Ok, so its not a TV, but it does have a CRT and displays (supposed to) a picture. Mods by all means please move if this is in the wrong category.
I need a little help with this unit which I acquired some time ago. I cleaned out the cobwebs and let it dry out thoroughly. I couldn't see any sign of damage, bulging or exploded capacitors or scorched resistors so once it was thoroughly dry I eventually applied power. The lights come on and the CRT flickers momentarily and the tube lights up a bit if I turn the brightness all of the way up so at least we know that the CRT tube is working. There are no artefacts or squiggly lines that would indicate flyback or timing issues.
The idea was to use it for a Pi project to display retro games on a CRT monitor. I have purchased a HDMI to RGB adapter so that I can view the image on the CRT and connected up the Pi to HDMI and the PVM to the RGB inputs. However, I cannot get a stable picture. I see various colour and white sloping squiggles flashing by so clearly there is an input from the Pi but it is obviously all out of sync. I have tried various resolution options including 576P, 576i, 480i etc but none work. I am not sure which is the correct frequency to use, but I have tried all of them and none work. The problem is that I have no idea at this point whether that's down to the Pi, the adapter, or the PVM itself and I don't have anything else with which to prove whether the PVM otherwise works OK or not.
There are a number of inputs so presumably something could be used to test it, but I am not sure what to look for? I am guessing that a TV pattern generator may not be the best choice as there is no UHF TV input. It is possible and indeed likely that the monitor needs some work as it had apparently been in storage for quite a number of years prior to my acquiring it.
I would appreciate any insight into what I might need to test it?
@waveydipole In brief - 576i for the Pi and most pattern generators have an unmodulated (baseband) video output. Where are you getting the syncs for the monitor if you're feeding it RGB? Not all monitors 'do' syncs on green.
Hmm, that's a valid question and its possible that I am not. The adapter I have does not have a Sync output. However, I do see on the monitor that there is an EXT SYNC input. The outputs on this thing are actually marked Pr, Pb and Y. I had assumed that Pr and Pb are red and blue, so by elimination Y must be green, but am not familiar with these markings.
Possibly there is somewhere internal to the adapter where sync could be picked up from, or perhaps I can split the Y to both the G and EXT SYNC terminals?
Noted its 576i. Thanks.
OK, Pr, Pb and Y are called Component Video. Works like this:
Y is the Luminance or B&W signal and should also contain composite sync.
Pr is the Red colour difference signal, that is, the red where it differs to the luminance.
Pb is the same for Blue.
What about the green, you ask? Well, if you know the Red and the Blue and the Luminance, you can derive the green. It's like if you know two sides of a triangle, you also know the 3rd side. Best I can explain it without resorting to the maths!
If you connect the Y signal to the monitor's Composite Video input and get a locked B&W picture, the monitor can handle your scan rate. My guess is it probably cannot, it is basically a composite video monitor for TV scan rates. What you need is an HDMI to PAL converter.
This all sounds very familiar! I got my hands on a PVM-1271 some time ago, See this thread for my attempt at reviving it.
I was getting confused about feeding it a signal, as I thought that RGB and component video were the same thing! I also didn’t know that the monitor needs external sync. I ended up making a SCART to RGB plus sync/composite adapter cable which works very well. So if you have a component video connection, plug that into the sync socket, and it should then sync, so long as you have external sync selected. But if you are feeding it component video then you’ll end up with a funny coloured picture!
But if you are feeding it component video then you’ll end up with a funny coloured picture!
Now compare with SLog3 pictures on an ordinary monitor, or ordinary pictures that have been through a SLog3 LUT...
OK, Pr, Pb and Y are called Component Video. Works like this:
Y is the Luminance or B&W signal and should also contain composite sync.
Pr is the Red colour difference signal, that is, the red where it differs to the luminance.
Pb is the same for Blue.
What about the green, you ask? Well, if you know the Red and the Blue and the Luminance, you can derive the green. It's like if you know two sides of a triangle, you also know the 3rd side. Best I can explain it without resorting to the maths!
If you connect the Y signal to the monitor's Composite Video input and get a locked B&W picture, the monitor can handle your scan rate. My guess is it probably cannot, it is basically a composite video monitor for TV scan rates. What you need is an HDMI to PAL converter.
Thank you for the detailed explanation and I get your point about the triangle. Maybe I did buy the wrong box. There is a flood of various boxes available. Having had another look, I see there is a cheap (7GBP) "HDMI to AV/Componsite CVBS S-Video/RCA/NTSC/PAL" box available. This has a HDMI socket available on one side and three phono sockets - two audio phono sockets plus one yellow video socket - on the other side. Would this be the type to get? The is also a more expensive version in a metal case which has the same HDMI in, white, red and yellow phono sockets on the other side, but also an additional HDMI output as well, but is more expensive (27GBP). Both seem to do the same thing, i.e HDMI to CBVS/NTSC/PAL. The later also adds the words 'auto scaler'. Not sure what that does? Would the yellow video output then go into one of either Video1 or Video2 BNC terminals of the PVM?
I tried putting Y into Video1 and Video2, but got nothing.
