HD1000 video head photos - AVS Forum
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post #1 of 13 Old 05-30-2001, 12:43 AM - Thread Starter
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I recently took up the task of repairing my ailing "demo" HD1000. The results were so successful that I thought I would share a little of what I learned.

This HD1000 had worked well for several months, running a few hours each day, but then it started showing block noise near the end of tapes just recorded. The problem quickly got worse, and the last tape I recorded would not play back at all. Cleaning the heads only helped briefly, and it passed other checks such as recording current, so I decided the heads were worn out.

Because this was a demo machine with no warrantee I figured I had nothing to loose by attempting the repair. I ordered an "video head/upper cylinder" #VEHS0578 from Panasonic for $231.44. While waiting for the new cylinder to arrive I pulled the old one out and took a few pictures.

http://home.earthlink.net/~rogercc/_...s/Photo1tn.jpgEnlarge
On the left is the underside of the demo cylinder showing 8 heads. Two of the heads are "doubles" so there are actually 10 heads total. The 4 heads marked "K1" are the digital heads. The remainder are VHS. The black cylinder in the center is the transformer primary that couples the head signals to the circuitry on the chassis. The upper right photo is a closer view of one of the digital heads. Lower right is an even closer isometric view (about 100x thru a Nikon microscope). You can see that the head is glassy and transparent underneath the gap. You can also see the 30 degree azimuth angle of the tips of the head.

http://home.earthlink.net/~rogercc/_...s/Photo2tn.jpgEnlarge
Left two photos are face views of digital heads one and two, shown next to each other to display the one track offset between them. There are two identical heads on the opposite side of the cylinder. Four digital tracks are written for each revolution of the cylinder. The photo on the right shows the gap, which should not be visible at this magnification, but these are very worn heads!! If you look closely you can see a faint curved line to the left of the gap where the wear starts. The .007" is the total thickness of the head chip. The actual track width is less than .002".

http://home.earthlink.net/~rogercc/_...s/Photo3tn.jpgEnlarge
Photo on the left is a profile of a digital head on the "demo" cylinder. On the right is the same head on the new "consumer" cylinder - clearly different material. The demo head also protrudes above the cylinder surface more than the consumer.

It looks like the demo heads had deeper gaps and protruded more to provide longer playback service. The deep gap would weaken the record capability.

The process of replacing the cylinder was unbelievably quick and easy. The only tool you need is a small philips screw driver. Remove two screws, slide the old head off, slide the new one on, and replace the screws. No other adjustments should be necessary. I immediately tried the tape that wouldn't play at all, and it played perfectly.

So to all my fellow lunatics, those of you poking around the guts of your HD1000 with deerskin swabs and 10:1 probes trying to track down the source of square-bubbles and green-blotches, I say: Go for the Final Solution.

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-Roger
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post #2 of 13 Old 05-30-2001, 04:25 AM
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Gridleak,

Bravo! Wonderful pictures of your cylinder swap. Have you tested recording performance?

Charles
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post #3 of 13 Old 05-30-2001, 07:02 AM
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Wow! Thanks for sharing that...hope this thread gets promptly archived.

HD Media Keen Videosaurus
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post #4 of 13 Old 05-30-2001, 01:28 PM
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Interesting. I am having the same issue at the end of St160's. I dont have the demo deck. So any idea why you say it was the heads and not tensioning or something?

dave
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post #5 of 13 Old 05-30-2001, 04:52 PM
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Quote:
It looks like the demo heads had deeper gaps and protruded more to provide longer playback service. The deep gap would weaken the record capability.
This jives exactly with what I've observed on my demo HD1000. It makes a great player, and a crummy recorder. Nice job on the photos and repair.

-Dylan

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post #6 of 13 Old 05-30-2001, 07:16 PM
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Every once in awhile I read a thread worth printing out. This is one! Thanks much for your excellent report and I will be saving your post with part number, pictures and all to a color print out for my PVHD1000 manual. If anything else you just saved me an hour's worth of on the phone trying to track down a part number in the future. BTW- that price is a bit high for consumer heads but I guess it's digital dual design explains why.

One question, Could you post the phone number of the parts order desk where you ordered this head? What was the wait time to get the part or was it in stock?

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post #7 of 13 Old 05-30-2001, 08:03 PM
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What a fantastic piece of detective work!!! (as well as absolutely incredible photography!)

Bravo as well!
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post #8 of 13 Old 05-31-2001, 06:32 PM - Thread Starter
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Thanks, everyone, for your kind remarks, and Don, I'm honored to have found a place in your HD1000 manual.

I ordered the cylinder from Panasonic Services Co. Parts Division. Their phone is 800-833-9626. They shipped within 3 days. Their website at www.pasc.panasonic.com lists nearly all the parts in the HD1000, including the upper cylinder. Orders can be placed directly at the website for all parts except the circuit boards. The circuit boards are "RTL" items (retention time limited), meaning that they are no longer manufactured. I would guess that they are sold on an exchange basis only.

