Benq Q7T4 FP71G

[Davi.p]

Re: Benq Q7T4 FP71G

Canadan: get a piece of metal wire (copper wire 4 exmpl) thin the point (tip) and wrap around the the iron tip leaving one lead over the iron tip, use this thin "second" tip to solder the tiny fuse, to desolder it use the cutter gently..

[Vivio]

Re: Benq Q7T4 FP71G

Sorry for reviving the thread, but I have a problem with this monitor also.

In the inverter zone I had the electrolytic capacitors with the electrolyte liquid leaked. So I've replaced them all.

Beside that I have replaced the two MOSFET and the all 4 2SC5707.
Since I did not had 220nF/160V i have used some old ones. The picofuse was replaced with a normal one rated 3,15V/250V.

After several days the monitor is having the same defect: nu illumination.

From what I read here I'll do the following:
1. replace again the MOSFET and 2SC5707
2. put new 220nF/160V
3. solder all the connections in the inverter area
4. replace again the picofuse with a 3,15A one

Do you think I do the right thing?

[retiredcaps]

Re: Benq Q7T4 FP71G

You must resolder all the inverter transformer pins otherwise the picofuse is likely to blow again.

[EGuevarae]

Re: Benq Q7T4 FP71G

You must resolder all the inverter transformer pins otherwise the picofuse is likely to blow again.

And the 07's will go too.Resolder All areas that you see odd/strange.
Post pics. And what about the other caps?

[Vivio]

Re: Benq Q7T4 FP71G

retiredcaps thank you!

EGuevarae
to be sure the 2 MOSFET and the 4 2SC5707 will be replaced, along with the capacitors between them: 220nF/160V.


The picture is from the first repair right after the monitor was opened and the quality is not that great. Sorry for that.

In the pic is shown with RED: all the components that have been already replaced the first time and I will not be replace them now. Exception is the 220nF/160V.

With BLUE: the components that I intend to replace. The first time I have not replaced C811, but I will do it now just to be sure.

That picofuse give me nightmares, is such a problem if I put a normal fuse in there?

My girl was very happy when I had repaired her monitor the first time. Hope I'll do it again A late valentine present

Thanks for your advices!

[retiredcaps]

Re: Benq Q7T4 FP71G

On ebay, you can buy "c5707 kit" which will have the c5707s, fu9024 fets, and a picofuse. Price is around $4 USD.

Unless the grey cap is visibly bad, you don't have to replace it. We don't hear much about those caps going bad although it is possible. At minimum, add some fresh solder to the cap legs.

[Vivio]

Re: Benq Q7T4 FP71G

One of those gray caps had some problems. At first repair I had put some old caps from a cannibalized TV Now I'll buy new ones to be sure.

At the same price I can buy the c5707s, fu9024 here in Romania from a store directly without waiting for the package and paying the shipment more then the parts itself. The problem is to find a proper replacement for the picofuse. That makes me mad

Thanks for your input!

[Vivio]

Re: Benq Q7T4 FP71G

Update:

I have replaced the 2 MOSFET and the 4 2SC5707, along with the capacitors between them: 220nF/160V.

The picofuse has been replaced with an part that is almost similar FSK03.15

Also, I have soldered the whole inverter area. For two weeks the monitor works well, hope it will last forever

[killian6pk]

Re: Benq Q7T4 FP71G

Were you able to get the bezel and back plastic case completely apart. The one I am working on does not want to come apart in the center of the button bar. There seems to be an injection molded connection between the top and bottom plastic. If you have some idea how these two pieces come apart, I would appreciate it if you could let me know.

[Vivio]

Re: Benq Q7T4 FP71G

well, not my best work...
At the button level I have squizzed a small screwdriver and little by little the lid was freed.

There are few marks, maybe look for another advise also

[killian6pk]

Re: Benq Q7T4 FP71G

Thanks, I found out it is under the part of the stand that stays attached to the monitor. You have to take two screws out of that stand part and slide that part out of the back of the monitor and then there is a small screw that you can get out and the two halves of the plastic case come apart.

[Vivio]

Re: Benq Q7T4 FP71G

Sorry I thought you have taken out the screws. My problem was to detach the silver cover

[killian6pk]

Re: Benq Q7T4 FP71G

You have to take off the two stand offs that the VGA Plug Screws into. Then that cover will slide off. I bent mine a little also until I realized those two were actually through the silver cover also.