Dell 1905FP Won't Turn On

[obscurehero]

At work, we have a 1905FP dell 19" LCD monitor (from '05) that stopped turning on. We have a history of just buying new monitors and throwing the old ones out, so since I've been here I've rescued one. I ended up just buying a replacement PSU board for one monitor rather than replace caps as I hadn't done much since H/S with the soldering iron and it still was half the price of a new monitor (it was a 22" ws and replacement board was $70). I should've just bought caps and done it, but I figured that was easier and cheaper than buying a new one.

ANYWAY, I opened the dell 1905FP up and pulled out the PSU board. I noticed two CapXon 10V 1000uF capacitors, bulging with leaked, dried electrolyte coming out the top. OBVIOUSLY bad. The others are fine, and there is one other one of the same size and rating that has not gone bad. I checked out the specs on CapXon's site for the KF capacitors and found this:

-40-105C; 1.04A RC; 76mOhms Imp;

I also found a table that gives a "multiplier for ripple current vs. Frequency" and for 120Hz it lists 0.72 as the multiplier. I have no idea what that means. I just took one course on E&M in college, so I def don't remember this.

I looked at Digi-Key for caps, and I found these:

Panasonic-ECG
Nichicon
United Chemi-Con

Which ones should I choose, and should I replace the other caps as well. It looks like they're all from CapXon which seems to be a rather shitty manufacturer. Also, what type of solder should I use? Maybe a rookie question, but I noticed radio shack had two different kinds. I will be buying an iron for this job, and thought I'd get it there.

Lastly, the manufacturer placed some type of heat paste on the MOSFETs' (I think that's what they are) heat sinks that are then screwed tightly into the back of the monitor. I'm guessing they're trying to transfer the heat to the entire back of the monitor. Anyway, should I replace that paste as well, or just leave what's there, there and call it good?

Thanks for the help all!

[jetadm123]

Re: Dell 1905FP Won't Turn On

Members suggest that you replace ALL caps except the large 450V cap, unless of course, it's bulged or leaking. Many will suggest Panasonic FM or FC series caps for replacements from digikey.com. See instructions below:

As for the white paste, it's a heatsink compound for heat transfer. No need to replace.



Here's the best way to order from digikey:

1) Go to digikey.com

2) In the "parts search" window type: panasonic fm and select "GO" button

3) Under the Capacitor heading select "Aluminum"

4) The first two columns you see are capacitance and voltage. Highlight the value and voltage with your mouse and select the "Apply Filters" button

5) You'll see several selections available. Here's what to look for:


a) Look at the quantity available and minimum purchase. If "0" are available, then there's none to purchase. Some selections require a minumum purchase of a 1000 units, which you also don't want. I think you get the picture.

b) height and diameter. Measure the original caps and compare to what's listed.


6) If your value is out of stock, go back to the beginning and type in "panasonic fc" and go through the same process

7) During the checkout process select USPS First Class shipping, since this will give the best ship rate.

[EGuevarae]

Re: Dell 1905FP Won't Turn On

Members suggest that you replace ALL caps except the large 450V cap, unless of course, it's bulged or leaking.

I agree. Change them all to save future unit rework...

[obscurehero]

Re: Dell 1905FP Won't Turn On

the panasonic I listed above is an "FC". The FM search only yields caps that have incorrect impedance and ripple current. Should I go with the FM's that have the wrong RC and Impedance or the panasonic FC?

[PlainBill]

Re: Dell 1905FP Won't Turn On

The Panasonic FC will work; I prefer Panasonic FM, which are a little better, and cost slightly less. And I echo the comments of others; replace ALL the electrolytic except for the 450 volt one. As you have discerned, Capxon caps have a bad reputation.

As far as the white paste, as long as there is enough to make good contact, don't sweat it.

For solder I use Kester 63/37 "44" rosin core .025 diameter. Equivalents are available by other manufacturers. I use Kester baecause 30 years ago I did a favor for a friend; he gave me a roll of the Kester, I'm still using that roll.

PlainBill

[obscurehero]

Re: Dell 1905FP Won't Turn On

Thanks all!!

