Canon T90 and T70: Rescuing victims of leaked battery electrolyte

[BrianShaw]

You're lucky to got any solder connection at all. Those contaminated wires can become beyond challenging to solder.

 

[Andreas Thaler]

You're lucky to got any solder connection at all. Those contaminated wires can become beyond challenging to solder.

That is also my experience.

The wire contaminated by the electrolyte has difficulty bonding with the solder. I would have had to replace all the cables in that area, but that would have meant dismantling the camera. And that is not possible for me with the T90.

But as long as the cables are conducting, I will leave it as it is. I also assume that the electrolyte has already destroyed what it wanted to over the years

 

[Andreas Thaler]

After this positive experience, I hope to get the second T90 and the T70 up and running again

 

[koraks]

And that's with electronics that are decades old, cables that - like here - are no longer in perfect condition and solder joints on circuit boards where you're lucky if you can still solder anything at all.

Yeah, so what you do in a case like this is one of either options:
1: Remove corrosion from the conductors more effectively, e.g. by locally treating the copper with an acid (citric acid would be a good choice to begin with). Mechanical abrasion also helps, but is less effective on stranded wires.
2: Snip off another 10-20mm of wire; since you're doing a splice anyway, it's not a big deal if it's slightly longer.

That solder joint looks bad as it is and while it may appear to work now, I'd consider it bad practice to leave it there as it's liable to develop intermittency problems as corrosion creeps up the strands of the wire.

You will rarely achieve textbook-like soldering in camera repairs

It's relatively easy to do this a lot better. Give it a try.

 

[Andreas Thaler]

Yeah, so what you do in a case like this is one of either options:
1: Remove corrosion from the conductors more effectively, e.g. by locally treating the copper with an acid (citric acid would be a good choice to begin with). Mechanical abrasion also helps, but is less effective on stranded wires.
2: Snip off another 10-20mm of wire; since you're doing a splice anyway, it's not a big deal if it's slightly longer.

That solder joint looks bad as it is and while it may appear to work now, I'd consider it bad practice to leave it there as it's liable to develop intermittency problems as corrosion creeps up the strands of the wire.



It's relatively easy to do this a lot better. Give it a try.

Dear @koraks, you know that I value you very much. But here you are very self-confident in your assessment of my work.

Again: ALL corroded cables would have to be replaced here and it is pointless to only do it partially because nobody knows how far the electrolyte has penetrated. I am not crazy enough to start dismantling this camera.

Principle 1 in camera DIY repairs: As little intervention as possible.

If this T90 has survived for so many years, it will continue to do so for years to come.

The more you tinker around here, the higher the risk that you will make a mistake and endanger all the work done so far.

Space is limited in these cameras, the cables are single-wire and fine, and when you attach the battery compartment, you have to position the cables exactly, otherwise you will crush them. If you make them longer, the problem will get bigger.

If you want to repair such cameras, you have to think differently.

You have to improvise, make compromises, constantly make decisions, weigh up the lesser of two evils and realize that your chances of success are slim because you usually only have one attempt.

I'm serious, I'll send you the second rotten T90 and see what you do with it!

 

[zaneman]

If this T90 has survived for so many years, it will continue to do so for years to come.

That's not how long-term reliability works, unfortunately. The older the item, the more likely something will fail. Entropy is a tireless force tearing down everything that is purposely built.

Try to be less sensitive regarding critiques of your work. It's meant to help, and soldering might seem easy but it is a skill that requires practice and feedback. A poor quality solder joint is a very common source of latent defects in electronics.

 

[Andreas Thaler]

I'm not saying that you can't create nice solder joints in old devices.

Here are two that should satisfy any vocational school teacher

I made them on the circuit board of a Minolta Autowinder G when I was replacing an electrolytic capacitor.

The conditions here were ideal. No corrosion, new component, plenty of space to be able to make a good fire with a wider soldering tip. I used lead-containing solder.

