Broken Dell 1800FP Power Supply - when and when not to resolder?

[Shane711]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

Well I have this power board and I am not sure what is wrong with it but I seem to have narrowed it down to the IC chip or the the transformer. I removed all the caps and they tested good. All diodes test good. The ICE2AS01 is shorted at pins 6 & 7 with 5ohms but I am reading 40v at all 8 pins. I got 168v going into the transformer and about 1v coming out. I think it is the transformer but will the ICE2AS01 cause this? I am not getting any voltage out at the plug going to the main board.

[jetadm123]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

The 11N60C3 is rated at 650V versus 100V for the IRF510. The 100V rating is way too low for the application.

[budm]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

The later version of this power supply has 20V 1Watt ZENER Diode between VCC pin and Ground, suppose to protect the IC from voltage spike during power supply start up.

[Alohamora]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

I ran into a 3rd dead 1800fp and could couldn't resist buying it for $5 (goodwill), even though I still haven't found a home for the other 2 I fixed.

This one had a shorted ICE chip, which I replaced, but it still didn't work. D906 and D903 had crappy soldering so I re-flowed them. F901 was blown. It helped to have a working power supply to compare to and also the schematic and I have found that Q902 is shorted.

Q902 is a 11N60C3. My question is if there is some other common IC that can be substituted? (I have a few IRF510 on hand).
11N60C3 on alldatasheet - I'm not sure which suffix to use?

[Alohamora]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

You say "dead, no LED", but you still had a fluctating 12V/5V output?

Yes, fluctuating. I double-checked with a better meter.

Touching up the solder joints did not help.

However replacing the 47uf cap did the trick! Got my cap order today and I replaced the 47uf first, and then the monitor started turning on!

I did replace the rest of the caps after that anyway, all but the one really large cap. I don't have an ESR meter but the cap meter says the old ones I pulled out measure from 12% to 27% low.

Same story with monitor #2, except I replaced all the caps in one sitting.

These two monitors were $10 each from Goodwill. I may go back and see if they have any of the $5 CTX monitors left.

Thank you so much for the advice!

[jetadm123]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

More likely a bad cap. Suggest you first try replacing the 47uf startup cap and re-soldering all transformer pins.

[Alohamora]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

No luck pressing anything with a popsicle stick, but the hairdryer worked on both monitors! Blowing on the area of the ICE chip and the two little caps, first the LED turns on and then the backlight.

Bad solder? I can have another go at re-soldering everything later this evening.

[jetadm123]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

You say "dead, no LED", but you still had a fluctating 12V/5V output?

Sounds almost like a bad solder joint. You can try the following:

1) using a small wooden or plastic stick, try pressing down on various parts on the power supply.

2) using a hair dryer, heat up various portions (especially areas around the ICE chip) to see if that aids in startup.

3) re-solder the joints for the pins of the main (yellow) transformer of the power supply as they are a known problem with this power supply.

4) if the above fails, try measuring the voltage of the startup cap. I believe it's the small 47uf 50V cap next to the ICE chip.

[Alohamora]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

Yes, I've swapped boards between the two monitors. I swapped logic, keypad and power boards. Nothing made a difference but the power board. The "semi-repaired" board turned on a few times in both units. But this morning, it's back to acting totally dead, as in no LED.

I double-checked voltages on the connector P902 going to the logic board, both 12V and 5V lines are low and fluctuating wildly.


Let me know if you want pics of anything else.

[jetadm123]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

I have 2 of these Dell 1800 FP monitors. Neither would turn on when I got them, no power LED. I pulled the power boards, one seems to have pretty clean solder joints. The other had dodgy solder joints so I reflowed D903 and D906 and replaced the ICE chip. Now, the monitor with that board will sometimes turn on. The longer it's off, the more likely that it will get a green LED and power up, once it's on, it seems to work, but if turned off it doesn't come back on again until it's "rested" for a while. I haven't done anything to the power board board with the better looking soldering.

If I disconnect the P902 connector between the power board and the logic board, I find 12V and 5V on that connector, but if I leave it connected and check voltages they are low, 7 or 8 and under 4.

Not sure where to go from here. Replace the "Sam Young" caps?

Since you have two of these monitors, did you try the power supply you just fixed on the other monitor? If you see the same problem, then it's a power supply issue. If no, then the problem is elsewhere.

