Re: Dell 1504FP Monitor Year of Manufacture 2003

[Teodule]

Hi guys

I have a dead Dell 1504FR monitor on my desk. I got it from the local dump (you may wonder what I can find there!!). The monitor doesn't show any sign of life.
I have disassembled it and checked the PSU board. The first symtoms are two blown fuses a dead big cap (C5). The white glue visible on other postings is dark brwon. Arcing signs between thermistor (TH1) and dissipator of IC1.

My guess:
the glue went conductive inducing the arcing, the capacitor C5.

My questions:
Should I expect IC1 to have been killed by the arcing? Or some other component?

My ideas so far: replacing all caps. Replacing fuses....

I enclose 3 pictures: a main view of the PSU and two views of the place of arcing

Any suggestion is welcome. Thank you

[selldoor]

Re: Dell 1504FP Monitor Year of Manufacture 2003

You must enjoy a challenge? - Take it you have a multimeter and soldering equipment
Do you know how to test individual components (at least for shorts)
Picture of the bottom of the board?
Add R2 to the list of casualities.

Is this just for experience - could be a lot of work for a 15" monitor.
Have you anyway of testing the bulbs

[Teodule]

Re: Dell 1504FP Monitor Year of Manufacture 2003

Hello Selldoor,

Thank you for your quick answer! You are right I love challenges ...and gathering experience. A 15'' monitor might not be actual for using as a desktop monitor but could be great to be used for navigation in your car, or as a spare.

I have here some testing equipment , although I am now in my vacation cottage I never travel without basic equipment like DMM. soldering iron (no scope right now)

Back to the psu: R2 is OK, rectifier is OK, thermistor is conductive. and here is a picture of the bottom of the board.
I couldn't test the lamps as I don't have an corresponding power supply.

I will try replacing defective parts first. My only concern is I don't now how to get spare parts here (France, ....)

[budm]

Re: Dell 1504FP Monitor Year of Manufacture 2003

R1 and R2 are connected in series for discharging C1 and C2 X caps, the unit will work without the resistors, they are part of the compliance to discharge the caps down to< 50V after 30 seconds.
You should check the SMPS IC1 for Source to Drain shorts, and the Source resistor to make sure it is not open.
Unit that old can have worn out lamp also.

[selldoor]

Re: Dell 1504FP Monitor Year of Manufacture 2003

Ok - you measured R2? it has a big chunk of ceramic missing? - dont know if it will stand up to mains voltage.

I cant really help you with parts in France - there are the major suppliers
digikey and mouser but postage is quite expensive. Unless someone from France can suggest your best chance might be to pick up another cheap set on ebay and build one from two.

For fuses you dont have to have exact replacements as long as they have the same amps/volts - some people use pico fuses or even household fuses in a holder when they cant get originals

The capxon caps dont actually look too bad (not that that is really anything to go by but maybe lay off replacing them until you have some voltages to test.

It may be worth you setting up a 75w filament bulb in series with the mains+
as it could save you blowing new components when you do get some.
Just google Dim Bulb Test.

I guess from your heading you must have been reading the threads from Matt in Malta I dont think we were aver able to fix those

[Teodule]

Re: Dell 1504FP Monitor Year of Manufacture 2003

Hello, I am back here.

Yeap, R2 is still fine. I changed the capacity C5 with a 82microF/450V -taken from a computer PSU-. And guess what?, it works! So I thank you all for your contributions.
The next repair is an LED 37'' Samsung TV. Also from the local dump! It is amazing how few components are used in this piece of equipment. I'll check the caps in the psu again but I am afraid the processing card is faulty....(samsung 37" D5000 Series 5 Full HD LED TV, Model number UE37D5000PW).
Have a nice day!

[selldoor]

Re: Dell 1504FP Monitor Year of Manufacture 2003

Well done! Had the glue rotted the capacitor?

[Teodule]

Re: Dell 1504FP Monitor Year of Manufacture 2003

Indirectly, yes. I guess the arcing in the R2 area induced a surged that killed C5. And/or C5 dried out.