Get a head start on next Avanti issue - Videokarma.org TV - Video

TinCanAlley · #1 09-10-2013, 04:34 PM

Okay, after the jail bars, my next task is to find out (and fix) the tearing at the top of the screen using a VCR. One would think that using a VCR from '79 would work like a charm with a set from '74, but it doesn't. I know it's not the macrovision as it happens on tapes I've recorded for testing purposes.

The tearing is so bad at times it covers roughly the top 6" of the screen and can bend anywhere from 1" to 5" to the right side of the screen.

So now you know what's coming next.

lnx64 · #2 09-10-2013, 04:42 PM

Usually the tearing is due to tape tension in the VCR, and not the TV itself.

Something like a time base corrector will fix that I think, if you can't fix the VCR mechanically.

TinCanAlley · #3 09-10-2013, 04:45 PM

Quote:

Originally Posted by lnx64

Usually the tearing is due to tape tension in the VCR, and not the TV itself.

Something like a time base corrector will fix that I think, if you can't fix the VCR mechanically.

It doesn't happen on my other CCII or my plasma. Maybe I'm using the wrong term. The top few inches of the image bends to the right. It's not steady, so it's like watching trees bend in the wind.

lnx64 · #4 09-10-2013, 05:12 PM

Yea that's tape tension. Some TV's are better at handling that sort of thing, but not others. The plasma will definitely have a time base corrector built into it.

Not the CCII, but I bet it handles the tape tension issue better.

Trust me on this. I used to repair VHS decks, THIS is my specialty.

andy · #5 09-10-2013, 06:32 PM

...

TinCanAlley · #6 09-10-2013, 07:00 PM

What about plugging it into the RF modulator? The old VCR does have a composite out. It's back in the closet for now and I'll only pull it out if the RF will work.

zeno · #7 09-10-2013, 07:34 PM

The bending is NORMAL on that set. I am pretty sure
there was a different module available for that set.
I think it was called 9-57-VCR but you will have to find
someone with the factory bulletins to look it up.
Then you have to find one !!
There were also mods for 6U10 sets IIRC.
Before you go nuts be sure the 330 ohm on the
9-57 is OK, they all went. Change it to a 1 watt if its not.
Wont fix it but will improve it.

73 Zeno

walterbeers · #8 09-10-2013, 07:37 PM

That was a real common problem with older TVs when VCRs became popular. Yes, the horizontal sync was more of an averaging circuit, so they didn't respond to variations due to tape tension, tape wear, and especially with tapes that were recorded on one machine and played on another. I remember Zenith had a modification for it, which involved changing some resistors and caps in the horizontal afc, but don't have any idea what it was anymore. Never had a time base corrector, didn't even know that such a thing existed, but I do know there were units to remove the copy guard (macrovision) that was encoded onto tapes. Maybe if you could get a hold of such a unit that might correct it. I remember showing a movie to some friends that dropped over with my "new" vcr and the bending made the movie look like crap.

zeno · #9 09-10-2013, 07:43 PM

http://www.antiqueradios.com/forums/...?f=15&t=194005

Just found this so I aint dreaming. The 9-90-02 was in
later CC II uprights & had an IC & hoz hold IIRC. If there are
no changes other than "matching" the pins it will
be easy to make one. Really need to find someone that
has one to be sure............

73 Zeno

TinCanAlley · #10 09-10-2013, 07:58 PM

Quote:

Originally Posted by zeno

http://www.antiqueradios.com/forums/...?f=15&t=194005

Just found this so I aint dreaming. The 9-90-02 was in
later CC II uprights & had an IC & hoz hold IIRC. If there are
no changes other than "matching" the pins it will
be easy to make one. Really need to find someone that
has one to be sure............

73 Zeno

My 19JC55Z has a 9-90-01B and it doesn't suffer from the waving.

I have a spare, used, 9-57 and don't mind modifying it. So if anyone has any suggestions for changes, let me know.

Also, I'll check out the 330ohm resistor you mentioned.

lnx64 · #11 09-10-2013, 08:03 PM

I think with better tension though it could be improved.. I've got my early 80's top loading Panasonic improved so well my old Samsun no longer has the waving at the top.. Then again, these older sets, I've never messed with them

Findm-Keepm · #12 09-10-2013, 08:06 PM

...I'll dig through my limited amount of Zenith Tech Tips and see what is available. Zenith and GE both produced modules that were mod'd to accept the wide range of horizontal sync from VCRs. In the early days of the web, there were even websites with suggested mods for tube and solid state sets.

If anyone else has Zenith Tech Tips, do TCA a favor and check. It'll be a day or so before I can sit down and go through them - I start in 1972 and stop in mid-1977, so it may be for nothing. Doug/DRH4683, are you following this saga???? I know Doug has some Tech Tips, and may have beyond what I have. I think the Zenith manual for the Avanti is either CM-122 or CM-123, so folks that might have the tech manual, give it a check for any VCR mods.
I don't have that range of manuals - I stop after the 20Y1C38 or similar set until the System 3 stuff. All my CCII stuff went to a friend with 6 of the EC/GC sets.

CHeers,

Jeffhs · #13 09-10-2013, 08:07 PM

My Panasonic PV-4022 VCR (bought new in 1989) works perfectly with both my CRT TVs and my flat screen. No problems with picture bending.

One thing I thought of while reading the posts in this thread is the tracking adjustment on the VCR. If the tracking is off, the picture will bend. Newer VCRs have automatic digital tracking (with manual control if the digital tracking doesn't cure the bending), but older machines have a knob or a thumbwheel on the front panel labeled "tracking" that will allow the user to compensate for differences in tapes or VCRs; this is useful if you are watching a tape on your VCR that was originally recorded on another machine.

BTW: Since getting a DVD player I do not use my VCR much anymore either; I only use it occasionally to watch tapes of old TV shows and movies. (I don't record off-the-air anymore either; in fact, there is no antenna or cable connected to the VCR at this time.) My Panasonic VCR has never given me five minutes worth of trouble in the ten-plus years I've owned it, and before I got my first DVD player in 2005 I used the VCR quite a bit. But the DVD era changed all that, so when I got my first DVD player (a CyberHome CH-DVD300) the VCR quickly took a back seat to it, and is hardly used at all these days except for the purpose I mentioned earlier.

lnx64 · #14 09-10-2013, 10:10 PM

Some of the auto tracking isn't good, either.

I prefer the manual tracking, I get it to my liking.

This reminds me, I need to clean the idler wheel on my old VCR, it's slipping a little in rewind.

Findm-Keepm · #15 09-11-2013, 05:50 AM

Quote:

Originally Posted by zeno

The bending is NORMAL on that set. I am pretty sure
there was a different module available for that set.
I think it was called 9-57-VCR but you will have to find
someone with the factory bulletins to look it up.
Then you have to find one !!
There were also mods for 6U10 sets IIRC.
Before you go nuts be sure the 330 ohm on the
9-57 is OK, they all went. Change it to a 1 watt if its not.
Wont fix it but will improve it.

73 Zeno

Perhaps the 9-70 is the 9-57VCR??

http://videokarma.org/showpost.php?p...72&postcount=6

Cheers,