Dell P1110 21" CRT repair thread

[R_J]

Re: Dell P1110 21" CRT repair thread

Does the fuse blow as soon as it is plugged in or do you need to press the power button and then it blows?
If it blows as soon as it is plugged in, suspect VDR601 is shorted. Next could be the bridge rectifier, I don't suspect the mosfets that are bad as there is a fuse resistor in the supply to them (R620, 0.1Ω), I also don't suspect IC601 as it should blow R610 & R611 if it's internal mosfet was shorted.

[Per Hansson]

Re: Dell P1110 21" CRT repair thread

On PDF page 7 you have the mains input on the left.
Just measure between live and neutral with your multimeter with a new fuse in the monitor.
Since it blows as you plug it in I expect a really low resistance reading.
Now start looking further into the monitor (referring to the schematic here)
Follow the path and test each component, the one with the lowest resistance will be the shorted one.
You can also of course take out components until the short is no more.
A good start is the bridge rectifier, then Q640/Q641

[blizzak]

Re: Dell P1110 21" CRT repair thread

Bump from another dimension (6.5 years since last post on this thread), hope this is OK as opposed to starting a new thread! Also seems I can't post new threads right now anyways...

I have a Dell P1130 that won't turn on at all. It was having some issues for a while but I wasn't sure if they were software or hardware, was using a DP to VGA adapter. Sometimes on starting PC the monitor would not display image or turn on (orange light showing), though the PC thought it was outputting to it. If I disabled the monitor in Windows and reconnected it would come back. Colours were not perfect but after warming up it seemed OK, did some tweaks but nothing crazy.

Fast forward to the other day when I was printing off some things for a friend and printer runs out of paper (older beast of a Brother laser MFC); connected to the same circuit as this monitor (note: never do this). Apparently the Brother was doing some mean things to the circuit while waiting for paper (seemed like constantly cycling fuser on and off maybe) and was in this state for a while. Come back and the P1130 won't turn on at all, no lights.

I find the post below from Th3_uN1Qu3:

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

So I open up the monitor, check fuse and it's blown. Order more fuses, replace fuse and on attempting to power up monitor again it blows. Suspect the main switching transistor per the above post. Try to look at the service manual but haven't analyzed circuit diagrams in a long time:
https://www.manualslib.com/manual/72...ron-P1130.html

No evidence of swollen caps, nothing obvious on the boards from a bird's eye view. If anyone has any suggestions let me know, if I get into it and make any headway will post here.

[momaka]

Re: Dell P1110 21" CRT repair thread

thanks for your reply master

about the "big flash and cracking"... what the hell this could be,?a bad weld ?
the flyback? an aged cap?

It's the high G2 causing it. I don't know why, though. Most likely there is a protection circuit that kicks in due to the abnormally-high G2 causing other issues.

On my Dell D1626HT, it was a different type of "cracking" - more of a static discharge, actually. And it would happen randomly, regardless if the monitor was warm due to hours of use or cold. Even have a thread for it here:
https://www.badcaps.net/forum/showth...hlight=d1626ht

I looked at the G board quicly and I don't noted any inflated cap

These Sony monitors run cool and they have good quality Japanese caps inside (Nichicon, United Chemicon, and Rubycon), so unlikely that you will see any bad caps.

I will upload a video later showing my monitor starting cold before I make the IC 406 mod, then of course I will make a new video with the mod done to see the differences

Sounds good. Keep us updated.

if flashes and cracking still persist I will dismantle the G board to look around where is the problem, I'm almost sure the problem is located there

Again, I doubt the G board is the problem.
However, it is a good idea to inspect the solder joints around all regulators and large parts. One of my Sony GDM-FW900 monitors had cracked joints on the stand-by regulator and heater regulator. It made the monitor hang in stand-by mode all the time (a signal would not wake up the monitor at all). Once I re-soldered those joints, it started working correctly.

ok I done a video of this monitor starting cold, no crackling or flashes this time
( sometimes it does not make)
as you can see the black is tinted in green, is out of brightness but this can't be noted very well in the video

Yes, I can see the green tint quite well. Classic G2-overbright issue, indeed. Do the IC406 pin mod and see if the monitor does the crackling and flashes again.

