Dell E152FPg - 2 seconds to black

[smalltownguy]

Re: Dell E152FPg - 2 seconds to black

Attaching some new photos, since my originals seem to not be working...

[alexanna]

Re: Dell E152FPg - 2 seconds to black

Your to the point where I would ask for help also,
So HELP

[PlainBill]

Re: Dell E152FPg - 2 seconds to black

Attaching some new photos, since my originals seem to not be working...

This is a Royer oscillator; it's used by a number of manufacturers, most notably Benq (Dell and HP). There are several possible causes - bad solder joints on the transformer are the most likely cause but since you have soldered them we can eliminate that.

The tuning cap - it looks like .1uF, 100V is another suspect, as is the zener diode. Don't substitute transistors - this circuit is fussy. And if one transistor is shorted always replace it's companion too.

PlainBill

[smalltownguy]

Re: Dell E152FPg - 2 seconds to black

This is a Royer oscillator; it's used by a number of manufacturers, most notably Benq (Dell and HP). There are several possible causes - bad solder joints on the transformer are the most likely cause but since you have soldered them we can eliminate that.

The tuning cap - it looks like .1uF, 100V is another suspect, as is the zener diode. Don't substitute transistors - this circuit is fussy. And if one transistor is shorted always replace it's companion too.

PlainBill

What would the companioin to Q110 be? Do you mean that I should replace all 3 transistors?

The zener diode is ZD101 - any idea the value of that? I've never purchased a zener diode before, so I'm not sure what to order here.

The box cap is a .18uf box cap. That I've ordered before, so I can get those.

Anyone know where I can get the 1606 transistors?

[PlainBill]

Re: Dell E152FPg - 2 seconds to black

What would the companioin to Q110 be? Do you mean that I should replace all 3 transistors?

The zener diode is ZD101 - any idea the value of that? I've never purchased a zener diode before, so I'm not sure what to order here.

The box cap is a .18uf box cap. That I've ordered before, so I can get those.

Anyone know where I can get the 1606 transistors?

ZD101 is a location number, not a part number. It should be identical to the zener at ZD100. I don't have any idea what the part number would be.

Q106, Q107, Q108, and Q109 are identical parts and are probably NPN transistors.. Q105 and Q110 are also identical and are usually FETs, which would explain why the 2SC1815 smoked.

PlainBill

[alexanna]

Re: Dell E152FPg - 2 seconds to black

What would the companioin to Q110 be?

What are the part numbers stamped on Q105&Q110 on your good board?

[retiredcaps]

Re: Dell E152FPg - 2 seconds to black

One of the nice thing about have 2 identical monitors (one working and one not) is that you can compare multimeter readings.

So with power off on both, you can measure each component in the inverter section and and compare which one is not correct.

[smalltownguy]

Re: Dell E152FPg - 2 seconds to black

What are the part numbers stamped on Q105&Q110 on your good board?

They are B 1116's.

Anyone know where to get them?

[PlainBill]

Re: Dell E152FPg - 2 seconds to black

They are B 1116's.

Anyone know where to get them?

That is probably a 2SB1116. That could be verified by doing a diode test on the pins of Q105.

Without knowing what country you are in, it is difficult to make a suggestion. It's specs (PNP, 80 volt, 1A, .75W, 120 Mhz) should be easy to match.

PlainBill

[smalltownguy]

Re: Dell E152FPg - 2 seconds to black

ZD101 is a location number, not a part number. It should be identical to the zener at ZD100. I don't have any idea what the part number would be.

Q106, Q107, Q108, and Q109 are identical parts and are probably NPN transistors.. Q105 and Q110 are also identical and are usually FETs, which would explain why the 2SC1815 smoked.

PlainBill

Um, yeah, so sticking a NPN transistor in a curcuit where a PNP is called for is generally not a good idea.

The ensuing smoke that arrived on my workbench was proof of that.

I located some 1116 replacements at Mouser, so I've ordered 4 of them. When they arrive, I'll swap them in and see if they cure my issue. Hopefully I haven't done any further damage to this board by using the wrong spec....

[PlainBill]

Re: Dell E152FPg - 2 seconds to black

Um, yeah, so sticking a NPN transistor in a curcuit where a PNP is called for is generally not a good idea.

The ensuing smoke that arrived on my workbench was proof of that.

I located some 1116 replacements at Mouser, so I've ordered 4 of them. When they arrive, I'll swap them in and see if they cure my issue. Hopefully I haven't done any further damage to this board by using the wrong spec....