[Alohamora]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

I have 2 of these Dell 1800 FP monitors. Neither would turn on when I got them, no power LED. I pulled the power boards, one seems to have pretty clean solder joints. The other had dodgy solder joints so I reflowed D903 and D906 and replaced the ICE chip. Now, the monitor with that board will sometimes turn on. The longer it's off, the more likely that it will get a green LED and power up, once it's on, it seems to work, but if turned off it doesn't come back on again until it's "rested" for a while. I haven't done anything to the power board board with the better looking soldering.

If I disconnect the P902 connector between the power board and the logic board, I find 12V and 5V on that connector, but if I leave it connected and check voltages they are low, 7 or 8 and under 4.

Not sure where to go from here. Replace the "Sam Young" caps?

[jetadm123]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

Your power supply is not known for failed caps. However, without photos or any voltage testing, if I had to replace a cap, I'd start with the startup cap on the power supply. It's a small cap probably rated at 47uf 50V.

[abced123]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

I just resolder transformer joints, still persists. While the LCD is on , there is no clicking sound. Let it idle (yellow LED) for around 30mins, the LCD will turn itself off and clicking sound is heard.
Any suggestion on which caps I should (how to) check or replace? They all look OK to me , no bulging. Thanks

[jetadm123]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

Another problem with your model monitor were bad solder joints on the power board's main transformer. Have you tried resoldering the transformer pins?

[budm]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

That can be bad caps with high ESR, ESR will go down when the cap is heated up.

[abced123]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

Hi all,

Following this thread for years, but I was lazy, using a newer LCD, and my rarely used 1800fp working fine with an external atx PS. However, I decide to give it away, so trying to fix it ...

Here is my current problem. Whenever I want to start the LCD, I have to use a hair dryer to blow on top of the PS board for 30s-1min, then the LCD will start to work perfectly.

I already tried to resolder D903 and D906, but problem still persists . When turning it off, I hear very small click sound from the PS board. What do you think ?

Thanks,

[budm]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

That is the typical failure mode of the ICE2AS01: shorted VCC pin. You need to get the same IC, there is no sub for this ICE series IC. The later version of this power supply, they added 18V Zener Diode (Vcc pin to ground to clamp the max spike voltage to 18V) to stop the power supply from destroying this IC.

[Naity-sama]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

Hello!
I picked up an old 1800FP a few years back. I never tried to do anything with it because it didn't work, but now I've got a use for it and I'd like to get it up and running. I'm not the best at this kind of thing, but I've done some work on smaller things.

It's got a lot of the basic issues I've seen throughout the forum for it's model.
Doesn't turn on at all, no LED power light, bad solder on the power supply, flux all over the place, etc., etc. Also, the capacitors are definitely staying charged for about 10 minutes (Well, they did at least one time) because after I disconnected the PS and unscrewed it so I could remove it, it electrocuted the #^&*)^%$ out of me when I touched it.

I'm getting all kinds of interesting readings on my voltage meter. I've alreay checked D902 out of circuit and it's good. I resoldered a few of the solder joints that were bad. One on D903 was completely separated. (Also, can someone please tell me where/which ones are the duo diode paks so I can re-do them?)


From what I hear, it's most likely the ICE2AS01 on IC901. If I ground my meter on pin 7, and check on pin 6, I get a little less than 3.5 ohms on the x10 setting. Does that mean it is shorted?

Also, if it IS the ICE2AS01, can I replace it with a SG6841D KAQ92650425E from an AOC brand LCD? It is the same size and shape, and has the same number of pins, but I am unsure if it would be compatible.

If you have any ideas for what I can do elsewise, please tell me! thank you very much!
(I'm sorry the over all picture isn't the best!)

[wdwillis]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

I would like to thank the informative folks who have posted in this thread. I bought a couple of them about a year and a half, and after only about 3 weeks, one failed. I got the seller to swap me the dead one for a good one. another one died and i tossed it (it had been a couple of months.
then last week another died ( i have about half a dozen of them running at the moment).
I was about to toss it today, when i came across this thread, and decided to take a whirl, since i was gonna toss it anyway. (whats the worst that could happen?)

It's now running, and I couldn't be happier. Thanks a lot folks.

[retiredcaps]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

I have a Dell 1800FP which doesn't turn on.

1) Post clear focused top down view pictures following my sig file below exactly.

2) Does the power LED come on at all?

3) Do you have a multimeter and know how to use it?