[G Tablet General] TheBastage:
Another success. And step by step procedure.

Thanks for the info!

After reading about your issues, I decided to pop open the gTab and see what I could do. My gTab was able to charge but only when the cord was in a very particular position (cord wrapped around the outer edges of the device). Since it charges intermittently, I decided that it'd be good to pop open the case and see if I could fix the connection problems.

Disclaimer: If you're not comfortable with soldering, using a digital multimeter (DMM) or handling electrostatic discharge (ESD) sensitive components, I'd try to get someone who is. Please follow at your own risk. The instructions below will void your warranty. Good soldering skills are a must as you have to be careful not to leave cold solder joints, overheat nearby ICs, or leave gobs of solder. Be neat and clean!

Tools required:

Static free area to work with (conductive metal table tops are a no no!) If you have a grounding strap for your wrist even better!

Digital Multimeter (one with continuity and resistance testing)

Soldering Iron (hopefully one with high precision. I needed over 750 degrees F and a very fine tip to get the solder to adhere to the motherboard pad and DC input pin.

Solder (Good quality) I used the silver solder from Radio Shack.

Optional:

Helping Hands (to hold components together while you solder)

Hot Glue Gun (to hold components together while soldering if you don't have a pair of Helping Hands)

If you have a pin that's completely separated from the pad, or it's broken off, you might need bridge wire or some spare wire.

Solder sucker, or solder wick

LocTite

My steps:

Extracting the Motherboard

1. Remove the four corner screws underneath the rubber caps first!

2. Please watch the tear down video first before attempting as it has some good pointers regarding screws and cable (re)attachment. I found a good tear down video on YouTube (search for "gTab Tear Down") (I'm new to posting on here so I can't post links yet.) t3h_g3n3ra1 has a good post here too: http://xdaforums.com/showthread.php?t=842354

3. Remove back cover as in the video. Don't pull too much as the tabs can break off. Work slowly!

4. Get rid of static now. Touch a grounded metal component. Use a static wrist strap if you can.

5. Remove the power cable first! (Don't throw away the blue tape as you'll be using it later to fasten it down when you reconnect the battery.

6. Remove all other the cables connecting the device to the motherboard (just the green section). You only need to remove the motherboard so you can easily get to the DC Input. You can leave all the other components connected to the chassis, battery and LCD in place. You shouldn't need to mess with these.

7. Unscrew the motherboard screws. Mind the screw placement because they're not all the same size. I used a piece of tape sticky side up and placed the screws in the relative position of their placement on the motherboard. You can also draw a rough diagram of the motherboard on the tape with a sharpie if you like. (You should be used to doing this if you've dealt with Apple products or if you mess with laptops regularly.)

8. Remove the motherboard and place it aside in a static free area (or static free bag).

9. Put the chassis and back cover aside.

Testing the solder joints on the motherboard.

If the DC Input just falls right out, I'll show you the pads that need to be resoldered. However in the my case where just the center pin was just not connected well, I'll give you the steps here.

1. First test the center pin. Hopefully I can post images and I can show you where to test. Using the DMM, test the center pin and the pad on the motherboard it should be connecting to. Out of the 5 pads that the DC input should be connected to, it's the only one off the center pin at the end. The other 4 connectors will be connecting to chassis ground. With your DMM probing the motherboard connection pad and the center pin in the housing, test for continuity and also test for resistance. On my model, continuity was intermittent showing that a connection was there, but not reliable. Testing for resistance, I was measuring a range from 0 to infinity, but it was mostly hanging above 400 ohms. For comparison, a good solder joint should show good continuity, with no breaking as well as < 10 ohms in resistance. With my measurements, I concluded that the center pin needed to be resoldered.

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2. Before jumping to the soldering gun, just for due diligence, you should test the 4 other ground connectors for connectivity and resistance. An easy way to do this is touch your first probe inside the DC input jack (by the center post, but do NOT touch the center post! It's like the game "Operation!" If you can't do this reliably, maybe you shouldn't try the soldering part.) The second probe should be touching one of the four pads on the motherboard where the 4 ground connections should connect. Test each individually. They should all show good connectivity (no breaks in sound, and little to no resistance. At this distance, your resistance really should be reading 0). If any of them shows a resistance > 10 ohms, you might want to think about resoldering.

