Re-Aligning Umatic Deck to play a particular tape?

[peahix]

Hi, hopefully this is the right category for this question. I have several umatic tapes shot by a news cameraman in the 80s. These are the raw NTSC tapes from the camera. After struggling to get them to play, and trying all the usual things (baked them for 24 hours, repeatedly cleaned heads, etc), I suspect the problem is the camera they were shot on was misaligned. I know how to adjust tape guide alignment on consumer decks, but am not sure of the procedure for umatic decks. I have two NTSC decks available: Sony VO-5850 and VO-5600. Both decks play good condition tapes fine.

Thanks!

[timtape]

Pea, it might be worth uploading a short sample video illustrating the problem. It may show whether guide adjustment will help, and perhaps which guide needs adjusting. I think maximum file upload here is 100 MB.

[peahix]

Thanks! Sorry for the late reply, just had a busy weekend! Here's a typical example.

[timtape]

Not much there! Anything in fast cue?

[peahix]

hi, yes, there's signal on these tapes. occasionally i can get it to track, and often it's visible in fast cue.

[timtape]

Is there any tape edge damage such as a long crease, or "crinkle cut" from tape stretching at the edge? These can prevent the tape from making reliable contact with the control track head.

[peahix]

No, there's no such damage. I've been working with the tapes more and I think I've now concluded, even after 48+ hours baking time, that they're simply still shedding too much oxide onto the heads as they play. It's confusing because when I clean the heads, only a modest amount of oxide comes off- the typical amount that good condition tapes will play fine with. Although when I try to play a good condition tape while the heads are still dirty from the problem tapes, I get snow until I clean the heads. The problem tapes are Agfa, not sure when they were made, but presumably late 70s to early 80s era.

[timtape]

Specs Bros shows an Agfa UMatic tape from that period with SSS as well as others.

http://www.specsbros.com/white-paper-common-signs-of-8203problem-34-and-beta-videocassettes.html

Are you cleaning the entire tape path including rotating and stationary drums, guides, any flutter rollers, A/C head, capstan and pinch roller? Not just the tiny video heads themselves. Thorough tape path cleaning after a SSS tape can take some time. I inspect my cleaning work at each point with a magnifier so that I can see if it's fully clean.

At what temp are you baking the tapes? In what sort of oven?

[peahix]

hi, yes, i clean the whole tape path, and after i've dirtied up the tape path, i've tried cleaning the different parts one by one, leaving the actual heads for last, and each time the only thing that brings the signal back (until the path is dirtied again) is cleaning the heads.

i'm baking the tapes in a food dehydrator at 135 degrees and leaving them to cool for at least 12 hours.

[timtape]

OK. What baking time have you been using?

[peahix]

hi, as previously stated, with these problem tapes, i've baked them 48+ hours. with other tapes, usually 24 hours is sufficient.

[timtape]

I'd bake it again at the same temp for maybe 24 hours but with the case opened to allow much better air circulation (7 of the 8 bottom case screws must be removed) and also allow for the 3/4" tape which takes longer than say 1/2" or 1/4".

If that improves things but still not quite enough I'd try another 24 hrs under the same conditions.

[peahix]

All the baking I've done so far is with the tape reels completely removed from the cassettes.

[timtape]

I dont hear of that too often. Well done.

[peahix]

well, the tapes definitely should be "well done" by now! but the problem remains...

[timtape]

Yes we'd think so. What does the linear audio track sound like? Any chance of a sample?