BlackDuck

I have an LG V8824W video tape recorder that when a tape is put in and played the audio is soft and it makes a popping/clicking noise for about 5 seconds until the message, Playing. Auto tracking. disappears.

Then frequently the picture gets white lines and the Auto tracking message reappears and the picture stabilises for a while.

Is there some adjustment I can make to eliminate this problem?.

Thanks,
Duck.

__________________
The one absolutely certain way of bringing this nation to ruin, or preventing all possibility of its continuing as a nation at all, would be to permit it to become a tangle of squabbling nationalities. Theodore Roosevelt

At any given time, roughly 50 per cent of the Australian electorate are morons.

dashinson

I've had to replace the pinch roller on a couple of these.
open it up and with the tape running check to see if the tape is creeping up or down on the capstan spindle, and also check the back tension brake assembly



Dash.

BlackDuck

Thanks for the response Dash,

The pinch roller, capstan and the tensioner are all OK, It seems to be something to do with Auto tracking.

When you look down onto the drive system there is a vertical post that looks like a tape head reader, it's at the right of the drum, this has 3 adjusting screws for alignment and if i move it by hand it causes the problem and the M/C has to track again to stabilise the picture.

Duck.

__________________
The one absolutely certain way of bringing this nation to ruin, or preventing all possibility of its continuing as a nation at all, would be to permit it to become a tangle of squabbling nationalities. Theodore Roosevelt

At any given time, roughly 50 per cent of the Australian electorate are morons.

Bibliophile

I agree with dashinson. Sometimes you can get away with just cleaning it. Have a look and if it's shiny, almost glass like, try giving it a good clean with acetone. If it wont all come off, try rubbing it with a Scotchbrite scourer and then clean it again. Be sure to rotate it while you are doing both operations (with the power off of course) so the whole surface is treated.

Bibliophile

Sorry, last post was a bit late.
I would not adjust the audio/control head unless you have a very good reason as it will affect audio playback quality, control track recovery, tracking and interchangeability with other machines. You really need an alignment tape to do it properly. If, as you say, it comes good after a bit, something is causing the tape to move up or down as it moves across the A/C head and the most likely cause is the pinch roller or back tension band.

BlackDuck

Hells bells Booklover,
When I first read this post I thought it sounded painful and somewhat obscene, then I realised that you were refering to the capstan.
I think you're on the money here bibliophile, I suspect that this is where the problem is, control track recovery and tracking. as the tape is not missaligning on the head as it runs.

The picture stabilises for about 10 seconds and then gets white lines again and the audio gets softer, then it autotracks again, just keeps repeating this cycle. so from what you've said I need to get hold of an alignment tape.

__________________
The one absolutely certain way of bringing this nation to ruin, or preventing all possibility of its continuing as a nation at all, would be to permit it to become a tangle of squabbling nationalities. Theodore Roosevelt

At any given time, roughly 50 per cent of the Australian electorate are morons.

Bibliophile

Try running your fingernail up and down the A/C head from top to bottom. If you can feel a "step" then you've got a worn head which could be causing control track problems.
Just to explain the symptoms, the lines in the picture and the pop sounds in the audio are the result of low RF signal from the video heads, possibly caused by a tracking error. The audio becoming softer is probably caused by the machine losing the HiFi signal and reverting to the linear audio track.Your rocking of the A/C head is actually shifting the control track phase.
The auto tracking works by phase shifting the control track pulse while looking at the peak value of the recovered RF signal from the video heads.
If it can't find a peak or it's too low, it just keeps on trying.
This could be caused by dirty or worn video heads.

BlackDuck

Checked the head as you suggested and couldn't find any ridge or step, seems quite smooth.

__________________
The one absolutely certain way of bringing this nation to ruin, or preventing all possibility of its continuing as a nation at all, would be to permit it to become a tangle of squabbling nationalities. Theodore Roosevelt

At any given time, roughly 50 per cent of the Australian electorate are morons.

Bibliophile

I have edited my previous post with more information while you were posting yours.

dashinson

On the pinch roller assemblies I have replaced its been the bearing inside the pinch roller that has failed!

Dash.

