Question about guide rollers

[mahongg]

Hello,
My friend gave me hes old Panasonic NV-HD640 that he used for transfering VHS to Digital. But this machine has "one small" problem. After he completed the transfer there was couple of trouplesome cassettes left, and he tried to adjust the guide rollers so that he could save those cassettes. So now the adjustments are not in the place.


So if i have understood currently the left side roll adjusts the upper part of the image and right side adjusts the bottom part.
But now comes my question: When you turn those guide rollers left or right, what really is happening?

The reason why i am asking because i dont see it nor the tape move up or down while adjusting, and it feels like left side stays really tight all the time and right side is much looser than left, and they dont get tighter nor looser upon adjusting.

[Cobaltblue]

Hi and welcome to the Forum

Please put pictures in the Forum

Cheers

Mike T

[mahongg]

Originally Posted by Cobaltblue

Hi and welcome to the Forum

Please put pictures in the Forum

Cheers

Mike T

Hi and thank you. Here is the image of my VCR and what i am talking about.

[John123]

This might be of use.

[mahongg]

Originally Posted by John123

This might be of use.

Thanks for the reply. I have already binge watched many of his alignment videos, but i still dont understand that how the rotating of the rolls really affects the tape.

Because when i turn them left or right, i dont feel them getting tighter or looser, and i also dont see those rolls or the tape moving up or down upon adjusting them.

If i put measurement tape next to those rolls and adust them, i should see the change, but i dont. Thats why i am asking, that what it is really doing.

[Graham G3ZVT]

Hi there.

The guides are on a very fine screw-thread, if you can rotate the split slot at the top counter-clockwise, the roller must be moving up.
If you can turn them clockwise the roller must be moving down, they wont "tighten up" unless you adjust them past their limits.

However,

There may be a tiny hex screw at the bottom of each guide roller which locks them in place and that's probably is the reason why you need to apply more torque to the left side.

It is possible to adjust the guide rollers with just a known accurately recorded tape and just by watching the screen, but I wouldn't say it is easy if you've not done it before.

[Welsh Anorak]

When this happened with a customer's video ("we just tightened those little screw things to see if it worked") I'd lace up an old tape and adjust the guides by eye so they lined up with the 'ruler' on the lower drum. As Graham says, I think there's a very small hex screw at right angles to the guide on the lower mounting block. When we did this they needed very slight adjustment to get the FM waveform right. However, you can just play a known good tape and watch the picture. Entry (left) guide for noise at the bottom of the picture and exit guide for the top. Pick the central 'sweet spot' then lock the guides.