How to troubleshoot LCD problem in a Canon Powershot G12?

Question

I have a two year old Canon Power Shot G12. A couple of days ago, out of nowhere, the flip LCD screen turned on misaligned, with the bottom half-inch of the image or so clipped and on the top of the screen, with a thick black line in between the clipped part and the rest of the image (see attached picture). Kinda like a misconfigured computer monitor back in the golden days of manual calibration... Also, it's hard to see in the attachment, but the color in one of the image halves is always missing the red channel, though which one it is varies (just pressing the display button makes it change sometimes).

The camera is ostensibly out of warranty, and I'm confident that I could do the needed replacements myself if I know what part to replace, but I fear the prolem may be on the motherboard, so the question is:

How can I determine whether the problem is 'just' a faulty lcd screen or if the motherboard needs replacement? Could this be a software issue? If so, how can I re-install/update/check the camera's firmware? I've looked around for two days, but I have been unable to find any service guides or anything similar for this model, and the Canon support site I was able to find is less than helpful. Related: Is it possible to get a lower level access to the hardware for diagnostic purposes? How?

Answer 1

The Canon G12 specification indicates that the screen is a TFT. For that kind of screen the issue you showed it should be direct connected with Vertical Synchronization (Vsynch) of the image. From the indication you supplied it seems that the gap is fixed and not moving and due the fact that some colours channel changes with touching the screen, it could be due to some wire that have been detached (or just a false contact) after rotating the screen.

No official firmware updates have been released from Canon for the G11 and G12 model. If you would like to use a custom firmware you should try the CHDK custom firmware with all the disclaimer of the case. In the same place there are several firmwares dumped by users.

Answer 2

I'm not sure there is going to be an easy way to tell. The screen is most likely driven by a frame buffer and it looks like the wrong address is being used for sending the information to the display. The problem could either be that the timing on information going in to the buffer is wrong (which could be either in the screen or in the main board of the camera) or it could be that the image buffer is correct but the display itself is refreshing the wrong row because of the screen itself having a timing issue.

Short of trying to hook it up to another screen, I'm not sure of any easy way to determine the problem. If the camera is a bit old, you might consider buying a non-working camera on e-bay and just trying it. If you can find one with a broken lens, the main circuit boards and display are likely still intact. The electronics SE site might also be able to offer further insight since this is really more of an electronics question than a photography one.

Answer 3

Not so much an answer as to a solution, found a UK company that supplies canon parts, emailed them the fault with so is it, The door hinge wiring assembly, LCD driver board or the LCD display itself ? There reply is below.

Hi Andrew,

Canon supply above part as Whole LCD Assy with Hinge Unit.

Please send it to our workshop and we will replace it for £69.00 + Postage (£5.00)

-- Many Thanks,

Eurohitech Photographic Services Ltd 13 Quad Road, East Lane Business Park East Lane, North Wembley London, HA9 7NE Tel: 02089040900 Email: [email protected]

Sending mine off tomorrow, the sum total of all the parts from eBay is more than £74