The problem observed is that the Wacom monitor fails to turn on properly. When the power button is pressed it boots up normally and displays an image for about a second, then the screen goes black and appears as though the monitor has failed, however all the other lights are still on and the computer still recognizes the monitor as being active. Shining a light on the monitor shows that an image is still there, just the backlight has failed.
Currently I can observe a buzzing noise and the smell of ozone during the monitors start up which indicates arcing somewhere. When running, there is a background buzz in my external speakers which would also suggest some interference in the earthing nearby.
At the moment there are 3 available solutions, 1, forcefully warm up the monitor (such as with a hair drier), the warmer it gets the more likely it will stay on when turned on, 2, leave the monitor running in a failed state, the monitor still uses power in running its internal system separate to the backlight, this warms the back plate directly, which is touching the CCFL tubes, which in turn helps it start up after about an hour, 3, leave the monitor on, the speculated failure is that the CCFL tubes have been altered by DC bias in the inverters AC output, causing mercury to collect in one end of the tube which makes starting it up difficult. Once up and running though this no longer presents as so much of a problem so the monitor should be safe to be allowed to continue running non stop, in the long run this may even fix the tubes, but im not entirely certain of that, I do know that the high voltage leaking into ground decreases as the monitor warms up.
Upon opening the monitor up I experimented with the inverter board
Here we can see 6 sets of inverters each presumably for its own CCFL tube.
There is also a set of input wires on the bottom right, ranging from blue to black. The function of these wires are an either 3v or 5v fail indicator (outputs as long as the inverter is working) which just outputs voltage, a 3 or 5V PWM input for the brightness, 2x 24V lines, 2x ground lines and another ground which I think directly goes to the main ground for the board. I did not properly record all this so it needs another looking at next time I open the board.
I found that by blowing warm air on the entire board I could make the monitor start up properly, then make it fail by using refrigerant spray on the second bottom blue HV capacitor on the inverter HV output. Eventually I was making it fail and work selectively by altering that capacitors temperature. After replacing that capacitor with an identical one, which was a 3Kv 15pF (in retrospect should have used 6kv) and repotting it, the monitor no longer worked, and after further testing I discovered that many of the HV outputs where they touched the metal back plate were discharging power, via a visible corona in the dark, this was what was causing the audible noise and ozone, and it seems that the more power allowed to discharge into the backplate, the more likely the backlight was to start successfully. During its startup for about 15 seconds or so the buzz and visible arcs would be strong, then it would fade almost to nothing once the backlight had fully lit up.
At this stage I concluded, along with insight from members of the #electronics channel on freenode irc, that the CCFL tubes were failing, caused by failure in the inverter.
A quick google search and more advice showed that the CCFL tubes could be replaced, however a better solution given the standalone nature of the inverter board would be to remove the tubes and simply use white LED bars inplace of the CCFL tubes, or some other LED alternative. A simple circuit could be rigged up to even allow the backlight to be controlled via the PWM signal produced by the monitor.
In general it seems CCFL tubes are perishable and designed to be replaceable.
Further replacement of more of the output capacitors does not appear to fix the issue, although the HV discharge seems to be lessened.
For the replacement, the capacitors were re-potted successfully with pure, acid free, clear, general purpose silicone, which testing with a 70kV supply showed it had extremely high insulative properties even before it had cured, wherein its resistance would be the lowest. I was able to completely insulate 70kV with at most 4mm of silicone.
The silicone I used however was from a foil tube instead of a large caulking cylinder as I was sceptical that bulk was the same quality given the similar prices. Also I only needed a little anyway.
My recommendation at this point would be to replace the capacitors at the first sign of backlight tube failure, this might fix the DC bias in the AC supply and keep the tubes healthy/repair them to an even state. Incase I hadn’t mentioned it earlier, CCFL tubes failing in this scenario where warming them up helps start them and there is a lack of conduction during startup is where all the mercury condenses to one electrode in the tube, which ill note is quite long, the mercury is attracted to either the positive or negative. Running the tube with its normal ideal input should redistribute everything back to normal, but replacing the tubes may also be a viable option too as damage takes quite a while to occur, also tubes are very cheap.
Still I would go with using LEDs and totally remove the HV element from the system.
Here is a photo of the entire board
The high voltage leads run right under the boards processor without any particular shielding, some of the hole-thru type parts have soldered leads not trimmed that get awfully close to the HV leads and this might be the cause of some sudden failures experienced by users.
A helpful note to remember too is that when sending in a board for repair, you don’t have to include the frame and weighted stand, just send in the screen though ask that this is ok first before doing it.
Another note is that the power button wire is directly over the HV leads and discharge may be responsible for the monitor randomly turning off. Also when opening the monitor, you may need to remove the earthing lead from the USB port, make sure to re-apply it, its easy to miss. Overall many of the screws in the top and bottom seem unnecessary so as long as the mounting parts are secure, you can leave your monitor ready for disassembly between uses.
One last note, the black tape around the edge of the metal plate is what needs to be undone to get to the numerous CCFL tubes, my next entry or a future one will be about getting at that and finding the tubes, ill also look into what might happen if I turn them all around, healthy tubes should be unaffected while damaged ones will change state, and the time it takes to stop working correctly will indicate if simply replacing tubes but leaving the inverter damaged, is a viable option, although all my capacitors are now replaced, there might be some other factor that has put the inverters out of tune.
Wow … fast back … thank you.
Ok so I’ll leave it on all the time while waiting for the video.
Is there a setting directly on the cintiq so that it does not go into standby without a pc connected?
Or should my pc also be running all the time as now?
