Gateway Solo 2500 no backlight

[Compu dummy]

Hi everyone. I'm new to the forum but have had success in the past repairing the CCFL inverter in my LG Flatron monitor, using helpful information found searching this forum. The Flatron's failure was due to failed caps. Now I am trying to solve a similar issue on my ancient Gateway Solo 2500 laptop.

There is a specific purpose for which I need this laptop. I am an automotive diagnostic and engine performance specialist and I run a programmable EFI controller in my own project car. The EFI system is older(1999) and uses DOS based Calmap software for programming. The software is antiquated and can only run with true DOS. Since apparently anything later than Windows 98 does not allow access to true DOS, I have to run this software on a system running Windows 98.

So...I am stuck either replacing the entire EFI system with something newer that uses newer software (which I will do eventually but would like to put off for now), replacing yet another old laptop with whatever the market offers (options getting slim), or repairing the laptop I have.

I have done quite a bit of testing and have traced the problem to the inverter itself. I performed a test, which I found here on this forum, to be sure the inverter is not shutting down due to a failed CCFL. I used a paper clip connected across the high voltage output terminals with a 1/4 inch gap and watched for a spark to jump the gap when the unit is powered up. There was no spark. I measured voltages on the 4 wires into the inverter. I found a good ground on the red wire, varying voltage on the orange wire according to the brightness setting, .9 volts on the yellow wire which I assume is the enable signal, and 19 volts on the green wire. I tested what appears to be a ceramic fuse on the inverter board for continuity and it's okay.

I would like to be more certain that everything is as it should be but can't find schematics for this unit anywhere. If anyone has them, and if you have pin out values for the inverter, please post them for me. I have not found any inverter for this unit either new or used. I have found an LED conversion kit that looks promising. Has anyone had success with this conversion?

Any help with this case would be very much appreciated. Or if any gurus out there have a better option, I am open to suggestions. Thank you in advance for any help. Mark

[Compu dummy]

Re: Gateway Solo 2500 no backlight

Update: I tried a test using a 9V battery to apply power to the enable circuit of the inverter. I was concerned that the .9V I was seeing there wasn't enough to activate the IC. With power applied from the battery, the CCFL lit up. This shows me that the inverter is okay. I now need to trace the enable circuit back to see why I'm only getting .9V. I keep wishing I had a schematic diagram for this unit. I am going by visual indication of power flow and guessing alot.

[Compu dummy]

Re: Gateway Solo 2500 no backlight

I'm not giving up just yet. I understand that technical information from Gateway is hard to find. I think I have traced the loss of the enable signal to the part marked K2 in the upper middle of this photo. Please bear with me on picture quality. I spent some time trying to get the best clarity I could. I hope you can see the hot area around the part I'm referring to. The puzzling thing is that I have 3.3V at the middle terminal on the RH side(as viewed in the photo). This would be the enable signal, but I can't find any continuity between this terminal and the enable circuit of the inverter harness, even away from the part as in a broken trace. The closest I can find continuity to the enable circuit is at the intersecting ends of L22, L23 and R6. Can anyone make sense of this? Does this design structure look familiar to anyone? Am I looking at a likely broken trace issue?

EDIT: I mentioned the part marked K2 as a possible cause of no enable signal. I just realized how illegible the print on this part is. To clarify, it is the part labeled U2 on the PCB.

[Compu dummy]

Re: Gateway Solo 2500 no backlight

I performed a pin out voltage test on the part I suspect of being the cause of no enable signal. The pins in my drawing are laid out as in the photo in my last post. Pin C appears to be ground. I'm thinking that pin A should be passing on the 4.95V supply voltage when the gate is activated, which it would seem to be by the 3.27V signal at pin D. Does anyone have any thoughts on this? I'm about to start looking for another old laptop. I would love the satisfaction of repairing this one and keeping another piece of electronics out of the scrap heap. I noticed also that the fan wasn't working when the unit was powered up. I could feel that the processor was getting warm too. I'm wondering if this one switching unit might also enable fan operation.

I tested the fan itself with the same 9V battery I used for the inverter test and the fan motor worked. Of course I did turn it by hand once or twice and if it has a bad winding it may have just worked the one time. I'll check this out some more as I move ahead. If anyone has any thoughts on this thing, please don't hesitate to post them. I am worse than a novice so you can only be helping me. Thanks

[lti]

Re: Gateway Solo 2500 no backlight

This is interesting. My Solo 2500 would turn the backlight off after a couple minutes, but it suddenly fixed itself.

The fan on mine runs during POST, then shuts off when it starts searching for a bootable disk. There is a power saving setting in the BIOS that allows you to choose between starting the fan or underclocking the CPU when it gets hot, and it could affect that. I don't remember exactly what it is called, but the manual talks about it. I should remember what it is called since the CMOS battery is dead.

