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, which are integrated directly into the vertically moving focal plane shutter unit.

They can only be reached after deeply dismantling the camera, which is an extremely tricky mission with the T90 due to its dense construction with flexible circuit boards.


Is it the sticky damper that is causing the problem?

I found some information online that the HELP/EEE problem was associated with stuck shutter blades.



There is a foam damper in the lower part of the shutter, which turns into a sticky mass over the decades and contaminates the shutter blades. This contamination is visible.

If they are very dirty, the blades are blocked and the T90 responds with the two error messages mentioned.

Cleaning the shutter curtains and removing the remains of the damper will remedy the problem:



A problem that is not visible

I also found a note online that this problem occurs with T90s that have not been used for a very long time.

My guess is that the damper on such T90s has become sticky and one or both shutter curtains have stuck.

Since the camera was not triggered during this decomposition process, there are no traces to be seen of the sticky damper on the shutter blades. Therefore, no connection can be established and the cause of the problem remains unclear.

If this is indeed the case, the problem should be solved by removing the damper residue and cleaning the shutter.

The cause is then not dirty magnets, as seems to be the case with the mirror magnet:


I have two T90s that show HELP and EEE. On these, the visible part of the shutter is clean.

I will see if removing the damper will get the cameras working again.


On the trail of the last major and unsolved problem

There are solutions for all other common problems with the T90, such as the sticky shutter, the mirror magnet not triggering or the control wheel that has become unreliable:


The issue with HELP/EEE is the last big challenge in preserving a milestone in camera construction for the future

Looking again, the rear shutter curtain rests above the smaller damper part when not in action. There‘s no contact.

The front shutter curtain rests on top of the bigger part, but I have never seen any problems with stickiness here.

Anyway, I only have two options anyway:

1. Remove the smaller damper part at the front with the probe, clean the area with Zippo lighter fluid on a strip of blotting paper and then flood the shutter with Zippo to loosen any stickiness.
2. If that doesn't work, there's still an expedition to the shutter, which is a separate project.

We‘ll start tomorrow.

Of course, the damper that I'm removing has a function and it would be better if it stayed in place.

But since this thing has now rotted into a sticky mass in practically all T90s, it has to come out, otherwise the shutter could become blocked.

The only way to fit a replacement is to remove and dismantle the shutter. But then you also have to remove the larger part of the damper, as it decomposes in the same way. I think it's a fantasy to replace it adequately.

Tomorrow I'll also look at the shutter sequence on my T90s where I already have removed the damper. For this I will using the time-lapse function on my iPhone to see if I notice anything unusual here.

Examination of a T90 with a flashing arrow and „EEE“ in the display



The candidate in used and good external condition.




After inserting the batteries and turning the main switch to ON, the usual displays appear on the LCD.

When the shutter button is pressed, the mirror does not react, the arrow for the motor mode and self timer flashes. This means that the mirror magnet is stuck, which I remove and clean.




The orange wire to the magnet is cut, I did that myself on a previous project.

I should have checked my repair log.






So I stripped the two cable ends and soldered the parts together, which wasn't easy but worked. The blue shrink tubing fixes and insulates the connection point.




Now the mirror and the shutter release when you take the picture, but the latter not completely. One of the three motors makes a howling noise and „EEE“ appears on the display.

The T90 no longer responds to any inputs.




When you press the battery check button, the error message is deleted and the normal LCD display appears again. The camera can be triggered and the previous sequence will run again.




I remove the sticky damper residue from the rear bottom of the shutter unit.

I have described how to do this here:



The camera shutter sequence in time-lapse recording

Since I had already seen that the vertical focal plane shutter was only partially closed, I filmed the process using the slow motion function on my iPhone.

Here are screenshots from it, looking from the shutter to the lens:



The rear shutter curtain before the shutter is released. It fully covers the film window.




Release - the rear shutter curtain opens downwards.




The front shutter curtain follows, but stops after about 2/3 of its way down. It should close the film window completely.




The rear shutter curtain moves up.




The front shutter curtain also moves upwards.




The rear shutter curtain covers the film window.

The sequence is over.

