[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]

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.

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.

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.

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.

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.

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.

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.

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...

[rogerxyz]

Thank you, Butters and Zeb, for your consistently insightful feedback and your eagerness to share your wisdom!

First things first, let me just untie the grounds from the PC and TV and see what happens. I will report back. I thought we were okay here since they are both on the same mains circuit and we're talking about the low-voltage side of the trinitron motherboard, but this is what you get when you have armchair electronics idiots like myself who are handy with an iron but have never learned anything past Ohm's law.

As for it being an input issue (e.g. external to the chassis) I think we can rule this out since I can see this pattern when the tube is dim on completely other inputs and even when disconnecting any inputs.

Hopefully it's just my dumb mistake tying the power switches. Fingers crossed.

[rogerxyz]

No real luck leaving my extended leads to the front panel's power tact switch floating, I'll get to work removing the trinitron's main board and undoing my work there nonetheless.

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.

I tapped into the little tactile momentary power switch button on the front panel, in the control cluster with the other physical controls Vol/Channel/Menu/etc., I was under the impression that was more of a soft/logic level switch, gosh I really hope I didn't make a dumb assumption.

I want to correct that the issue is visible with no input, that's not correct. It's definitely dependent on sync as the pattern changes between video modes. But on disconnecting the Pr component, the traces are still there and still red, if that affords any information. Swapping out the input with a playstation 2 using the same component connections exhibits the same red scanlines on dark screens.

Will report back after reconnecting the main board to the neckboard, I'll use that time to check all the connections more thoroughly, though I did a cursory check before. Thanks for sticking with me.

EDIT 1: It's also worth reiterating that I somehow created this issue the last time I opened the cabinet; I did not notice it before. It seems less likely then that this would be down to a cold solder joint but I don't want to rule anything out. 🙏

EDIT 2: I was thinking, and I was like "would I really have tied the PC and monitor together?" and I remembered, no, I checked that the switch was DPST first. I re-verified this just now. So I don't think they were ever on the same circuit. (I do a quick flip to ON/closed and back instead of leaving it toggled, to mimic the momentary switches on the PC and monitor)

EDIT 3: I should emphasize that the photo I've shown was taken in complete darkness to better illustrate. In reality the flood and travel lines are very faint. And again, only visible on a screen that's mostly or totally black.

Assuming you have tried simply turning down the red bias

This should be a simple enough thing to try; is this equivalent to adjusting the "R Drive"/"RDRV" in the service menu? Won't that affect the picture overall? I also seem to have access to "R Cutoff" lower and upper thresholds, if those would be useful.

[buttersoft]

Drive is gain is highlights or the brightest part of the signal. This is often called contrast when talking about all three colours at once.
Bias is cutoff is lowlight, or the background level of the signal. This is brightness when talking about all three colours at once.

Here, with no signal, you're getting a red tone, so you want to lower the red cutoff level. Hopefully that helps.

[Zebidee]

Good luck with the neckboard, I hope you can find the cause of the issue. I think we've given you as much advice as we can, so far.

Sometimes TVs do separate the mains power switch and the control circuit momentary button, like you described.

I won't worry you anymore about your original switching arrangements - if it is related to the red overdrive issue you're having, I don't know how, and in any case you have dismantled it.

As promised: one simple way to simulate a button press & release on connecting power is with a basic time delay circuit, which is just a resistor and a capacitor:

- solder a resistor (for this example I'll use a 1000 ohm or 1k resistor) to the positive lead (+, longer) of an electrolytic capacitor (for this example I'll use 100uF), so that the resistor and capacitor are now together. Now solder the resistor end to the momentary switch's active terminal, and the negative end of the capacitor to the ground terminal. It'll look like this:

Active---------[resistor]------[ + capacitor - ]------GND

When you apply power, this will initially be a closed circuit (like you have pressed the button in), but within a short time the capacitor will become charged and then it will block the current, acting like an open circuit (like you released the button). The capacitor just gives you a short delay before the button "release", literally a fraction of a second, giving your TV control circuits some time to wake up and register the button release.

You can control the time delay by adding/changing the value of the resistor, with a larger resistor giving you more time delay. You can also extend the delay with a larger capacitor, but it is easier to change the resistor (or use a pot). If you want to know the math:

T = R x C

Plugging in the example values of 1000 ohms and 100uF (micro farads, so really 0.000100), we get:

T (seconds) = 1000 x 0.000100

T = 0.1 seconds

Obviously if we used a 10k resistor instead then you should get a longer 1 second delay (which should be more than enough). If you wanted to work out what values work for your TV, try using substituting a 10k pot for the resistor and dial it in. Once you are happy with the pot setting, replace it with the appropriate resistor value.

Some caveats:

- This may work fine even without a resistor, there will still be some short delay as the cap charges initially and larger caps take longer to charge.
- If a resistor value is too high it may prevent the control circuit from properly registering the "press". So start with a lower resistor value and work up.
- Be aware that not all grounds are the same on a TV, esp between the HOT and COLD sides. If you aren't 100% sure then probably best to take your GND back to the relevant spot for the original button at the control circuit.
- 1/4 watt resistor and 16v capacitor ratings should be sufficient, but...
- Appropriate resistor and cap values may vary for different TVs.
- Might not work with every TV.  For example, some TVs may want to register the circuit as "open-closed-open", this only gives you "closed-open", if that makes sense.
- This is a hack. If you do this, you do it at your own risk. If your TV blows up then don't blame me.

