Dell 2407WFPb Monitor - Bad Cap

[pkanar]

Re: Dell 2407WFPb Monitor - Bad Cap

I can not afford so check out! to the name of the element choby I could buy and put them in there, help me please:!

I don't have a 2405, or have the 2407 board handy, but looking at the picture (page 5 of this thread), they look like Schottky rectifiers/diodes in TO220FP package (common cathode on middle pin). The 5 capacitors are 470μF, 35V, 105°C (Elite EJ series).

[oko]

Re: Dell 2407WFPb Monitor - Bad Cap

I can not afford so check out! to the name of the element choby I could buy and put them in there, help me please:!

[lexwalker]

Re: Dell 2407WFPb Monitor - Bad Cap

Hi guys, help determine which there were? received in this form! thanks for the help! may have a schematic for this power supply??

Just trace the pins and figure out the circuit. From the picture, judging from the SMPS transformer nearby, I would guess those missing ones are schottky rectifiers. If the connections to the pins are direct from the transformer then definitely they are rectifiers.

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

Oh, OK. What DC voltage do you get at the main 450VDC filter cap, measure right at the two pins of the cap? Can you also post the pictures of your board and the location of the pins you are measuring the voltage?
"i tried the external power mod that is on page 8 or 9 of this thread. still no go. i get 20v on yellow orange and red wires to inverter board, 20v on red wire to display board, and only 1v on the green wire to display board. i believe the green wire is supposed to be 7v. any ideas where the issue could be? the external supply i used was 90w 20v 3.5a" since the pin out of the 2407 are not the same as 2407, we need verification, especially 20v for the DISPLAY (T-CON?) is not right at all, it should be ONLY either 5 or 12V or may be you mean the MAIN Board?.
The Green and Blue wire on the whit connector of the power supply that goes to the main board are for BL_ON (Backlights ON), and Backlights Dimming signals which are generated by the main board and routed through the power supply board out at the other connector of the power supply board to the Inverter board.

[VIPER1988a]

Re: Dell 2407WFPb Monitor - Bad Cap

forgot to mention. i have the 2405fpw not the 2407

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

The main power supply is only single output around 19VDC, then other switching power supplies on another board are generated from this 19Vdc for running other circuits.
http://s807.photobucket.com/user/bud...?sort=3&page=1

[VIPER1988a]

Re: Dell 2407WFPb Monitor - Bad Cap

i tried the external power mod that is on page 8 or 9 of this thread. still no go. i get 20v on yellow orange and red wires to inverter board, 20v on red wire to display board, and only 1v on the green wire to display board. i believe the green wire is supposed to be 7v. any ideas where the issue could be? the external supply i used was 90w 20v 3.5a

[oko]

Re: Dell 2407WFPb Monitor - Bad Cap

Hi guys, help determine which there were? received in this form! thanks for the help! may have a schematic for this power supply??

[pkanar]

Re: Dell 2407WFPb Monitor - Bad Cap

All failures of the big cap seem to be the same: no evidence of leaking, but corrosion and eventual disconnection where + terminal enters the body.

[jetadm123]

Re: Dell 2407WFPb Monitor - Bad Cap

Glad to finally see some success stories for this monitor. And thanks for sharing your success story with us. Just out of curiosity, was the large 120uf leaking?

[BastiaanNaber]

Re: Dell 2407WFPb Monitor - Bad Cap

Thanks everyone for your help. I have been able to restore my wives monitor.

I have replaced the following:

R670 0.22ohm Farnell 1903854 (10)
C605 120uF/450V Farnell 1828683
IC651 L6561D Farnell 9882464
IC601 NCP1200D Farnell 1652430
Q651 STP10NK60ZFP Farnell 9935517
ZD601 15V 0.5W (diode) Farnell 1469418
Fuse holder and Fuse Farnell 1162740 and 1354592

I hope it will keep going for a while. I will also replace the big cap in my own 2407, just in case.

[sgt_az]

Re: Dell 2407WFPb Monitor - Bad Cap

IC651 should be oriented with pin 1 down and to the left by the black dot on the board. Pin 1, where the indention is on the encapsulant, should be toward capacitor C621 just below it in the orientation you took the photo in.

[BastiaanNaber]

Re: Dell 2407WFPb Monitor - Bad Cap

Can anyone tell me how IC651 is supposed to be oriented on the board? Attached is the picture of my replacement part and also the way that I'm holding the board. Thanks in advance!