The other caps on the board are not all CapXcon, but they all have the same color 'wrap'. I'll definitely replace all of the CapXcon caps as they seem to be the prime suspects.

The small capacitors are by the other manufacturer, Su'scon. They are 2.2, 4.7, 10, and 220uF at 50V. Should I replace these as well?

Also for the caps I order, is it ok if the impedance and RC are a little off? like 55mOhms (panasonic fc) vs 65mOhms (CapXcon)

[Krankshaft]

Re: 1905fp

If the heatsink the FET is on contacts the metal backplate of the monitor you can replace the compound between that junction if you wish.

If the compound is silicone grease you can wipe it off and replace it. If it's gray or white thermal compound I'd replace it. If it's a gray thermal strip don't worry it can be reused just make sure it stays on top of the heat sink when the back plate goes back on.

They do this because the heatsinks don't have enough surface area to dissipate the heat. So they couple the heat sinks to the back plate which provides a larger surface area for thermal dissipation.

To match the Crapxon specified ESR and ripple current you can use Panasonic FM series caps. Although personally I don't trust the specs of crap cap manufacturers. Replace all of the secondary caps. Any of the big three manufacturers make good caps but I stock mostly Panasonic so it's their series designations I'm most familiar with.

Radioshack has tin/lead solder and tin/lead/silver solder. I just use straight tin/lead for general purpose electronics work since the bit of silver adds cost and I've never really noticed a difference between them accept a lighter wallet on the silver bearing solder.

[obscurehero]

Re: Dell 1905FP Won't Turn On

I accidentally duplicated my thread, so for everyone's reference, I've posted what Krankshaft posted on my other thread.

If the heatsink the FET is on contacts the metal backplate of the monitor you can replace the compound between that junction if you wish.

If the compound is silicone grease you can wipe it off and replace it. If it's gray or white thermal compound I'd replace it. If it's a gray thermal strip don't worry it can be reused just make sure it stays on top of the heat sink when the back plate goes back on.

They do this because the heatsinks don't have enough surface area to dissipate the heat. So they couple the heat sinks to the back plate which provides a larger surface area for thermal dissipation.

To match the Crapxon specified ESR and ripple current you can use Panasonic FM series caps. Although personally I don't trust the specs of crap cap manufacturers. Replace all of the secondary caps. Any of the big three manufacturers make good caps but I stock mostly Panasonic so it's their series designations I'm most familiar with.

Radioshack has tin/lead solder and tin/lead/silver solder. I just use straight tin/lead for general purpose electronics work since the bit of silver adds cost and I've never really noticed a difference between them accept a lighter wallet on the silver bearing solder.
__________________
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[Toasty]

Re: Dell 1905fp monitor

Replace all the caps except the large mains cap.

Leave the paste. It's usually okay as is. You can also drill a hole in the back plate and use the second hole to attach the central heat sink evenly. From the factory it's only connected with one screw. I'm sure you noticed that the paste wasn't touching at one end... I have pics if you want to do so.

You can not go by the caps appearance... I have a beautiful looking car. Great paint and shiny chrome. The interior is all split and the motor is seized...

Presently available at DigiKey:

Dell 1905FP

[ Max cap height 22mm ]

3 - 1000@10v - 10x16 - Capxon KF - Pana FM == P12353-ND - EEU-FM1A102
1 - 1000@25v - 12x16 - Capxon KF - Pana FM == P12379-ND - EEU-FM1E102
1 - 2.2@50v  - 5x11 - Capxon KM - Pana FC == P10313-ND - EEU-FC1H2R2
1 - 4.7@50v  - 5x11 - Su'scon  - Pana FC == P10315-ND - EEU-FC1H4R7
1 - 10@50v  - 5x11 - Capxon KM - UCC KZE 5x7 == 565-1702-ND - EKZE500ELL100ME07D
1 - 22@50v  - 5x11 - Capxon KM - Pana FM == P12927-ND - EEU-FM1H220
2 - 220@50v  - 10x16 - Capxon KM - Pana FM == P12397-ND - EEU-FM1H221
4 - 470@35v  - 13x20 - Capxon KF - Pana FM @ 50v == P12400-ND - EEU-FM1H471
  {Sub for FM - UCC KZE == 565-1712-ND - EKZE500ELL471MK20S}
1 - 150@450v - 18x45 - UCC PAG  - Not Replaced; not a common failure

-------
15 caps - 14 replaced

Forgot the solder:
Unless you're expecting to do a lot, just a 2oz. or 4oz. tube/spool should be fine:

SMDSW.031 2OZ-ND = 0.8mm = 21 AWG
SMDSW.031 4OZ-ND = 0.8mm = 21 AWG (2x as much for a buck more!)

