Warning! Do not try any of this at home! Messing with internals of electronic devices is dangerous and can lead to electrical fires, serious injury and even loss of life.

My dad started using a super 8 film camera as early as 1967 (the system was launched in 1965). He stopped doing it in the 1980s as it became pretty much impossible to buy film. Ever since then the films have been stored in multiple cardboard boxes in his basement. Recently he moved to a smaller apartment so all the films and related hardware had to go somewhere else. Namely, to me. Here is a representative sample.

The picture does really not make justice to the projector. It is perhaps the only household appliance I have ever owned that could survive a head-on collision with an IBM Thinkpad from the 2000s. The projector weighs 10 kilos and consumes 200 watts when running, half of which is taken by its halogen light bulb. For comparison a typical modern LED light bulb consumes less than 5 watts.

The projector has not been used this millennium so unsurprisingly it did nothing when I plugged it in. The back cover could be opened (with a screwdriver) revealing two glass fuses, one of which was burnt. I replaced it and plugged the machine back in. It immediately let loose the magic smoke even though everything was turned off. Fortunately I had kept the back cover open so could see the smoke the second it appeared and managed to cut the power before flames appeared. Unfortunately the smoke originated deep inside the machine so I could not see which component was the source. To get deeper I would have to remove all the covers. That is no small feat, mind you, I had to buy a whole new ratchet set to get all the various screws out.

This thing predates printed circuit boards that would tell you which holes belong to which components. Instead all components have been soldered to the board by hand with Japanese meticulousness. The board won't give us any help on deciphering how things should work. Visual inspection also does not reveal any immediately broken components. Neither did poking around with a multimeter.

The only life line was that even though a component had started smoking the fuse had not blown. In theory I could plug the machine in for a second and see if smoke appears again. If it does I can see the exact component faulty component. At this point I'd like to remind you of the warning at the top of the post. If you have a known broken electrical device, you should never connect it to any sort of a power source. Seek advice from a qualified professional instead. Even if you manage not to burn your house down, electric shocks are nasty any resulting smoke is almost certainly noxious.

Anyhow, after taking sufficient precautions I plugged it back in and immediately got smoke and could decipher what was wrong. One of the main electrolytic capacitors (the one that was in the most inconvenient location, obviously) had dried out and shorted. This caused one of the bridge rectifiers to have its positive and negative output leads short circuited. Here are the problematic components.

The dark blue capacitor on the right is the broken one. For some weird reason the three decoupling capacitors have different voltage ratings (16V, 25V and 50V) even though there is only one transformer and input voltage (12 V). The black circles are the bridge rectifiers. The one on the right is the broken one. In this picture the cracks are fairly visible but trying to detect them in person is very difficult, even with a magnifying glass and a flashlight. According to multimeter measurements the other two capacitors and rectifier are working, but it's better to replace all of them. 50 year old eletrolytic capacitors have a short life expectancy and the additional work needed to fix all instead of only one is insignificant.

Here is a comparison shot of the old components and their modern replacements.

After soldering in the new components you enter a paranoid session of measuring every possible combination on the board to ensure you have not accidentally created a short or put any of the components in the wrong way. Any failure can give you a live Electroboom experience in your own home. Even though it sounds exciting, you really don't want to see it with your own eyes. I don't speak from experience here, and intend to keep it that way.

Anyhow, eventually you have to plug the power and try if the machine works. Amazingly enough it did without a hitch. Once you have it running you can truly appreciate how well the mechanical parts of the projector have been designed. It runs silent, smooth and with zero visible jitter. There is only one plastic knob in the entire device. Unfortunately it is the lens focus adjustment wheel, and it has broken off (as you can see in the first image). You can still sort of twist it with your fingers but the experience is inconvenient to say the least.

What next?