Dell P1110 21" CRT repair thread

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Haven't kept you up to speed with the news, have i? A while back i got a P1130. It only had the excessive brightness issue, after adjusting with WinDAS everything is fine. As opposed to my P1110, it didn't do the whole "start up bright then slowly drift back to normal" thing. And by slowly i mean slowly - the darn thing took over 2 hours for brightness to stabilize, and if the computer went idle and turned the monitor off, then it would do the same thing over again. The P1130 worked normally after i adjusted the G2. Interestingly, the P1130 got a G2 voltage of almost 100 volts above the P1110 for the same brightness range, and i started to dig further.

Turns out there was a little difference in the video circuitry of the P1130 (built in 2003) as opposed to the P1110 (built in 2000). Attached you will find the relevant portion of the schematic of the P1110. Take note of pin 17 of the cutoff amp, with the funky self-biasing transistor circuit. Someone had analyzed the circuit before and it turns out it was some kind of thermal compensation, but noted that it does affect brightness. Well, compensation or not, the P1130 didn't have this, and instead connected pin 17 directly to ground. It also didn't have the brightness drift issue.

So, connecting the dots, i bypassed the drift correct thingy on the P1110. The brightness got significantly lower, i had to adjust G2 value with WinDAS again. The new G2 voltage for the P1110 was almost identical to the one the P1130 wanted. And... NO MORE BRIGHTNESS DRIFT!!!! I can finally have a proper monitor. Well, in fact, now i have two proper monitors.

Now, some might wonder what was the circuit doing there in the first place. Well, i think i got an answer for that. As you know, vacuum tubes take a while to warm up, and CRTs are no exception. A CRT monitor starts up dark and takes a few minutes to warm up and get to normal brightness. What Sony wanted to do was to eliminate this warmup period, so they put that little transistor that shifts the cutoff amp's bias point during this warmup of the tube, so the brightness starts up at nominal levels from the get go.

At least that's the theory. And it probably even worked when the monitor was brand new. But apparently the bloke who put that little transistor in there forgot to factor in the aging of the tube... and thus the circuit ends up overcompensating, causing the brightness drift i mentioned above. A monitor that takes 5 minutes to brighten up is lots better than one that starts up over bright and takes two hours to get to normal. Plus given its position on the board, i cannot possibly understand how that transistor could have ever sensed the temperature of the tube, or even of the video amp for that matter... No wonder it got removed in the following version.

Anyway, there you go. If you ever see one of those, now you know how to fix it. IIRC lti had a Sony Trinitron with the same brightness drift issue, get to work already man!

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

PlainBill asked for WinDAS so here it is.

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Course you can. Resize as close to 2000x2000 as possible, click on advanced under the quick reply form and upload using the attachments function.

[deathamatend]

Re: Dell P1110 21" CRT repair thread

Thank you so much for replying. I do very well with soldering so I can pretty much handle it all. I did one of those 19" Westinghouse monitor power supply re-caps successfully. P1130 is just huge and many components. Inside is spotless and everthing is readable. Just need some pointers for another successful repair. Can I upload pitures at Badcaps? It would help. Thanks

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Start by checking the mains fuse. If the fuse is blown, check the main switching transistor, it probably failed shorted. It doesn't go on its own - so check the capacitors too, one or more could be bad.

If the fuse isn't blown and the transistor looks fine check the controller IC in the power supply. Btw, if the main supply runs but seems to be in protection mode (listen for a ticking noise), check the HOT (horizontal output transistor). That is by far the most common part to fail in CRT monitors.

The service manual is pretty easy to locate and the schematics are very detailed so troubleshooting should be straightforward. If you can't find it i'll upload it here. Edit: This is it: http://www.eserviceinfo.com/download..._CPD-E500.html

[deathamatend]

Re: Dell P1110 21" CRT repair thread

I was wondering if anyone could give me some pointers on a no power condition on a P1130 Dell monitor I have had since new? It had a great picture until it went out in July. Thanks!

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Well, since here everybody jumps on free stuff, someone else picked it up before me. Looks like i'll use that 19" LCD i have sitting around as my main monitor, while i tear down and fix the Dell.

[momaka]

Re: Dell P1110 21" CRT repair thread

Well, my wish has been granted. I'll be picking up yet ANOTHER 21" Trinitron, it's an IBM.

