Gateway 700G repair didn't take

[alexanna]

Re: Gateway 700G repair didn't take

Even with the brightness set to 60% you should get a good picture, sometimes changing the contrast helps. By reducing the brightness I think you putting less demand on the inverter.
What type of capacitors are installed in your monitor, And how old is the monitor? Even though the caps do not appear to be bloated. There is a good chance replacing the capacitors with good quality ones will fix your problem

[retiredcaps]

Re: Gateway 700G repair didn't take

The monitor goes black quick, But after some messing with the settings if I have it set to around 60 instead of 100 it stays on

I have a Benq that when set to 90 brightness, it will stay on for about 20 minutes and then go off. If the brightness is set to 25, it will stay on indefinitely.

I alreading replaced the boards internally with an identical Benq and narrowed down the problem to the ccfls or the ccfl wiring. As ccfls age, they draw more power causing the pwm inverter IC to shut down the backlights.

I haven't bothered narrowing down the problem and use this Benq as my "test" lcd for various measurements.

[Bouncer]

Re: Gateway 700G repair didn't take

Even with the brightness set to 60% you should get a good picture, sometimes changing the contrast helps. By reducing the brightness I think you putting less demand on the inverter.
What type of capacitors are installed in your monitor, And how old is the monitor? Even though the caps do not appear to be bloated. There is a good chance replacing the capacitors with good quality ones will fix your problem

The caps say SAMXON and the date on the monitor says 2005, Althought as far as im aware 2-3 years the monitor didnt get used at all and was in storage

[alexanna]

Re: Gateway 700G repair didn't take

A bad CCFL and or its wiring could cause the problem you are having. Capacitors that are not up to spec. are another. I have had inverter transformers cause a 2 second to black problem after they have been on awhile and got good and hot. There are also other reasons.
If you have a good panel you could hook up just the backlights of the good panel to the monitor you're having problems with, and see if the lamps will stay on at 100%
I don't know why but my gut feeling on your monitor was capacitors.

[retiredcaps]

Re: Gateway 700G repair didn't take

The caps say SAMXON

If they are Samxon GF series (look for GF on the sleeve), they are a problematic series.

[recycler82]

Re: Gateway 700G repair didn't take

I have been searching the web and came across this forum about the 700g fpd1760 monitor. i have seen a few issues in the past usually its the on for 2 seconds then off or flashing but this one is a new one to me. i plugged it in and at first i didnt even notice it but the screen at a really low level flashed though im not even sure if i could describe it best with that word. but i took it apart and looked around saw one bad cap at first look but rest werent bulged so i replaced it. went and hooked it back up and same thing so i took it back apart and tested the pin out as they have it labeled and the 12v i got 11.97 roughly but the 5v was bouncing between 3-5v would just keep fluctuating. i did verify the logic board and bulbs were good hooking the logic board to both 12 and 5 v and had a cfl inverter board from a case mod to power cfls and it came up with a display and functioned what seemed to be perfect. any suggestions? or if anyone has parts to on let me know.

[Rtech]

Re: Gateway 700G repair didn't take

If your board is the same as the photo in Post #40, then the first job, would be to test the two Large diodes that rectify the output from the Transformer to give you the 12v and 5v...one of them may well be faulty.Also of course caps do fail and show nothing ...

[selldoor]

Re: Gateway 700G repair didn't take

So few caps on this board - replace all except the large one with good quality
Panasoninc FR FM FC or nichicon. Will give you a good start point and check the diodes
as Rtech says. The startup cap (small one near the transformer) may be going.

[recycler82]

Re: Gateway 700G repair didn't take

i have been testing the diodes and they seem to be fine but without the specs for them i cant be 100% but a front to back test shows they are functioning in one way only likey they should be. i found a pic online as there are many to go through on this post. i did replace that one cap i talked about before but the can is slimmer and taller and after some reading i see that can make a difference but i doubt it would make it fluctuate like i described. any other ideas ? im looking at getting the other caps and replace them shortly.

[Lumberjack777]

Re: Gateway 700G repair didn't take

im looking at getting the other caps and replace them shortly.

That will probably fix your problem. A cap doesn't need to be bulging to be bad. It can have high ESR, or sometimes they are dried up. You want to replace the caps before they take an expensive component with them. Good luck.

[recycler82]

Re: Gateway 700G repair didn't take

well just replaced all the caps on the board and now both 5 and 12 volt rails are fluctuating between 3-6 volts roughly and it was making a weird pulsing noise. not sure which would cause the noise but it is close to the outputs around the bulk of the caps.

[selldoor]

Re: Gateway 700G repair didn't take

Are the caps in the right way round? - perhaps another picture?

[Rtech]

Re: Gateway 700G repair didn't take

So are we saying that the Board is the one you show in Post #49 ??? and not the one referred to in Post #40 ????/if that is the case, then the Schottky Diodes must be the first thing to test,then no doubt there are Mosfets to drive the backlights on the bottom of the Board,and if one of those are faulty then this could give you a similar fault symptom.

[recycler82]

Re: Gateway 700G repair didn't take

well I double checked and all caps are in correctly and of correct values. there are 3 transistors on the top part of the board and one at the bottom near the big cap. I checked the diodes and they seemed to be good.

[Rtech]

Re: Gateway 700G repair didn't take

You have missed the point !!! The bottom of the board means 'underneath',not the top !!!!
The DC voltage to feed the Mosfet drivers,which are on the bottom of the board go through links JP301 and JP302 located in the centre of the top of the board.You need to disconnect these and then re-measure your 5v and 12v, if those are now steady then the problem is 'probably' the mosfets .

[recycler82]

Re: Gateway 700G repair didn't take

ah. sorry bout the delay lots has been going on. I forgot to double check the diodes I found out one was backwards. opps flipped and now is fixed. thanks for all the advice.

[budm]

Re: Gateway 700G repair didn't take

Thanks for the repair feedback, it is always good to recheck the works that were done after the components are replaced.

[chevelle_nut]

Re: Gateway 700G repair didn't take

I was ready to trash one of these units as well, recapped the PS [ (5) 470uf @ 25v & (4) 220uf @ 25v GF SAMXON originals 3 of the 470s were leaking ] and still had same problem. No power indicator light, and it would almost pulse faint light flashes- hard to see in daylight but still enough to draw your eye. Checking the rail voltages at the header gave a pulsing 5v rail that was clicking at same freqency as display flash, and a low 10.4v on the 12v rail.
From the another thread on the 900g I noticed EGuevarae (and stroogly )had repaired units with a bouncy 5v rail by replacing the 47uf cap near the switching transisitor. I pulled the cap and installed a 100uf 16v ( changing capacitance value is something I would normally NEVER do-but they stated they had success with it so whynot try it I already spent 9 caps on it )and bingo ! Both voltage rails rock steady 12.02v and 5.01v, blue indicator on. Hooked up panel and voila a working monitor, customer will be pleased as she is dreading giving up XP by next April to move to new OS.
At least she can stay with this system for now.

You guys rock, another device saved from a landfill !!