[pkanar]

Re: Dell 2407WFPb Monitor - Bad Cap

Q654: 2N3906S by KEC (PNP transistor 40V, 350mW, in SOT-23 package)
IC651: L6561 by ST Micro (power factor corrector, in SO8 package, can also use L6562)
C605 is 450V

[sgt_az]

Re: Dell 2407WFPb Monitor - Bad Cap

I've got a Dell 24" monitor that has burnt surface mount components. One is a transistor (Q654). The part has the following markings: "ZA 49". I can't find any information on that part number. Does anyone know where I can find a cross for it? The second burnt component is IC651. I can't read anything on IC651 but I found the part number through another BadCaps thread. https://www.badcaps.net/forum/showthread.php?p=178133 The 120uf 400V capacitor is also bad. Any information on Q654 would be greatly appreciated. Thanks.

[pkanar]

Re: Dell 2407WFPb Monitor - Bad Cap

Just got a test report that my repair of the power board was a success.

All parts were from Mouser, with substitutions done as follows:

Q651: 2SK3502 -> STF16NK60Z (14A in a plastic package)
IC601: NCP1200A -> NCP1200 (60kHz)
IC651: L6561 -> L6562

The full Mouser part list was:

667-EET-ED2W121BA
511-STF16NK60Z
863-NCP1200D60R2G
511-L6562D
576-0215004.MXEP
756-W21-R22JI

[pkanar]

Re: Dell 2407WFPb Monitor - Bad Cap

The consensus here is that C605 is the origin of this failure. Check the ripple current spec on the replacement; it should be at least as high as the OEM, which was 740mA @ 120Hz. Also, my impression (from reading this thread) is that the PFC chip usually fails together with R669, but sometimes does not fail, however the PWM chip (IC601) has to be replaced every time, even though the measurements do not pick up anything obviously wrong with it.

The 15V Zener regulates the rail that supplies both IC's. If yours is toast, replacing both IC's is prudent. That PFC chip did drive the power MOSFET to its death. Now, the PFC cannot see the ripple current that hits the circuit after C605 disconnects, except on pins 1 and 8. And I am guessing what actually happened is that it was fed with too many volts on pin 8.

[nothin]

Re: Dell 2407WFPb Monitor - Bad Cap

You really can't use a capacitance function to check this chip. You can try a quick test by setting your meter to 1K resistance setting and checking for a short across the Vcc and ground pins.

I think there was a post earlier here where a bloke had deemed it faulty as a connected cap was giving incorrect readings when on the board, but checked ok individually, though I may have mixed this up with another IC anyway

If you're going to order all your parts from one source, go ahead and order the L6561D anyway, since it's a low cost chip.

Makes sense - I've got 3 of these monitors, so was probably gonna order some extars anyway. On this topic, is there a consensus on which component or components actually trigger this fault? I wouldn't mind replacing these on the other two monitors, since they're of about the same age. And also, does anyone have recommendations for somewhere that ships to AU that would have all these components available? Most of our local electronics retailers carry a pretty limited range of stock...

[jetadm123]

Re: Dell 2407WFPb Monitor - Bad Cap

IC651 - L6561D - physically appears ok, my multi doesn't have a capacitance check, are there any other test for this one?

You really can't use a capacitance function to check this chip. You can try a quick test by setting your meter to 1K resistance setting and checking for a short across the Vcc and ground pins.

If you're going to order all your parts from one source, go ahead and order the L6561D anyway, since it's a low cost chip.

[lexwalker]

Re: Dell 2407WFPb Monitor - Bad Cap

Q651 - STP10NK60ZFP, Zener protected N-channel MOSFET, TO-220, FEC code 993-551

Check surrounding components linked to this MOSFET, especially trace connections from the gate to the PWM I.C for possible failed components....

R670 - 0.22 ohm

Is R670 a 1/2W?

This one sounds like Rsense (ie. resistor for current sensing). That one is usually at least 2W or higher. Recommended replacement would be wirewound type resistor, rather than carbon film. Also trace the connections from this Rsense as well for any other failed components.

IC651 - L6561D - physically appears ok, my multi doesn't have a capacitance check, are there any other test for this one?

Not sure if this power factor correction I.C is spoiled, though in my opinion usually they don't usually spoil easily. In your case, I could be wrong though...