Awesome!
Good to see yet another nice CRT monitor saved from the trash.

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Well, my wish has been granted. I'll be picking up yet ANOTHER 21" Trinitron, it's an IBM. Probably the P275 like i have at my grandparents'. So i can tinker away at one of them while still having a nice main monitor. And when i'm done, i'll just swap 'em around and fix the other one.

Btw, can't beat the price. F-R-E-E. And the guy giving it away also happens to live 15 minutes from my place.

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Some said it could be the tube, but that's something i'm not willing to accept, especially since i scoped the signals going to the tube and there is some ringing on them (which indicates some type of signal issue somewhere). There are a ton of small caps on the signal board. I wish i had two monitors with identical tubes, so i could swap boards around and see if the issue moves from one another.

[momaka]

Re: Dell P1110 21" CRT repair thread

That's what i have too. As for that thread, if you looked for "dell p1110" it would have been among the first 5 results... http://icrontic.com/forum/showthread.php?t=19549

Thanks.
After using my Dell D1626HT yesterday, I feel that I might have to turn down the G2 on it sometime soon. Right now I have to set the brightness to 10% or less in order to get a completely invisible black screen at night. I guess it's okay for now, but if it gets brighter, I'll do it.
Contrast is also rather unimpressive, but still better than any LCD.

I don't think it's the same issue. Here's the white shadow i am talking about, albeit on a different monitor, a 19" Eizo which isn't a Trinitron.

Yeah, that looks much more different from what I have.

Next step is changing all the caps, but they're all Rubycon and United Chemicon...

I don't know if that will help, but I guess it's worth a try.

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Call me stupid but I can't find a link to that thread. Any chance you can post it here? I have quite a few Sony monitors, so it would be nice to have. All I have is this:
http://www.piclist.com/images/com/ge...ndas/index.htm
Any idea if this article/web page is any good?

That's what i have too. As for that thread, if you looked for "dell p1110" it would have been among the first 5 results... http://icrontic.com/forum/showthread.php?t=19549

Can you post some pictures of that? I have an old HP A4032A (Sony Trinitron tube) that has 2 thick bright bars in the vertical direction - not sure if that's the same problem as yours, but I'm curious anyways.

I don't think it's the same issue. Here's the white shadow i am talking about, albeit on a different monitor, a 19" Eizo which isn't a Trinitron. I took that one apart and cleaned it, we'll see if it's still there when i put it back together. Next step is changing all the caps, but they're all Rubycon and United Chemicon... The severity of the shadow depends on the horizontal scan rate (that means both higher resolution and higher refresh rate make it worse, but high refresh rates at low resolutions are fine).
http://www.imgurl.ro/di-NB2I.jpg

[momaka]

Re: Dell P1110 21" CRT repair thread

A Sony Trinitron monitor thread without me - that can't be!

Alright, that software almost made me have a heart attack. But, eventually, it is solved. I also posted this in the relevant thread on Icrontic, which is 24 pages and several years long...

Call me stupid but I can't find a link to that thread. Any chance you can post it here? I have quite a few Sony monitors, so it would be nice to have. All I have is this:
http://www.piclist.com/images/com/ge...ndas/index.htm
Any idea if this article/web page is any good?

Did you try the monitor's "color return" feature (accessible via the normal menu)? That brought most of the Dell Trinitrons at work back to normal color, even some of those that were showing the retrace lines.

I don't know how accurate this is, but I read that if this trick doesn't work, you can also turn up the brightness all the way up, then run the color return and it will supposedly turn down the G2. But again, this may be false information. I just remember reading it on some forum when I was looking at random articles for my broken GDM-FW900. The GDM-FW900 also has MCU-controlled G2. In fact, I think most (if not all) Sony CRT monitors do.

Alright, fiddled with it a bit more. I did the "color return" thing and it's funny - it got a bit brighter again (albeit the G2 value stayed the same, i checked), but the greenish tint did not go away. Fortunately it has an "expert" color menu, where you can set bias and gain of each individual gun. I lowered the green bias and that took care of it. I then used this page to calibrate the colors: http://www.photoscientia.co.uk/Gamma.htm I went for 2.2 gamma.

