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Author Topic: Commodore 1081 PAL screen jitter oddity  (Read 1286 times)

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Offline AF-Domains.netTopic starter

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Commodore 1081 PAL screen jitter oddity
« on: September 14, 2011, 10:43:36 PM »
Greetings,

Not entirely sure whether this is down to a possible fault that was fixed in a later design or not..

While using the 1081 to watch a PAL DVD (widescreen format usually), the screen will jitter intermittently vertically.

Unable to provide any photos at this time that may help describe this.

This does not surface when viewing NTSC DVDs.

This oddity does not seem to surface at all on a spare 1084s.

Anyone else encountered anything like this?

What could be a possible cause?
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Offline save2600

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #1 on: September 15, 2011, 12:11:54 AM »
My various model 1084's and 1084s's ALL produce a consistent high-speed jitter when viewing PAL on the 60hz American electrical grid. Are you referring to this natural phenomenon?
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Offline AF-Domains.netTopic starter

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #2 on: September 15, 2011, 12:24:03 AM »
Greetings,

I probably should've clarified there.

I'm located in the UK, 50Hz here.
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Offline AF-Domains.netTopic starter

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #3 on: November 11, 2011, 05:23:39 AM »
Although it has been a while, still haven't been able to find a possible cause as of yet.

I've however attached a photograph to display what occurs.

I apologise if my general terminology was completely off.
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Offline Zac67

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #4 on: November 11, 2011, 07:31:04 AM »
You've checked v-hold, haven't you?
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Offline CritAnime

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #5 on: November 11, 2011, 08:55:26 AM »
I have seen something like this before. I dunno if its the same thing but When I tried watching some DVD's on my PC I got serious interlacing issues which was fixed after altering some settings in Video Lan. Which produced an effect much like yours. Now I don't know how to remedy this for you. But it might be a potential cause of this. So I would check to see what the settings are.

Just a suggestion.
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Offline AF-Domains.netTopic starter

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #6 on: November 11, 2011, 03:10:46 PM »
Greetings,

I've checked the V-Hold, that appears to be set correctly.

This also tends to be intermittent.

The image is stable during certain scenes, while appearing to almost roll vertically on others.

I have a 1084S that doesn't seem to be afflicted by this, though it's currently in for repair.
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Offline Framiga

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #7 on: November 11, 2011, 03:43:05 PM »
if you have already tried playing a bit with the "V-Height" knob in the rear panel, probably is the analogic DVD copy protection that makes some old monitors (in need for some face lifting), acting like yours.
« Last Edit: November 11, 2011, 03:48:11 PM by Framiga »
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Offline Zac67

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #8 on: November 11, 2011, 06:12:41 PM »
Yes, that Macrovision crap may well be a problem... There are video stabilizers that'll remove the problem. Bought a "Video Boy" switcher+stabilizer years ago for some 5€ or so.
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Offline AF-Domains.netTopic starter

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #9 on: November 12, 2011, 12:13:53 AM »
At the present time, the DVD player is connected to the 1081 using the Scart socket (RGB mode rather than CVBS, on the faint chance there'd be some improvement), no change to the vertical frame roll.

Regarding a video stabilizer, will attempt to get ahold of one to see if that does the job.

With any luck it does.

More or less out of ideas as to what else could be done, short of replacing the monitor entirely.
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Offline AF-Domains.netTopic starter

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Re: Commodore 1081 PAL screen jitter oddity
« Reply #10 on: November 12, 2011, 05:38:10 PM »
Unfortunately, a video stabilizer had no noticeable effect.

Was hooked up correctly, but still the same picture jump effect on PAL depending on the scene.
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