Calling All Digibeta Experts DVW-A500

[ARC Tech-109]

I recently scored a Sony A500 Digibeta deck with numerous issues. First was in the power supply with a number of blown caps, spent an afternoon replacing them. Voltages are close to the board markings, the +8v is running at +7.60v while the -8v is -7.34v. both 15v rails are on target as is the 18v, 5v and 3.3v.

The one odd issue is a chroma green during analog playback, on the vectorscope I'm seeing good burst but no phase differences just a full saturation green, digital playback works just fine so I suspect its within the analog CTDM side... just where the heck is that?

Third issue is the tape elevator keeps cycling like a tape has been inserted going about 1/4 thru the travel then out again, I can insert a tape if I coax it in an follow the cycle.

Digital recording to a D32 tape via SDI works perfectly as is the playback, Im using a Newtek TC550 Tricaster for the SDI I/O and AES audio. I also cleaned up and replaced the old factory grease so everything is moving smoothly.
What I'm not finding is a service manual, there's an operations manual and parts breakdown pdf which I downloaded but it covers nothing I'm dealing with, given the sheer complexity of the A500 I suspect the service manual is going to be far larger than the NYC phone directory.

Anyone shed some light on this overly complex heavyweight beast? I know my way around the BVU decks but this has me stumped. Any help would be greatly appreciated.


109

[Chip Chester]

This might help:

https://docs.sony.com/release/dvwa5001_318882104_im.pdf

Capacitor problems may exist in the A to D boards, too. Are the terminators working in that circuit? Newer Sonys have self-terminating BNCs, but they don't always work, over time.

On edit: It looks like "Part 2" of the manual is what you need...

[ARC Tech-109]

Update.... Chip Chester you hit that one right on the head! A number of smaller caps leaked out on the Video Proc (VPR-1) board in the input block and DAC areas and over time the contents eroded the traces away thru electrolysis. The caps in question are all local supply decoupling filters and I suspect their failure was a result of HF supply ripple getting thru after the supply caps popped. A weird failure indeed thats exhausting my parts supply, all the boards are going to get re-capped on the supply rails.

I owe you a cigar!

109

[kf4rca]

I saw that problem on a BVP-370. Of course, I had a working one right beside it so I could swap modules. I was able to get it up and running by Noon News.

[Chip Chester]

On certain vintage decks (15+ years old), you also need to watch out for the brown or yellow glue situation. It's an adhesive used to physically mount components that may otherwise fatigue the mounting leads/solder attachment because of vibration in shipping or mobile use. The glue becomes acidic and conductive over time, which can really spice up your troubleshooting/benchwork. More info from one of many electronics forums that have discussed it:

https://www.eevblog.com/forum/projec...lue-easily/25/

I'm willing to bet it's been discussed here and on AK as well...

[kf4rca]

Those silver filter modules on the Y/C boards in analog Beta's had the same glue problem. You had to remove the filter and scrape the glue off with a solvent (like xylene). I'd touch up the solder before re-installing them. There was a service bulletin out concerning this.
Not so adept techs would just order a new filter from Sony but then you had a machine down for a week.

[ARC Tech-109]

Thanks for all the replies. Unfortunately this has become the deck from hell and soon to be a pile of parts to repair another Digibeta. My feeling is Sony rushed the technology out the door just to beat out the competition and keep a hold on the betacam format... didn't we see this with 3/4, Betamax and that 8MM format? On the flipside Sony really pushed the envelope the the overall construction of the betacam machinery, they could have invested in better electrolytics considering the new machine cost... I seem to remember this being around $58,000, the cost of a modest house in 1993

Will post more when the other deck arrives.

109

[Chip Chester]

There was a big capacitor thing back in the day. They all sourced from the same places, and they pretty much all had the same issues. Tales of incomplete industrial espionage and imperfect production abound.

[MIPS]

Originally Posted by Chip Chester

There was a big capacitor thing back in the day. They all sourced from the same places, and they pretty much all had the same issues. Tales of incomplete industrial espionage and imperfect production abound.

There is another problem I've been running into with professional A/V gear from Sony (really all the big names in general) which is their heavy adoption of surface mount style capacitors starting in the late 80's. It's been well accepted for at least a decade now that these were not faulty like the crap cap plague but they are reaching the end of their useable life and internally breaking down and leaking their electrolyte. The leaking electrolyte and the drifting cap values causes all sorts of problems and really the only fix is to replace them even though some tape transports can contain hundreds of them. I got multiple DVCAM decks piled up that are basically unusable because it's presently just not worth it to replace over 100 capacitors.

That all changes however with modern SMD caps. I'm concerned how many devices I've run into that were less than five years old and were populated with caps but most had already drifted out of spec.

[kf4rca]

I think it's the environment the equipment is in. Our station inherited some SP equipment (BVW75s) from our Phoenix station. I was surprised to see signs of electrolyte running out of the leaded caps. That was a dead give away in repairing it.
But who knows what kind of environment those machines were in. Maybe they were sitting in a hot storage room for a while.
The machines naturally ran hot so it was important to have good ventilation in the area.

[Chip Chester]

MIPS wrote: "I got multiple DVCAM decks piled up..."

I've got three myself -- DVCPro Panasonics -- that worked fine when last used about 6-8 years ago, but who knows now.

Need some tape stock?

[kf4rca]

Here's what I know about DigiBeta:
A major source of trouble was the slip ring assembly. You had to clean it periodically and afterward run an auto setup. You played an alignment tape and it did the setups automatically. If it passed, you cursored down to save to NVRAM and then exit. If it didn't pass most likely you need a new slip ring assembly.
The DigiBetas are 10 Bit Discrete Cosine Transform and they SX's are 8 bit MPEG so they are not interchangeable.
Digibeta is a production format and SX is an ENG format. Both decks will play analog tapes. At one time we had THREE formats in each of our eight edit rooms. That was after the new company bought us and decided to go DVC Pro. The news photogs liked the SX cameras the best. It was the most robust. The DVC Pro seemed to be the flimsiest and gave a lot of trouble. But the cameras were cheaper. A DVCPro camera with lens was about $17K. And Panasonic was giving a special deal to CBS stations who bought them.
A possible source of parts is AheadTek:
http://www.aheadtek.com/

[ARC Tech-109]

Wish I had the room for a type-C deck...

[Chip Chester]

Pretty much the same footprint as a 21" CRT. And twice as tall if the TBC is integrated. 3x as tall if it's a separate unit. I had a couple of them for a year or two, before the format swing to digital. Ended up donating them to a kid's science museum where they let kids disassemble/reassemble them, under un-powered supervision, of course...

[ARC Tech-109]

Yeah they were big. I got my first taste of the Type-C format as a student of broadcast & production during my sophomore year 1986 and spent the morning of January 28 at our local ABC affiliate capturing the press pools on 3/4 and a B-roll of raw NASA video on a BVH-2000. I remember looking up at the monitor bridge just when the shuttle exploded, the rack was taller than I was at 16. I still have that B-roll today