Looks like a good article. I'll definitely read it when I have time.
I had the same green-tint problem with the working GDM-FW900. It took a bit of playing around with the color biases and gains while viewing some pictures that I've viewed over 100 times on many different monitors. Ended up doing the same as you - just turn down the green bias and gain. I've only played with that monitor for about 1 hour, though, and I believe there was still a trace of green tint when I was done. Right now it's summer and it's just too hot to be running that monitor, so I'm using different monitors. But as soon as we get cooler weather, I'll be putting it on my desk .

By the way, I remember my GDM-FW900 had funky convergence when either the bias or the gain (I don't remember which) was set above 90%. Might be worthwhile to check on yours. My 21" Dell D1626HT doesn't have those problems, though.

Next up, contrast. I like to run my monitors really dim at night. If i turn the contrast on my Nokia to minimum, i can't see $*!#. At night i run it at 20 or maybe 15. This one, contrast is too high even at 0. Not as bad as the IBM i have, but it's certainly going to require more tweaking...

Why not turn down the brightness instead? On all of my Sony Trinitrons, I have them set so that the contrast is at or near 100%. I then adjust the brightness to the point where I can't tell if the monitor is on when displaying a full black screen.
If needed, go further down in brightness, and turn up the gamma a bit.

And finally, there's that god-awful antiglare film. Not only is it scratched, but when cleaning it with regular household cleaning products they all leave a blue hue... and you have to rub it with the cloth over and over till it goes away. I'll have to take it off.

I think all monitors with anti-glare coating have this problem. My Samsung SyncMaster 955DF is probably the worst I've seen - no matter how much I clean it and rub it and polish the screen, it still looks like it has finger prints on it (and it doesn't, it's just the anti-glare that looks spotty).
If you end up removing the anti-glare on yours, let me know how it goes. There's a Sony Trinitron E540 at my the workplace I volunteer that has a really deep tear in the anti-glare coating. No one is using that monitor and I'm pretty sure they will throw it away eventually (they already threw out one E540). I just want to know in case I salvage it .

Nooooo... It has the very same white shadow on the right of dark stuff that the IBM has... Like i said, it isn't as bad, but enough to make stuff appear that isn't there. It's impossible to do any graphics editing on this thing.

Can you post some pictures of that? I have an old HP A4032A (Sony Trinitron tube) that has 2 thick bright bars in the vertical direction - not sure if that's the same problem as yours, but I'm curious anyways.

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Nooooo... It has the very same white shadow on the right of dark stuff that the IBM has... Like i said, it isn't as bad, but enough to make stuff appear that isn't there. It's impossible to do any graphics editing on this thing.

Speaking of which, the 19" Eizo in the living room isn't used anymore due to exactly the same problem... And that one isn't even a Trinitron. They've gotta have something in common and i believe messing around on the signal board can provide some answers. I'll practice on the Eizo and see what i get.

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

It's just the nature of the beast, that's what the tube does when it ages. Now the really funny bit. I've spent my past couple hours setting up various resolutions. What looks best is - hold on to your seat - 1856x1392. At 84Hz.

It's unofficial, unsupported, and probably even unsafe. But it looks f'n awesome. The downside is that you can almost see every little circuit of this monitor at work - the edges wiggle ever so slightly, every little step in the geometry menu affects the picture a lot, and it even got a bit of the contour on the right side of stuff thing my IBM has... fortunately nowhere as bad as that one. Well, it's the same platform, so it's kinda obvious it'll have the same quirks. Looks like there will be work to do on the signal board.

I'll probably move back to a more sane resolution now.

Alright. Let's have some upsides now. Colors are more vivid and better defined than on the Nokia. And at the same 1440x1080 @ 85Hz that i ran on the Nokia the Dell does indeed look crisper. But, it probably does so simply because it's larger. I'll keep tweaking... maybe something good will come out of it.

[lti]

Re: Dell P1110 21" CRT repair thread

The Dell P1110 is $&@#!^* bright for like the first half hour, geometry, size and position also being slightly off.

My Sony Trinitron monitor does the same thing, but it didn't when it was given to me.

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Alright, fiddled with it a bit more. I did the "color return" thing and it's funny - it got a bit brighter again (albeit the G2 value stayed the same, i checked), but the greenish tint did not go away. Fortunately it has an "expert" color menu, where you can set bias and gain of each individual gun. I lowered the green bias and that took care of it. I then used this page to calibrate the colors: http://www.photoscientia.co.uk/Gamma.htm I went for 2.2 gamma.

