Canon T90, main repair project for 2025: Hunting for errors with the HELP and EEE codes

[Andreas Thaler]

We've discussed the Canon T90, arguably the most complex 35mm camera with MF, several times here.

It's encouraging that most of the common problems can be solved DIY, see:

Canon T90: recommendations and notes

Based on my previous (repair) experiences with the Canon T90 with regard to preservation/problems/repair options, I would like to give a summary of the following recommendations/hints: Sticky shutter - gummed-up shutter blades: Can be permanently repaired, damper in the shutter area that has...

www.photrio.com

However, one problem that means the camera will fail completely has yet to be solved:

The blocked shutter with the HELP and EEE error messages in the viewfinder and on the camera's LCD.

We've discussed this at length in this thread without finding a definitive answer:

Canon T90 shows the error messages HELP and EEE: Tracking down the last major problem

One of the most common problems with the T90 is still unsolved: the shutter blocking, accompanied by the messages „HELP“ in the viewfinder and „EEE“ on the display. Until now, I assumed that the cause of this problem was dirty magnets for controlling the shutter. The T90 has two of these...

www.photrio.com

The current state of the discussion is assumimg that the two shutter magnets are dirty and are not firing. Broken plastic shafts in the shutter control could also play a role.


I'd like to restart the topic here from scratch

because, by a stroke of luck, the C & C Electronic Troubleshooting Guide for the T90 is now available, in addition to an excellent article in the SPT Journal and the Canon Repair Manual.

These error messages are dealt with in detail there providing new insights and perspectives for repair.

I'm considering this topic my main repair project for 2025; I have two T90 with this problem to work on in stock.


Highlights to come

• Removing the mirror box to get to the shutter. A particular challenge with the T90 due to the dense installation with flexible circuit boards.
• I also want to explore the T90's setting options; it even has its own built-in test mode.
• The success of these adjustments will be determined again using the Reveni Labs Camera Tester.
• Insights into the interior and technology.
• Advanced tips and hints for DIY work on the T90.

An exciting and long-term project is coming up; we'll start after Easter.

Stay tuned!

 

[Gregory_Nolan]

Great! Looking forward to your repair report.

 

[Andreas Thaler]

Great! Looking forward to your repair report.

Hopefully I won't completely lose my mind dealing with this topic!

 

[Peláez]

It will be interesting to see if he manages to fix the “EEE, HELP” error on the Canon t90 camera, although I fear that those of us who lack the necessary knowledge to undertake such tasks will have to be content with using the camera as a paperweight.

 

[Andreas Thaler]

It will be interesting to see if he manages to fix the “EEE, HELP” error on the Canon t90 camera, although I fear that those of us who lack the necessary knowledge to undertake such tasks will have to be content with using the camera as a paperweight.

I'm starting this project precisely to prevent the T90 from becoming a mere paperweight

As always, I'll aim to structure my corresponding repair report to be as understandable as possible and helpful for DIY projects.

The T90 isn't a magic box either; with the technical documentation mentioned, there's a realistic chance of making progress.