JVC 4dd-5 for total newbies!

[captainwrong]

Started this earlier topic, but after taking the thing out of the box, some of the calibration information makes sence.

However, I do have a specific problem. The Radar light stays on all the time, even when I'm not playing a record. Is that normal?

It sounds like I'm not getting any front/back seperation, either. Is trying to set this up with out a test record going to be an excercise in futility?

This thing is confusing the heck outta me.

 

[sqdave1975]

The CD-4 radar light should only come on, and stay on, when a CD-4 carrier signal is present. Try unplugging all of your audio cables and powering it it up. If the light is still always on, we may have a bit of an internal problem. Whilst rotating the separation pots you should clearly be hearing the separation come and go. It's not strictly necessary to use a test record when setting up your demodulator. I think quite a few people just use a good CD-4 record instead.

 

[captainwrong]

The radar problem seems to be with my table. Specifically the right channel. When I unplug the right, the light goes off. Plug it back it, and there it is.

I thought maybe the cartredge was doing something funky, so I hooked everything up with the cart off and still got the problem.

Oddly enough, switching the cables so they're going in the opposite input also cures the problem.

I'm not sure what could be coming from my turntable with no signal and the cartredge removed that would trigger this in the right channel. Any thoughts?

 

[sqdave1975]

What a bizarre fault ! I'm stuck! I'm sure you're satisfied that the turntable is performing perfectly i.e. you've checked the continuity of the cables running from the tonearm right up to the RCA jacks and is the grounding wire OK?

I was always under the impression that only audio signals in the ultrasonic frequency range (upwards of 30kHz) would cause the demodulator's circuitry to kick in.

No television sets, computer monitors or other such like switched on nearby ?

I'm not totally familiar with the 4DD-5, but a friend has one. For a laugh, we extended the output leads of his turntable with a cheapo 3 metre phono cable just to see what would happen - remarkably it still worked reasonably well, considering that the cable length from turntable to demod was now almost 5 metres long.

I just can't think what can be causing your problem - any other thoughts, guys ?

 

[captainwrong]

I think I figured out the problem and it is with the turntable. There's something screwed up with the grounding in the table it self. It grounds well enough for stereo playback but when I switch it over to 4ch, it's playing havoc with the subcarrier loop. With the table open, if I touch the screw is connecting the grounding cable, the radar light goes off. I'm not sure what the deal is and I can't find anywhere else to ground it that will solve this problem.

I tried everything with my other table which is on it's last leg and sure enough it worked fine.

Not too big a deal. It's a cheap-o Pioneer I've been looking for an excuse to replace for a long time.

 

[The Quadfather]

Interesting problem. Possibly something with the turntable causing the preamp to break into oscillation. That would do it if the oscillation was around 30KHZ. If you know it's the table, and you hate it anyway, get another table!

The Quadfather

 

[captainwrong]

Yeah, it was making a terrible noise as well. I though maybe the 4DD-5 was broken, but flipping to 2ch took the noise away. When I touched the gorunding in the turntable, the noise was gone.

Now I gotta find a decent table without breaking the bank. Ahh well.

 

[QEight]

Look for a Pioneer PL-530 Turntable. Oddly enough, it is almost exactly the same as a Marantz turntable (model number escapes me at the moment).

Plus, they can be found fairly cheaply. I scored mine for $22 off ebay and with a little cleanup and a new cartridge/stylus I was rockin' and rollin' ! :rollin:

 

[The Quadfather]

I use a Marantz 6300. Very nice solid piece of gear. It's direct drive and I understand that audiophiles don't like that. But, who cares what they think. I love it.

The Quadfather

 

[sqdave1975]

I know what you mean about purists moaning about direct drive turntables. I use a Technics SL-1210 Mk.II, primarily due to the sheer amount of adjustments available, it's so easy to set up for CD-4, etc. Plus I have a variety of cartridges and the rugged arm makes frequent changes a breeze.
Technics worked very hard to engineer this turntable. Wow and flutter, which frequently plagues DD turntables is almost completely absent on the 1210. Wow and flutter 0.01% WRNMS, rumble -78dB (DIN B)
This is probably due to Technics' unique motor design, in which the platter itself actually forms part of the motor. Only the driver coils remain in the TT when the platter is removed. I still find it hard to believe that you can buy it in London for £300 ($489). Worth every penney. I've had mine for 2 years, a friend 7 years, without a single problem. They still look like new. Such a beautful design. I couldn't live without mine.
They have one on permanent exhibit in the Science Museum in London.