I would like to see a service manual. I want to know how to take it apart so I can change the battery soldered to the motherboard. The schematic would be nice as well since I also have issues with the backlight.

It looks like that part is marked H2 and is in an SOT-23-5 package. Searching for that brings up an MC74HC1G08, which seems to match the pinout of that part. However, its markings are slightly different than the part you have. If that is the correct part, the voltage on pin 2 (marked D in your drawing) is a little low.

[Compu dummy]

Re: Gateway Solo 2500 no backlight

Thank you Iti, for your response. Yes, that looks like the right part and I see what you mean that voltage at pin 2, IN A is a little lower than IN B. It could be that the difference between IN B and IN A is causing it not to activate, by what I can discern from the function chart. Though 3.27V is still above the minimum at Vcc 4.5V. I admit though that I don't clearly understand the terminology. I may try to insert 4.95 at pin 2 and see if the gate activates. The thing was obviously hot though so I won't be surprised if it's dead. I will also look for the cause of IN A being low.

I wish I had schematics for this thing. I searched this morning again and nothing. I am tempted to go ahead and buy another laptop. This time one that is better supported, which is pretty much any other brand. I know that Gateway plays their cards close to the chest but that there is no public sharing of tech info, even on this old unit is kinda weird. I see some pretty decent offerings on ebay and I can put this one back together and store it away to play with later on when I have more time and patience. I am going to price that H2 gate from ON though and probably go ahead and get it coming.

As far as pulling the unit apart, I have mine down the bare essentials right now. I see the battery soldered to the mother board. I would need to go a little further to remove the mother board from the case for soldering. At this point it would just mean removing the DVD drive and hard drive assemblies.

To disassemble the unit, I first removed the screen bezel which meant peeling off the two stick-on screw covers at the bottom then remove the screws and the bezel snaps off with some gentle finger work around the edges. I may helped it a little also with my handy pocket screwdriver. Then with the screen rolled back as far as it goes, I snapped off the portion of the case top closest to the screen that includes the hinge covers. It snaps off from the keyboard edge and I gently popped it off. Then the screen connectors and the screen hinges. With the upper portion of the case top removed you see the screws that hold the keyboard down. With those out, the keyboard comes up. I laid it back on its top while I removed the processor heat sink/cover and the processor board and cleared the way to access the keyboard and mouse connectors at the motherboard. The mouse pad slides out towards the screen side of the unit. This exposes the remaining screws attaching the case top. Once all the case top screws are removed, the case top snaps off.

Then the SD memory card drive lifts off after removing two screws and the ribbon cable from the same PCB that I have photographed and that houses the H2 switching gate and of course the RF shield from this same PCB. You end up with a big pile of screws.

What does that battery do that is attached to the mother board? I see the CMOS battery is installed under the keyboard.
EDIT: Im sorry for trying to sound like I know what I'm talking about. I really know nothing about this thing. I thought that was the the CMOS battery under the keyboard. I don't know what it is.

[Compu dummy]

Re: Gateway Solo 2500 no backlight

Okay, I tried applying 4.9 volts to pin 2 of gate H2 and voila! I have backilght. So, aside from this part obviously being hot at some point, it does work when the correct voltage is applied. Now, I just need to find the voltage drop to pin 2.

[Compu dummy]

Re: Gateway Solo 2500 no backlight

Played with the trace coming from pin 2 of the H2 gate and now I have a visible screen. The trace runs out towards the down left direction under L21. There appears to be a break in the trace just below the L21 stamp on the PCB. I'll play with it a bit more to pinpoint the break then solder it.

EDIT: The break is at the pin 2 connection to the PCB. Now just figuring out how to solder this thing. Even my smallest tip seems like a tree trunk when held next to this tiny thing.

[lti]

Re: Gateway Solo 2500 no backlight

As far as pulling the unit apart, I have mine down the bare essentials right now. I see the battery soldered to the mother board. I would need to go a little further to remove the mother board from the case for soldering. At this point it would just mean removing the DVD drive and hard drive assemblies.

To disassemble the unit, I first removed the screen bezel which meant peeling off the two stick-on screw covers at the bottom then remove the screws and the bezel snaps off with some gentle finger work around the edges. I may helped it a little also with my handy pocket screwdriver. Then with the screen rolled back as far as it goes, I snapped off the portion of the case top closest to the screen that includes the hinge covers. It snaps off from the keyboard edge and I gently popped it off. Then the screen connectors and the screen hinges. With the upper portion of the case top removed you see the screws that hold the keyboard down. With those out, the keyboard comes up. I laid it back on its top while I removed the processor heat sink/cover and the processor board and cleared the way to access the keyboard and mouse connectors at the motherboard. The mouse pad slides out towards the screen side of the unit. This exposes the remaining screws attaching the case top. Once all the case top screws are removed, the case top snaps off.