Further damage - probably not. From experience I know this circuit is a bear to troubleshoot once you get beyond the obvious failures. There are multiple feedback loops that will destroy the transistors within seconds if something isn't correct.

PlainBill

[smalltownguy]

Re: Dell E152FPg - 2 seconds to black

That's the last time I place a big order at Mouser and choose the 'don't ship until all my parts are in' option. Cripes.

Got my 1116's today. I swapped both of them to be safe.

Still dim. Now what?

[PlainBill]

Re: Dell E152FPg - 2 seconds to black

That's the last time I place a big order at Mouser and choose the 'don't ship until all my parts are in' option. Cripes.

Got my 1116's today. I swapped both of them to be safe.

Still dim. Now what?

Whoops!!! Something seems to have changed. Earlier you were having 'Two seconds to black', with one CCFL not lighting. Now you mentioned 'dim'. Has something changed?

PlainBill

[smalltownguy]

Re: Dell E152FPg - 2 seconds to black

Sorry about that, I thought I mis-typed. I meant to type 'still going dim'


But I went back and double checked. The monitor IS in fact dim now, not even firing for 2 seconds any more. What does that mean?

[PlainBill]

Re: Dell E152FPg - 2 seconds to black

Sorry about that, I thought I mis-typed. I meant to type 'still going dim'


But I went back and double checked. The monitor IS in fact dim now, not even firing for 2 seconds any more. What does that mean?

It means we aren't communicating well.

Let's agree on these terms. A normal display can be seen easily in full light; it will also light up a dark room.

'Two seconds to black' starts with a normal brightness screen, then it goes dark. An image may be visible, especially if a flashlight is used, but it won't light up a dark room.

A dim screen can be easily seen in a poorly lit (or dark) room, but is much harder to see in a brightly lit room.

'Two seconds to black' indicates the protection circuit has shut down the backlights. 'Dim' indicates the backlights are still working, just at low brightness.

PlainBill

[smalltownguy]

Re: Dell E152FPg - 2 seconds to black

It means we aren't communicating well.

Let's agree on these terms. A normal display can be seen easily in full light; it will also light up a dark room.

'Two seconds to black' starts with a normal brightness screen, then it goes dark. An image may be visible, especially if a flashlight is used, but it won't light up a dark room.

A dim screen can be easily seen in a poorly lit (or dark) room, but is much harder to see in a brightly lit room.

'Two seconds to black' indicates the protection circuit has shut down the backlights. 'Dim' indicates the backlights are still working, just at low brightness.

PlainBill

I agree with everything you just said. This problem began as a '2 seconds to black' problem. Somewhere after resoldering the transformer and replacing Q105 I lost the '2 seconds' part. Now the panel does not attempt to light at all.

[PlainBill]

Re: Dell E152FPg - 2 seconds to black

I agree with everything you just said. This problem began as a '2 seconds to black' problem. Somewhere after resoldering the transformer and replacing Q105 I lost the '2 seconds' part. Now the panel does not attempt to light at all.

Aha!!! The nature of the problem has changed. If there is a fuse to the inverter, please check it. Also measure the BL_On and Brightness pins. Oh, and check for 12 volts.

PlainBill

[smalltownguy]

Re: Dell E152FPg - 2 seconds to black

Aha!!! The nature of the problem has changed. If there is a fuse to the inverter, please check it. Also measure the BL_On and Brightness pins. Oh, and check for 12 volts.

PlainBill

Inverter fuse tests OK. How/where do I test the BL_On and Brightness pins?

[PlainBill]

Re: Dell E152FPg - 2 seconds to black

Inverter fuse tests OK. How/where do I test the BL_On and Brightness pins?

Use a DMM, test on the circuit board.

Refer to the picture of the bottom of the power supply / inverter you attached to post 21. In the upper right corner of the picture is the connector for the cable to the signal card. The pin on the extreme right would appear to be Brightness, the one next to it is BL_ON (On / Off).

PlainBill

[ek2oo2]

Re: Dell E152FPg - 2 seconds to black

hi guys, this thread got a different power board than the one i got here. Could anyone please tell me the exact part number of u101 because mine got burned that's why I'm having no power/ dead set.

i know i have to post another thread but i cannot just yet because I think I'm just a newbie here and I'm guessing this is my first post/reply. So please pardon me.

Anyway I'm attaching a pic I downloaded from Ebay.

The 8-pin IC on the bottom is the one that i need to be identified. Thanks..