Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
So this is the resume of the situation and I don't know what to do now:
tested all resistors and found three of them with bad readings (R603, R607, R611 test as they should):
R625 orange,black,orange,gold -->00.1 omh (!!!) -> UNSOLDERED
R615 red,red,silver,gold -->00.6 omh (!!!) -> UNSOLDERED
R702 blue,gray,silver,gold -->00.9 omh (!!!) -> UNSOLDERED
tested for resistence mosfet Q601 (part number: K3530):
black on S,red on D= no readings...
nicoursi
Member
Last Activity: 02-24-2013, 01:26 PM
Joined: 01-31-2013
Location: brindisi
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Re: A guide on how to troubleshoot 2 seconds to black
I am afraid there is some no coherent information about mosfet testing
this means (please correct me if I am wrong):
a) black on pin S- red on pin D - record ohms
b) black on pin S- red on pin G - record ohms
c) black on pin D- red on pin G - record ohms
Below it is written:
I wonder which of the two information is the right one. black on D, red on G or the other way around? (black on G and red on D)
I would say the correct is the first one,...Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
Thanks for answering. So:
S1 to S2 -->.377
S3 to S4 -->.378
About the mosfet, yes it is offset. Sorry for confusion
I get the 1. on the left no matter where i set the multimeter at.
So these ones are the results for mosfet Q601 again:
pin1 to pin2-->offset
pin1 to pin3-->offset
pin2 to pin3-->.906 ohm (multimeter set to 2k)
Does this still indicate a shorted mosfet?
What can you tell about resistors...Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
I just tested the transformer T601 and I am afraid there is something wrong with it too
To test it i followed the instructions here: [url]https://www.badcaps.net/forum/showthread.php?t=10419[/url]
So, black pin on 1, red on 2 , and so on (multimeter set on 2k and 200):
pin 1 - pin 2-->00.4 ohm
1-3-->00.4
1-4-->a big number then 1.
1-5-->a big number then 1.
1-6-->1. nothing happens
1-7-->1. nothing happens
1-8-->1. nothing...Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
so this is the situation:
R611 - red,red,brown,gold -216 omh -->ok
R607 - blue,silver, orange, gold - 68.2 -->ok
R603 brown,silver,orange,gold - 17.72 -->ok
R625 orange,black,orange,gold -->00.1 omh (!!!) -> UNSOLDERED
R615 red,red,silver,gold -->00.6 omh (!!!) -> UNSOLDERED
R702 blue,gray,silver,gold -->00.9 omh (!!!) -> UNSOLDERED
D601 -->67.7 and 68.2 (with inverted polarity) UNSOLDERED
D602 -->.856 (multimeter...Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
retiredcaps: all the mesurements i have done are according to the multimeter and mosfet section. That's the first thing I read
When I join together red probe and the black one i get 00.3 ohm
so here the mesurements:
R607 (Red Red Silver Gold): 1 ohms;
R615 (Red Red Silver Gold): 0.5 ohms
R625 (Red Red Silver Gold): 99.3
R609: 1 ohm
R608: 1 ohm
D601: 1
D602: 1
L605: 0.03
L604: 0.03
L608: 0.03
R611: shows some big numbers for a sec...Last edited by nicoursi; 02-05-2013, 07:42 PM.Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
Eureka! Thank you very much! The heatsink is glued, but thye mosfer is not. It was enough to unscrew the mosfet and voila!
So, testing it again with the multimeter i get:
a) black probe on pin 1 and red probe on pin 2 - 1 ohm
b) black probe on pin 1 and red probe on pin 3 - 1 ohm
c) black probe on pin 2 and red probe on pin 3 - 1 ohm
I assume the mosfet is dead?
Without unsoldering i get the same with IC702. Should I unsolder IC702? What other tests should...Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
Thanks! Adding some leaded solder to the solder I was trying to melt did the trick! But the question now is: is the heat sink glued to the board? I sucked up the solder with a pump but the heatsink looks like glued. Is that right? Just to know how I should proceed.
Sorry for my incompetence, but slowly slowly I will get there! I'm just trying to avoid damage
Thanks again!Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
Guys, i didn't manage to unsolder the Mosfet I cannot melt the solder. I tried to unsolder caps and other componens on a scrap board and it worked normally.
Can it be due to the heatsink sucking all the heat? Shoud I remove the heatsink first or do u know any trick to do it?
Sorry but I am a beginner here
Thanks for all inputs,
NicolaLeave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
We are talking about testing for shorted transistors "in circuit", with power off and unplugged. So no harm possible bro'...
Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
Yes it is bent over but it does not touch anything. Is it safe to bend components straight back or is it better to leave them as they are? I found many bent components on this board, is it normal?
I tested also IC702 (between the two heatsinks) and it behaves very similar, so theoretically faulty. But I am starting to think if I am doing something wrong. The pins of IC702 are not numbered but they have letters: R, A, K. I tested black on R, red on A first and on K second. Later A black...Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
Here better pictures.
I will do the tests later and post results....Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
Sorry it is Q601 (not Q301). Yes, it is the one with the heatsink. Its is the mosfet. Sorry for confusion
What other tests do you suggest? Thank you!...Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
Thanks guys for your help!
I didn't know there were more than one fuse
So, the following are the tests I run so long:
1. F601 and FP801 they both mesure 0.4 ohm
2. Big capacitor tested with power on with black(COM) on negative leg: 316 V.
3. Mosfet Q601. With Black probe(COM) on pin 1 and red on pin 2 (or pin 3) I always get 1ohm. With black on pin 2 and red on pi 3 i get a big number for a second and then 1 ohm again.
4. I couldn't check the other mosfet yet (IC601)...Last edited by nicoursi; 02-01-2013, 06:08 AM.Leave a comment:
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Re: Benq fp71g+ dead. No light no signs. Capacitors look alright
i hope these picture are better.
i tested the fuse with the multimeter and it beeps.
Nicola...Leave a comment:
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Benq fp71g+ dead. No light no signs. Capacitors look alright
Hello to everyone!
My father's monitor started to blink and my father used a toothpick to keep the two middle buttons pushed together (right arrow and left arrow). This temporarly solved the problem. My father was able to use the monitor with no problems for a month or two.
One day the monitor stopped working. Now it is not possible to start it, no led, no light no signs of life.
I opened it and i see no signs of bad capacitors. Everything looks fine.
The big capacitor (450v, 100 uF) though, even if it is not bulged or anything. it is a bit dirty, a...
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