That's nice to know for when I finally buy a replacement battery. I have replaced the keyboard and tried to figure out why the fan never stops running once the CPU gets hot enough for the fan to start. I'm going to try replacing the thermal pad some day.

What does that battery do that is attached to the mother board? I see the CMOS battery is installed under the keyboard.
EDIT: Im sorry for trying to sound like I know what I'm talking about. I really know nothing about this thing. I thought that was the the CMOS battery under the keyboard. I don't know what it is.

I actually don't know what each battery does. There is a memory backup battery that powers the RAM while Windows is in standby so the computer does not need to be completely shut down to change the main battery. The battery that is most likely to be the RAM backup battery (based on its voltage and capacity) is the one sold as the CMOS battery. Nobody talks about the battery soldered to the motherboard.

[Compu dummy]

Re: Gateway Solo 2500 no backlight

I really appreciate your help Iti. Your input, the link to tech data on the H2 gate and your clue to voltage at pin 2 being low, was the final piece needed to get me to a solution. I was wrong about the fault being at pin 2 of the H2 gate. I thought it was there because after working in that area, the backlight powered up and worked for a while with no further intervention. Then it stopped working again and no amount of fiddling around pin 2 helped. I went back to following the trace away from pin 2. I traced it to where it passes through to the opposite side of the board and to what I believe to be the break(3.3V on one side, 4.95V on the other), right at the edge of a Quanta IC. There was no practical way for me to repair the break there. I thought about installing a patch from pin 2 to the 4.95V source but the pins on the H2 gate are so small.

I finally settled for bridging pins 1 and 2. This basically combines the dual gates. It limits the function of the H2 but for my purposes, since I only use the device for brief periods of time and the sleep function of the screen isn't really vital to me, it should be fine. As long as controlling both gates doesn't overload the control circuit to pin 1.

So far, after having the unit powered up for 2 hours yesterday, all is well. I reassembled everything and took it home to charge overnight. Knowing now that there are two other batteries in this unit, and at least one of them is a Ni-cad, I won't just keep the device in my car with no charger connected for months on end anymore. As it is, I'm pretty sure the CMOS battery must be dead anyway since the unit shuts down pretty quick when power is taken away. The main battery has been poor for a while now. Even after charging, I can only run it for a few minutes without connecting a charger. I did find batteries priced fairly reasonable by doing a search. Just $56 and change I think for either a 4.4Ah or a 8.8Ah. As long as the aftermarket batteries actually fit correctly.

[Compu dummy]

Re: Gateway Solo 2500 no backlight

Oh boy, I was curious what type of equipment I should have to properly repair this type of PCB, in case my repair ends up failing in the future. I reviewed the equipment and techniques forum and found the work stations link. That's quite a setup and funny that it's just about exactly what I had envisioned. I was thinking that hot air or perhaps preheating the board must be the correct way to de-solder and re-solder these multi pin microchips. I have fought with them in the past with my clumsy soldering iron and yesterday I really sweated destroying the unit in my attempt to fix it. That H2 is so tiny.

I enjoy repairing these things. It's an exciting challenge and I feel great pride in having repaired this old laptop rather than scrapping it for another that would have ended up breaking eventually as well. I think I may invest in a workstation for future repairs.

This has been a fun little adventure. Thank you again Iti for coming along on this fix with me. Oh, another note on disassembling and reassembling the case. I got it all back together and had 2 screws left over. I searched the case and couldn't think of where these two went. I finally pulled the battery and flipped the unit over. There is one screw on each front corner from the underside. One under the battery opening, and one under the front-most hard drive unit.

I used to hate and fear this kind of thing. Perhaps working in auto repair and especially dealing with modern snap together interior trim has helped me adjust to working with this kind of assembly. I almost halted on going into this unit. I was afraid I would never figure it out anyway and at first I couldn't really see how to get it open. Then, I decided to say what the heck and give it a shot. I just went in carefully. I have learned to really search thoroughly for fasteners. Manufacturers like to get tricky with their assembly methods and hide screws in odd places. if it doesn't seem to want to come open, I look again for more screws. In the long run, the unit was not that bad to take apart and much easier to put together, although there is a certain sequence you must follow. If you skip a step somewhere, you'll be back tracking to get it right.

[lti]

Re: Gateway Solo 2500 no backlight

It might be possible to solder that tiny chip with a small tip on the soldering iron. A thin pencil tip could work, and there are small tips designed for this purpose.

A dead CMOS battery would cause the BIOS settings to be lost after the computer is left sitting for a while. That does happen to mine.

In the BIOS, there is a Cooling Control setting. If you can't get the fan to run, change that setting to Silence. The user manual has BIOS setup information, and there are a few places where you can download it.