Bibliophile

That's a good point dash.
Worn bearings would cause a cyclic speed variation that could give similar problems.
Was there any 'wow' evident in the audio?
But, of course, if it didn't drop out of HiFi there wouldn't be.

BlackDuck

I've cleaned the heads several times to no avail.
As I said earlier, I think you're on the money with the A/C head and Phase shifting as I've had a feeling that the M/C electronics are trying to correct some error in signal alignment/reading/tracking or similar.

The heads look good but this means nothing.

The person who gave me the machine said that it's only a few years old and had little use, It just didn't work any more.

When I took the cover off I found that the power board had been broken by someone pressing down on it, this was easy to fix by soldering a bridge across the broken tracks.

As the machine owes me nothing it will be no real loss if I can't get it working, but it would have been handy in the guest room as there is no satellite connection there.

again Bibliophile and dashinson,
thanks for the help and ideas,
Duck.

__________________
The one absolutely certain way of bringing this nation to ruin, or preventing all possibility of its continuing as a nation at all, would be to permit it to become a tangle of squabbling nationalities. Theodore Roosevelt

At any given time, roughly 50 per cent of the Australian electorate are morons.

mate

hey blackduck, a non technical aspect. is it more than one tape that gets the effect?

__________________
i suppose i'm just not bogan enough

mandc

Thinking the same thing. The ferric oxide coating comes detached from the backing as the tape ages (or is cheap crap) so the heads only last a short time before the muffled audio kicks in.
Used to happen all the time on my old cassette deck with old dodgy tapes. From memory the audio head is a separate part from the helical scan head unless its Hifi...not sure about this though.

Fernbay

Sounds like a worn ACE head.

If I remember correctly, they are not avalible as such. They come as an intergrated part of the main deck assy.

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"What you lose on the hurdy-gurdy you pick up on the roundabout"

BlackDuck

Problem occurs on all tapes, old or new, but seems worse on tapes recorded on a mono machine.
The problem is something to do with auto tracking, as the sound is low and muzzy until the Auto Tracking message appears on the screen, then the sound and picture become clear.

As I don't know the working principle of the auto tracking system it makes it a bit of "Hit and Miss" to try to work out how to adjust it.

__________________
The one absolutely certain way of bringing this nation to ruin, or preventing all possibility of its continuing as a nation at all, would be to permit it to become a tangle of squabbling nationalities. Theodore Roosevelt

At any given time, roughly 50 per cent of the Australian electorate are morons.

Fernbay

Trust me - The ACE head - (Audio / Control head) - In LG's they are built on the brink

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P.M. me for the Selectv Card Only Austech member deal. $39 inc post with 1 month FREE! Or $29 for Premium Members for a short time only.

FS:- DM518s - $120 , DM500 2A PSU - $15, DM800HD - $360 (limited stock)
PM for details



"What you lose on the hurdy-gurdy you pick up on the roundabout"

moeee

If you are familiar with what the CTL head is, then watch the tape as it rides across it.
The tape should not be drifting up or down , but should be following the exact same path across this head.
Any vertical movement, even 1 millimetre could cause loss of ctl pulses.

BlackDuck

You're probably right Ferny, I think most of the LG stuff is on the brink when it leaves the factory.

I might seem to be a dinosaur sticking with tapes but I have 4 DVD players and only 1 will play a DVD right through, the others play about 3/4 the way through and start to jump and lock up despite cleaning the laser lens and keeping the DVD's in pristine condition.

__________________
The one absolutely certain way of bringing this nation to ruin, or preventing all possibility of its continuing as a nation at all, would be to permit it to become a tangle of squabbling nationalities. Theodore Roosevelt

At any given time, roughly 50 per cent of the Australian electorate are morons.

BlackDuck

I assume that the CTL head (ACE?), is the head about 40mil after the scanning head.

I have watched the tape transport system for any indication of missalignment or any minor deviation in the track taken by the tape, nothing seems amiss, so I'm sure that it's an electronic feedback problem.

__________________
The one absolutely certain way of bringing this nation to ruin, or preventing all possibility of its continuing as a nation at all, would be to permit it to become a tangle of squabbling nationalities. Theodore Roosevelt

At any given time, roughly 50 per cent of the Australian electorate are morons.