Diagnosing the DXC-M3A

[sdsw4]

So, I recently got ahold of a Sony DXC-M3a. Being a 40-year old camera, I expected troubles.

However, this issue is baffling me.
Note, the videos have a flickering which may trigger epilepsy.
https://nsysdev.com/badcamera/cameraglitch.mp4
https://nsysdev.com/badcamera/cameraglitch2.mp4 (set the switch on the camera to camera-generated color bars at the end)
The camera was not touched at all making these videos, just grabbed the composite with a capture card (the viewfinder also shows the same thing).
Objects used in the first video

Scene in the first and second videos.


I checked the HV supply board, the caps are within tolerance and the voltages are within specification. The amplifier board checks out as well, switching the opamps and ic's between channels did nothing.
Also, when switching the tubes (plugging the red and blue tubes into the then working green's and blue's plug) the issue doesn't follow with the tube, green now just shows what the respective tube is picking up without issue. So at least the vidicons are good, *knock on wood.*
Lastly, checked the deflection board through the test points, and the waveforms match with what is expected.

I'm looking for advice on where and how to look next to figure out what may be wrong. I'm lost as to what other board(s) may be causing the issue, and I could have even overlooked something.
Thank you!

[ARC Tech-109]

I've owned my DXC-M3A since the early 90's and looking at your caps I'm only seeing a bad red/blue registration. Can you better describe the glitch or issue? I still have my M3a and it still looks great.

[sdsw4]

Thank you for the reply. The videos showcase pretty much what's going on with the unit, but I don't know where/what board to look (or what I should be looking for e.g. waveforms at test points or voltages) that's causing it.
But specifically, yes the lack of blue and red that does the periodic and usually rhythmic "flashing back" before dying again.

I'm honestly stumped, when I first got the camera it produced a beautiful image for a few minutes and then this started happening.

[ARC Tech-109]

Hmmm this has me puzzled. They are a static deflection camera with only magnetic focus, guess I'd start with the voltages on the green tube socket and work my way around from there. The M3A is three discreet camera sections one for each color coming together at the IQ encoder board but I'm unable to play the mp4 encoded video content so I can't see the actual glitch, only the opening frame.

Sony had a bad habit of using an adhesive on the boards to secure jumper wires and that adhesive is known to break down over time and become conductive see picture-002. This is on the back of the PS board. Just above the PS board connector is a line of test points see picture-004.

Does both the red and blue glitch at the same time or is this a random thing with the two colors? On the EN board move the right switch to the MON position, this will switch the viewfinder over to the R-G B-G alignment mode where you can actually look at what the tubes are seeing, one inverts the color over green for doing the registry alignment. I don't recall what the positions are for what function so you will have to play around with them. no damage can be done here. Another switch (pointing at) selects the viewfinder between color/B&W mode, B&W is the default here. There is a 3-position slide on the far end marked S4, this is an encoder test switch that by default is in the center position.

You have quite a challenge on your hands here with this one. The M3a was one of the most advanced cameras of its day and the favorite of news crews before the BVP-3 package took over. I used mine with a a JVC CR-4700 U-Matic at first before going with the Sony BVU-150 then graduated to BetacamSP.

[sdsw4]

Gotcha. The glue on the back of the boards actually looks like... glue and wasn't conductive. But it's on my books to remove it since my experience with vintage computing tells me if it's not bad now it'll go bad later. And destroy the board in the process.

I also verified voltages at the board where the tubes connect to: they match what the service manual says they should be not only at the connectors but throughout the board, and remain stable when the tubes are connected.

The red used to be the only color that would "come back" "flash" then die, repeating in a rhythm. Now red is completely dead, and it's blue that does it.
If needed I can re encode the videos to something you can view. Surprising to me, mine looks to be in better condition than the one in your pictures. But I suppose condition means nothing if it doesn't work right...

[sdsw4]

Well I apologize for le dobule post, however I've decided that instead of wasting time trying to "figure out" the problem, I have opted for the nuclear approach.

Since the tubes are tested fine, I have begun documenting every single tantalum and electrolytic capacitor in the camera and will place a large order. I have also begun socketing the op-amps and other failure prone ICs in order to make future replacement easier.
As such, since I decided I'm no longer diagnosing but overhauling, I would like the thread title changed to "Overhauling the the DXC-M3A" as I will be documenting the process.

That being said, I have a question for the community. What are places or people I should ask about acquiring replacement saticon tubes? I can't find the specific tube in this camera online, but I suppose there has to be someone holding onto NOS tubes or knows of an equivalent.

[ARC Tech-109]

Good luck on the saticon tubes, I have not seen any replacements for the better part of 30 years and whatever is out there is questionable at best. Sorry to be the rainmaker but with over 30 years of experience I'm only saying it like it is. Once CCDs and the ENG package took over the M3 series quickly fell out of favor. Despite being almost blind it's a wonderful camera for those who have the lighting budget, they have a wonderful color accuracy and picture "look" that says I'm a real professional without getting edgy with the contours.
I have not used my M3 for anything serious in 25+ years and it's since become a corner piece collecting cat hair.
Before taking the shotgun approach I'd strongly suggest finding a service manual for the M3 series and familiarize yourself with the details especially with the front end amplifiers hiding in the tube ends.

