Weird, Finicky (but consistent) SVHS Blanks in PV-HD1000 - AVS Forum
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post #1 of 7 Old 07-08-2001, 08:57 PM - Thread Starter
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Has anyone else experienced this with their PV-HD1000?:

I was told that good quality SVHS tapes work just fine with the deck, so I purchased 10 Maxell SVHS tapes from a local retailer.

Six of the tapes worked perfectly; four won't work at all. The ones that don't work have an extremely unstable picture, with lengthy audio dropouts, block artifacts and green block blobs every few seconds.

The ones that work always record and playback fine, all the way through the tape. I have tried re-recording on them and the re-records also always work perfectly. Not a glitch.

The ones that don't work the first time never work, and don't work for the entire length of the tape. I've tried re-recording, and they don't work on the re-records either.

It seems like these tapes are clearly either good, or they're bad. If they're good, they're perfect; if they're bad, they're dreadful, and for the entire length of the tape.

What's weird is that some of the good and bad tapes even share the same lot number.

Should I just give up and go to real DVHS blanks?

Has anyone else experienced something like this with their PV-HD1000?

Thanks in advance,

Steve R
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post #2 of 7 Old 07-09-2001, 04:05 PM
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I had the same issue. Get a new head from the post from gridleak. Fixed mine for a fast 259 bucks!!!!!

dave
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post #3 of 7 Old 07-09-2001, 06:13 PM
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I had similar problems too. Replacing the heads did the trick. Its definately worth the $250 and the install couldn't be easier. Thanks Gridleak!

Jeff
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post #4 of 7 Old 07-09-2001, 11:08 PM - Thread Starter
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Wow, I just got this player a month ago. It's supposed to be a "factory refurb" -- reconditioned, and not used since the refurb. Wouldn't this imply the heads are new, or in like new condition?

It's also a consumer unit (not the dealer demo unit that many have replaced the heads on).

Are you sure I need to take the radical step of replacing the whole head assembly?

I suppose it's only $250, but I wouldn't want to spend that and find out it's not the issue (or the problem pops up again in a month).
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post #5 of 7 Old 07-10-2001, 09:36 PM
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Steve,

I'm sure you're familiar with the expression "When you hear hoofbeats you don't think of zebras." From your description of the symptoms, zebras are the things like defective tapes, bad alignment, misadjusted electronics, etc. Worn or clogged heads (the horses) are just a lot more likely to be the source of your problem. With the 4 HD1000's that I've maintained, the only parts I've replaced are upper cylinders and iLink jacks. No other adjustments or repairs have been necessary.

However, I'm bothered by two things you said. The fact that 6 tapes are perfect and 4 are bad every time you try them seems a little odd. That, combined with "factory refurb", and I start to worry about some of the zebras.

If I were in your position I would do the following:

1) Open the machine and wet clean the heads.

2) With the machine open I would run one of the bad tapes and carefully examine the tape path, with good light and a magnifying glass (if you use a flashlight the machine may stop occasionally). I'd look for the tape hitting the upper or lower limits of the posts, hitting the lower edge of the lower cylinder, or rippling (waves) showing near the edge of the tape as it moves.

3) I'd repeat the same process with a good tape to see if there's a difference.

4) If I saw differences, then I'd try a different brand of tape. If the problem continued, or if I saw any sign of tape edges being curled permanently I'd return the machine to Panasonic for repair.

5) If I was convinced the alignment was ok, I'd then look for wear on the lower cylinder, at the point where the tape detaches from the cylinder. If there is heavy wear then replacing the upper cylinder is not a permanent fix.

If, after all the above, I saw nothing wrong, then I'd order an upper cylinder.

------------------
- gridleak...
Analog -- Always out of adjustment.
Digital -- Always one more bug.

-Roger
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post #6 of 7 Old 07-11-2001, 03:21 AM
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You could also try the tapes in a different deck. Low probability of having 4 defective tapes at once, but it costs nothing to check.

Mike
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post #7 of 7 Old 07-11-2001, 12:45 PM
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Successful digital recording and playback depends on a large number of variables, amongst which are the Signal to Noise Ratio (SNR) and resolution of the tape. The resolution of the tape measures its ability to distinguish between successive bits without smearing them together.

DVHS tape almost certainly has better SNR and superior resolving power than SVHS tape.

With reference to SNR, a reduction of only 2 db can worsen the playback error rate by an astonishing factor of something like a thousand to one.

For this reason, DVHS tapes must have a few db of built in margin for SNR so that worst case samples of DVHS tapes operate properly with worst case players. SVHS tape is made to different (and lesser) standards so it would not be surprising if some worked and others did not. I suspect an SNR reduction of less than 1 db between two different tape samples could make all the difference.

The moral is: before hidef recording something special on SVHS tape, check to see if it works.
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