Gateway 900G frustration

[PlainBill]

Re: Gateway 900G frustration

ok so when unplugged from power, both 5V and 12V sit at 4 mV

when power is plugged in the 12V sits at 4.4 mV and the 5V jumps randomly anywhere between 338 and 78 mV without any particular order...

I'm getting volatages nowhere near 5 or 12 V

See suggestion for pulsing 5 Volt supply. While you are at it, you may as well replace the rest of the caps.

PlainBill

[arpcentralone]

Re: Gateway 900G frustration

Hi all, wow, I left for a week and LOTS of stuff was talked about. I got the ccfl mod kit in, tested the lamps in the monitor screen with the mod kit's inverter, and all tested fine. They lit up and stayed on. I will try the mod kit's lamps with the monitors inverter next and see what happens, probably cut back off again. I believe it has something to do with me replacing the cap "in the blue circle" with the wrong mF value. I got the voltage right on it tho.

[Bobdee]

Re: Gateway 900G frustration

I believe it has something to do with me replacing the cap "in the blue circle" with the wrong mF value. I got the voltage right on it tho.

To be honest this link of your earlier posting on this cap
https://www.badcaps.net/forum/showpo...5&postcount=16
never added up to me, you say that a 470uf replaced a 47uf, thats 10 x original value that to my understanding has been a No No in cap replacement, way to high
then you mention the uf to be lower, I asume that to have been a error
Having said that I dont know if this cap is the cause of your b/light turning off
Hope I havent put my foot in my mouth, I am not one of the brighter stars in the sky
bob

[PlainBill]

Re: Gateway 900G frustration

To be honest this link of your earlier posting on this cap
https://www.badcaps.net/forum/showpo...5&postcount=16
never added up to me, you say that a 470uf replaced a 47uf, thats 10 x original value that to my understanding has been a No No in cap replacement, way to high
then you mention the uf to be lower, I asume that to have been a error
Having said that I dont know if this cap is the cause of your b/light turning off
Hope I havent put my foot in my mouth, I am not one of the brighter stars in the sky
bob

I'd say you are right twice. Replacing a cap with one 10 X the original value (or .1 X ) is generally a bad idea. However, this cap is part of the power supply. It's value was chosen as a trade off between low cost and a stable voltage for the power supply controller. I have looked at the original data sheet on this IC, it recommended a 22 uF capacitor.

You are also right, this capacitor would have nothing to do with the 'two seconds to black' problem.

PlainBill

[koshposh]

Re: Gateway 900G frustration

ok thanks, I'll that a try. first gotta find a good place to buy caps

[PlainBill]

Re: Gateway 900G frustration

ok thanks, I'll that a try. first gotta find a good place to buy caps

Sometimes it helps to read the FAQ. An amazing amount of information can be found.

PlainBill

[IRShifty]

Re: Gateway 900G frustration

Just wanted to make a quick post giving thanks to all the info in this thread. I was able to fix a customers 900G in about 20min with all the great info here.

[Bill Aldridge]

Re: Gateway 900G frustration

This guide helped me repair 700G.After replacement of 470uf caps it was the little guy.Put in a 100uf and it works great.I did not have any ticking,or obvious blown-swollen caps.I did have faint backlight flicker,thought it was my fluorescent lights or eyes, no blue button or anything else.Thanks for all the great info.

[tswan]

Re: Gateway 900G frustration

I've got the "ticking" problem coupled with the 5v supply oscillations.

I replaced all the electrolytic caps and the also tried the shunt regulator and the problem still exists. It is interesting to note that the period of the ticks was about once/second before I swapped the caps and now it is more like 2 seconds.

I'm competent, but not terribly strong with these repairs. Any advice on what components to consider or a schematic would be very helpful.

Thank you to all who offer advice.

[EGuevarae]

Re: Gateway 900G frustration

...I replaced all the electrolytic caps ...

Did you replace also the smaller ones? What did you use for replacement?

