CD-4 - The thin line between success and failure, but still in the fight!

[edisonbaggins]

ahh.. i did that with one of my 4DD-5's, played around with some pots and it went totally goofy!

although it wasn't working properly in the first place, which is why i took it apart and started tinkering with its' innards!

lesson learned; leave the fiddling about to the experts. oh and Uncle Ernie. he's an expert at fiddling about, fiddling about!

If you weren't quoting lyrics, I'd be a bit concerned for you.

J/K

I'm definitely concerned!!!

 

[proufo]

Best not to touch it or you may never get it to work right again!

Imagine someone like xraytonyb (Tony Bevilacqua) at youtube doing a video on it.

At one point he fixed a Lafayette Quad receiver but never got to adjust the SQ decoder.

 

[audiomaster]

Just a side step in threads here from Mr. Baggins' thread here.

My latest Panasonic SE-405 (as with all my Quad gear) is hooked up with Blue Jean LC-1 cables. I consider these to be pretty good quality shielded cables. The hum is not found with my other gear, like my Surround Master v2 etc.

I'll soon record in the hum I currently have in the Pany SE-405 and post here later for folks to listen to it. As I said before, I can usually hear voices in the background if cranked up; it could very well be some kind of local Radio interference IDK.

@barfle mentioned a part called a “power supply filter capacitor”, don't know if @Sonik Wiz replaced that one in my Marantz or not? But, all three Demodulators I now own have the same type of hum: Marantz CD-400B, JVC 4DD-5 & now the Panasonic SE-405. So even if it's that “power supply filter capacitor”, and you could find old one's out of a parts Demodulator for replacement, you'd still be using really old and unreliable parts IMO. So, are these “power supply filter capacitors” available new that would work in the Demodulators?

I probably mentioned this before, but when converting some of these 70's Japanese Cd-4 LPs I have to raise the recording-in amplitude by about 12-16 dbs to get a decent level with my current cart., an AT-15S. That just raises the levels across the board for stuff like hum to come out and it's very difficult to reduce after the fact. It might take 3 passes with Noise Reduction software to quiet it down which isn't good because I believe it is taking some dynamics out of the music and mudding it up a little IMO.

One way to determine if the noise is coming thru the wiring or thru the air is to take each piece of equipment at a time and rotate it slowly 90 degrees. If this changes things, the hum is being picked up thru the air.

 

[edisonbaggins]

One way to determine if the noise is coming thru the wiring or thru the air is to take each piece of equipment at a time and rotate it slowly 90 degrees. If this changes things, the hum is being picked up thru the air.

If the hum disappears, leave the item rotated.
Might look a bit wonky, all out of whack, but the sound, baby!!!

 

[jupp369]

See page 4 of this service manual to get an idea of how complex the adjustment ("alignment") of a CD-4 demodulator is.

Circuit of 405 and 5436 shows a lot of test points - but not what to expect there:
KEEP YOUR FINGERS AWAY !

 

[Paul Pettegrove]

I had a great idea in my sleep last night ;-)

https://emf-protection.com/product/...3YFFD4TvSVTmiU4NDvZZjjk6h6ARfu9kaAr1LEALw_wcB

 

[fredblue]

I had a great idea in my sleep last night ;-)

https://emf-protection.com/product/...3YFFD4TvSVTmiU4NDvZZjjk6h6ARfu9kaAr1LEALw_wcB

i needed a fallout shelter and an asbestos blanket last night after the stupid cow out the back started making toast at 3am and nearly burned the place down!

ahh.. a chorus of interlinked smoke alarms is just the thing to perk you up in the middle of the night.. i shouldn't whinge, those little alarms save lives.

 

[J. PUPSTER]

i needed a fallout shelter and an asbestos blanket last night after the stupid cow out the back started making toast at 3am and nearly burned the place down!

ahh.. a chorus of interlinked smoke alarms is just the thing to perk you up in the middle of the night.. i shouldn't whinge, those little alarms save lives.

Hey, who needs sleep ‘round here anyway, it’s close to 3am here and I’m posting up instead.

Is there even the smallest chance that the old power cord of the Demod. is acting as an antenna somehow; aren’t Bose radios set up with an antenna in their power cord?

