Head switching noise

[Cirruz]

Hi there,

This post is slightly out of topic... I have a VCR that outputs a lot of head switching noise in the bottom of the picture. The noise is visible even in TVs with large amounts of overscan . Is there anything I can do to fix this, besides taking it to a repair store and almost certainly pay more that it costs? Is there a "standard" procedure to repair? Thanks a lot in advance.

[davideck]

If a good cleaning of the tape path doesn't help, then you could try adjusting the scanner exit guide. Make sure to mark the original location just in case. The guide slides along the loading mechanism and then guides the tape as it leaves the scanner. It doesn't take much to change its alignment, so tweak it slowly.

I assume that you've already tried the manual tracking adjustment...

[Cirruz]

Hi davideck!

As always, thanks a lot for your response. I've studied carefully the internals of a VCR, in order to try to understand your solution. But I don't seem to find the way to adjust the mentioned "scanner exit guide"... Is the "scanner" the heads drum? Do I adjust it in a screw, with a screwdriver? Sorry for my ignorance... Again, thanks,

Cirruz

[edDV]

Hi davideck!

As always, thanks a lot for your response. I've studied carefully the internals of a VCR, in order to try to understand your solution. But I don't seem to find the way to adjust the mentioned "scanner exit guide"... Is the "scanner" the heads drum? Do I adjust it in a screw, with a screwdriver? Sorry for my ignorance... Again, thanks,

Cirruz

Some head switch noise is normal.

A repair shop knows how to do this. They will align the transport to a precision standard tape.

The problem is, if your tape was recorded on a machine that was not perfectly aligned, the tech would need to optimize adjustments to that particular tape. After you get that tape captured, return the machine to the shop for alignment to the standard tape.

[Cirruz]

edTV, thanks for your response, the problem is that everytime I take my VCR to the repair shop, I have to pay something like 30€ (more than 30 dollars)! That's not fun at all.

Is the alignment procedure viable to do at home? I'm used to mess with electronic devices and have college formation in electronics. That is, I understand the electronics of the device (eraser head, audio head, video heads, etc..), but the mecanics are intriguing!

Thanks again,

Cirruz

[edDV]

edTV, thanks for your response, the problem is that everytime I take my VCR to the repair shop, I have to pay something like 30€ (more than 30 dollars)! That's not fun at all.

Is the alignment procedure viable to do at home? I'm used to mess with electronic devices and have college formation in electronics. That is, I understand the electronics of the device (eraser head, audio head, video heads, etc..), but the mecanics are intriguing!

Thanks again,

Cirruz

You can buy books on VCR repair. You will need an oscilloscope, special tools and one of those standard alignment tapes.

[davideck]

But I don't seem to find the way to adjust the mentioned "scanner exit guide"... Is the "scanner" the heads drum? Do I adjust it in a screw, with a screwdriver?

Yes, the Scanner is the Head Drum.

Here is an image of a VHS transport;
http://en.wikipedia.org/wiki/Image:VHS_m-loading.jpg

The guide that I am referring to is labelled the "Take-Up Adjustable Guide Roller".
Typically, this guide is on a threaded post with a hex set screw that holds it in place. Loosen the set screw slightly and rotate the guide 1/4 turn. Retighten the set screw, play the tape, and see if the adjustment made things better or worse or the same.

Sometimes you can grab the top of the guide and rotate it while the tape is playing to see the result immediately.

The Take Up Guide should have an effect towards the bottom of the picture while the Supply Guide has an effect towards the top.

The adjustment range may span over several revolutions. Be sure to keep track of the original position.

[Cirruz]

Yes, the Scanner is the Head Drum.

Here is an image of a VHS transport;
http://en.wikipedia.org/wiki/Image:VHS_m-loading.jpg

Thanks davideck,

Unfortunetly, that guide isn't adjustable on my Philips VR 685... I guess I'll just have to get another VCR to do the job. The main reason I was trying the Philips soo hard is that some of the VHS recordings that I want to convert to DVD were recorded with it. And I guess that the tape recorder is always a decent same tape reader.

Anyway, thanks again!

Cirruz