2025-09-22 - Cleaning Battery Leakage on a Canon T50
----------------------------------------------------

WARNING: The flash capacitors used in cameras can hold a dangerous
charge even when the camera is off and the battery has been
disconnected. Do not attempt a repair if you do not know how to watch
out for such capacitors and discharge them if necessary. Since this
camera doesn't have a built-in flash, this warning probably isn't
relevant, but it doesn't hurt to be on the safe side.

I've had to repair damage from leaky batteries quite a few times
already, but I think the Canon T50[0] analog camera I saved several
months ago was the worst I've seen so far. One of the batteries was
stuck so tight that I had to pull it out with pliers, completely
ripping open one side in the process[1][2]. Since the battery
compartment was completely covered in battery leakage[3], I decided
to take the camera apart to clean it properly.

Several screws have to be removed on the bottom, including one longer
one inside the battery compartment[4][5]. There are also two screws
on the sides, one on each side[6][7]. I'm not sure if I also had to
remove the piece on the side[8], but I seem to remember that removing
it was unnecessary. Before the circuitry at the top can be accessed,
the plastic part around the lens/sensor needs to be removed. After
four screws are removed[9][10][11][12], the plastic part can be
removed[13] (the cover over the sensor also has to be removed, but
it can be reattached to protect the sensor after the plastic part
is gone). Finally, four more screws need to be removed, two at the
front[14] and two underneath the eyepiece[15] (the eyepiece can simply
be pushed up to remove it).

The top part is still held on by the film winder (or whatever you call
that thing)[16], but this doesn't need to removed completely. Instead,
I just pushed up the plastic washer underneath so the top part could
be pulled up a bit[17] and moved to the side[18]. There are many wires
underneath, so care must be taken not to damage anything. Note that
the neck strap has already been unscrewed on one side in the images
because I had already taken the camera apart once before and then
came back later to take the pictures.

Once the top has been removed, the rubber grip on the side can be
removed to clean it properly[19]. The switch to change the camera mode
can simply be unscrewed and removed[20]. The exposure counter on the
right was very difficult to remove because the screw was stuck, so I
had to use a tool to grab the screw on the sides to turn it[21]. The
label on top came loose during this process, so I had to stick it
back on with some glue during reassembly. There is also a spring
sticking out from the counter that has to be unhooked to remove
the counter[22][23]. The three wires can then be desoldered and the
plastic holder unscrewed[24].

In order to properly access and remove the metal plate on top,
the ribbon cable/flexible circuit board needs to be unscrewed and
desoldered first[25][26][27][28]. Some of the traces had turned black
due to the corrosion, but they still seemed to be continuous[29]. On
a regular circuit board, I would have removed the corrosion and then
covered everything in UV solder mask, but that wouldn't really work
on a flexible circuit board like this one, so I just left everything
as is. Perhaps I could have cleaned the corrosion and covered the
traces with some sort of tape, but I'm not sure what the best option
would have been there.

Next, there are three black screws around the edges of the metal plate
that need to be unscrewed[30][31]. A small metal piece covering two
small plastic gears also has to be removed by prying off the retaining
clip[32][33] (watch out because the clip can easily fly off and land
somewhere where you will never find it when it comes loose). The metal
plate can then finally be removed[34][35]. I'm not sure if I had to
remove any other screws -- I do remember that I unscrewed some screws
on the bottom of the camera, but I'm pretty sure that was unnecessary.

In order to clean away all the battery leakage, I first used white
vinegar to neutralize it and then washed that off using isopropyl
alcohol. I did remove some of the gears at the top, but I decided
that it wasn't worth it to take the entire mechanism apart since the
main damage was around the battery compartment, so I just made sure
that the vinegar didn't get into the mechanism and damage anything
there. The battery contacts can be seen before cleaning in [36],
and the cleaned top of the camera is shown in [37]. Note that one of
the gears has a spring inside[38]. I don't actually remember exactly
how it was attached, but it's probably better to just leave it
attached unless it absolutely has to be removed in order to clean
the top properly.

One issue was that the switch was slightly broken because one of
the contacts had corroded and broken off at the end[39]. It still
sort of worked, but I wanted to improve it, so I cut off some sort
of grounding contact from a broken phone I had lying around[40]
and soldered that to the switch[41].

After cleaning everything, I had to resolder the wires around the
battery compartment, which required quite a bit of flux because
all the corrosion made it difficult to get the solder to stick. The
purple wire also had broken off due to the corrosion, so I had to
resolder that[42]. Care needs to be taken when reattaching the wire
holder since it also is responsible for pushing parts of the trigger
switch into the correct position[43]. After soldering the wires onto
the circuit board, I isolated them a bit with pieces of tape just as a
safety measure, but this shouldn't really be necessary[44]. At first,
I soldered the red wire into the wrong position, so it was good that
I looked back through the pictures I had taken and found my mistake. I
also used some UV solder mask where the corrosion had been the worst,
but as mentioned before, this wouldn't have worked properly for the
other parts of the circuit board since it's flexible and not rigid
like normal boards.

When reattaching the exposure counter, the spring needs to be put back
into the correct position. After resoldering the other connections on
the circuit board, the top cover can be put on again. When putting the
cover on, the switch needs to be in the correct position so it matches
the position of the knob on the outside, and care must be taken to
avoid getting any cables stuck on the outside accidentally. Of course,
the plastic washer in the film winder also needs to be pushed back
down afterwards.

I guess this repair was kind of useless because the camera really
isn't worth anything anymore, but at least I got to practice the
repair of battery leakage in case something more valuable with the
same problem comes my way.

[0] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/canon_t50.jpg
[1] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/battery1.jpg
[2] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/battery2.jpg
[3] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/battery_compartment.jpg
[4] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_bottom1.jpg
[5] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_bottom2.jpg
[6] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_side1.jpg
[7] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_side2.jpg
[8] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/side_piece.jpg
[9] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_front1.jpg
[10] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_front2.jpg
[11] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_front3.jpg
[12] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_front4.jpg
[13] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/front_removed.jpg
[14] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_front5.jpg
[15] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/screws_eyepiece.jpg
[16] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/film_winder.jpg
[17] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_open.jpg
[18] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_side_open.jpg
[19] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/side_grip.jpg
[20] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/switch_removed.jpg
[21] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/exposure_counter_screw_removal.jpg
[22] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/exposure_counter_spring.jpg
[23] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/exposure_counter_removed.jpg
[24] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/wire_holder_removal.jpg
[25] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/flex_pcb_removal1.jpg
[26] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/flex_pcb_removal2.jpg
[27] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/flex_pcb_removal3.jpg
[28] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/flex_pcb_removal4.jpg
[29] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/flex_pcb_traces.jpg
[30] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_plate_removal1.jpg
[31] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_plate_removal2.jpg
[32] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_plate_removal3.jpg
[33] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_plate_removal4.jpg
[34] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_plate_removal5.jpg
[35] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_plate_removed.jpg
[36] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/battery_contacts.jpg
[37] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_cleaned.jpg
[38] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/top_gear.jpg
[39] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/switch_broken.jpg
[40] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/switch_replacement_contact.jpg
[41] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/switch_fixed.jpg
[42] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/purple_wire.jpg
[43] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/wire_holder_reassembly.jpg
[44] gopher://lumidify.org/I/phlog/2025-09-22-canon-t50/wires_soldered.jpg