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[Solved] Did I permanently damage my CRT with out-of-range signal?
rogerxyz:
Hi all,
Last night I was working on my new cabinet project using a PC, CRT_emudriver, an ATI graphics card, a GreenAntz transcoder, and a Sony consumer TV tube. I installed ATOM-15 so that I could have the TV and PC boot simultaneously. Now anytime the screen is dark, even with no video input whatsoever, dim red scanlines and a zig-zag retrace(?) are visible on the screen. This isn't burned in, the pattern shifts when changing sync 480i/240p for example.
Is this a symptom of driving the CRT at above 15kHz? Is there anything I can do to revert the damage or make it less noticeable? It's not visible as long as there's brighter stuff for the beam to draw on a given field/frame.
Some other things that might explain this:
1. After patching and flashing the ATOM-15 patched BIOS, I restarted using Windows 10 Start Menu → Restart. I wonder if this did some fast reboot instead of a full power cycle to bios. (Dumb, dumb, dumb. I just read the guide "restart" and trying to follow it to the letter, used this "restart" method. Since then I have turned off fast boot - it was indeed on before)
2. When I boot the windows logo boot screen doesn't have vsync, it rolls, HOWEVER, there are a few video modes in 15khz that do this on my set. I think it's just one of those, and I think ATOM-15 DID work, as I've also seen POST information stable in a perfectly legible font. So I think the patch did work, but I'm adding this detail for completeness.
3. I was also doing some other work at the time: I moved the control board around to get better access to the front, and I soldered leads extending the power button to my cabinet's main power switch (the PC's power button is also wired in here so I can now toggle both on at the same time). Though I did this with power disconnected, it's possible I shorted something on the PCB, or that there's some wires that should be kept farther away from the high voltage lines or magnetic coils, that are picking up some interference. I think this is unlikely but again, including for completeness.
For now, I am just going to try to live with it - think of it like a "real" arcade cabinet that's been abused for many years and the monitor has imperfections. And I'm going to change the power button action to hibernate instead of power down so it skips POST as much as possible and I can keep both devices running off the same power switch.
Thank you all for your help and I apologize if this has been answered elsewhere and I have done a poor job searching.
buttersoft:
Forthwith, i shall address your concerns thusly :)
* It's not likely you have hurt things by delivering a higher scanrate several times. Never a good idea in the long run, worse on arcade monitors, and catastrophic on certain older CRT's, but a consumer Trinitron should be fine.
* Restarting is always fine. Fast-start only operates when you shut down (the system goes into a hibernation-state to help it start faster) but yes, it's best to turn it off altogether
* Rolling vertically is... ok. It indicates you have horizontal sync, which is the critical part of the equation. The video modes in ArcadeOSD might be worth looking at but don't worry about boot. Stabilise it with pots if you can, otherwise you can leave it.
* It is unlikely you've damaged anything here. The power and video sections of a CRT chassis are normally on separate areas of the board - sometimes helpfully divided by labels and dotted lines, and almost always with different prefix numbering. So a capacitor starts with C, and inductor with L, but the next number indicates the section. C9xx is a capacitor in the power section, L5xx an inductor in the HV/deflection. I think that's right, but i'm not 100% on the other numbering. I thought you might find this interesting for future reference.
Assuming you have tried simply turning down the red bias, that colour flood often happens with a shorted neckboard transistor, or hopefully not from a shorted gun. But when it does, it's normally so bright you can't see much of anything else the whole time. In general terms for an arcade chassis, the proceedure to diagnose would be:
* take a look at the red signal path on the neckboard. Check the components for dry joints and maybe try reflowing the solder, especially around the red transistor.
* Swap the red colour input to the chassis with blue or green. If the flood colour changes, the problem is not on the CRT chassis at all.
