DELL E197Fp blown fuse

[rayfloyd170]

I have a Dell E197Fp LCD which has a blown fuse. I replaced it and powered it ON. While powering it up, it showed the DELL Screen display logo but again fuse gets blown (maybe less than 5 seconds after powering it ON.).

I believe there is a short somewhere but I am just a newbie and all I have is a DMM and a solder. Can you help me what to do first? Which part to test first and how to do it.


Please be patient with me. thanks


see sample powersupply board below

[SteveNielsen]

Re: DELL E197Fp blown fuse

Show a pic of the actual board you're working on.

[rayfloyd170]

Re: DELL E197Fp blown fuse

okay when I get home, I will take an actual photo of it. thanks.

[stj]

Re: DELL E197Fp blown fuse

both sides of the board please.

[rayfloyd170]

Re: DELL E197Fp blown fuse





The 2nd pic shows the replaced fuse also gets blown. original fuse is red in color. but i replace with a glass type with same values. Also it was properly insulated with rubberized electrical tape to avoid shorting. In this pics the insulation for the fuse is already taken out.



the wires below are for the power button board.

[rayfloyd170]

Re: DELL E197Fp blown fuse

the bridge rectifier is PEC FL406. i dont know how to test it.. hope you can guide me. i also suspect the bridge rectifier (D850). mostly based on what i read this should be tested first. i am not sure though.

[stj]

Re: DELL E197Fp blown fuse

check for shorts between any of the legs on d850 and q850

and be carefull about your new fuse not touching that metal plate on it's left.

[Agent24]

Re: DELL E197Fp blown fuse

the bridge rectifier is PEC FL406. i dont know how to test it.. hope you can guide me. i also suspect the bridge rectifier (D850). mostly based on what i read this should be tested first. i am not sure though.

Yes it's one of the first things you should check.

A bridge rectifier is just 4 diodes connected together a certain way. You can test them individually as you would a single diode by connecting your multimeter to the right pins of the bridge.

See the attached image for how they are connected inside.

The DC output pins for positive and negative are marked with + and - symbols and the AC input pins are marked with a ~ symbol.

Test each diode of the bridge individually to make sure it's OK.
It's also a good idea to check across the two AC pins to make sure there's no continuity there either.

[rayfloyd170]

Re: DELL E197Fp blown fuse

Yes it's one of the first things you should check.

A bridge rectifier is just 4 diodes connected together a certain way. You can test them individually as you would a single diode by connecting your multimeter to the right pins of the bridge.

See the attached image for how they are connected inside.

The DC output pins for positive and negative are marked with + and - symbols and the AC input pins are marked with a ~ symbol.

Test each diode of the bridge individually to make sure it's OK.
It's also a good idea to check across the two AC pins to make sure there's no continuity there either.

Thanks. i will do this now. But first I have a question. Should I desolder and remove the rectifier diode (D850) and the Q850 transistor when testing it? i guess i need to... sorry for asking too many things.

[rayfloyd170]

Re: DELL E197Fp blown fuse

check for shorts between any of the legs on d850 and q850

and be carefull about your new fuse not touching that metal plate on it's left.

thanks.. yes, i was putting an elect'l tape on that one.

[rayfloyd170]

Re: DELL E197Fp blown fuse

check for shorts between any of the legs on d850 and q850

and be carefull about your new fuse not touching that metal plate on it's left.

for Q850, how to check for shorts?


hahaha, i just googled it and it is pretty easy.. thanks men.. after work i will remove this two parts and test em.

[Agent24]

Re: DELL E197Fp blown fuse

for Q850, how to check for shorts?

For each pin, check between it and the other two.

[rayfloyd170]

Re: DELL E197Fp blown fuse

I removed and checked first the rectifier ( + ~ ~ - ) and found out that theres a short at ~ and -. The mutimeter ringer sounded even if i swap the probes from either way. Also when i tried using the diode mode (2k) it really has a 0.01 value both ways i tried it. Is it safe to replace this part first (rectifier) and then try to power up again? Or it would be better to change q850 also. I will still have to source out these parts here and could take some time. Although the rectifier i think would be easier to have

[stj]

Re: DELL E197Fp blown fuse

meter q850 just to be sure, you can do it on the board usually.

if the rectifier is bad, you may be lucky and not have any other problems.
dont forget to get the right type of fuse.

[rayfloyd170]

Re: DELL E197Fp blown fuse

Its good i found a replace rectifier from an old shop and its still working good... For the q850 how to test it? I will check first maybe there is a youtube video for it. Again thanks. I feel excited

[rayfloyd170]

Re: DELL E197Fp blown fuse

Wadahhhh im so happy. It is now working... Really im so thankful to you guys!

[rayfloyd170]

Re: DELL E197Fp blown fuse

I only changed the bridge rectifier and thats it

[stj]

Re: DELL E197Fp blown fuse

good.

[rayfloyd170]

Re: DELL E197Fp blown fuse





Cheers! Special Thanks to STJ and Agent24 for helping me. This is my very first time to fix a monitor myself with you as my guide. I was determined to fix it because when i go to the shop they asked me $$$$$ and i was not willing to spend either since i already got another Dell monitor as of the moment. Really im amazed coz i spent around 3USD only for the parts...

[Agent24]

Re: DELL E197Fp blown fuse

Awesome