I was exaggerating about taking 1 hour to full stabilize in good colors and normal brightness, it takes around 20-25 mins, I controlled using a clock

Same for my Sony E540.

also another wrong thing I said is the monitor is based on the sony G500, according to the specs it seems is a sony G520

Oh no!
Externally, that looks the same as my Sony E540, too. And according to the E540 service manual schematics, IC 406 is already grounded :\ . Check your A board and see if that is the case. If yes, then we have the same monitor. What's worse is that I noticed yesterday that my E540 is also starting to develop an G2 overbright issue. Not sure how to permanently fix this one if there is no "Drift Correction" circuit to disable. Perhaps WinDAS to adjust the G2 only? Let me know what you find with yours. Maybe I will pull and disassemble mine as well so we can compare.

[laser]

Re: Dell P1110 21" CRT repair thread

ok I done a video of this monitor starting cold, no crackling or flashes this time
( sometimes it does not make)
as you can see the black is tinted in green, is out of brightness but this can't be noted very well in the video

I was exaggerating about taking 1 hour to full stabilize in good colors and normal brightness, it takes around 20-25 mins, I controlled using a clock

also another wrong thing I said is the monitor is based on the sony G500, according to the specs it seems is a sony G520
Tomorrow I will make the IC406 mod and I will use windas to normalize G2 to a normal level if is required ,and I will upload a new video starting in cold

https://youtu.be/ndTqymJUZVc

[laser]

Re: Dell P1110 21" CRT repair thread

Unlikely.
The caps in my D1626HT are much older (monitor is a 1998 vintage), and it doesn't have any overbright issues. It does occasionally do the "big flash and cracking" sound, though. But I think that is an unrelated issues, because it does it regardless if the monitor is warm or not (most likely the flyback is going out in mine). The newer Sony CRTs are pretty solid in that regard.

thanks for your reply master

about the "big flash and cracking"... what the hell this could be,?a bad weld ?
the flyback? an aged cap?
I looked at the G board quicly and I don't noted any inflated cap

I will upload a video later showing my monitor starting cold before I make the IC 406 mod, then of course I will make a new video with the mod done to see the differences

if flashes and cracking still persist I will dismantle the G board to look around where is the problem, I'm almost sure the problem is located there

[momaka]

Re: Dell P1110 21" CRT repair thread

regardless the IC 406 - PIN 17 to ground mod

my question are:

1 : how many time takes the monitor to warm up exactly doing the pin 17 to ground mod?

None.

With this mod, the monitor will start a little dark, just like any other normal CRT monitor and will take probably about 15 to 30 minutes to warm up to full brightness.

I have a 21" Dell Trinitron D1626HT CRT monitor that is a generation or two older than the CPD-E500 chassis. It does not have this "Drift Correct" circuit at all (actually, it uses discrete transistors instead of a Cut Off Amp IC), so it does not have any overbright issues whatsoever.

2: you guys are you sure that a big warm up time, part of the problem is not the aged capacitors in the power supply area in the G board ????
Im talking about the big cap 450v 320mf and the ones located near vertical IC ie some of them are 4700 mf 16 volts

Unlikely.
The caps in my D1626HT are much older (monitor is a 1998 vintage), and it doesn't have any overbright issues. It does occasionally do the "big flash and cracking" sound, though. But I think that is an unrelated issues, because it does it regardless if the monitor is warm or not (most likely the flyback is going out in mine). The newer Sony CRTs are pretty solid in that regard.

[R_J]

Re: Dell P1110 21" CRT repair thread

Its been a very long time since I worked on these but I do remember some that had a bad capacitor for the heater supply voltage. I know the 17" monitors had a problem so check the voltage on cn652 pin #9

[laser]

Re: Dell P1110 21" CRT repair thread

BUMP

hello guys I have a monitor SUN 21 GDM-5410 , is the same monitor I believe is a sony CPD-G500 manufactured by SUN

long time ago I done a serial > TTL converter and I adjusted G2 several times because it goes out brightness frequently
This fuckiiing monitor is working fine but have the classic warm up time problem, it takes about 1 hour or so from cold start to normal brighntess
even when I turn on the monitor the screen goes totally green and there are big flashes and explosions until warms

OK

regardless the IC 406 - PIN 17 to ground mod

my question are:

1 : how many time takes the monitor to warm up exactly doing the pin 17 to ground mod?