[tswan]

Re: Gateway 900G frustration

Hi, I replaced all that I saw. The smallest one (the 47uF cap) was replaced also with a 47uF. When it did not work I tried a 100uF cap as someone else had done.

[EGuevarae]

Re: Gateway 900G frustration

Hi, I replaced all that I saw. The smallest one (the 47uF cap) was replaced also with a 47uF. When it did not work I tried a 100uF cap as someone else had done.

With what brand/series/values?

[tswan]

Re: Gateway 900G frustration

I replaced all the 470uF with 470uF 50V, and all the 220uF with 220uF 50V. They are a collection of caps from both NTE and Xicon. I replaced the 680uF with a 680uF 50V. It's physically too big for the board to go back into the monitor, but I thought I would replace it just in case....assuming I can get this working I'll find a smaller 680uF.

Things have also changed. The 12V supply is now moving around and the 5V supply that as swinging between 3 and 5V is now swinging around 1-2V. Not sure if I've done more damage or if something is degrading.

I did not replace the 100uF 450V cap.

[EGuevarae]

Re: Gateway 900G frustration

I did not replace the 100uF 450V cap.

It rarely fails.

[tswan]

Re: Gateway 900G frustration

I got it fixed. In fact, it was probably fixed yesterday and I did not realize it.

After I replaced all the caps I checked the 5 and 12 volt signals with the board out of the monitor (no load). When I saw the 5V output oscillating I thought that was wrong and kept goofing around. It looks like I ended up blowing a fuse in the process of poking around so much. Once I replaced the fuse and tested the 5 and 12 volts signals under a load they were fine. I'm sure it was the capacitors all along.

Thanks.

[EGuevarae]

Re: Gateway 900G frustration

I got it fixed. In fact, it was probably fixed yesterday and I did not realize it.

After I replaced all the caps I checked the 5 and 12 volt signals with the board out of the monitor (no load). When I saw the 5V output oscillating I thought that was wrong and kept goofing around. It looks like I ended up blowing a fuse in the process of poking around so much. Once I replaced the fuse and tested the 5 and 12 volts signals under a load they were fine. I'm sure it was the capacitors all along.

Thanks.

So it is now just a matter of finding the smaller 680 replacements?
Good to ear that.

[capamatic]

Re: Gateway 900G frustration

Just picked up one of these 900W`s and tested the offending caps.
All Samxon caps, none visibly failing/failed.
The 47uF read as 48uF and 0.15 esr (good, hhmmm)
The 470uF`s read 0.05 esr (good) but all 4 were within a uF of 423uF.
That`s exactly 10% reduced capacitance, so probably the fault cause.

Has anyone subbed anything other than 470`s back in?
Looking at the board, it`s easy to replace at least 2 of them with a 1000uF cap.

[EGuevarae]

Re: Gateway 900G frustration

Just picked up one of these 900W`s and tested the offending caps.
All Samxon caps, none visibly failing/failed.
The 47uF read as 48uF and 0.15 esr (good, hhmmm)
The 470uF`s read 0.05 esr (good) but all 4 were within a uF of 423uF.
That`s exactly 10% reduced capacitance, so probably the fault cause.

Has anyone subbed anything other than 470`s back in?
Looking at the board, it`s easy to replace at least 2 of them with a 1000uF cap.

If in parallel, you can, but why not stick to original specs?

[capamatic]

Re: Gateway 900G frustration

I`ve got a stash of quality 1000`s , and better esr specs at that rating should prolong it`s life. C205 / C206 are in parallel and are under the most stress.
Just wondered if anyone has done it.

[EGuevarae]

Re: Gateway 900G frustration

I`ve got a stash of quality 1000`s , and better esr specs at that rating should prolong it`s life. C205 / C206 are in parallel and are under the most stress.
Just wondered if anyone has done it.

I've done it two or three times. Units are stable as of today (two or three months ago, on units that work 24/7).