 

[Sonik Wiz]

Hey, who needs sleep ‘round here anyway, it’s close to 3am here and I’m posting up instead.

Is there even the smallest chance that the old power cord of the Demod. is acting as an antenna somehow; aren’t Bose radios set up with an antenna in their power cord?

Any RFI picked up by the power cord would be 100% filtered out by the power supply components.

 

[Paul Pettegrove]

I found myself wondering... but the internet says it is possible . . .

 

[Sonik Wiz]

Is there even the smallest chance that the old power cord of the Demod. is acting as an antenna somehow; aren’t Bose radios set up with an antenna in their power cord?

I still tend to think it boils down to ground gremlins & hopefully will be solved. But your earlier post gave me some good food for thought while at a couple of soccer games today. To the mentioned buzzy dimmers & other suggestions I'll add: ham & CB radio XMTR's.

With either one a faulty antenna cable or actual problems inside the XMTR or a CB radio with a big linear power amp to boost way over the allowed 5 watt limit, these could all be problems.

When ham & CB radios were at their peak these problems were pretty common. Then radio gear improved, and audio gear with better design reduced this. But of course now your back to dealing with 70's vintage stuff that doesn't have that benefit.

So I'd suggest checking out your neighborhood for TV like ham antennas & whip antennas were popular even for home CB operations. Maybe your HOA doesn't allow these installations but I'll point out that our own hobie1dog lives in a condo & still manages a clandestine antenna set up as he's a licensed ham operator.

The ARRL also says in checking RFI or problems from power line XFMR's going bad, walk around the neighborhood with a portable AM radio. Tune to a dead spot & listen for noise that comes & goes but seems strongest in a particular spot. Gives you a clue where the source of the problem might be.

 

[J. PUPSTER]

I still tend to think it boils down to ground gremlins & hopefully will be solved. But your earlier post gave me some good food for thought while at a couple of soccer games today. To the mentioned buzzy dimmers & other suggestions I'll add: ham & CB radio XMTR's.

With either one a faulty antenna cable or actual problems inside the XMTR or a CB radio with a big linear power amp to boost way over the allowed 5 watt limit, these could all be problems.

When ham & CB radios were at their peak these problems were pretty common. Then radio gear improved, and audio gear with better design reduced this. But of course now your back to dealing with 70's vintage stuff that doesn't have that benefit.

So I'd suggest checking out your neighborhood for TV like ham antennas & whip antennas were popular even for home CB operations. Maybe your HOA doesn't allow these installations but I'll point out that our own hobie1dog lives in a condo & still manages a clandestine antenna set up as he's a licensed ham operator.

The ARRL also says in checking RFI or problems from power line XFMR's going bad, walk around the neighborhood with a portable AM radio. Tune to a dead spot & listen for noise that comes & goes but seems strongest in a particular spot. Gives you a clue where the source of the problem might be.

I've also thought, if it's possible to filter out most of the actual hum from a sample I'll be Uploading soon; leaving the buried voices in the audio and boosting those. That way, I can listen for what's being said and it may be an indicator I'll recognize for where it's coming from (cable/DSL/radio/etc.)

 

[Sonik Wiz]

I've also thought, if it's possible to filter out most of the actual hum from a sample I'll be Uploading soon; leaving the buried voices in the audio and boosting those. That way, I can listen for what's being said and it may be an indicator I'll recognize for where it's coming from (cable/DSL/radio/etc.)

Pulling unknown voices out of the ether. This could be getting into Twilight Zone territory. I mean, what if you can understand the voices and it's someone you know who is dead?

Speaking of ham radio & voices from beyond, wasn't there a film that combined these both? Oh yeah:

 

[par4ken]

I haven't had that sort of (intererance) problem for quite awhile. Back in the day I used to have trouble with pickup of the local AM radio station whose tower was located just across the road. Poor shielding, grounding etc. all affected it. It even came in through the phone line, my father's medical alert system would not even work because of it. Just touching the input to an amplifier you would hear a hum plus the local AM radio station!

At one time I even made a crystal radio by connecting a germanium diode in series with an antenna wire to a speaker with the other side connected to ground. It sounded good and was fairly loud!

