Dell - 1504FP W/Pictures

[PlainBill]

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

Attach clear pictures of the top and bottom of the power supply / inverter board. Also, a little clearer description of the problem would be useful.

PlainBill

[ic000001]

Re: Dell - 1504FP W/Pictures - SOLVED

Hi guys,

Firstly thank you to all contributors - your wisdom really helped!

I had two Dell 1504FPs exhibiting the dreaded "2 seconds to black". I changed caps C17 A,B,C and D... C17 and C23 - but still no luck.

Checked the primary and secondary resistances on T1, T2, T3 and T4 and found the problem. Each monitor had a single transformer whose secondary was higher than the specified 0.9k. They were approx 1.7k and 1.9k respectively. So I removed them.

I took a healthy txformer from monitor A and replaced the bad one on monitor B and VOILA! - it works.

Now just need to scrounge around to find another healthy SPI 8TT00006. PS.

Nice CCT diag of the txformer attached.

Cheers all,

[sceva]

Re: Dell - 1504FP W/Pictures

I have seen several of these in another monitor (possibly a Samsung 193). The three main problems I ran into were bad caps, bad inverter transformers, and bad transistors under the 4 small caps in the inverter area.

Most monitors gave either 2 sec to black, or no backlights at all. I would first plug in external ccfl's and turn it on. If one or more of the transformers were faulty you could see one or more of the lamps not turn on. I never could find a place to purchase the transformers affordably, so I salvaged transformers from other boards. A ring tester is a great tool!

If all the lights came on, and then off in 2 sec, I would replace all the caps in the inverter area (which is a good idea anyway, as most of the small "stubby" caps in the inverter area tested close to the limits with ESR meter even when working)

If still 2 sec to black, I would investigate the 4 transistors on the bottom side. Usually one or two of them would be bad. I assume they went bad because the caps were failing... I was able to purchase some of these online, and also used some from other boards. About 1/2 the time these would either show the burn marks on the top side of the board, or have cracks or bulges on the transistor to help you determine which one was bad, but not always. I had to remove them from the board to accurately test them. ChipQuick is a good tool for removing the smaller components.

[ic000001]

Re: Dell - 1504FP W/Pictures - new problem

Hi guys,

As luck would have it of the two monitors I fixed, one has come back in when the smoke escaped from another component ... I'm just not sure which component it was. Any ideas what needs to be replaced there? See attached shots) ... and what may have caused it to fail? I suspect that after re-capping and replacing the busted txformers, the unknown component was next in line.

I may be able to get the second monitor back to compare PCBs and identify the burnt component(s) but thought I'd check here first.

Thanks in advance.

[mhakat]

Re: Dell - 1504FP W/Pictures

http://www.diyprojects.info/bb/ftopic41030.html

NAMA - check out the above link a guy called Michael seems to know what the issue is

Sorted it! I soldered a 47k surface mount resistor over the surface mount
capacitor (C25, on underside of PCD, near BIT3105- in case anyone has this
problem in the future) and it works fine. OLP circuit disabled. I think I'll
notice if any of the lamps die- dont need all that overengineered circuitry.
Thanks for your help people.

[PlainBill]

Re: Dell - 1504FP W/Pictures

http://www.diyprojects.info/bb/ftopic41030.html

NAMA - check out the above link a guy called Michael seems to know what the issue is

Sorted it! I soldered a 47k surface mount resistor over the surface mount
capacitor (C25, on underside of PCD, near BIT3105- in case anyone has this
problem in the future) and it works fine. OLP circuit disabled. I think I'll
notice if any of the lamps die- dont need all that overengineered circuitry.
Thanks for your help people.

Disabling the Open Lamp Protection isn't the stupidest thing someone can do, but it comes close.

PlainBill

[ahmedjaan]

Re: Dell - 1504FP W/Pictures - SOLVED

Hi guys,

Firstly thank you to all contributors - your wisdom really helped!

I had two Dell 1504FPs exhibiting the dreaded "2 seconds to black". I changed caps C17 A,B,C and D... C17 and C23 - but still no luck.

Checked the primary and secondary resistances on T1, T2, T3 and T4 and found the problem. Each monitor had a single transformer whose secondary was higher than the specified 0.9k. They were approx 1.7k and 1.9k respectively. So I removed them.

I took a healthy txformer from monitor A and replaced the bad one on monitor B and VOILA! - it works.

Now just need to scrounge around to find another healthy SPI 8TT00006. PS.

Nice CCT diag of the txformer attached.

Cheers all,

thanks dear Inshallah i check these transformers..thank you all .

[vagos_89]

Re: 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


<br>

Please, Could someone tell me if it's easy the code of component with 6 pins which is above the heatsink, to the right of large capacitor(120μf 400V)
It's defective and i can't see the code, it has a small hole in front and can't read it.. Thank you in advance and sorry for my english :p

[budm]

Re: Dell - 1504FP W/Pictures

TOP247:
http://www.electronicrepairguide.com...or-repair.html