---

Conclusion

• This EEE problem is caused by the camera shutter not working properly. The front shutter curtain does not complete its travel.
• The rear shutter curtain functions normally.
• The problem obviously has nothing to do with sticking of the damper residue in the shutter. There are no damper residues visible on either shutter curtain.
• It looks more like the front shutter curtain is blocked on its travel or is not being moved completely by the shutter's spring system.
• The two shutter magnets cannot be the cause because they trigger, otherwise the shutter curtains would not move.
• For further examination, the shutter unit would have to be removed, which is not possible for me at the moment.
• Therefore, I see no way of solving the problem here. A T90 with this fault can therefore only be used by me as a spare parts store.

---

What do you think about this?

Have you ever encountered such a camera shutter problem?

What could be the cause?

There may also be multiple problems with the shutter that lead to EEE and HELP. Today I had EEE on a T90, which disappeared after a few shots.

It is interesting that Canon had planned for these two error messages on the T90. They were obviously expecting the shutter to malfunction.

I will keep this T90 and try to remove the shutter this year. Less to repair it than to go the Way of the Cross of disassembly

Not an electrical problem, but a mechanical one?

I continued working on the T90 with EEE/HELP today.

I had previously observed that the second shutter curtain did not close completely after the shutter was released.

To investigate this further, I tricked the camera by releasing the shutter in BULB mode.

The first shutter curtain ran completely from top to bottom.

When I took my finger off the shutter button, the second followed - and at that moment I pulled the battery holder out of the camera a little.



Now only the second shutter curtain was visible before it was wound up by the motor together with the first.



The second shutter curtain could be freely pushed back upwards against spring pressure.



But it didn't let itself be dragged down any further.





Even using two fingers to pull it more easily didn't work.

The shutter curtain was locked and should have been able to move downwards freely.


Conclusion

• The two shutter magnets are not the problem, as they release both shutter curtains.
• I also rule out resin build-up/contamination, as that would not create such a resistance.
• That just leaves a mechanical problem in the shutter unit.

I will try this a few more times with the battery holder.

Maybe I pulled it out too late and that is why the shutter curtain could not be moved down any further because it had already been pulled back up.

This is of course a purely experimental technique on a test camera and should not be repeated

Well, now the shutter is completely blocked and the arrow on the display is flashing. Obviously the shutter/mirror sequence is now out of sync.

That doesn't matter, it was an experiment that brought some insights.

To investigate further, I would have to disassemble the T90 and I will do that later, perhaps I can detect the problem in the mechanics.

But for now I have spare parts for other T90s

The spring tension for the shutter curtains is set with 2 little plastic screws. These can break and will release all the spring tension in either shutter.




I managed to print a replacement on a resin printer and got the shutter block working again, but when i reassembled it the flashing cursor error appeared. It appears to be a faulty mirror coil, but it's strange that it just started happening after repairing a different fault.

Attempts to remagnetise the coil worked to some extent but it always reverts to locked shutter and flashing cursor

I just set the camera to bulb release and I will leave it overnight in the hopes that the coil will re-magnetise, (on reccomendation from a different forum post), but i suspect that the coil is pulsed for the release rather than set permanently high. If this doesn't work i could de-solder and energise the coil with 3v for a period of time for the desired effect.

I also seem to get 14.8v for VDD on the DC/DC converter rather than the expected 15.2V so maybe the pulse just isn't strong enough to release it. Energising the coil directly results in release without fail.

Maybe the smart thing to do is swap the DC/DC converter and test it again

joe_laroids said:

The spring tension for the shutter curtains is set with 2 little plastic screws. These can break and will release all the spring tension in either shutter.


View attachment 387909

I managed to print a replacement on a resin printer and got the shutter block working again, but when i reassembled it the flashing cursor error appeared. It appears to be a faulty mirror coil, but it's strange that it just started happening after repairing a different fault.

Attempts to remagnetise the coil worked to some extent but it always reverts to locked shutter and flashing cursor

I just set the camera to bulb release and I will leave it overnight in the hopes that the coil will re-magnetise, (on reccomendation from a different forum post), but i suspect that the coil is pulsed for the release rather than set permanently high. If this doesn't work i could de-solder and energise the coil with 3v for a period of time for the desired effect.