This all sounds very familiar! I got my hands on a PVM-1271 some time ago, See this thread for my attempt at reviving it.I was getting confused about feeding it a signal, as I thought that RGB and component video were the same thing! I also didn’t know that the monitor needs external sync. I ended up making a SCART to RGB plus sync/composite adaptor cable which works very well. So if you have a component video connection, plug that into the sync socket, and it should then sync, so long as you have external sync selected. But if you are feeding it component video then you’ll end up with a funny coloured picture!
Looking at the photos in your thread, externally at least, the unit I have looks almost identical to yours but the controls are a little different. I tried plugging Y into EXT SYNC and switching Sync to EXT. This did do something. Briefly there was a red full screen background followed by some patterns which I think were the distorted Retropi logo. Couldn't see any characters though and it wasn't stable, but it did respond to vertical hold somewhat and at least I could see that it was trying to display something, which is more that I have been getting so far.
Incidentally, the second HDMI port on the Pi was already set to 576i with a frequency of 50hz, which is the lowest 576i option available. I tried 576i at 100hz and the lines were horizontally doubled. I guess it can't sync at either of those frequencies.
I will purchase the other box if someone can confirm that I am describing the correct one?
I’ve just realised I made another cock up on my last post where I said:
So if you have a component video connection, plug that into the sync socket, and it should then sync
Which should have said:
So if you have a composite video connection, plug that into the sync socket, and it should then sync
sorry about that! Too many words beginning with comp…
Those little converter boxes can be a minefield of misinformation, the descriptions on listings tell you they are RGB, but actually it’s component, just with red green and blue plugs! Can we confirm if this monitor can accept component video? Or is it just RGB like the one I have? I sort of gave up looking for a HDMI to RGB adapter as I couldn’t find one that actually was RGB… can you try the monitor with any other signals? Such as composite?
The monitor has several inputs which are illustrated and described in the manual:
LINE A / LINE B VIDEO IN/OUT:
BNC - Accepts video output from a Videotape Recorder or Video Camera.
VTR:
8-pin (2 rows x 4) plug that I have not seen before. Accepts input from a VTR
The illustration shows professional type devices being connected to these three inputs rather than consumer level devices.
EXT SYNC:
2 BNC connectors for IN and OUT
Nothing illustrated as being connected here.
RGB:
Three pairs of In/Out phono connectors for R, G and B
Computer:
25-pin D connector with TTL pins that can control the on/off state of various functions such as the mode select switch, RGB/Normal, V-sync, luminance and blanking, but also has RGB and audio input pins.
The RGB and computer connectors show a computer connected to them. All the BNC connectors have a 75ohm switch next to them. Each group of video inputs also has an associated stereo audio input.
There is a note saying that if a microcomputer has a composite video output connector, then it should be connected to LINE A or LINE B VIDEO IN connector. This would suggest that the two VIDEO IN connectors accept composite video input. I am not sure whether professional level devices have different standards to consumer devices?
VTR:
8-pin (2 rows x 4) plug that I have not seen before. Accepts input from a VTR
The illustration shows professional type devices being connected to these three inputs rather than consumer level devices.
Standard connector used by Japanese VTR manufacturers in the 70s and 80s - made by Hirose if memory serves me. Does video and audio in/out.
There is a note saying that if a microcomputer has a composite video output connector, then it should be connected to LINE A or LINE B VIDEO IN connector. This would suggest that the two VIDEO IN connectors accept composite video input.
Correct. Well done.
I am not sure whether professional level devices have different standards to consumer devices?
No they don't, else there'd be little point in calling them 'standards', wouldn't there? It's absolutely the same: 1V peak to peak into 75Ω.
Ok, I have another little black box on order. This one takes a HDMI input and claims to output CVBS so I am hoping that a single phono-to-BNC cable connected from the yellow phono socket to the LINE A or LINE B socket (plus the audio cable) will work. It shouldn't take too long for it to arrive.
Yes, that should work. I have one of the HDMI to AV boxes which does that. I had another look for one that does HDMI to RGB, but couldn’t find one, only HDMI to component.
OK, that 8 pin connector has the following layout:
1 5
2 6
3 7
4 8
Pin 1 is audio in to the monitor.
Pin 2 is video (CVBS) 1V p-p into the monitor and is terminated with 75 ohms
3, 5, 6 and 7 are Ground for the pin nearest it.
Pin 4 is CVBS output from a tuner, if the TV has one.
Pin 8 is audio output from a tuner.
You would plug your UMatic VCR into it and, if there was a tuner, you could record from it.
The standard goes back to the days of 1/2 inch EIAJ reel to reel B&W video recorders.
The scary thing is, I didn't even need to look that up! It's well and truly imprinted from lots of use, many years ago!
The new HDMI to CVBS converter box arrived today and seems to be working. The first thing I got when I plugged it in and powered it up was a stable colourful bright test card which finally proved that my monitor is working OK. I couldn't initially get any output from the Pi, just a 'NO SIGNAL' message until I changed resolution, initially starting at VGA. I then tried 720p and 1080p both of which did display an image. At 1080p the text is illegible, at 720p barely. I then went back to 576i and got the 'NO SIGNAL' message again, so I tried 576p and got a picture. It does appear rather condensed though. I was expecting a bit of a black border, but I don't remember it being quite this wide. I probably need to tinker a bit to see whether I can't get the image to fill the screen a bit better.
Anyway, thanks for the advice. Clearly I had purchased the wrong converter box the first time around.