By browsing these forums I just read that to lower the muminosity of 100% to 60% will solve the problem … what do you think? I have not tested …
Claude
running it lower would probably conserve its lifespan yes
Well and after 7:00 am my screen does not start directly.
I am obliged to “heat it”.
I warm the rear part about two minutes.
I concentrate my action on the whole of the bottom and then on the whole of the top.
I dare not put too much heat on the front face for fear of damaging the screen with a strong heat see to take off the plate.
I say that I “warm” it while the screen is on.
The screen remains black but after heated it so 2 to 3 minutes I turn it off and immediately I turn it on.
If the screen turns black again after 1 second then I turn it off and I turn it back on again, I repeat this operation as much as necessary, but not more than 10 times in a row.
I wait for 1 to 2 minutes and I recommence the extinction / ignition on the same rhythm.
I verify in the meantime that the temperature of the back of the screen is warm otherwise I add a little heat stroke.
Very quickly my screen stays on.
This morning,
Ignition, rear heater, turn off / turn on for about 10 minutes.
In reality I plan to leave my PC / screen in constant operation with active screen saver.
In this spirit what is the impact on cintiq?
In your opinion, it is better to turn off the cintiq if it is not used or leave it in operation as I intend to do thus avoiding the manipulations of putting into function?
Thank you very much for the responsiveness of your response.
I think your accurate information will help a lot of people in my situation.
Following your replacement of the tubes by the LCD on your cintiq, does it work well now have you noticed any changes?
Does it behave differently, pereil or better?
Friendly, Claude
you will cause more damage turning it on than leaving it on, so its better to just keep it running all the time.
I replaced the tubes with LEDs, at the moment its not as bright but otherwise it works normal.
The reason its not as bright is because of the LED driver/regulator, its designed to safely run 1 strip, but the monitor takes 2, also the regulator accomodates 2 strips. I explained this at length in many posts. Long story short the 2 strips are run with half the power they need, so i replaced the regulator with a stepdown converter set at exactly the right voltage the LED strips need to run properly, which is 9.6-9.8v or as much as it takes to have them draw 400-600ma each.
I havent done the final replacement yet, that will come with the video but i expact the final brightness of the monitor to be about the same as the CCFLs.
Hello,
I read your blog and found it very interesting, it really captivated my attention.
I have a cintiq 24 HD and like you I am concerned with the problem you describe, since about 01 year.
I managed to put it back into operation using a simple method:
I turn on my screen which turns black after a second, I wait about 30 min and then I turn it off and I click on it several times in succession until the screen stays on.
I do not know if it degrades it a little more but I found nothing better until reading your blog …
Unfortunately, I do not have half of your technical knowledge and I was unable to establish your diagnosis and still less to find solutions.
That being said I went to your method:
Overheated the back of the screen to dry hair to allow it to ‘turn on faster.
Some questions came to me:
Should the screen be heated to on or off?
Where to heat the screen wisely?
Should the external alloy block also be heated?
I look forward to your video and after that I may be in his repair.
Excuse my approximate English, I am french and I use google trad in order to be more readable for you.
My sinceres thank you for your blog that really enlightened my knowledge of the problem we encounter.
Cordialment,
Claude
the CCFL tubes are siutated at the top and bottom of the screen so if you are applying heat thats the only place you need to warm up. the exact location of the tubes is in the black border right at the screens edge. Again, top and bottom. Once the tubes are on they should be fine, im fairly certain all damage is done as it turns on, and you shouldnt have a problem if the monitor never turns off for any extended amount of time.
Also, im currently studying at university and use my monitor constantly which is why i havent done the rebuild video, its my top priority and ill do it as soon as i can, problem is its not just a matter of quickly installing the new lights, i also have to make sure i present it properly as well.
Thank you so much for your return.
I actually followed your advice by heating the screen.
It starts very quickly.
However, in order to be the most efficient, the best is to heat the back of the screen or rather the front.
I just let my screen run for a week non stop with the screen saver on.
I’ll stop him now and see his behavior tomorrow morning.
I understand that according to you that a prolonged operation could make that the magnetism of the tubes “erases”. Can you confirm this point or have I misunderstood.
I think that as people are in our case and that the alternatives offered by Wacom for those still under warranty only delay the deadline.
Reading your blog, allows me to finally understand what is wrong and also to redo my cintiq.
For now, the fact of heating the screen to make it functional does not displease me any more than that so as much to make it as efficiently as possible.
Of course when your video is available it will allow me to see the complexity of the steps to be taken for a definitive repair and also to see if I am able to perform it myself.
Thanks again for sharing your experience, I read countless internet pages where people in my situation no longer know what to do, up to your blog.
Sincerely, Claude.
blowing hot air into the exhaust/intake would be most efficient yes, as you would be heating the heatsinks directly which can work backwards to absorb external heat and dissipate it directly into the tubes.
Once the tubes are up and running, after successfully starting up, they should for the most part be very balanced, also, the inverters will lower their voltage to between 400-1000v, probably closer to 400v though, and even if the capacitors are diminished, they should be better at serving their function balancing and filtering the output. Any fluctuations in power however would cause the voltage to rise, i asume, to prevent the CCFLs cutting out. ANd bad tubes cause fluctuations all the time, but, the damage the leaking HV causes is not so bad once the tubes are up and running.
Anyway, after inspecting my own tubes, ill have to take back what i said, there is no repairing the tubes by running them continuously, however, they will probably not get much worse. Most of the damage is done every time they start up and are running cold. Once warmed up, the mercury vapor inside distributes more evenly and it should last longer.
But, im confident that running LEDs properly in the monitor will remove the need outright to use CCFLs.
The video is comming soon.