I found that RF interference was much less of a problem using better equipment. I had to stop using my Sinclair Project 60 preamplifier when the CBC began testing their new FM transmitters. The test tone came blasting through the speakers.

I also remember CB radio blasting through peoples TV and/or stereo speakers.

The old TV's vertical oscillator used to interfere with my then favourite AM radio station, 630 CKRC. 15750 Hz x40 = 630 Khz. It could also effect CD-4 (x2 is close to 30Khz). The setup manuals usually recommended keeping the turntable and demodulator away from TV sets. The Ortofon preamp has a switch for CD4 that applies filtering to help reduce such interference problems.

If you suspect that interference is coming in through the power line place one or more ferrite beads around the power cable.

Today all our digital equipment emitts broadband noise. For me AM radio reception is no longer possible at home. Thankfully I have no problem with CD-4!

 

[Sonik Wiz]

Today all our digital equipment emitts broadband noise. For me AM radio reception is no longer possible at home. Thankfully I have no problem with CD-4!

Well that's how it goes when you literally live on "Transmitter Road"!

 

[Sonik Wiz]

Hey Jeff
The more I think about @par4ken suggestion to use power cord ferrite noise suppressors, the more I like it. Dunno if it's a guaranteed fix but it's cheap and easy to try. The power cord on the Marantz & Panasonic is a little on the small side. So rather than trying to find a perfect fit I see Amazon has kits of wide range of sizes.

https://www.amazon.com/s?k=ferrite+...rrite+core,aps,153&ref=nb_sb_ss_ts-doa-p_7_12
It would also be good to put these ferrite filters on as many pieces of gear that you can. And also you can put more than one on a power cord for increased attenuation.

 

[J. PUPSTER]

Hey Jeff
The more I think about @par4ken suggestion to use power cord ferrite noise suppressors, the more I like it. Dunno if it's a guaranteed fix but it's cheap and easy to try. The power cord on the Marantz & Panasonic is a little on the small side. So rather than trying to find a perfect fit I see Amazon has kits of wide range of sizes.

https://www.amazon.com/s?k=ferrite+...rrite+core,aps,153&ref=nb_sb_ss_ts-doa-p_7_12
It would also be good to put these ferrite filters on as many pieces of gear that you can. And also you can put more than one on a power cord for increased attenuation.

Thanks, at this point I'll try just about anything - is out!!!

 

[J. PUPSTER]

Hey Jeff
The more I think about @par4ken suggestion to use power cord ferrite noise suppressors, the more I like it. Dunno if it's a guaranteed fix but it's cheap and easy to try. The power cord on the Marantz & Panasonic is a little on the small side. So rather than trying to find a perfect fit I see Amazon has kits of wide range of sizes.

https://www.amazon.com/s?k=ferrite+...rrite+core,aps,153&ref=nb_sb_ss_ts-doa-p_7_12
It would also be good to put these ferrite filters on as many pieces of gear that you can. And also you can put more than one on a power cord for increased attenuation.

I notice a lot of gear in my Quad/computer room has little clamp-ons like these on their power cords- i.e. Monitors, NUC, Involve gear etc.; is that what those are also?

 

[Sonik Wiz]

I notice a lot of gear in my Quad/computer room has little clamp-ons like these on their power cords- i.e. Monitors, NUC, Involve gear etc.; is that what those are also?

Yup. Those came to popular use as switching power supply's & other digital stuff became potential emitters of noise & RFI. In fact if you look at a lot of digital stuff you will find a notice that goes something like;" This unit conforms to the requirements of FCC Part 15." Now this is interesting because Part 15 is an old regulation, pertaining to the strength of low power transmitters, like CB walkie talkies!! Again I don't think your CD-4 power lines are acting like an antenna but there still may be some power line noise that the ferrite filters might reduce.

 

[J. PUPSTER]

Here's a couple of attached files (CD-4 Quad pre-needle drop) of the hum for folks to check out. I boosted them about +20dbs already.

Pany SE-405 & Marantz CD-400B

The vocals are actually much more buried into this than I remember; but I do believe they are there (I'm not on any prescriptions for my mental state AFAIK )

Let me know if I'm hearing things please?