RCA VDT-350 How to adjust tracking?

[stragulus]

Originally Posted by Ed in Tx

Most of the noise is at the top of the pic so that's the entry side of the tape to the head drum. Could be alignment, but if the entry and exit guide rollers are secure probably not. Or could be the back-tension band has worn out, the felt liner fell off the tension band or somesuch, seen that happen many times. Or maybe the tension spring that hooks onto the back-tension arm came off. Should be 20-30 grams of back-tension on the tape in play mode, measured with a Tentelometer. Without proper back-tension the tape will not be in good contact with the heads.

This is the golden answer. I have read up on this topic now, and as you say, the back tension is the cause. The band has simply snapped. Is this made of common materials so I can attempt to recreate one? I don't have a tentelometer, but I read about a trick with v-hold to align image on top and below the blanking section which would probably be good enough for this sparingly used deck.

[Ed in Tx]

You need to find a proper replacement tension band. Too critical for correct performance. As far as looking at the switching point down just above the vertical sync and adjusting it that way, that would depend on how accurate the dihedral alignment of the video heads was on both the machine the tape was recorded on and the machine playing back. That is how close to a perfect 180° opposite they are on the drum to each other. A certain amount of tolerance was always "normal" and a little bit of difference where the switching point occurs was typical, but sometimes that alignment could be "off" enough to cause video "flagging" on a different machine playing back. Same tape would play fine on the machine it was recorded on. So do you by chance have a tape that was originally recorded on that VCR?

[Ed in Tx]

I just looked at what VCR we're talking about, one of the RCA top-loaders made by Matsushita. Very common parts in a lot of those old machines whether Panasonic, RCA, Magnavox maybe a few more names I don't remember. The tension band would be the same. Find a junker somewhere with a good tension band in it. Or maybe someone here has one of those old machines in their collection..?