Panasonic VCR quit playing back in hi-fi stereo, still recor

[larrymoencurly]

I have a Panasonic PV7520 VCR, at least five years old, that a few
days ago stopped playing back in hi-fi stereo, but only tapes recorded
by it in the past few days. Tapes recorded earlier still play back in
hi-fi, and recently recorded tapes play back in hi-fi on other VCRs.
Changing cassettes and recording speed make no difference. This
isn't just a matter of the VCR's hi-fi/normal indicator not working
because I can hear the difference when I manually switch between hi-fi
and normal audio.

I tried cleaning the VCR by hand again, but it didn't change anything.
I clean it about twice a year, previously about three months ago, by
holding the leather swab stationary and rotating the cylinder back and
forth.

Could this be the mode switch? I thought that it wouldn't matter
since hi-fi/normal is switched electronically, isn't it?

 

[Andy Weir]

Isn't the audio head downstream from the drum on the way to the takeup reel?
Clean that too.

Andy

 

[larrymoencurly]

u1061771156@csi.com (u1061771156) wrote in message news:<slrnbjqlhs.f5.u1061771156@csi.com>...

Could just be the heads wearing out, as they get marginal then
record+playback on the machine will be worse than interchange with
another VCR as the signal goes through the marginal head twice.
Hifi audio is often the first thing to fail, due to the way audio is
written first then partially overwritten by the video.

Do you feel the picture is as good as it always was? If you play back a
tape recorded a while ago, is it getting more sensitive to tracking
adjustment than it used to be?

The picture still looks good, better than that of my lightly used JVC
HR-S4600U SVHS recorder, regardless of which VCR created the tape, and
there are no tracking problems, but when I fast reverse, some tapes
give nothing but a blue screen, and it's more likely to happen near
the beginning of the tape than near the end. Could that be back
tension? I can see the tape act jumpy where it exits the drum when
that happens, and the pin that seems to check back tension jerks
around a lot. The felt strips around the hubs can't be adjusted on
this machine.

 

[u1061771156]

In article <755e968a.0308160952.30aa0f77@posting.google.com>, larrymoencurly wrote:

u1061771156@csi.com (u1061771156) wrote in message news:<slrnbjqlhs.f5.u1061771156@csi.com>...
Could just be the heads wearing out, as they get marginal then
record+playback on the machine will be worse than interchange with
another VCR as the signal goes through the marginal head twice.
Hifi audio is often the first thing to fail, due to the way audio is
written first then partially overwritten by the video.

Do you feel the picture is as good as it always was? If you play back a
tape recorded a while ago, is it getting more sensitive to tracking
adjustment than it used to be?

The picture still looks good, better than that of my lightly used JVC
HR-S4600U SVHS recorder, regardless of which VCR created the tape, and
there are no tracking problems, but when I fast reverse, some tapes
give nothing but a blue screen, and it's more likely to happen near
the beginning of the tape than near the end. Could that be back
tension? I can see the tape act jumpy where it exits the drum when
that happens, and the pin that seems to check back tension jerks
around a lot. The felt strips around the hubs can't be adjusted on
this machine.

Playback in fast reverse is, in my experience, often a bit flakey on
many VCRs. The mechanism to set tape tension in this mode is not a proper
one (with the tension pole feedback mechanism) but just a brake on
the take-up sppol. So tension is not well controlled and this will make it
much more sensitive to head wear in this mode. If the tape path is visibly
jumpy though then you need to look for a mechanical problem. I worked on a
VCR where the tension pole vibrated wildly in rewind, turned out a plastic
piece was missing that was supposed to retract it in that mode...

Another thing to be aware of is that different head combinations are
often used in the fast play and reverse play modes, so they may switch
to an LP (in UK, EP in the US?) head which may be more or less worn.

Mike.