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Old 05-13-2009, 01:49 AM   #1
Nama
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Question Dell - 1504FP W/Pictures

Hello!. Well I'm on monitor 2 of 80 i have to fix. So you will be seeing lots more of me in the near future. Monitor one went very smooth with the help of this forum.

This Dell powers up shows display perfect then back lights kick off. I replaced 3 CapXon caps with obvious bulging still the problem remains.

As you can see in the picture c17a,b,c & d have discolored the board around them. But with no markings at all on the "what i would guess to be a cap" I have no idea what to replace them with.

Would you also suggest replacing all caps on the board?

Thanks in advance. Jacob


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Old 05-13-2009, 02:57 AM   #2
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Default Re: Dell - 1504FP W/Pictures

black caps with gold lettering that have over heated are hard to read, best remove a cap one of the rightside pair and look at it in good natural daylight with magnifying glass, you should find the info you require
I dont know this board but I do know inverter caps dry out due to heat on some inverters and still look good to the naked eye
So I think you solved your own problem
good luck
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Old 05-13-2009, 08:37 AM   #3
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Default Re: Dell - 1504FP W/Pictures

This is good monitor to fix, made by Samsung for Dell.

Yes, need to buy ESR meter and check these electrolytics.

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Old 05-13-2009, 09:01 AM   #4
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Default Re: Dell - 1504FP W/Pictures

You also might want to look at the opposite side of the board. While it is possible the caps overheating discolored the board, it is more likely that the transistors driving the transformers are located on the bottom side of the board, and are the source of the heat.

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Old 05-13-2009, 09:15 AM   #5
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Default Re: Dell - 1504FP W/Pictures

Correct PlianBill. The transistors are located directly on the other side. I guess it would be cheaper in the long run to buy a ESR meter and not recap every monitor. Thank you all I will let you know how it goes. Should I re size the pictures of boards in my future postings? or is it better to have them large?. I know these posts will be valuable to the next man just as the old ones have been to me. Jacob
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Old 05-13-2009, 12:38 PM   #6
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Default Re: Dell - 1504FP W/Pictures

Quote:
Originally Posted by Nama
Correct PlianBill. The transistors are located directly on the other side. I guess it would be cheaper in the long run to buy a ESR meter and not recap every monitor. Thank you all I will let you know how it goes. Should I re size the pictures of boards in my future postings? or is it better to have them large?. I know these posts will be valuable to the next man just as the old ones have been to me. Jacob
An ESR meter is a good investment, but can become a crutch. If in doubt, replace the caps. Many monitors have inferior caps, NOT replacing a Fuhjyyu cap because it almost meets specs would be a false economy.

I would emphasize that if you buy from the proper source, caps are NOT expensive. I would say most monitors can be recapped for under $10 (including shipping) by shopping at Digikey.

We each have our preferences on pictures. I prefer to see thumbnails, with the ability to see a large picture. It allows me to see more detail. And of course, if you aren't sure what you are looking at on the caps, include views that show the labeling on them.

The poorest picture is still better than "My monitor isn't working. How do I fix it?"

PlainBill
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Old 05-13-2009, 11:54 PM   #7
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Default Re: Dell - 1504FP W/Pictures

I used 100uf 25v but I forgot what the originals were. I suspect they are the set of 4 pink CapXon 47uf 25v caps I have in my junk bin. I was not able to complete my 1504FP because one of the SPI 8TT00006 transformers was bad and I couldn't find one or a board they are on anywhere. The BIT3105 controller will shut off the backlight if it detects a bad transformer.

Last edited by severach; 05-13-2009 at 11:58 PM..
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Old 05-14-2009, 12:16 PM   #8
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Default Re: Dell - 1504FP W/Pictures

How exactly did you come to the conclusion your transformer was bad?. I have replaced all caps on this board and nothing has changed. I still have the 2 seconds to black issue. I do not have the money yet to buy an ers meter. can i use this to test the transformer?.




Thanks again for all your help. I learn very fast and hope to be able to help others here in the future.
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Old 05-14-2009, 02:14 PM   #9
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Default Re: Dell - 1504FP W/Pictures

Quote:
Originally Posted by Nama
How exactly did you come to the conclusion your transformer was bad?. I have replaced all caps on this board and nothing has changed. I still have the 2 seconds to black issue. I do not have the money yet to buy an ers meter. can i use this to test the transformer?.



Thanks again for all your help. I learn very fast and hope to be able to help others here in the future.
Nope, a VOM won't cut it. At this point you have two more things to try.

1. Try the monitor in a darkened room (face down), you are looking for signs of arcing around the transformers.

2. Buy a case mod kit, the kind with two CCFLs and a cheap inverter. Use the CCFLs to test the monitor's inverter. (It will be necessary to test each output of the inverter with the CCFLs.) Use the inverter to test the monitor's CCFLs.

PlainBill

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Old 05-14-2009, 02:54 PM   #10
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Default Re: Dell - 1504FP W/Pictures

Will do. I have already tested the CCFL's on the monitor.
I will now try the dark room.

I do still have one question,
From what I've read the inverters components monitor the voltage to the CCFL to create a flicker free signal.

Here is where my question come in.

Is it possible to bypass the controller by hooking up a ccfl directly to the transformer? For testing purposes

I would think if the CCFL lit up the transformer would be ok.

