Fault finding on an EOS 1000D sold as not working - for spares

[Gina]

I bought a non working 1000D from an ebay auction to use the sensor for testing debayering as mentioned in the debayering thread. I plan to sell off some of the parts and so I'm trying to find which part(s) is/are faulty. Alternatively, I may take certain parts such as the main board and test it in a working camera.

I've decided to try and find the fault on the non working camera as I have plenty of experience of fault finding electronic equipment. I'm posting my results as it might be of interest to other members.

[Gina]

I started the fault finding before I had a working 1000D, the latter being on order.

The fault showed itself as the camera failing to show any sign of life at all when switched on. This led me to think it may be a power issue so not having a battery I soldered wires onto the battery connections on the power board in the camera. I had taken it apart first.

Connected camera to bench PSU and it's drawing current but the current doesn't increase when the ON/OFF switch is set to ON so I've removed the contacts and cleaned them with IPA. Back together but still no change with ON/OFF switch. The contacts operated by the battery cover DO work. If the circuitry is silimar to the 1100D (and with multi wire connectors there's no way of knowing) the battery cover contacts operate power control circuitry on the main board.

I've taken the top apart to see what connects to where. The two pairs of wires from the power board connect to the flash unit and have nothing to do with the power on circuit. The ON/OFF switch, function dial and push buttons all connect through a ribbon cable that goes to the main board. I have visually checked the ribbon cable, contacts and connections and can see nothing wrong. Things are pointing to a main board fault or possibly the power board. The usual way of diagnosing the fault would be to swap major components with working ones but I can't do that until I get the working 1000D, of course.

This takes it as far as I reported in the debayering thread. I now have the working 1000D and can fault find by swapping parts.

[Gina]

I have now done some swapping of bits. I thought I'd start by trying all the main suspects on the non-working camera. So I took the power board, main board, sensor assembly, top section complete and back part complete from the working camera and put them into the non-working camera. Still no sign of like. So presumably the fault is in what's left. Just to be sure I hadn't caused any problem with this I put all the parts back in/on the working camera and check that all was working properly - it was.

[DIYASTRO]

Gina,

even if you can not get this camera working you will gain lots of info from your interesting experiments. I would just ask,, does your working 1000d draw current with the switch in the off position? Just find it odd that your non working camera should be 'calling' for power in off position. Perhaps this is normal but sounds like a dead/ short circuit. Interested to hear if working 1000 is drawing power when off. Good luck hope you get it working.

Boyd

[Gina]

Gina,

even if you can not get this camera working you will gain lots of info from your interesting experiments.

Yes, that's true

I would just ask,, does your working 1000d draw current with the switch in the off position? Just find it odd that your non working camera should be 'calling' for power in off position. Perhaps this is normal but sounds like a dead/ short circuit. Interested to hear if working 1000 is drawing power when off.

That's a good point - I'll check that by putting the power board that I soldered wires onto in the working camera and run it off the bench PSU.

Good luck hope you get it working.

Boyd

Thank you

[Gina]

I've done some further checking and there's another board associated with power on the back of the battery box behind the main board. I didn't change that over so that could be where the fault is. I have now removed the battery section from the main frame and taken a couple of photos.

1. The back of the box with the suspect board
   
2. The front with the board I soldered wires onto
   

[Gina]

I've just checked the working camera with the wired power board and apart from an initial surge (presumably charging a capacitor) it draws no current when switched off with power applied. BUT it also didn't work properly - it wouldn't take a photo and eventually came up with Err 99 and saying shooting wasn't possible (or something like that). So it seems there is a fault on that board. I now think there is more than one fault.

I think the next stage will be to test parts from the non-working camera in the working on - as I've just done with the wired power board. I may also swap the working battery box complete with it's 2 PCBs into the non-working camera and see if it then works. That's for tomorrow - I'm packing up now.

[DIYASTRO]

Gina,

Thats very interesting!

If it was me,

I would swap tha battery boxes first. i.e. good one from working camera to non working and vica versa. Easy to see that it may be a double fault but I would try this option first, then change it back to check that you havnt damaged the battery box circuits first before you proceed.

I am sure you will solve this!

Boyd

[Gina]

Thank you Boyd - I'll do that

[Astrobits]

It strikes me that simply swapping components like this is risky. If the power supply board has a fault that gives an overvoltage or reverse voltage to a circuit down the line then that would not only give multiple faults but could damage the good one that was being tried. Hence you would end up with two faulty cameras.

I would check the voltages out of both the power supplies, and anywhere else I could, as a first job.

Nigel

[Gina]

It strikes me that simply swapping components like this is risky. If the power supply board has a fault that gives an overvoltage or reverse voltage to a circuit down the line then that would not only give multiple faults but could damage the good one that was being tried. Hence you would end up with two faulty cameras.

I would check the voltages out of both the power supplies, and anywhere else I could, as a first job.

Nigel

Thank you Nigel Yes, I've been thinking about that myself. I've been running through what could have gone wrong. Particulary the two fault scenario. eg. a failed component on say the main board could cause a fuse to blow on a power board. And as you say, a power board fault could cause damage to another board. I've been lucky so far but with every component swap I'm taking a risk.

I think I might stick with the original idea of having this camera for the sensor and see about any repairs later. What I have concluded is that there is more than one fault and the it isn't just something simple that could be fixed easily. This doesn't mean I've given up on finding the faults just that it taking second place to using the sensor for debayering tests.

[DIYASTRO]

Gina,

You could try using a multimeter on the output of the known good battery unit, record the results and compare those to the readings from the suspect one. Readings such as continuity, ohm values from output when not under power can also be usefull for comparative assesments, even though they dont mean much its to check if both units give same results thus possibly illiminating a suspect board.

Boyd

[Gina]

Considering there are two multiway connectors - one with a dozen lines and the other with at least twice that as well as 3 or 4 dual connectors. I think that may be quite difficult. I know some of them carry signals/voltages to do with the flash. And that's just the front card.