There are some other ways to get the TV to come on once you apply power, such as using a 555 timer and a relay, but this is by far the simplest.

I've assumed, with the above, that your TV won't come on automatically when you apply power. If it does come on anyway then just ignore everything I've just said and go buy a smart strip with master/slave outlets, and plug PC into the master, TV into slave. Or use a relay.

[bobbyb13]

Whew!
I'll need to read this a few more times for some more to stick.

The technical knowhow of a number of you here still stuns me.

[rogerxyz]

Happy to finally close the loop on this thread. I really, REALLY thought I had screwed the pooch in a big way - I mean even more than I had at the start of this thread. After hooking everything up again after doing some debugging it turns out I hadn't inserted the anode cap securely enough. It started spewing high voltages all over the place, real real bad news. But seemingly not fatal, after I discharged everything and reseated the anode cap (after about a week of grieving lol).

So all of that is besides the point, it just explains the delay. To the original issue:

* None of the service menu adjustments I made changed the dim lines. Interestingly, even turning off the red channel didn't affect those lines.

* An incredibly simple fix that I should have tried immediately (at least I got around to it). I simply turned down the overall DC offset? bias? G2 voltage? Not sure the correct term, at the flyback. Honestly this issue may have totally been there before anything I mentioned in the OP, and I simply bumped the G2 voltage during some of the dis/reassembly. Those dim lines receded away and I didn't lose any brightness that I couldn't bring back in the main menu.

As for triggering the TV power cleanly, here's where I ended up:

* I 3d printed some rails to mount the TV's main PCB cleanly with lots more support

* took those extended leads out to the front panel's standby switch and instead of risking messing around with the main switch, I pulled this out to be a nice chonky button that's still inside the cabinet but just relocated to be convenient. Not the primary means of toggling the power.

* dug up an Arduino Pro Micro and some IR LEDs and receivers I had lying around, used it to record the most common button presses from the Sony remote. Using the awesome IRemote library

* desoldered the IR receiver from the Sony's main board and extended its leads too, mounting it inside the cab

* wrote an arduino sketch that listens on USB for serial commands and translates them into the desired IR blasts (e.g. w a s d for up left down right, m for menu, ! for power and so on)

* wrote some python code that takes an argument and sends that command to the arduino over serial. So you have like `sonyir m` → serial → arduino → IR blaster → IR receiver on TV

* wrote another python script that 1. fires off power toggle 2. idles forever 3. registers a handle for SIGINT that fires off the power toggle again

* installed the python script as a Windows service with nssm, which cleanly shuts down the service on shutdown, instead of killing it berofe the signal could send out like other approaches I tried

So far so good! I can post the code if there's any interest but I'm sure it's all been done a hundred different ways. (Where's the fun if I don't solve the problem my own way though)

[Zebidee]

Wow, someone really should have suggested that you turn down the flyback focus knob - it is actually the first thing I thought of, but assumed you hadn't touched the knob and it had happened spontaneously. Reminds me that when troubleshooting you shouldn't assume, check the simple and obvious things first!

Glad the TV is OK.

Using an Arduino like this is an innovative way around the TV on/off issue, and in addition it lets you access remote functions easily. The "cap trick" I mentioned before, or resistor/capacitor (RC) delay on the switch, is cheap and easy but won't emulate a remote like you've done here.

I see a GreenAntz hiding back there, makes me happy

Any screenshots of games?

[buttersoft]

Truning down the flyback knob turns down the G2 bias and reduces brightens but it doesn't fix the colour imbalance. You'll probably still want to look at that.

[Zebidee]

screenshots will tell

[rogerxyz]

By popular demand, some shots, as you know it's not that easy to capture CRT well, and daylight + a glass bezel don't help, but I tried here

Also keep in mind I think I'm on the cool temp preset, and I haven't had time to recalibrate after these last rounds of modifications

https://imgur.com/a/I5R0NC2

[Zebidee]

By popular demand, some shots, as you know it's not that easy to capture CRT well, and daylight + a glass bezel don't help, but I tried here

Also keep in mind I think I'm on the cool temp preset, and I haven't had time to recalibrate after these last rounds of modifications

https://imgur.com/a/I5R0NC2

Looks awesome, the colour balance looks good. Certainly no issues with the CRT guns.

Speaking of which, the "colour balance" pot on the GreenAntz affects the Pr signal only, so red most and blue not at all. Factory setting/default is just below middle/centre position. So if the reds seem a little too bold to your eye, you can tweak that pot down to bring it back into "balance" with the Pb/Y signals.

Similarly, for the "luma" pot the factory setting/default is just below middle.

[rogerxyz]

Speaking of which, the "colour balance" pot on the GreenAntz affects the Pr signal only, so red most and blue not at all. Factory setting/default is just below middle/centre position. So if the reds seem a little too bold to your eye, you can tweak that pot down to bring it back into "balance" with the Pb/Y signals.

Similarly, for the "luma" pot the factory setting/default is just below middle.

That's great to know! I'll probably do most of my settings in the menus but it's good to know that's an option

I may or may not have mentioned it but this Sony KV-20FS100 was a curb rescue! Someone in a local commodore 64 group posted that they saw it in their neighbourhood and I swung by and grabbed it off the lawn. Little ratty on the outside but some minor adjustments to the convergence pots on top of the set (convenient! thanks sony) and I think it looks pretty decent.