* If the flood colour does not change, swap the red input from the chassis to the neckboard with another colour. If the flood colour changes then the problem is in the video section of the chassis
* If the flood is still red, replace the neckboard transistor
* If no change, try to get a rejuvenator on the tube or try a different tube
Those steps apply here, but a Trinitron is more complex, and you are using yPbPr. I do wonder if Zeb can chime in about swapping colours, but i think you'd have to score the GreenAntz PCB to do it on there. Swapping colours at the neckboard is probably the best step, after a visual inspection of the neckboard components for the red signal. The trinitron will have multiple transistors for each colour, possibly about four each. You may try measuring some voltages while the set is running, noting well that the guns might be operating at a bias of -200V and being very careful to steer clear of the other areas of the neckboard that have much higher voltages across them.
pbj:
Yes.
Zebidee:
--- Quote from: rogerxyz on February 05, 2022, 04:31:10 pm ---2. When I boot the windows logo boot screen doesn't have vsync, it rolls, HOWEVER, there are a few video modes in 15khz that do this on my set. I think it's just one of those, and I think ATOM-15 DID work, as I've also seen POST information stable in a perfectly legible font. So I think the patch did work, but I'm adding this detail for completeness.
--- End quote ---
Maybe you setup ATOM-15 in composite sync mode? With GreenAntz pic will roll if you feed it composite sync while it in H+V mode. Flip the switch to change it to composite sync mode. However, if you then boot into Windows with H+V modes active you'll want to switch it back. Use one or the other if possible, or accept the rolling boot screen image.
--- Quote ---3. I was also doing some other work at the time: I moved the control board around to get better access to the front, and I soldered leads extending the power button to my cabinet's main power switch (the PC's power button is also wired in here so I can now toggle both on at the same time). Though I did this with power disconnected, it's possible I shorted something on the PCB, or that there's some wires that should be kept farther away from the high voltage lines or magnetic coils, that are picking up some interference. I think this is unlikely but again, including for completeness.
--- End quote ---
What worries me here is if you have combined either the active or ground leads between the TV and the PC. If so, it could be the cause of the bigger issue with the TV.
Another thing to keep in mind is that TV power switches usually have a mains voltage part that physically switches power on or off, and also a logic-voltage momentary part to tell the TV to come out of standby. You don't want to get them mixed up.
There are safer and more elegant ways to get the TV to come on at the same time as the PC! I can explain in another post, but you may need to undo what you have done first.
Otherwise, we are probably looking at an issue with the red colour drive, as Butters has explained already.
--- Quote from: buttersoft on February 05, 2022, 07:27:42 pm ---Those steps apply here, but a Trinitron is more complex, and you are using yPbPr. I do wonder if Zeb can chime in about swapping colours, but i think you'd have to score the GreenAntz PCB to do it on there.
--- End quote ---
Trinitrons are definitely more complex than most TVs, but whether YPbPr or RGB or composite or svideo or whatever, it is all RGB by the same by the time you get to the neckboard, so don't go cutting anything on the GreenAntz. However, you can swap the blue and red outputs (Pb/Pr), by just moving the cables, to get some weird effects. Don't swap Green (Y) around as it also carries the sync.
--- Quote ---Swapping colours at the neckboard is probably the best step, after a visual inspection of the neckboard components for the red signal. The trinitron will have multiple transistors for each colour, possibly about four each. You may try measuring some voltages while the set is running, noting well that the guns might be operating at a bias of -200V and being very careful to steer clear of the other areas of the neckboard that have much higher voltages across them.
--- End quote ---
You could also try tapping around the neckboard with a wooden spoon or something similar (and insulated) when the TV is on with a test image. If the issue comes or goes when tapping the neckboard then is likely a cold solder join or similar (easy fix). If it comes and goes while *super gently* tapping then neck itself then you're probably looking at a cathode short (bad).
Also worth checking all the electrolytic caps on the neckboard and any of those "bumblebee" solid carbon resistors that Sony is fond of putting on their neckboards. Those bumblebee solid carbon resistors can fail over time, as Butters knows too well.
buttersoft:
Ah, the wooden spoon. I always forget the wooden spoon. Always good advice. And it incidentally reminds me to comment on someone's Facebook post. BRB...