 

[captainwrong]

Thanks for the suggestions. Keep em coming!

Yeah, the whole direct vs. belt drive thing is kinda silly. If the table is made well, I think you're going to get good performance anyway. Anything would be better than the BSR Minichanger that was my frist table. :rollin:

 

[The Quadfather]

BSR eh? I don't think my first turntable was even that good!

The Quadfather

 

[captainwrong]

Update, to those of you playing along at home...

I got a "new" turntable (actually a old Yamaha, but new to me) and it came with some funky AT cart I can't find any info about (HB100 Mk II, anyone???) Lo and behold, it works! Kind of. Can't seem to get the calibration right.

So I'm thinking maybe it's the cart. I change to the Grado Red I was using before (saw somene else mention using a Blue with a CD-4 setup and I happened to have one anyway) and I get the problem with the radar light AGAIN! Grrr!

Well, by some strange luck, I notice my Sony SACD/DVD (which is in my stereo rack) is in standby mode rather than being turned off. As soon as I turn it off, the radar light goes off! Huzzah!!!

So let this be a lesson, if you're trying to use a CD-4 demod and a Grado cart, be sure you don't have the DVD player in standby! Now if I could get the thing calibrated...

 

[ranzy]

So, this means that the first turntable is OK then? Right?

Ranzy

 

[captainwrong]

Naah, the first TT is still a POS :rollin:

Seriously tho, I checked that table with the cart off and was still having the problem. I'm completely at a loss as to what was going on with it. I can say this, there was a problem with my old turntable. I just haven't the slightest as to what it was.

 

[cam i am]

i read that you use a marantz 6300. i have just been given one myself when my wife was cleaning out her parents storage place. i am amazed with the quality. i am trying to find out all i can about this fine machine, and and info you would like to share would be helpful. oh, excuse the stupid questions, but what's the problem with direct drive?

-c-

 

[The Quadfather]

Supposedly belt drive isolates motor noise better than a direct drive table. However, since the motor turns at the rate of the turntable on a direct drive, and there are no brushes, there is not a problem with noise on a direct drive table. I have never experienced motor noise.

The Quadfather

 

[radioheadrox]

Personally, I think direct drive turntables are wonderful. On mine, I have never heard any motor noise at all. In fact, my other turntable (that is belt-drive) has an large amount of hum caused from the motor that gets picked up by the stylus.

 

[Quadwreck]

I think that the idea that a belt drive turntable is quieter is a myth. If you stretch a rubber band, which is essentially what a turntable belt is, it conducts vibrations much like a string on a musical instrument, right to the platter, which is conducted to the stylus in play. A direct drive motor consists of heavier, more sound-dampening pieces that are separated by a larger magnetic field. They are a definite improvement.

 

[The Quadfather]

Hey Cam Iam:
I have a service manual for my Marantz 6300. I got it from W7FG Vintage Manuals ( [email protected] ) . It tells all about how to set up the turntable and includes a schematic diagram and exploded view diagram. It also has a parts list. It's a great piece of gear, you'll enjoy it very much. It's one of the very few turntables I've seen that allows a pivot heigth adjustment. Fact is, just about everything is adjustable. The great thing is I got this fine piece of gear on a trade! I got rid of some old junk and got this great turntable! That's even better than when I paid 15 bucks for my JVC 4DD5 CD-4 Demodulator in an Alabama flea market. What next? a box full of Tates at a garage sale for five dollars?! I'll have that QSD-1 too! Oops, sorry about that, I just lapsed into a happy daydream! Oh well, Email that guy and get him to send you a manual. It'll tell you everything you want to know about your Marantz 6300.

The Quadfather