2: you guys are you sure that a big warm up time, part of the problem is not the aged capacitors in the power supply area in the G board ????
Im talking about the big cap 450v 320mf and the ones located near vertical IC ie some of them are 4700 mf 16 volts

[CRockT]

Re: Dell P1110 21" CRT repair thread

Okay, so what I had to end up doing was scrape all of that stuff off with my iron because I guess I had already burned the stuff pretty good onto the tab. However, I managed to get all of it off and complete the process! I ended up using stranded copper wire, and the finish was not pretty, but it definitely got rid of the over-brightness.

It seems really dark now, but I am going to be messing with all the settings before I mess with the G2 voltage.

Thank you all very much for the advise and help!

[CRockT]

Re: Dell P1110 21" CRT repair thread

Thanks! I will give that a go right now!

[goontron]

Re: Dell P1110 21" CRT repair thread

that is actually cooked rosen left over from when the device was made. all that takes is rubbing alcohol ( or really strong moonshine. dont ask me how i know. ) a toothbrush and a careful hand so is not to damage the tiny SMD chips around it, and use the alcohol and toothbrush to scrub the gunk off.

[CRockT]

Re: Dell P1110 21" CRT repair thread

Shot 0645 shows how clean the second closest tab to 404 is; shot 0648 shows how messed up the tab right under 404 is.

[goontron]

Re: Dell P1110 21" CRT repair thread

So, I am finding it very difficult to solder a wire to the metal tab because it looks like there is some kind of glue stuff that is all over it; the solder will not stick to the tab. Will it be okay for me to try the next closest metal tab? And in case that does not work out, what are my other options?

Resistor error 404 solder pad not found? can you get a picture of the glue spot? it could just be that the solder won't melt right.

[CRockT]

Re: Dell P1110 21" CRT repair thread

Just solder a wire from pin 17 to the large metal tab you see under R404.

So, I am finding it very difficult to solder a wire to the metal tab because it looks like there is some kind of glue stuff that is all over it; the solder will not stick to the tab. Will it be okay for me to try the next closest metal tab? And in case that does not work out, what are my other options?

[Topcat]

Re: Dell P1110 21" CRT repair thread

I had one of these back around 2002. It too had the brightness problem, and abck then, DAS software and cables were nowhere to be found....I cured it with the resistor trick.

[Th3_uN1Qu3]

Re: Dell P1110 21" CRT repair thread

Just solder a wire from pin 17 to the large metal tab you see under R404.

[CRockT]

Re: Dell P1110 21" CRT repair thread

Okay, so it definitely sounded easy, but now that I have gotten to the part where I connect pin 17 directly to ground, I just realized I have no idea how to do that. Am I supposed to desolder pin 17 and move it somewhere else? And if so, where? I have a picture of the area if someone can show me what I am supposed to do.

[CRockT]

Re: Dell P1110 21" CRT repair thread

Thanks for the explanation, momaka! Sounds easy enough; hopefully I can find the time to do this before the week is over.

Either way, I will update everyone on how the mod works out for me.

[momaka]

Re: Dell P1110 21" CRT repair thread

See attached image in post #25.

Basically, you need to find the Cut Off Amp first - IC406. It is located on the A board - the board that attaches to the back of the CRT tube. Here's what this board should look like more or less (picture is of my 21" Dell D1626HT, which is an older Trinitron with same board layout)
https://www.badcaps.net/forum/attach...8&d=1361437452
(basically, once you take the plastic cassing off of the monitor, the A board will be under a metal shield).

So find IC406, and then locate Pin 17 (it's an end pin). On it will be attached that self-biasing transistor circiut (labeled as "Drift Correct" on schematic). It is comprised of transistor Q401 and resistors R404 and R405. NOTE: these components are SMD (at least on my GDM-FW900 they were, and that monitor has the same "Drift Correct" circuit on the cut-off amp).

So all you really have to do is connect Pin 17 on IC406 directly to ground. This will bypass the dripft correct circuit completely.

With this mod, you may find that you have to adjust the G2. When I tried this mod on my GDM-FW900, it became a little too dark. Since I didn't feel like playing with WinDAS and messing with the G2, I re-enabled the drift correct circuit again (so this mod is completely safe and reversible!). Later, I added a resistor in parallel with R404 (forgot what value), to make the drift-corect circuit bias "more". This helped to reduce the brightness, but only a little.

The best way really is to do it like Th3_uN1Qu3: disable drift-correct circuit and tweak the G2 accordingly.