3. If you can physically separate a joint, just leave it alone. Don't pick at it. It won't heal if you keep touching it! Wait until the soldering section!

Soldering

Note: This should be done for all the joints that you have identified as faulty in the previous section.

1. Use a fine or very fine tip on your soldering gun.

2. Heat your soldering gun to 750 or 800 degrees F. You could use less, but when I tested, I could stay on the pad or the part and the solder would NOT liquify. (Started at 600, then upped by 50 degrees until I got to 800).

3. Have the pad and the pin from the jack touching while you solder. Don't allow for gaps if you can. (optional) If you have a set of helping hands, use some plastic or rubber on the alligator clips so that they're non conductive. Have the clips hold the DC Input jack in place so you can solder the pads that have come loose. Sometimes you can use the hot glue gun to hold the jack in place while you solder. Sometimes easier than a set of helping hands. Just put a SMALL dab of hot glue on the opposite side of the jack from where you're soldering. Jut make sure it's out of the way. Note: if your jack has completely broken off, you may have to use a piece of bridge wire or spare wire to allow for a clean connection.

4. (Optional but usually good practice). Clean your connection. Remove old solder using a solder sucker or solder wick. If not cleaned you could be soldering on to a bad connection. There was so little solder on mine that I barely got any off with soldering wick.

5. Heat the parts your fusing. With the pin from the DC Input touching the pad on the motherboard, heat both together and then apply solder to insure a good connection. Failing to heat one part, could cause a cold solder joint. With the amount of force that your power cord puts on the connector, a bad mechanical connection will also cause the connection to become unreliable again.

View attachment 910401

6. Apply a small amount of solder to cover the pin from the DC Input to the motherboard pad. There should not be a giant bead of solder left over. Using too much solder you might accidentally fuse to some of the other connection pads that are very close to your joint.

Testing your soldering

As in the above testing section, retest all your connections, even ones you didn't solder! Often when working with surface mount components that are close together, people often create junctions that are not supposed to be fused.

View attachment 910405

1. Test the center pin for connectivity. Test continuity and resistance. Resistance should be < 10 ohms. The center pin should have excellent connectivity to the motherboard pad.

2. Test the center pin for non connection to grounding pads. With your probe on the center pin, test the 4 grounding pads for the DC Input. None of the grounding pads should show any connectivity to the center pin. If you used too much solder on the center pin, desolder it and resolder it again with just a connection to the motherboard pad.

3. Test the ground pin to the 4 ground pads. Put your probe in the DC Input sleeve (make sure to touch only the ground). Then put your other probe to the each of the 4 motherboard pads in succession. You should have good connectivity.

Reassembly

Note: Leave the power cord disconnected until everything else is attached and connected. If something explodes or smokes at this point don't say I didn't warn you.

1. Place the motherboard back in place.

2. Start placing the screws in the locations where they belong. Tighten each half-way only. When all screws are in, you can fully tighten them. If you want to use LocTite here, now's a good time. This is a mobile device after all.

3. Leaving the power cord until last, connect all the other cords and ribbon cables. Make sure they're connected.

4. Make sure the routing of the cables are in places that won't get bent beyond the bends they already have. Make sure nothing will stick out of the sides of the unit. The thin speaker cables are pretty bad and should be fastened down with a bit of tape.

5. Attach the power cable.

6. Double check all your cables and connections.

7. Keep the unit face down, otherwise the power and volume buttons could fall out. Turn the unit on. Should boot normally.

8. Using Spare parts battery information, Battery Spy, Battery Monitor or any other battery debugging app from the market monitor the battery.

9. Insert the DC Adapter. You should now show that the battery state is Charging (AC). If it's not then you may have another connection problem somewhere else. (beyond the scope of this article).

10. Replace the back cover.

Finish

In conclusion, the fix for my particular break was pretty easy and took about 40 minutes to actually perform (30 minutes testing, 10 minutes fixing). I know my method is quite conservative. I'm just trying to cover the largest audience with these instructions. I had shelved my gTab for a bit until I had time to do some research on how to fix the DC Input. My Xoom was fitting the bill for a while, but I felt the gTab needed some love. Now it's running solid, and with TeamDRH's beta of ICS, I just have some OS/Kernel tweaking ahead of me. I'm just excited that I can reliably power my gTab while testing ICS!

Hopefully you'll find this fix easy and helpful. Peer review or suggestions welcome. Thank you all for reading.

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