I found the service manual and tweaked the convergence pots on the back of the deflection a little, and it's looking really good. I figured it's good enough to go on my desk as my main monitor.

First impression? Mixed emotions at best. I knew my Nokia 920C was a good monitor (i also put quite a bit of work in calibrating it), but only now i realize it isn't a good monitor - it's an AWESOME monitor. The P1110 Trinitron is bigger? Yes. Brighter? Yes. But can i call it better? No... In fact, put head to head, the Nokia wins, hands down.

First of all, let's start with power up. From a cold start, the Nokia has some slight convergence issues, which normalize in the first 15 minutes. Nothing else. The Dell P1110 is $&@#!^* bright for like the first half hour, geometry, size and position also being slightly off. I'm used to it from the IBM i have at my grandparents' place - first half hour is basically tweaking the brightness and contrast till it settles. Any normal tube gets darker as it ages - a Trinitron gets brighter.

Next up, contrast. I like to run my monitors really dim at night. If i turn the contrast on my Nokia to minimum, i can't see $*!#. At night i run it at 20 or maybe 15. This one, contrast is too high even at 0. Not as bad as the IBM i have, but it's certainly going to require more tweaking...

Focus. On Trinitron tubes, focus gets softer as refresh rate increases. 75Hz at 1600x1200 is significantly better than 85Hz, but the Nokia can do 1600x1200 @ 75Hz just fine as well, it's just that my eyes can't take it. Even the custom 1440x1080 @ 85Hz that i had on the Nokia looks slightly blurrier on the Dell. Now, i'm sure this can be improved and i'll take my time, but again, good ol' Nokia wins.

And finally, there's that god-awful antiglare film. Not only is it scratched, but when cleaning it with regular household cleaning products they all leave a blue hue... and you have to rub it with the cloth over and over till it goes away. I'll have to take it off.

Don't get me wrong, this is not a bad monitor and i like it... It's just "not quite there".

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Was the screen voltage adjusted improperly at the factory or is it the result of corrupted data in the EEPROM?

Corrupted data.

So how does the MCU regulate the voltage to G2? PWM?

As far as i've read, yes.

Doesn't seem to me like it would save the manufacturer any money in component costs. It's baffling why they went with this setup.

It's not for saving money. It's for having that nifty "color return" function, which supposedly compensates for the aging of the tube and brings the monitor to like-new condition. Unfortunately, that function has the habit of turning the G2 up, up, and up, till the issue described takes place.

Btw, the guy told me it isn't scratched. I think he meant, it isn't scratched a lot. It has quite a few vertical scratches. They didn't pierce thru the anti-glare coating all the way so they're not extremely annoying (on the IBM i have a horizontal scratch all the way thru the film at the top right), but there's a number of them. I'll probably take the anti-glare coating off. My Nokia doesn't even have it and there's been no problem with reflections.

I got the VGA cable now. It's going to require a bit of adjustment but overall it's looking good. Picture is nice and stable, focus is decent, convergence needs to be done but that's available from the menu, and even with no adjustment it's perfectly readable at 1600x1200. Btw, i dropped the G2 even lower, to 76, and the brightness still has enough range.

[Krankshaft]

Re: Dell P1110 21" CRT repair thread

Was the screen voltage adjusted improperly at the factory or is it the result of corrupted data in the EEPROM?

Man this is a lot of effort for eliminating a screen pot. What we're they thinking? If they had to over complicate the matter why didn't they just have a hidden service mode where it can be adjusted on screen like 99% of all other CRTs factory settings?

Engineers they're always finding a way to make something simple more complicated .

So how does the MCU regulate the voltage to G2? PWM?

I'd think they'd have to take the boosted line voltage from the flyback and pass it through some type of external voltage regulating circuit.

Doesn't seem to me like it would save the manufacturer any money in component costs. It's baffling why they went with this setup.

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

I steered clear of that method because i read it messes up the colors and sometimes even the brightness control. If it is MCU controlled let's do it the right way.

Btw, i also got WinDAS working on my Win98 laptop, i had to copy the OCX file in the activex folder to the main WinDAS folder to get it to open the model list. The monitor still wants 5v supplied externally like i said, but that laptop does also have an USB port so i can get it from there.