Engineering question: Tube Camera Survivability
 

So in coupling with my other thread about the M3a, I bring this question for engineers.

In my collection, I have the Sony M3a (being worked on) as well as a similarily aged and even more beat-up HVC-2200.
However, right now, somehow the consumer 2200 is the only tube camera I have that is actually operational. And I bought it partially broken out of a pawn shop.
Attachment 205376

Seems like the professional camera should have 100% outlived the consumer camera, but instead the professional camera needs the overhaul while the consumer camera runs fine.
So my question for preserving this hardware is, what exactly determines how a vintage electronic television camera survives as operational for 30+ years? Such as what forms of maintenance, design, use and storage allow some cameras to outlive others?

Deleted on review, irrelevant to query.

Cameras will be subject to the same failure modes as any other old electronics for everything except the pickup tube itself. This all depends on the components used, how stressed they are in the design (voltage/power ratings, heat buildup - you know the drill), amount of use.

The pickup tubes themselves are particularly prone to cathode wear compared to other tubes due to the small cathodes used to get a fine scanning spot. Standard definition tubes will have a longer life than high definition because of the larger cathodes. The longest life is obtained if the tube is fired up at least every three months or so for a few hours of use. This tends to sweep up any gas accumulation.

The first Sony HD Saticons were guaranteed for only 800 hours. In studio use, this would go by quickly. The ones we had in the early BTS camera at Zenith were run much longer than this and still had good performance, but after reaching many multiples of the rated lifetime we retubed the camera as a precaution (at a cost of $85,000).

Side note: the preamp for the Sony HD Saticons was soldered directly to the tube faceplate for minimum stray capacitance. Sony would not sell their proprietary low-noise preamps, but they were already installed at the factory. So, BTS could buy the tubes, but had to unsolder the Sony pre-amps and return them to Sony, and solder on BTS pre-amps.

A problem that's affecting a few earlier camera tubes is helium ingress. The glass is permeable to helium and despite the low concentration in the air, there's a density gradient across the glass.

The beam travels a long distance at low velocity so even a farily small amount of gas will cause trouble.

Yep. That's supposed to be reduced by occasionally firing them up. I don't think I knew it's specifically helium, but that makes sense.

I can't see how firing up te tube will make any difference to the helium. It will help with the cathode which often seems to become "sleepy" (for want of a better word) when not used. Many of us have seen CRTs that look bad when first switched on but cheer up after an hour or so.

That explains why my Samsung "thin" HD CRT looked really awful when I pulled it out of the grave, aka my basement after a few years but looked much better after an hour of use.

Of course nothing will fix the deflection flaw, but still a damn good TV.

I am only relaying the words of the camera manufacturer's rep: "gas."
Whether this was helium or something else, or was another effect, I can't say, but the connotation was that degradation would be permanent and worse with longer periods of disuse, not reversible like cathode "sleepiness." Whatever was going on, it was confidently stated that periodic use helped extend the life of the tubes.

One thing that contributes to the gassing of imaging tubes is the soft seal used to bond the target to the cylinder, this is not a glass to glass bond as the heat would destroy the target composition so instead its a polymer and they do deteriorate over time.

very interesting info
I had heard the advice to power up the tubes periodically but ignored the reasons

btw and slightly off topic, I'm also a proud owner and user of a Sony DXC-M3AP, a wonderful camera. it recently started to fail after some time in operation, picture from one tube suddenly twisted.

After much probing and ultimately swapping the coil circuits from one tube to another, and revising all the deflection electronics etc, I came to the conclusion that the focusing coil of the green tube assembly failed (short in the middle of the coil?)

I'm not sure if it's a frequent failure and what's the cause, but if you have some spare tube assembly to sell me please contact me :)

I've been able to capture the moment in which it allegedly fails, in the video below

see how the part of the sensor normally not scanned gets scanned after the coil fails, how bigger gets the FOV after that

https://drive.google.com/file/d/1SJG...ew?usp=sharing

(video download button at the top right part of the google drive preview page)

I'd look at the tantalum capacitors (and electrolytics) in the magnetic focus and deflection circuits. I had a DXC-M3A for over 30 years and know they're electrostatic deflection system isn't the most robust, I highly doubt the mag focus coil has shorted as these are running at only a few volts.
One thing electronics from this era is known for is the little dabs of bonding glue the factory used to secure various parts to the boards and it's known to rot over time and become conductive. The HV supply on the top has a number of parts secured to the board using this glue and it's a really good ideal to get in there and clean it ALL off using whatever methods short of a heavy wire brush. I found acetone works best with this but regardless of how you remove it all traces must be removed and it will take some effort. The glue is also known to damage the green solder mask along the traces so do be careful and recover them with clear acrylic nail polish.
Pull the plug from the board for the green focus coil and swap it with another say the red or blue and note the change.

That looks almost like when I tinkered with the camera focusing! It looks like the deflection on the green is still going, but something did "go."
I second the "plug swapping," but be wary of those HV connections when the camera is live, they pack a punch!

I second checking for rotting glue, then check for blown tantalums. On mine, the electrolytics also did literally "just blow out" recently so I would check those too.

But, if I simply unplug the the Green focus on mine it goes from this:
http://videokarma.org/attachment.php...1&d=1729750171

To this:
http://videokarma.org/attachment.php...1&d=1729750249
So it does look like the green isn't "completely" gone, but again I second investigating those circuits with the help of the service manual.
Luckily the one for the M3AP is readily available so that would be a good help as well.

I did make a "Diagnosing the M3a" thread a while ago. I wouldn't mind if you hijack it, and I don't think it would be a big bump either.
http://videokarma.org/showthread.php?t=275482
If you do need someone to make comparisons, the NTSC model isn't all that different from the PAL model, so I'm happy to help.
Especially since Arc Tech's dying camera helped bring mine back to life. Least I can do is help someone else fix theirs!

From my experience it seems to be a crapshoot which camera tube survives. Old Sony monochrome cameras from the early 70's have been the most reliable in my collection. AVC-3200, AVC-2350, AVC-3400 ect.

A Panasonic WV-033P (circa 1968) was the most troublesome to get running. It turned out to have a dead germanium transistor, a high ESR electrolytic and a dead Vidicon tube. It's been running good now.

I think there are a lot of other component failures in cameras that are being mistaken for tube failures these days. You have to consider that the average color vidicon camera is now over 40 years old running on it's original capacitors. I've powered up many that I highly doubt have seen power since the 1990's and the color was bright and sharp. More often they fail after a while and require readjustment to bring the colors back.

I would very much like to see footage from that WV-033P if possible please.

The best I can do at the time is photos off a tv screen. I still have to get something happening for analog to digital conversion. I'll post some screenshots in a day or two.