I also seem to get 14.8v for VDD on the DC/DC converter rather than the expected 15.2V so maybe the pulse just isn't strong enough to release it. Energising the coil directly results in release without fail.

Maybe the smart thing to do is swap the DC/DC converter and test it again

Click to expand...

Welcome to PHOTRIO!

Interesting work!

How did you disassemble the T90 down to the shutter? Did you have instructions for this?

The flashing arrow on my T90s was always the mirror magnet. Removing it and cleaning the contact surfaces solved the problem.

joe_laroids said:

I also seem to get 14.8v for VDD on the DC/DC converter rather than the expected 15.2V so maybe the pulse just isn't strong enough to release it.

Click to expand...

That doesn't sound like a very significant difference to me.

And welcome to Photrio!
Thanks for posting the information w.r.t. the plastic cogs. As a fellow T90 owner, that photo is kind of disconcerting...

koraks said:

Thanks for posting the information w.r.t. the plastic cogs. As a fellow T90 owner, that photo is kind of disconcerting...

Click to expand...

„The tank“ with a plastic gearbox!

Andreas Thaler said:

Welcome to PHOTRIO!

Interesting work!

How did you disassemble the T90 down to the shutter? Did you have instructions for this?

The flashing arrow on my T90s was always the mirror magnet. Removing it and cleaning the contact surfaces solved the problem.

Canon T90: Cleaning the mirror magnet

I have a T90 here whose mirror magnet no longer works. The usual symptom of a quiet clicking sound and a flashing arrow in the display occurs. The recommended cure of removing the front cover and activating the - easily accessible - magnet with a magnetized screwdriver tip works with patience...

www.photrio.com

Click to expand...

Yes I have a copy of the march/april 1990 SPT journal which i bought as a download from learncamerarepair.com

It goes in depth through disassembly as well as some trouble shooting

Once you've done it once it's not that difficult to get the shutter block out and back in. You can access the shutter screws with the shutter in place, and the mirror block out. But at that point you might as well take the shutter out too. From scrap cameras i would say these shutter screws are very valuable once you learn how to remove them. I'm not sure how long my 3D printed one will hold up

Regarding the error, you were right! I cleaned it a little whilst the mirror box was out of the camera, but i never took the coil out, i just did and cleaned the contacts properly and it's back to normal again!

Despite the plastic parts I still think the t90 is an underrated camera. I hope i can fix the other ones I have similarly, but the next one is showing no signs of life on LCD or anywhere, and the IC3 isn't producing a clock signal, so that one might be dead dead, as VBAT and DC/DC OUT are OK.

The shutter curtains are also replaceable, and it's easier to remove the melted shutter damper with the block removed

joe_laroids said:

Yes I have a copy of the march/april 1990 SPT journal which i bought as a download from learncamerarepair.com

It goes in depth through disassembly as well as some trouble shooting

Once you've done it once it's not that difficult to get the shutter block out and back in. You can access the shutter screws with the shutter in place, and the mirror block out. But at that point you might as well take the shutter out too. From scrap cameras i would say these shutter screws are very valuable once you learn how to remove them. I'm not sure how long my 3D printed one will hold up

Regarding the error, you were right! I cleaned it a little whilst the mirror box was out of the camera, but i never took the coil out, i just did and cleaned the contacts properly and it's back to normal again!

Despite the plastic parts I still think the t90 is an underrated camera. I hope i can fix the other ones I have similarly, but the next one is showing no signs of life on LCD or anywhere, and the IC3 isn't producing a clock signal, so that one might be dead dead, as VBAT and DC/DC OUT are OK.

Click to expand...

Great!

How much soldering work is involved in removing the shutter and how did you organize your work?

joe_laroids said:

Regarding the error, you were right! I cleaned it a little whilst the mirror box was out of the camera, but i never took the coil out, i just did and cleaned the contacts properly and it's back to normal again!

Click to expand...

Then we can conclude that the shutter magnets also have the same problem as the mirror magnet and the infamous EEE-HELP error can be fixed by cleaning.

