Sharp VCR playback distortion

I have Sharp VC-MH704 thats been working fine for the last 4/5 years through the RF sockets, but never through scart. It has even been used on 2 different TVs in this way with no problem.

However, now we have just purchased a JVC AV-28E50SK Digital Tv. (Also purchased a DVD recorder and recently changed it to another model, but problems occurs with both and without the dvd plugged in).

The problem is.....

The VCR will happily tune and playback the TV through both RF and Scart sockets, but with either scart or RF plugged in, as well as both plugged in, the video playback is distorted.

The picture is fine for about 5 seconds then it distorts diagonally along and goes black and white with sound problems for about 3 seconds and then is fine again and repeats.

We have tried every type of tv configuration in case of interferance as well as playing using just the RF to connect as well as just the Scart, but playback still has the same issue.

Tracking makes no difference.

We thought it may be interference, but no combination seems to help. Is it a problem with the VCR or with the TV?

As i said the tv will happily use the ariel signal from the vcr to show the tv channels.

It happens with all pre recorded videos, although we have no tried a home recorded one, or even tried to record on the vcr.

Any ideas please? This is sending us nuts!!!! Will happily get the VCR repaired or buy a new one if the problem is with it and not the new TV.


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That seems to be a contradiction, it plays happily but it distorts? I don't get it.

Try the VCR on other TVs. If it works fine it may be your new TV has a sync fault or has been maladjusted at the factory. In layman's terms, VCR sync isn't quite the same as broadcasted sync, which is why some old TVs required a special video channel to cope with the difference.


Reply to
Dave D

Reply to
Mike Berger

Have you tried changing the output RF modulation frequency on the VCR RF out and tuning in the TV to match ? Diagonal patterning is often due to beating of harmonics from the local modulator "transmitter" frequency and some internal or external freequency

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
n cook


By playsback but distorts i mean that it will play th tv through the vct but a tape distorts.

Im really sorry but i think we have tried this with no luck but it doesnt really make alot of sense to me! ...

"Have you tried changing the output RF modulation frequency on the VCR RF out and tuning in the TV to match ? Diagonal patterning is often due to beating of harmonics from the local modulator "transmitter" frequency and some internal or external freequency"

Anymore advice? Is it not likely to b a vcr problem that can b fixed by repair? This would be a nice easy solution!


n cook wrote:

Reply to

Have you tried the VCR on another TV as was suggested? Until you do that, no-one can answer for certain whether it's the TV or the VCR to blame.


Reply to
Dave D

Try to hook up the VCR to work through channel 3/4 (switch on the back for the internal rf-modulator) or 0 ("video", etc.), depending on your setup. Try this setup (if you haven't already):

Cable-in to VCR RF in ("cable"; "antennae"; etc...) VCR RF-out to TV ("out to TV") VCR A/V in from DVD (use digital inputs of VCR to process DVD signal)

The VCR's in-board block-converter will be able to automatically manage the two different inputs through the tuner. Often digital input is referred to "channel 0" on the VCR tuner like an additional channel, depending on model. Consult a manual for your unit.

Be sure that if you use any one channel to view from the VCR, that the channel is properly-tuned, and that if setup on channel 3, that both are set to channel 3 or channel 4 respectively. This sounds like an Automatic Fine Tuning conflict. An untuned channel will often go into a seek-mode with most modern tuners, hence the V-sync mismatch, because it cannot get a proper lock on the signal. The easiest starting point is to try retuning your VCR tuner to what signal you have available, then tune the TV to the VCR's signal.

If the above setup did not change matters, double-check that your TV is set to CATV and not AIR. If your VCR/TV does not have an RF output, you simply need an RF modulator.

I know exactly the problem you are describing and if I remember correctly, it is solely with the signal tuning. This is not indicative of a component problem with either the TV or the VCR. Set AFT to on for both TV and VCR (where applicable) after tuning each in the order specified above. Use channel 3 as a default for any input, use channel 4 if channel 3 doesn't work. Make sure ch3-4 settings match between all related tuners if such a setting exists (look on the back of the units near where the RF cable connects for any kind of switch).

Please post if the above does not work...

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Electromotive Guru

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