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.
- gridleak... biased toward HD