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1019 Ground issue

Posted: 14 Jun 2019 20:31
by Solist
I think Ive been chasing the wrong issue for a while now.

The problem was that the right channel from time to time started to occasionally distort and cut out.

I though the problem was in the headshell contacts, but today I have noticed that if I set the needle on the record and play everything works fine. The moment the tonearm returns to the rest position the distortion happens. It did not do that before.

I tapped on the top plate and tonearm and its a ground issue. The turntable has no ground cable, and it worked perfectly before.

Any ideas what could be going wrong? Will have a look tomorrow, its already dark where I live.

Re: 1019 Ground issue

Posted: 14 Jun 2019 20:45
by Japi Roelofs
I had a similar problem with a 1019 once. But that was more of a crackling and buzzing sound whenever I touched the headshell.

Someone here on the forum suggested this: the tonearm is grounded to the chassis through its bearings. If the bearing balls or bearing housing are corroded it could cause intermittent loss of contact.

I solved the problem by attaching an additional ground wire to the headshell. Worth a try?

Re: 1019 Ground issue

Posted: 14 Jun 2019 20:55
by Solist
Thanks! Will try, but I dont think that the tonearm bearings are corroded. Cant know for sure until I open them up.

I have tried again, I did not touch anything, and the right channel did not distort when the tonearm was on the rest. This time, the right channel sounded fine, but the left channel had only 50% sound. As soon as I hit the stop button the left channel went to 100% volume until the mechanical link cut the volume. When the tonearm returned to the rest position the right channel started to distort again.

Maybe the tonearm wires? Will try to also check the connectors on the tonearm. Are those held in place only with that 1 string?

Re: 1019 Ground issue

Posted: 14 Jun 2019 21:57
by josephazannieri
Yo Solist:

The 1019 has a muting switch. It is possible that your muting switch is either misaligned or loose, so it is not working properly, and allowing shorts to appear randomly in the signal wires. check to be sure that the muting switch is working properly. I had a Dual 1010 for many years, and I base my conjecture on my experiences with that unit. You could put a cheap DVM across the problem RCA and see if you are getting shorts across between the center pin and the outer ring. Depending on the cartridge, a properly wired cartridge should come in between a high of 1300 ohms and a low of about 800 ohms, and both sides should measure very close, and measurement should be steady.

And good luck from the old best-guesser,

Joe Z.

Re: 1019 Ground issue

Posted: 14 Jun 2019 23:07
by mrow2
You would not know if tonearm bearings are making intermittent contact. Not necessary to disassemble tonearm as long as it performs well tracking-wise). Best answer is to touch all bases
(old Amer baseball term) and tend to multiple possibilities like direct grounding of the tonearm, thorough cleaning of the mute switch, excellent contacts everywhere, proper skid positions etc. Note there are just a small number (what is it, 5 or 6 wires maybe?) in the cartridge connector wires/clips, and these become unreliable as they collect tarnish. As they wear, they become 3 or 4 strands, or just hanging on by a dodgy copper strand or two (possible meaning of "bent constable" in UK; not what I mean here #-o ). Also looking at the resistance of the circuit from the RCA ends to the cartridge clips (must use alligator clips for reliable readings, no other way) should reveal is there is a spotty connection issue in the wires. I always seem to get around 2Ω to 3Ω with meter set to the lower scale and no cartridge coil included, as acceptable readings. And with an intermittent problem, you might not catch it on the meter test. These are always troublesome areas, but once everything is clean, it's pretty reliable.

I think L & R cartridge coil resistance readings tend to be about 500Ω to 1,450Ω depending on cartridge brand and model, and like Joe Z says, both sides should be reasonably close (± 3%-7% or so, seems like).

Re: 1019 Ground issue

Posted: 15 Jun 2019 10:59
by Solist
I think I have found the problem. I checked all the connections from the turntable to the amp, and I have noticed that one of the input rca jacks on the phono stage was slightly loose. I opened the case and tightened it. It was probably loose enough to cause a ground issue. Upon tightening it, it seems to be working, for now :D

PS: and it does not work anymore #-o

There is a crackling sound when moving the tonearm I did not notice before.

So, any tips on opening and polishing the tonearm bearings?

Re: 1019 Ground issue

Posted: 15 Jun 2019 13:10
by Solist
I have checked the pictures on the dualcan site, so it gave me an idea of how to repair the tonearm.

One more thing I cant seem to find information, is how is the nylon piece attached to the tonearm:
1dual.jpg
(15.6 KiB) Downloaded 91 times
Are those tonearm wires wrapped around the plastic piece or are there just to hold the plastic in place? I tried using a mirror but Its hard to see where they lead.

Re: 1019 Ground issue

Posted: 15 Jun 2019 17:06
by mrow2
I would start with basics like you did with the plug. For one thing, the contacts in the headshell are still tarnished, why? Silver cleaner then isopropyl rinse, no sanding. Is that wire bare? I have forgotten. You might be on the right path with that. But look at all that tarnish! Needs to be perfect.

I still would not remove the arm until there is no other choice.

Re: 1019 Ground issue

Posted: 15 Jun 2019 17:51
by Solist
Its a photo I took from the internet. Mine are clean. But I checked with the mirror, and there is still some tarnish on the contacts but its under that plastic, so I need to take it off somehow.

I tried to use a separate wire, to ground the tonearm, but it makes no difference.

I am cleaning now the cartridge pins and plugs, we will see how it goes.

Agree, I would like to keep this repair as simple as possible.

Re: 1019 Ground issue

Posted: 15 Jun 2019 21:10
by mrow2
OK, sounds like the right plan. Anxious to hear progress. D

Re: 1019 Ground issue

Posted: 16 Jun 2019 15:47
by Solist
Found the problem. As usually my stupidity played a role in it.

The last time I did a full service, I was left with 1 screw which, I had no idea where to put it.

Turned out it was a quite important one. It was located on the muting switch mechanism and as far as i understand it was supposed to hold the ground post to the top plate.
1a.jpg
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Since there was only 1 screw, the whole muting switch rotated slightly every time the auto mechanism was deployed causing ground issues. Since I was there, I also cleaned the muting switches, and now it works like a charm!

Re: 1019 Ground issue

Posted: 16 Jun 2019 17:10
by Solist
josephazannieri wrote:
14 Jun 2019 21:57
Yo Solist:

The 1019 has a muting switch. It is possible that your muting switch is either misaligned or loose, so it is not working properly, and allowing shorts to appear randomly in the signal wires. check to be sure that the muting switch is working properly. I had a Dual 1010 for many years, and I base my conjecture on my experiences with that unit. You could put a cheap DVM across the problem RCA and see if you are getting shorts across between the center pin and the outer ring. Depending on the cartridge, a properly wired cartridge should come in between a high of 1300 ohms and a low of about 800 ohms, and both sides should measure very close, and measurement should be steady.

And good luck from the old best-guesser,

Joe Z.
I wish I have tried this earlier, you were right. I owe you a big one.

Re: 1019 Ground issue

Posted: 16 Jun 2019 18:13
by mrow2
Congratulations, and very good perseverance!! Am glad you did not need to disassemble the tonearm. ~ Don

Re: 1019 Ground issue

Posted: 16 Jun 2019 18:29
by Solist
Thank you! I was so relieved when I found out, I did not have to disassemble the whole tonearm. I have no idea how I would manage to put those preloaded bearings back together.

Its hard to describe how nice it felt listening to records again without worrying when the distortion would kick in \:D/