Canon T90: Address unresolved problems; broken plastic parts in the Copal S shutter, epoxy to stabilize, EEE/HELP again, replacement of the electronic

[Andreas Thaler]

I see, yes. Perhaps it's possible to glue it in situ?

Spring forces act on the spot. And that's where my fine motor skills end

 

[Andreas Thaler]

The epoxy is now solid.

When tightening, you can see that the spring moves slightly under the epoxy droplets on the left screw.

This is perhaps a good thing; in any case, the curtain travel times have remained stable and have even improved

I'm now installing the shutter into the T90 and am curious to see how the shutter speeds will work. The T90 controls these electronically. The camera must be mounted for this.

 

[Andreas Thaler]

EEE and HELP

The tests coupling the shutter and mirror to the motor worked after inserting the mirror box. This passed the most critical part.

During the first test of the T90 after complete assembly, EEE and HELP appeared. And immediately after switching it on.

I went through the troubleshooting instructions, removed a double diode to test it, re-soldered the circuit board connections, checked the connectors, as well as the magnets, which worked.

I then replaced the DC/DC converter three more times because a reference voltage was not appearing there.

Voltage measurements on IC3, the main CPU under the LCD, did not match the specified values. So I finally replaced IC3, but that didn't work properly with the soldering of the 60 pins. I'm not equipped for this fine work. And I was already outside the service instructions, which don't recommend it, but recommend replacing the entire mainboard

This puts this T90 in the spare parts box.

I'm removing the shutter, which I had treated with epoxy. It's going into the next candidate to test it


What could be the cause of the error?

What surprised me was that 15 volts weren't measured on the DC/DC converter; the voltage wasn't reaching the terminal. And that was the case with three DC/DC boards. So that rules out a fault.

But voltages were measured on the board. So, it wasn't a short circuit.

The only explanation I can think of is that IC3 was actually faulty. The voltages that weren't appearing at certain pins support this. And the technical documentation also says that.

Anyway, there's more to come.

Stay tuned!

 

[Andreas Thaler]

Replacing the electronics to fix the EEE/HELP error

After a long sleep and a hearty breakfast, I took the T90 out of the spare parts box and continued working

Since I couldn't locate the fault, I replaced the entire mainboard, providing most of the circuitry and connected to the mirror box which I also replaced. A spare parts T90 was looted.

But that didn't solve the problem either. As soon as the camera is turned on, the winding motor still moves briefly and EEE/HELP appears.

So today I removed the motor flex board from another spare T90 and will install it in my patient tomorrow.

Then most of the electronics will be replaced, and hopefully, the error won't have too many possibilities anymore.


Cleaning the release magnet

Before assembly, there is a test routine for the coupling of the motor, shutter, and mirror box.

During this process, the release magnet failed.

This was quickly resolved by removing the magnet and cleaning its contact surfaces with benzine.

You can see the contamination in the photos.


Simple tool to trigger the shutter magnets

To test the electronic triggering of the two shutter magnets, I built a double contact that is fixed with shrink tubing.

It is connected to the laboratory power supply, which is set to two volts.

This allows the magnets to be triggered directly via the contacts on the shutter board.


Curtains travel times hold

The shutter, which I adjusted yesterday and stabilized with epoxy, is doing well.

The curtains travel times are holding up.

Stay tuned!


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