Toast

[Toasty]

Re: Dell 1905FP Won't Turn On

Continue with which one now?

Need a mod to combine them or close one. This gets very confusing. Especially since I just spent an hour of time putting what you need together... IN THE OTHER THREAD!

https://www.badcaps.net/forum/showthread.php?t=13062

Next time, just post a note in the thread with a link to the correct one.

Cheers!
Toast

[obscurehero]

Re: 1905fp

I apologize, I accidentally duplicated threads. The main thread can be found here:

https://www.badcaps.net/forum/showthread.php?t=13063

[obscurehero]

Re: Dell 1905FP Won't Turn On

Continue with which one now?

Need a mod to combine them or close one. This gets very confusing. Especially since I just spent an hour of time putting what you need together... IN THE OTHER THREAD!

https://www.badcaps.net/forum/showthread.php?t=13062

Next time, just post a note in the thread with a link to the correct one.

Cheers!
Toast

Sorry Toasty! What you wrote was VERY helpful!

I've posted it here for reference.

Replace all the caps except the large mains cap.

Leave the paste. It's usually okay as is. You can also drill a hole in the back plate and use the second hole to attach the central heat sink evenly. From the factory it's only connected with one screw. I'm sure you noticed that the paste wasn't touching at one end... I have pics if you want to do so.

You can not go by the caps appearance... I have a beautiful looking car. Great paint and shiny chrome. The interior is all split and the motor is seized...

Presently available at DigiKey:

Code:

Dell 1905FP

[ Max cap height 22mm ]

3 - 1000@10v - 10x16 - Capxon KF - Pana FM == P12353-ND - EEU-FM1A102
1 - 1000@25v - 12x16 - Capxon KF - Pana FM == P12379-ND - EEU-FM1E102
1 - 2.2@50v - 5x11 - Capxon KM - Pana FC == P10313-ND - EEU-FC1H2R2
1 - 4.7@50v - 5x11 - Su'scon - Pana FC == P10315-ND - EEU-FC1H4R7
1 - 10@50v - 5x11 - Capxon KM - UCC KZE 5x7 == 565-1702-ND - EKZE500ELL100ME07D
1 - 22@50v - 5x11 - Capxon KM - Pana FM == P12927-ND - EEU-FM1H220
2 - 220@50v - 10x16 - Capxon KM - Pana FM == P12397-ND - EEU-FM1H221
4 - 470@35v - 13x20 - Capxon KF - Pana FM @ 50v == P12400-ND - EEU-FM1H471
{Sub for FM - UCC KZE == 565-1712-ND - EKZE500ELL471MK20S}
1 - 150@450v - 18x45 - UCC PAG - Not Replaced; not a common failure

-------
15 caps - 14 replaced

Forgot the solder:
Unless you're expecting to do a lot, just a 2oz. or 4oz. tube/spool should be fine:

SMDSW.031 2OZ-ND = 0.8mm = 21 AWG
SMDSW.031 4OZ-ND = 0.8mm = 21 AWG (2x as much for a buck more!)

Toast

[obscurehero]

Re: Dell 1905FP Won't Turn On

@Toasty

Some of the caps you listed were the "FM" variety, but they had impedance and ripple current values that don't agree with the spec's on the capXcon website. What is the importance of these two values, and does it matter to replace it with a cap that has a different value?

[Toasty]

Re: Dell 1905FP Won't Turn On

Well, 4 of them are running just fine after a year.

FM's, in many cases, are cheaper than other lower spec'd caps.