This means you have solved the last secret of the T90 when it comes to fixing typical errors.

Congratulations!

joe_laroids said:

I hope i can fix the other ones I have similarly, but the next one is showing no signs of life on LCD or anywhere, and the IC3 isn't producing a clock signal, so that one might be dead dead, as VBAT and DC/DC OUT are OK.

Click to expand...

So far I have had success with checking the contacts in the battery compartment, battery holder and the connecting cables on the circuit board.

Battery electrolyte had wreaked havoc here in places, but you can't always see it from the outside.

Would you like to make a tutorial on removing and repairing the shutter?

You would be the star of all T90 users and would definitely be ranked #1 on Google with such a post - worldwide

Can you explain the problem with the plastic screws again?

So there were two issues with the shutter: the screws and the contaminated shutter magnets?

Once you have removed the battery tray and the wires on the upper rewind side of the main flex there's not that much more to do. The main flex is attatched to the motor flex and SP flex with a pressure bar, so that's no soldering. But there are some tricky solder pads that are easy to damage on the DX flex and the shutter flex connections. There are also some pins that need to be desoldered with copper wick before the flex can come away from the body but it's not that tricky.

I organised my screws in the lid for one of my screwdriver sets and took lots of pictures, but the journal i have goes through it step by step so it's easy to backtrack for reassembly.

I have made a repair guide before for canon AF35ML, I could put something together for the t90 now that i've fixed so this many issues on one camera, but the guide does exist in this journal already so it's a little less pressing. When i have more time i might put one together.

Yeah the plastic screws set the tension and adjust the curtain travel time. It should be 2.7ms +/- 0.2ms, but I haven't checked the travel time on this camera. Any more tension and it weakens my 3d printed replacement. Once i improve my printing technique and refine the 3D model i might be able to get it to withstand higher tension. Especially if i start using specialty resins but they are much more expensive.

As far as i'm aware yes the shutter screws and the contaminated or weakened coils are the only EEE problems with the T90, along with the loose mirror box screws that cause strain on the aperture setting lever and lead to flashing cursor.

Flashing bc error appears to be caused by incomplete winding cycle, and can be fixed by manually applying 3V to the charge motor or sometimes by just pressing the shutter release. (Maybe other failure modes)

No LCD can be caused by poor contact between the FD and main flex at the rewind end (where the film door switch pin extends through both) or short to ground on reset pin

I also had locked shutter that was due to contamination in the rear button panel. Instead of the regular display on LCD it showed iso, so obviously the iso switch was earthed. Cleaning the contact pad resolved it.

So far i don't think i've ever encountered a t90 with a dead PCB backup battery surprisingly

Plenty more problems to find with these cameras i'm sure but overall it's not too difficult to work on. Many people blame faulty IC chips on electronic cameras, but i have never conclusively encountered any camera with a dead chip. The nikon L35 AF has this reputation, and people say it's unrepairable, but it's nearly always a mechanical issue or battery leakage.

Thanks!

joe_laroids said:

Many people blame faulty IC chips on electronic cameras, but i have never conclusively encountered any camera with a dead chip.

Click to expand...

Sounds totally plausible!

Andreas Thaler said:

Thanks!

Click to expand...

From me, too. I'm reading with interest.

I think it's great how new members are bringing in expertise, see also the Minolta 9000 @ogtronix

koraks said:

Sounds totally plausible!



From me, too. I'm reading with interest.

Click to expand...

I'm not doubting it happens! I just think not as often as it seems

I have a highlight on my instagram about the T90 with some more photos and videos

I'lll try and turn it into a thread on here but you can check it out on @joe_laroids in the mean time if you're interested.

When i was researching online i was surprised to find such a recent forum post about the T90! Normally they are all from back in the early 2000s

This forum seems like a valuable resource

Awesome, thanks! I've found the T90 story; it's pretty prominent on your IG. Great work!

joe_laroids said:

This forum seems like a valuable resource

Click to expand...

It is, thanks to people like @Andreas Thaler and yourself who share all this stuff - keep it coming!