switch between the output of a matrix decoder and CD-4 demodulator. Why on earth it would have to be switched though, just leave the internal LED on!

 

[gvl_guy]

View attachment 70221

WHAT? No position for "BOTH?"

 

[surround.sound.enthusiast]

I saw a JVC CD4-1 Demodulator on eBay today and was struck by something I’d not noticed on a demodulator before. On the rear panel it has this switch and socket for the 4CH “RADAR” (Always thought that was a particularly stupid term, but anyway….)

View attachment 70221

What is it for? There are two possibilities I guess. 1 – it sends the signal to an external indicator rather than to the front panel lamp, or 2 – it displays the signal from another demodulator rather than its own. But either option seems entirely pointless.
I could only find the Japanese user manual and so its explanation is rather lost on me unfortunately. An accompanying diagram shows the socket connecting to a JVC 4AD-10 unit, but I can find no references to such a unit on line so I’m none the wiser.
Any ideas?

I've wondered about this myself. To date, the only model I've seen with this output is the Victor CD4-1. That switch and output were eliminated by the time the improved Victor CD4-10 came out, which is housed in the same size chassis. Whoa, I take that back! I just flipped through my photo collection and found that the Victor CD4-20 (maybe only about twice as tall as a JVC 4-DD5, for reference) has the switch... but not the output...

I likewise got no hits for a JVC or Victor 4AD-10. Looking at the manual as well, it functions as some sort of interface between the outboard demodulator and a console 4-channel stereo - I mean check out how they route the output from the demodulator! For that matter, check out the speaker routing too.



It looks like that socket may indeed be used to trigger the CD-4 radar on the console stereo.

 

[Soundfield]

I just flipped through my photo collection and found that the Victor CD4-20 (maybe only about twice as tall as a JVC 4-DD5, for reference) has the switch... but not the output...

Wow that seems even more useless!

 

[Wurly1]

Wow that seems even more useless!

Can it be an input to decode the "not yet standard" future quad FM that never came to be?

 

[par4ken]

Can it be an input to decode the "not yet standard" future quad FM that never came to be?

No

 

[J. PUPSTER]

Well, I have a Panasonic SE-405 and a Technics SH-400 and they are both wonderful with the SE-405 perhaps a bit better in fidelity but it's real close. I never have to readjust either one, even after changing cartridges, which I do fairly often. Sometimes, I readjust them just for the fun of it but the settings always end up being the same

Of course, the SH-400 has the capability of supporting Semi-conductor (strain gauge) cartridges and is probably the most beautiful demodulator ever made. It also has all the controls on the front so there is no moving or tipping the demodulator up or anything like that. You can also adjust the carrier levels (or separation, for that matter) on the fly for each record. The meter allows this. You will find the carrier level on any given record may be subject to changes from the outer grooves to inner.

I am currently using the SE-405 and it is just flawless when the carrier level controls are adjusted per the manual.

And "Cat Stevens Greatest Hits" sounds really good with either one.

Doug

Hey @Doug G.! (or anyone else that may have one to share?)

would you happen to have an owners manual (pdf-etc.) for the Panasonic SE-405? I recently got one in to try; and it is without the manual, also my registration to Vinyl Engine lapsed and they say they're not taking new accounts.

Thanks - The Mutt

 

[J. PUPSTER]

Hey @Doug G.! (or anyone else that may have one to share?)

would you happen to have an owners manual (pdf-etc.) for the Panasonic SE-405? I recently got one in to try; and it is without the manual, also my registration to Vinyl Engine lapsed and they say they're not taking new accounts.

Thanks - The Mutt

Someone was already kind enough to PM me the manuals - thanks again!