Some VHS tapes play well, others not?
 

I'm transferring some VHS tapes yo my PC. My VCR is s Philips VR 720.

My problem is that some tapes plays well and some tapes only plays audio without any picture (10 tapes plays well, 40 tapes doesn't play picture). The same result if I test to connect to a TV instead of a PC. I have manually cleaned the head, the guides and roller. Buying a new VCR is maybe a solution.

What's is the most propably cause to my problem. My VCR or the tapes?
Any advice on how to fix the problem?

Do you see anything on the screen with the problem tapes? Snow, static, solid color screen, rolling bars, etc.
Is the sound you hear from the Hi-Fi or linear track?
Do you know the history of the tapes? e.g., recorder used, subject matter, etc.
Are the tapes all PAL?
Is there any factor common to the problem tapes that is not found with to the good tapes?

A first test would be to try a problem tape in a different VCR. Make the test with a tape that least important to your project.

I see nothing on the problem tapes. I don't know if the sound is Hi-Fi or linear track.
The tape history. They were recorded by another VCR. Various brands. All tapes are PAL. I see no common factory.

Unfortunately I have no other VCR to test with.

No friends with a VCR?

None. Their VCR:s are long gone.

Many VCRs will give a display as to which audio track is playing. However, many camcorders and VCRs only recorded linear track. Linear track audio can play OK even if the video head alignment is too far out to read the video and Hi-Fi tracks.

If 80% of the tapes are problematic and all are assuredly PAL, recorded on many different machines, it makes it more likely that the VCR is the issue.

While not a great source for serious use VCRs and becoming more scarce each day, thrift shops might still have a working VCR or two on the shelf at a low cost that you could buy and use to test. Some might even let you test on site if you ask (objective to see if it works before you buy). If you can, test with both a problematic and not problematic tape.

If 10 tapes play very well it is less likely a VCR fault, But with no information to go by, guesses are not going to help you.

Update. I bought a used Philips NV-VP23. The tapes play fine. The problem was my old VCR.

The only tapes that doesn't play fine are a dozen of NTSC tapes that doesn't play as they should on my PAL VCR. They play in black and white.
It might be that this could be changed in Menu -> Video system. Unfortunately I can't test is the guy who sold me the VCR gave me a remote control that isn't made for VCR. It has no arrows to navigate the menu.

So what was wrong with your old VCR? Just trying to make the thread useful for anyone who bumps into it in the future.

I don't know. It was cleaned several times and I don't know what was wrong.

Weird, It doesn't make sense that it plays 10 tapes and doesn't play the rest unless the 10 tapes it plays are of a different format.