Canon SL2 MCU at fault? Needs programming?

[liquidzorch]

Hello. I have a question about swapping the canon 200d MCU, since it has various issues, like e50 with the flash, it won't autofocus while in camera mode (eyesight) it just focuses in and out and never finds the spot, but it will autofocus perfectly in live view mode (through screen), AND sometimes I can turn it on even when the battery door isn't closed. Additionally something that used to happen but not much anymore is that I could switch it on in photo mode, it wouldn't turn on until I pressed any other button. Here is a little backround to the camera, please note that the issues appeared one after the other. You might not need to read the whole story to help me answer my two questions about the MCU, but just in case how the symptoms appeared helps, here it is:

I bought a damaged 200d off ebay a few years ago. It looked like just a battery connector issue, but after opening the camera, I noticed that there was a little bit of water damage (very little corrosion spots around and under the SD port on the motherboard), a faulty SD port plus the faulty battery connector. After cleaning the corrosion, making sure no traces were damaged, plus changing the SD port and battery connector, the camera worked with one small issue, the flash would give an e50. During that time (this was over 2 years ago) I checked every thing that could be related to the flash, the flash board seemed good, there was no water damage, all traces could be traced back to the motherboard connector, and there was no pulse being sent to the flash charge transistor (checked with an oscilloscope). So I let it be, didn't need a flash any ways. The camera worked fine for a few months, mostly used for video, but also some photography. After a few moths I took it out on a trip, nothing happened except it being really hot outside, but it took perfect photos. Then the next day the autofocus stopped working in the viewfinder mode, sorry I forgot the term, BUT it works perfectly in video or in live view photos. SO thinging it was a dirty sensor, I opened it up, got to the autofocus sensor on the bottom cleaned everything (wasn't very dirty anyways), but no go. The flex cables seem 100% fine. Soall this, plus the battery door switch (which has been tested and proven to be good) that sometimes doesn't even need to be pressed, I have concluded that maybe it's a MCU issue, since it is under the SD slot, where most of the damage was.

So two questions that I have not been able to find answers to anywhere are:

Is the MCU (f74966a) a piece that would control all three issues? I would imagine that it controlsthe door switch and maybe activate the flash board, but I'm not sure about the autofocus issue.

If I swap the MCU, does it need to be programmed? I have found some off aliexpress (the only place I could find them) but if it need programming then I don't think I'll even try the swap since programming software for the sl2 is super expensive.

Any input would be greatly appretiated. This is my camera, and I do have repair knowledge, but mostly for laptops, computers and things with schematics, which canon dslr's do not have, and I am not familiar with them since I have never really messed with any. Now the lcd ribbon cable has broken (after so many times I have opened and closed the system), so I would like to try and fix the issues before ordering a $50USD lcd ribbon for a camera that was already so faulty.

[liquidzorch]

Re: Canon SL2 MCU at fault? Needs programming?

This thread can be closed, it turns out that even though so many issues have occuered, they are all seperate. The autofocus issue was a resistor on the analog to digital converter SCLK line that was missing, I guess I left it loose when I was repairng the SD card slot, it is extremely close to one of the legs (and on the complete opposite side of where the autofocus analog to digital converter is, making me not check overe there). The issue with the camera sometimes turning on even though the battery door is open was due to the switch, when testing continuity it always worked, but there is a certain posistion that would cut the continuity while being open, very faint, and only happened at a certain angle.

The ONLY thing I have not been able to fix is the flash error 50. I have spent hours on it, replacing the capacitor, checking line continuity, cheking all simple components on the flash board, nothing seems bad. There is a transparant chip on the motherboard, where a fiber optic cable from the flash goes to, this same chip controls the mosfet that switches the flash transformer (never sees a single pulse on it's gate pin, checked multiple times with my oscilloscope), the line from the chip to the mosfet has continuity, but when I press the flash button, it never sends anything to it.

I would like to know more about the flash circuit, like does it do any tests before trying to charge the capacitor? I doubt it since there are alternate lines, just one that goes to the mosfet, one that goes from the secondary side of the tranformer (I guess to know when the capacitor is fully charged), and that seems to be it. So if it doesn't do any "testing" before sending the charge pulses, the fault sound be at this transparent IC on the main board (thinking outloud).