Canon T90: recommendations and notes

It is not recommended that you attempt to repair this camera. It is included here only to show what you’re up against when it comes to fully automatic electronic SLRs.

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koraks said:

I admire your patience in even getting to this point. I opened up one of my EOS30's the other day to see if I could easily spot its battery drain & (supposed) door latch problem. Removed the front and bottom covers, and quickly decided I found it still worked well enough to not risk making it any worse!

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koraks said:

Jiu-Jitsu and the art of camera repair.

It's going to sell. Mark my words.

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• I just have looked through Canon's service manual for the T90 (suaudeau.eu). Right at the beginning, additional information material that is not available is pointed out. Material that we lack for deeper understanding.
• After replacing certain parts such as ICs, extensive adjustments must be carried out, among other things. with devices that are also not available.
• A limit of what is possible in DIY service and repair has been reached here, at least for the hobby workshop at home. But I am not aware of any workshops that would accept the T90 for service, with the exception of one workshop in the USA.
• Anyway there is no reason to be sad, almost all common problems with the T90 can be resolved or prevented, as we have seen
• And if an electronic camera still works after around 40 years of manufacture, it should continue to do so for another 40 years. All I see here is quality and electronic circuits do not suffer from wear and tear, even if components such as electrolytic capacitors can age or fail due to overload.
• Since the T90 only has 6 volts of input voltage, which is converted internally to 18 volts, overloading should not be an issue, in contrast to devices powered by mains voltage generating heat by power dissipation.
• The T90 is also excellently sealed against dust and dirt, but there is no seal against moisture.
• The shutter and mirror mechanism are solidly designed. The three electric motors should run without wear.
• The T90 is also insensitive to shocks and impacts, as shown by the infamous method against stuck magnets. Here the camera is placed hard or worked with a rubber mallet.
• If you want to work with the T90, you should buy several copies as a backup that are kept fit through regular exercise. You get a lot of performance for relatively little money.
• It is a camera still far beyond its time, the best photo machine ever made for manual focusing.

Andreas Thaler said:

• It is a camera still far beyond its time, the best photo machine ever made for manual focusing.

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Andreas Thaler said:

1. Shutter does not release - flashing arrow in the display: The cause is the mirror magnet, which no longer works due to magnetization. Can be fixed with a magnetized screwdriver blade or replaced with only little disassembly.

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1. Shutter does not release - flashing arrow in the display: The cause is the mirror magnet, which no longer works due to contamination which can be cleaned with electronics cleaner or isopropyl alcohol. Alternatively try to fix with a magnetized screwdriver blade or replace with only little disassembly.

Andreas Thaler said:

I have just found a note from Thomas Tomosy (Camera Maintenance & Repair, Book 1) on how to lift the trigger switch assembly without damaging the cable connections. Then the contacts on the adjustment wheel can be cleaned.

To do this, the battery compartment must be removed and the cable harness installed in the handle must be loosened.

If anyone is interested, I would be happy to show it on one of my abandoned T90s.

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critterdoc said:

Please do! After 50 yrs. as a CET repairing video equipment before moving into robotic repair/programming, I had the chance to visit with a film camera (movies&still) in Toronto. It was 1994 & he was repairing/recalibrating a T90. I thought some Bolex & Leica gear was overcomplicated but Holy knotholes, Batman, when I saw the circuit boards, wiring harnesses & assorted bits of that T90 laid out on the bench, I was appalled! Reminded me of nothing less than an electronic train wreck! The repairmans secret?: A SECOND T90 in perfect shape to use as a metering& exposure standard! I didn't even ask what his hourly rate was. Nonetheless, he did say that the "injured" T90 would be good for another couple decades with a bit of care.

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