[sdsw4]

Originally Posted by ARC Tech-109

Before taking the shotgun approach I'd strongly suggest finding a service manual for the M3 series and familiarize yourself with the details especially with the front end amplifiers hiding in the tube ends.

Unfortunately, that's what I've been doing. Based on the waveforms and voltages, the camera should be functional. In the meantime, for the "edgy" and torturous feel, I guess I'll have to clean up and deal with the M7 since it's the only other vintage SD camera I have that is similar in capability.
Really sucks that nos saticons are nill, but it looks like the tubes in this one are good. It honestly looks like for most of this camera's life it was left on preheat mode in a studio. When I first got and fired up the camera, nothing quite matches my awe when I saw the quality it output, before failing.

Either way, I'll go board by board, starting with the PS board. I'll keep posted.

[sdsw4]

100000000 times THANK YOU ARC Tech-109!
The M3a is now functional thanks to you!


Granted it is in dire need of a tube alignment and white balance (and a better capture card), it works!
As I suspected, the PR-61 board on mine was faulty as well as the IE-7 board.
Had to have every flashlight and lamp pointed at the subject, but I expect that from a tube camera.

[ARC Tech-109]

Actually the registration isn't too far off judging by the picture here, just take your time and tweak the deflection board using the manual and it will all come together. Use the AWB and ABB then auto center switches on the front before getting carried away with the adjustments, the auto adjustments on these are quite good and M3 cameras are exceptionally sharp once adjusted right with a well lit subject.

A tangent but related.
I don't know if its in your budget but if you're looking for a good high quality capture medium I'd suggest looking at a Newtek Tricaster either the TC550 broadcast or the TC350 Studio. The 550 broadcast will accept composite, S/Video Betacam and SDI digital on 6 separate inputs plus 48K AES audio and genlock and it has the same signalling on both the preview and program bus. The box runs under WinXP and if you find one out there without a drive I can build a legit system drive back up for you as there is a system builder partition on the drives that I can build from, all you need is the serial numbers which are on the box side and back. I have the TC550 Broadcast and the raw capture of this is second to none, the TC350 is just as good but without the SDI, genlock or AES audio I/O. They however will NOT run under anything other than the Newtek specific Windows XP that is on the recovery partition of an OEM drive, yes a step back in OS tech but I have yet to find anything on the prosumer market that captures as well as the Newtek boards without the 4:2:2 RY/BY striping or fuzzies. In a later post I will do a screenshot from a composite laserdisc source so you can see for yourself.

[ARC Tech-109]

I looked through my tape archive and found one I did using that DXC-M3a feeding a Sony Sony BVW-35 Betacam of downtown Mpls the summer of 1993, these are the actual images from that camera captured with my Tricaster Broadcast in composite video, I had to crop them slightly to fit within the upload limits but what you see is exactly what the camera produced and how it was captured on the Tricaster. If you want larger (full NTSC) size images drop me an email and I will send them your way.

[sdsw4]

Oh that's awesome!
Yeah WinXP isn't a far shot for me, I still use a computer with Windows 2000!

But otherwise, the TC5500 is a consideration for future stuff, but it is rather pricey. The 350 is cheap enough, but it lacks a few of the features I want that the 550 has.

Also, I went through the manual and it turns out I can use a lot of objects lying around and the camera will auto-align the tubes. I just pointed it at a light switch and it did a very good job. Honestly, even coming out of RCA I am surprised at the sharpness.


I'm now excited to figure a way to capture the RGB+sync output and see what this camera can really do.

[ARC Tech-109]

Yeah that's about what the M3 can do, I don't know about doing an RGB/s capture but one thing to look for is the camera control unit or CCU for these. They offer far more in terms of outputs than the camera alone. There is a Sony CCU-M3 on Ebay right now for $15.00 buy it now and I'd strongly recommend getting it as it has the RGB jacks on it. Do an ebay search for Sony CCU, there are a number available right now along with a few of the 14 pin cables. Get these pieces and you will have a nice camera chain to work with and learn from. I run the CCU-550 triax CCU and CA-TX50 adapter on my DXC-55WS to keep everything digital.

[kf4rca]

Don't forget to check the bias light while you're in there. They go bad from age, get black on the inside, and shock (ENG use). That sets black level for the tubes. Otherwise the tube's noise floor is black.

[ARC Tech-109]

The one I sent has a new bias light bulb with maybe 30 hours on it, thankfully they don't need much to bring it up out of the noise but I knocked it out removing the camera from the tripod shoe and everything went to mush.
Got any of the big IO tubes?