VHS frequency response adjustment pot

[IanNVJ35]

Looking through my Panasonic service manuals for some of their 90's VCR decks I see reference to

"VHS frequency response adjustment"

With the following info as an example;

Test Point: TP3002
Adjust point: VR30005 (SP) VR30004 (LP)
Mode: playback of self recorded SP and LP
Input: Video sweep signal
Tape: Blank tape
Measurement: Oscilloscope
Spec: SP:0+-1 (dB)(90-110%), LP:0+-1 (dB)(90-110%)
Set video sweep signal as shown in and supply video sweep signal to video in terminal.

What I was wondeing is what is the effect of this pot - change of record or playback? Is it an internal sharpness adjust or something more than that?

[IanNVJ35]

Well I tried it (after marking the original set point). One way the picture got a bit sharper and the other way the picture got a bit softer followed by comet tailing like worn heads.

[flyingtech55]

Some VCRs had a 'Sharpness' control under a flap for the customer to twiddle. ISTR when I went on a Panasonic course for one of the VCR models this question came up. The stance Panasonic took was that there was a correct adjustment for that and that anything other than that setting was incorrect so why let the customer twiddle with it.

HTH

Tim

[PaulE27]

I had a Philips VCR with a sharpness control. I found it quite useful, and set it differently with different TV sets.

Paul