The spec's EXCEED those of the Capxon in both ripple and ESR. The only reason I did not use 100% FM's is that they do not have those values. So where you see FC or KZE being used is (a) no such value in FM or (b) no stock/backorder.

i.e. -
<<Better>>
1000@10v - 10x16 - Capxon KF - 1040mA / 0.079Ω
1000@10v - 10x16 - Pana FM - 1790mA / 0.026Ω

<<No value>>
2.2@50v - 5x11 - Capxon KM - 20mA / - no ESR given
2.2@50v - 5x11 - Pana FC - 45mA / 1.80Ω

>>What is the importance of these two values, and does it matter to replace it with a cap that has a different value?<<

Start on the FAQ pages and start reading...

Toast

[jetadm123]

Re: Dell 1905FP Won't Turn On

For solder I use Kester 63/37 "44" rosin core .025 diameter. Equivalents are available by other manufacturers. I use Kester baecause 30 years ago I did a favor for a friend; he gave me a roll of the Kester, I'm still using that roll.

PlainBill

Wow! That must be a serious size roll of solder! On the other hand, a little solder does go a long way.

[dood]

Re: Dell 1905FP Won't Turn On

Merged the threads for you.

[obscurehero]

Re: Dell 1905FP Won't Turn On

merged the threads for you.

thanks!

[obscurehero]

Re: Dell 1905FP Won't Turn On

Well, 4 of them are running just fine after a year.

FM's, in many cases, are cheaper than other lower spec'd caps.

The spec's EXCEED those of the Capxon in both ripple and ESR. The only reason I did not use 100% FM's is that they do not have those values. So where you see FC or KZE being used is (a) no such value in FM or (b) no stock/backorder.

i.e. -
<<Better>>
1000@10v - 10x16 - Capxon KF - 1040mA / 0.079Ω
1000@10v - 10x16 - Pana FM - 1790mA / 0.026Ω

<<No value>>
2.2@50v - 5x11 - Capxon KM - 20mA / - no ESR given
2.2@50v - 5x11 - Pana FC - 45mA / 1.80Ω

>>What is the importance of these two values, and does it matter to replace it with a cap that has a different value?<<

Start on the FAQ pages and start reading...

Toast

Thanks Toast, I appreciate it. Caps are ordered and hopefully on their way. I don't mind spending $20 for a monitor one bit!

[PlainBill]

Re: Dell 1905FP Won't Turn On

@Toasty

Some of the caps you listed were the "FM" variety, but they had impedance and ripple current values that don't agree with the spec's on the capXcon website. What is the importance of these two values, and does it matter to replace it with a cap that has a different value?

A quick explanation of the specs.

uF is a nominal value. Actual value is usually within 20% of nominal. Voltage is the maximum design voltage. If you exceed the design voltage endurance specs are not guaranteed.

Temp is for rating purposes, it's combined with the endurance. In other words, a cap rated for 4000 hours at 105°C is expected to be within 20% of rated capacitance after operating at or below the spec'd ripple current for 4000 hours at 105°C. ESR is a 'better than' spec. The ESR is guaranteed to be below 55 milliohms after operating for 4000 hours etc.

In actual practice, the ESR of new caps (Capxon, Panasonic, and other brands) are always well below their rated ESR when new. The precise details have escaped me, but I measured the ESR of some new caps that were rated at .06 ohms. They read .02 - .03 ohms. I also measure some caps that had been in use for two years. Most of them also read .02 - .03 ohms. Except for some that had 'popped' that read .5 ohms or greater.

PlainBill

[Lumberjack777]

Re: Dell 1905FP Won't Turn On

Great advice guys! Please also remember the Dell 1905FP and the 1704FPTt use the same IPS board. And that board has a manufacturers defect. They used a 22uf 50v at C112 when it should have been a 2.2uf 50v. I wrote about this on the last Dell 1905FP thread. https://www.badcaps.net/forum/showpo...8&postcount=55

He needs to order a matching 2.2uf 50v cap to be installed at C112. Not a 22uf 50v. That mismatched cap may have taken out inverter transformer with it also. Located at T102. Good luck