I recently got my hands on an old Panasonic AG-MD835 unit and was doing some initial testing against my other Panasonic AG-5260. I was planning on doing a small write up on the unit as there is little to no information on it, but ran into an issue that is appearing in the video output. I'll provide frame output comparisons as well as the full clips for review below.
The first test is the AG-MD835 connected through the DMR-ES10, using composite outputs for A/V from the VCR and S-Video from the DVD Recorder.
The second test is the AG-MD835 using S-Video for the output however NOT run through the DMR-ES10
The last test is the AG-5260 running through the DMR-ES10, using composite outputs for A/V from the VCR and S-Video from the DVD Recorder.
My opinion on the few results is that the AG-5260 has a far superior output, the colours appear to be much richer as well having an overall less noisy image. The differences between the first two situations are basically none from what I can see, however I would have thought that the AG-MD835 would have at least provided a similar quality if not better image.
My thoughts are that something is up with the unit, I haven't inspected it since I have purchased it but I do know that it was removed from a good working environment only recently and has less than 500 total hours. I'm not really well versed on VCR issues and the only things that spring to mind is either a dirty head or components otherwise, or something in the circuitry like the built in Line-TBC failing.
I would like to get a general idea of what to start looking for, or if this is simply just a normal difference between two different VCR's.
Note - The original test clip pertains to the last frame test and the other clip belongs to the first test (Second test clip not included).
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Were both decks in the same noise reduction mode? In other words, both have to be in EDIT mode or out of EDIT mode for a valid comparison.
The only option that should really make a difference in either of these tests is the Y/C filter on the AG-MD835, however for some reason it's called something different. I could only find a NTSC version of the manual which states this setting is a Y/C filter, the first two tests on this unit compare the difference. The first test is the exact same config as the AG-5260 and the second config is using the S-Video with what I'm guessing is the Y/C filter. When I get a chance I'll check what it is called in the menu as I can't remember off of the top of my head. As for any sort of "Editing Mode" I don't believe either of these units have anything like that.
For reference the AG-5260 has no configurable menu options, and like previously stated the only option that can be configured in the video signal for the AG-MD835 is the Y/C filter.
EDIT - Where the Y/C filter is in the NTSC manual on the PAL unit is called "Notch", whatever that means. Also on that same menu is the "Edit Mode" option which has been set to off and all of the tests will have been done with that off.
Last edited by Polsom; 15th Jul 2017 at 05:09. Reason: Added information
If you come across a NOS though I would still grab it simply for the fine tracking control, being able to scrub through footage frame-by-frame on an Analogue scale is a rare feature of any VCR. I'd also say there is definitely an issue with my unit and I wouldn't expect an S-VHS capable player to perform substantially worse than an Older Panasonic unit of the same class.
I have amassed a few more tapes that contain some unseen Analogue only footage, this along with the remainder of the other tapes I had left to convert that have just been left to deteriorate since, will hopefully get me interested in getting back into the project.
I found some interesting info posted by your host Lord Smurf. He seems to indicate this can be caused by worn out heads.
These medical units have all seen heavy use in hospitals. That's why I'm tempted to buy one that's never been used. I also know these Medical Panasonics circuits were based on the 7750 which has the vertical line issue on the overzealous TBC. I'm not sure if these would produce the same artifacts and Sony would be better, but it doesn't look to have the same chroma controls. However looking at your sample videos I'm not noticing any lines showing up in the image so that could only be an issue on the 7750.
Last edited by BenKlesc; 15th Apr 2021 at 09:38.
Did you try enabling edit in the menu of the AG-MD? Looking at the service manual at least the PAL version of the AG-MD830 uses the same main video ics as the NV-HS1000 (but is otherwise very different), and that one has a tendency to have weak color when edit is not on (i.e noise reduction is active.) I don't know if it's something inherent to the NV-HS1000 or if it's to do with electronics going bad.
EDIT: AG-MD835 seems to use pretty different digital video circuitry maybe akin to 7750 as mentioned and/or 1980p so maybe not. EDIT mode may make it clearer if it's not reading chroma well though. Weak chroma signal tends to result in more chroma noise.
Last edited by oln; 15th Apr 2021 at 12:49.
What will fade chroma though is a faulty or miss calibrated demodulator where the pure chroma signal got extracted or wrong setting.
The larger context of that conversation is that VCRs are to blame for "tape fade", and not the BS about the tapes themselves "fading". The color data is always present, but merely needs competent persons and equipment to properly extract it. Apparently lots of huckster services are/were incompetent, which we already know/knew.
Any claims of "NOS" are undoubtedly BS. From what I learned, those units were generally installed by a 3rd-party medical tech service, and hospital staff was trained on how to use those. These were never shipped in shiny new boxes to the hospital, and some local video/IT lackey forced to RTFM. I have friends that work in that sort of medical IT field (and IT includes basically anything electronic, not just compute).
My opinion on the few results is that the AG-5260 has a far superior output, the colours appear to be much richer as well having an overall less noisy image.
Here is the description off the original pamphlet.
"Panasonic AG-MD835P video cassette recorder with built-in digital time base corrector (DBT), 3-dimensional noise reduction, auto head cleaning. The Panasonic AG-MD835P is designed to meet increasing need for high quality video and audio recording/playback in the field of medicine. Advanced features like built-in TBC, DNR and 3-D Y/C Seperation circuitry help achieve the exceptional picture quality required for precise image analysis. The Panasonic AG-MD835P is classified by Underwriters Laboratories Inc. as to medical electrical equipment with respect to electric shock, fire and mechanical hazards only in accordance with UL 2601-1, Control number 76KA."