Just a thought.
I will be ordering my ESR Meter this weekend or early in the week. Any suggestions on what to get?. Jacob
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Old 05-14-2009, 03:16 PM   #11
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Default Re: Dell - 1504FP W/Pictures

I have PEAK Atlas ESR60 and I find it gives conflicting readings when measuring in circuit for ESR , oftet get diffrent readings when I directly retest, but when caps removed no problem, wish I had bought something else.
And would never trust it for capataince when in circuit at anytime

Last edited by Bobdee; 05-14-2009 at 03:20 PM..
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Old 05-14-2009, 04:05 PM   #12
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Default Re: Dell - 1504FP W/Pictures

Quote:
Originally Posted by Nama
Will do. I have already tested the CCFL's on the monitor.
I will now try the dark room.

I do still have one question,
From what I've read the inverters components monitor the voltage to the CCFL to create a flicker free signal.

Here is where my question come in.

Is it possible to bypass the controller by hooking up a ccfl directly to the transformer? For testing purposes

I would think if the CCFL lit up the transformer would be ok.

Just a thought.
I will be ordering my ESR Meter this weekend or early in the week. Any suggestions on what to get?. Jacob
Not really. The controller drives the transformer (through one or more transistors) AND monitors the output voltage and current. An arc between turns in the secondary of the transformer will result in reduced voltage and reduced current. Many controllers will shut down the backlights if the voltage goes too high, and if the current is too high or too low. The particular inverter you have uses the BIT3105 (now the BIT3713). I've attached a datasheet showing a schematic for an inverter based on it. Note the feedback lines from the CCFLs to the controller. A VOM wouldn't work, but someone with a oscilloscope could monitor those lines and quickly determine WHY the controller was shutting down. (Well, first he'd have to trace the connections, your inverter isn't identical to the one in the app note).

I'm using the Ana Tek ESR meter. I made a few comments about it's strengths (as well as a few weaknesses) here.

PlainBill
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File Type: pdf BIT3713 4 LAMPS H[1][1][1].B VER0.1S.pdf (36.5 KB, 169 views)
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Old 05-14-2009, 10:05 PM   #13
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Default Re: Dell - 1504FP W/Pictures

I see no sparks in the dark PlainBill. I opened up another 1504FP and replaced all caps. Same deal with both monitors. 2 seconds to black. I'll report back on this model after i get a ESR Meter. I would try swapping some parts but it seems they both have the same problem. Jacob.
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Old 05-14-2009, 10:30 PM   #14
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Default Re: Dell - 1504FP W/Pictures

Quote:
Originally Posted by Nama
I see no sparks in the dark PlainBill. I opened up another 1504FP and replaced all caps. Same deal with both monitors. 2 seconds to black. I'll report back on this model after i get a ESR Meter. I would try swapping some parts but it seems they both have the same problem. Jacob.
What caps are you using as replacements?
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Old 05-14-2009, 11:11 PM   #15
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Default Re: Dell - 1504FP W/Pictures

XICON 35v 1000uf
XICON 25v 220uf
NHG 50v 33uf

This may be my problem also. They do match match original specs.
They are the same Caps i used to fix this MAG and they also did not match the original specs of that lcd. I figured since they worked in the MAG I may also have luck with the Dell.

I will be ordering $50 worth of caps sunday. So I will try again. Jacob
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Old 05-14-2009, 11:24 PM   #16
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Default Re: Dell - 1504FP W/Pictures

Quote:
Originally Posted by Nama
How exactly did you come to the conclusion your transformer was bad?
Neither an ESR meter nor a VOM will test the transformer. The proper test tool is the ring tester. Without desoldering the 3 good transformers show all leds on the low voltage side. The bad transformer shows no leds. All transformers show no leds on the high voltage side. I didn't have the ring tester when I diagnosed this transformer so i did it the hard way.

It isn't too hard to test the transformer the hard way so long as the backlight flashes and there is more than one channel to test. Test each lamp in its channel separately with all the others unplugged. Watch for differences in the way each channel lamp lights up. Partially damaged lamps or channels may stutter and never reach full brightness which will get shut down by the controller. You might find that some channels flash their lamps and some are dark. Switch lamps and channels to test the unknown lamps in working channels and the unknown channels with working lamps.

In my case all lamps worked equally well and one channel was completely dark. I guessed that the transformer was the most likely failure so I desoldered and swapped the suspect transformer marked with an X into a working channel and the good transformer marked with a dot into the suspect channel. The formerly good channel went completely dark and the formerly dark channel was now good.

The ring tester is a lot faster. With two screens you'll get at least one working and have enough spare transformers to send one to me.
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Old 05-14-2009, 11:34 PM   #17
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Default Re: Dell - 1504FP W/Pictures

I destroyed the first board. You are more than welcome to the spare transformer. eguevarae has me thinking.... I may need the correct caps. I will order then Sunday. Are you in the USA?. If so im sure it would only cost me a few bux to send it out. Jacob
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Old 11-26-2009, 08:36 AM   #18
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Default Re: Dell - 1504FP W/Pictures

Has anyone found a source for the SPI 8TT00006 transformers?
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Old 11-26-2009, 01:48 PM   #19
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Default Re: Dell - 1504FP W/Pictures

Quote:
Originally Posted by bbear
Has anyone found a source for the SPI 8TT00006 transformers?
Google it. Several companies have them.

PlainBill

Last edited by PlainBill; 11-26-2009 at 01:55 PM..
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Old 12-10-2009, 11:24 AM   #20
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Default Re: Dell - 1504FP W/Pictures

I have tried to fix two of these so far with almost no success despite having fixed numerous other monitors. Can anyone reliably tell me which are the switching transistors on these boards. I have seen variuos posts describing "cures" but have yet to see a successful outcome
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