Sony DVW-790WS DigiBeta Issue

[ARC Tech-109]

Having an issue with my 790 widescreen, during playback I'm getting a checkerboard pattern of bad pixels despite having a strong RF envelope from the tape and the service menu reflecting no bit errors during playback. Tapes recorded on this camera play perfectly in my A500 editor so it appears to be a play only issue and everything else is good. Do we have any Digital Betacam experts, guru's or warlocks in the videokarma shadows?

[kf4rca]

Well, I went to DigiBeta school. on the DVW-A500 machine but that was 20 years ago. I'd start by cleaning the top of the drum. If that doesn't do it, it likely needs replacing. Check for gunk (oxide) in the lower guide edge of the drum. With the high bit rates of these, cleanliness is important.

[ARC Tech-109]

Cleaned the path again with the lower guide groove but the problem appears to be a chipped head, looked at each of the heads under an eyeloupe and one clearly is missing the trailing edge of the chip itself. The drum on the donor machine looks like it had fine grit sandpaper across it so unless I can find another drum it's going to remain. Record is good as the tape plays without an issue on both of my A500's so I'm going to leave it.

[kf4rca]

There used to be a company called Aheadtek that was a rebuilder. Our station had good luck with them. But that was 20 years ago. Check them out: http://aheadtek.com/video.php
They are probably not cheap as they have a niche market these days.

[ARC Tech-109]

They still have heads for it but the price is $$$$ and it would be cheaper to go after an HDCAM. Going to live with it for now as I don't use the camera much. Thanks for the input

[kf4rca]

Broadcast equipment is not very affordable in the home environment. I never did work with the 790ws. Our station was sold and the new company decided to go with DVCPro. As I recall, Panasonic was giving CBS stations a sweet deal on DVCPro equipment at the time. At one time we had 4 formats in the station- SP, SX, DigiBeta, DVCPro. The 8 edit rooms each had THREE formats- SP, SX and DVCPro. Everything was edited to SP which was the playback format in master control. DigiBeta was a commercial production format for us.
I remember hearing a CE talking about going to a consumer format as the cost of maintenance would be lower. If a camera got trashed they would just buy a new one.
So I knew my job was on the line as an ENG maintenance engineer. I knew what parts prices were and they were not cheap. Every month I had to send a lens out for repair at $1000 a pop. Those 18 crews we had out there were not cheap to maintain. We were still broadcasting in NTSC at the time. I heard from my CE that his budget was $3K a month. Also I heard that the GM's wince when they see the CE approach their office. There ain't nothing cheap in this business!

[ARC Tech-109]

Agreed nothing is cheap in the production world. Most of what I have is came from trades or deep discounts being I was producing a lot of educationals but despite that the margins were thin being a small operation even at $100/finished minute.

Never did care for that DV format be it DVCPRO or DVCAM and its variants. I have a total of four panasonic DVCPRO decks and three Sony, none of them work correctly be it worn heads or mechanical issues. The only true survivor here is my first PVV3 that I first docked to a 537 head then moved to a D55WS where it is now. Not a bit of trouble from that one. I'm not much for consumer formats having tried both S and Hi8 with crummy results, ended up "falling back" to 3/4SP for a period... those tapes survive today with great fidelity.

[kf4rca]

The only thing I've got broadcast related is an Ampex VPR80 that I fished out of a dumpster. Actually there were two in there. I removed the power supply and that made it removable by one person. It needs a pinch roller which is $1000. I had gone to school on the thing in the 80's. When I got back to Atlanta I fixed one for the Weather Channel and one for WABE TV30. The Wx channel needed a new TL084 op amp in the scanner servo and the one for TV30 needed a 10K resistor in the power supply.

[kf4rca]

I had worked with the Wx Channel guy while we were both techs at CNN. They had VPR-2's which do not have reel servo. His only request for me was to show up after 2AM. OK, no traffic!! We pulled the machine apart so I could access the scanner servo and I noticed one of the chips was cold. It was the TL084. He had a spare TL084 in his spare parts but NO 8 pin sockets. So we installed it without a socket. (Arrgh!) Powered the machine up and it worked. I was on my way home at 3:30AM. All I got for my time and trouble was a Wx Channel mug!

[ARC Tech-109]

Had a few of those in my day but found it paid in the long run with the reputation. Had a late night service call to a police dept where a DK driver had hit a pole and dropped the feeders, they grazed the phone lines and the resulting spike took out all the GDT's on the incoming block and SQM modules in the voter. They sent me an escort and I got breakfast on the chief in the morning.

I got my BVH2000 for a song, it had one bad RAM on the SY80 board so it wouldn't boot up no display nothing. At some point in the past someone had covered the diagnostic LED displays on the boards with black tape and a quick glance inside one would think everything was dead. I pulled the boards out and gave them a careful look and noticed it was tape and pulled it off. Powered it up and ran the diagnostics and it came back with a 21. Only paid a couple hundred for the unit with the internal TBC and under 500 hours on the meter which has an 86 date code so I believe it's original.
It was an after hours feeder deck for our local independent in an A/B/C arrangement running overnight movies, xmitter guy would thread everything up and when one would run to the end the other would switch over but this lasted only a short time before they were sold to a post production house where they did nothing until they recently folded.

[kf4rca]

Wow. Copper along poles can be problematic even during lightning strikes. Our station had Three remote lines to the transmitter over the years. First was Bell A2A system- a type of video coax. Then there was microwave and finally fiber optic.
Did you know there were fires at telegraph stations during the 1859 solar flare?
Now why would anybody cover up the diagnostic leds on a Sony? But I always remembered what a CE once told me. If it worked before, it can work again!

[ARC Tech-109]

Don't know why they didn't run the trunk lines underground being the building itself was completed in the late 80's, it was a small community at the time so maybe they didn't plan for the growth. All our state public safety has since migrated over to 700/800 P25-II digital and the dispatch centers consolidated to regional system.

As for covering the displays I can only speculate it had to do with "less technical" access to the TBC controls by those not familiar with the displays or their purposes, it could also be a job insecurity thing for whatever technician they had at the time with a need to know attitude. Hard to say I guess. The only issue I have with the deck is with an intermittent VITC I/O, sometimes it just blanks out at random times and others it's rock solid from power on to power off hours later. When I say blanks out it goes **.**.**.** while LITC timer 1 & 2 still functions. All the supplies are right on the money having been set with a 5 1/2 digit Keithley to the book and everyone else seems happy. Dunno... might just leave it as I can't find the specific maintenance manuals with the schematics, only the mechanical & operations. The deck is more of a want than a need anyway that doubles as a space heater but I have founds some oddball tapes over the past year that have been quite entertaining.