Charles,
I now use this unit as the recorder on my main system. It produces strong recordings that play on all my other machines.

Dave,
The heads on these machines wear out gradually. Even though the gap doesn't open up, the edges at the gap become rounded because the non-magnetic material in the gap wears away more quickly than the head tips. The heads become less efficient and produce weaker recordings. They also become less effective at reading tapes, which is why a machine with worn heads will have trouble reading its own tapes. The machine I just repaired could not read its own tapes, but those same tapes played perfectly in another, newer, machine. Near the end of a cylinder's useful life the machine will become very sensitive to all sorts of odd-ball things like tape brand and length, changes in tension from beginning to end of a cassette, even climate changes. They are also more susceptible to clogging because the face of the heads is no longer perfectly smooth.

http://home.earthlink.net/~rogercc/_...s/photo5tn.jpg Enlarge
As an example, this is the face of a digital head on the new consumer cylinder. The surface is completely smooth and there is no highlight outlining the head tips and gap. The gap is nearly invisible in this photo, and is even hard to see when viewing directly through the microscope; yet it is very apparent on the worn head because of edge rounding

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[This message has been edited by gridleak (edited 05-31-2001).]

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post #9 of 13 Old 06-02-2001, 02:00 AM
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Gridleak-

Thanks for that further information. I have printed this post too for my manual.

I'm much more familiar with head wear on analog machines than on the PVHD1000 so I was also intrigued by your description of the symptoms. In the analog world, the first sign of head wear is flashing chroma.

One point I would like to advise others is that when you do suspect any head clogs or dirty heads, avoid excessive use of the dry abrasive cleaning tapes. Better to use the hand head cleaning method with cleaning fluid. This is recommended for oxide based tape head cloggs. metal based tape will require an ocassional use of the dry abrasive cleaner tape to sand down the glazing that develops on the heads from metal tape use.

I suspect the normal wear on the PVHD1000's when we use them for straight playback and record with very little pausing and mostly new tape stock with few playbacks per tape will result in a very long term head life. Those of you who use your HD1000 for viewing rental tapes, use excessive pausing to edit out commercials, and have purchased a used / demo machine have extenuating circumstances that may result in "premature" head exchange.

FWIW- I never play rental tapes in my good equipemnt and have never used my PVHD1000 for anything other than DVHS HDTV recordings. I rarely rent videos anymore but ocassionally we get one in and I have one of those cheap $99 VCR's I use to watch. I don't even stick a rental tape in my SVHS VCR.

Thanks again for your excellent report and dittos on the great photography. BTW- they printed out excellent on my inkjet printer!

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post #10 of 13 Old 06-07-2001, 10:28 PM
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Please also add my thanks for the info on head assembly.

Question: my service manual shows the part number as
VEHS0575, and the website shows this part (at the lower price of around $202) also as available. Do you know if this is the demo machine upper cylinder unit?

Hal


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post #11 of 13 Old 06-08-2001, 12:29 AM - Thread Starter
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Hal,
The VEHS0575 is the cylinder WITHOUT any heads. It makes a beautiful ashtray for really narrow cigarettes.http://www.avsforum.com/ubb/smile.gif Otherwise it's not much use. I'm not quite sure why they include that in the parts list, but they probably have a lot in stock.

The demo machines did have different heads, and the only "remnant" of their former existance is the part number "VEGS0419 Cylinder Unit" still listed in the parts list. That's the whole shebang, lower cylinder, upper cylinder and head assembly that was on the demo machines. If you try to order that you will get the VEGS0422 Cylinder Unit (which is the unit used on consumer machines).

You definitely don't want to buy the whole Cylinder Unit. Replacing that involves removing the entire chassis from the recorder and unsoldering the connections to the head amp circuit board. Not a lot of fun.

The VEHS0578 is the only upper-cylinder/head-assembly they offer, and it contains the consumer heads.

I doubt demo heads can be found any mor

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post #12 of 13 Old 06-10-2001, 11:20 PM
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Quote:
Originally posted by gridleak:
The demo machines did have different heads, and the only "remnant" of their former existance is the part number "VEGS0419 Cylinder Unit" still listed in the parts list. That's the whole shebang, lower cylinder, upper cylinder and head assembly that was on the demo machines. If you try to order that you will get the VEGS0422 Cylinder Unit (which is the unit used on consumer machines).

You definitely don't want to buy the whole Cylinder Unit. Replacing that involves removing the entire chassis from the recorder and unsoldering the connections to the head amp circuit board. Not a lot of fun.
Not having the wherewithall to do the repairs you've
described so vividly, back in April I had my demo HD1000
repaired by Panasonic in Elgin.

They replaced TWO parts:

(1) VEGS0422 Cylinder Unit $264.13
(2) VEPS5017A Digital PC Board W/Compon $250.38

Labor charged was $90. Shipping, tax, total due $664.39.
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post #13 of 13 Old 06-25-2001, 08:39 AM
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Okay Roger, guess I will order some heads today. Dont know what else to try other than your experience seems to be just like mine.

Here I go with the call.

dave
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