Minolta Auto Winder D and G, Minolta Motor Drive MD-1: Service and repair

Review of Minolta Autowinder G #2 In this example, the motor also runs continuously when you press the shutter button on the camera. Capacitor #1 (10uF/16 V) has electrolyte on its terminals, so it is leaking. Capacitor #2 (4.7 uF/25 V) shows slight traces of electrolyte. The...

www.photrio.com

But unfortunately, as I said, the conditions in old photo equipment are often different.

So you can be happy if you can still get it to work without breaking anything.

At least that's my experience.

 

[Andreas Thaler]

Try to be less sensitive regarding critiques of your work. It's meant to help, and soldering might seem easy but it is a skill that requires practice and feedback. A poor quality solder joint is a very common source of latent defects in electronics.

I'm happy to accept feedback.

But I get tired when - as in this case - the basic conditions are not taken into account.

We're not soldering on new and clean perforated boards with new components, but on old, sometimes fragile equipment.

I have already commented in detail on the quality of this specific solder joint.

 

[Andreas Thaler]

That's not how long-term reliability works, unfortunately. The older the item, the more likely something will fail. Entropy is a tireless force tearing down everything that is purposely built.

That may be true, but as a collector, user and DIY repairer of 1980s photo equipment I have decades or even several years of experience. I also know that there are limits to what I can expect when it comes to repairs. See above.

This T90 will still be clicking away in five years, unless the only electrolytic capacitor runs out.

 

[Andreas Thaler]

But something is bothering me.

I have restored a rotten T90 that was already destined for the garbage can.

The only feedback I have received on this, including on my detailed report, concerns a single solder joint.

That is not very motivating.

It makes me wonder whether I should even go through all the work of documenting it.

 

[Andreas Thaler]

This also applies to my other repair reports, which become monologues. I no longer enjoy it.

Either my topics are not interesting, or I write too much, or maybe I'm just doing a botched job.

I'm going to take a longer break and think about it.

 

[BrianShaw]

If you don't mind me giving some advice... I'm quite experienced at writing stuff that few find intersting and even fewer respond. It was a profession. Self-motivation and self-satisfaction is all that keeps one going at times. Critics will always criticize, whether from a position of knowledge or not. And being put in a defensive position over a nit is really annoying. All I can say is that you, at least, got a ugly solder connection on a contaminated wire while I got no solder joint at all. You are one up on me! Paying attention to the "hit count" on the threads might be more telling than counting responses. Taking a break might be a good idea; we all need a break. Good luck in whatever you decide to do in the future.

 

[Willy T]

Congratulations on the restoration of power! I for one have been fascinated and whoilly engrossed in these threads and admiring of the determination and commitment needed to undertake such a project. I would have never though that this poor Pentax could in any way have been resurrected. Your documentation has been first-rate; many thanks for allowing us to peer over your shoulder.
Here's hoping that you will find more projects and the motivation to share them with us all.

 

[Willy T]

A decision to be respected.

I had nothing to offer by way of insight or assistance during this project, but regret that I did not take a moment while it was underway to express my appreciation for this illustration that old electronics may sometimes not become just more e-waste. Thanks again.

 

[forest bagger]

Hello Andreas,
I think your disappointment is to a noteable ammount due to the lack of ThumsUp in this forum, isn't it?

 

[Andreas Thaler]

Hello Andreas,
I think your disappointment is to a noteable ammount due to the lack of ThumsUp in this forum, isn't it?

No, I would like to have technical discussions that don't just help me.

Lately, however, I've been having monologues here.

And when well-intentioned tips come along that are completely irrelevant to the specific situation without addressing what I try to argue, I lose motivation completely.

I like writing my reports, even for people who come here externally via Google. Because I know myself how little information there is about DIY repairs.

Last but not least I was able to lure a few secrets out of Canon and Co that are new to the community. I allow myself to have so much self-confidence

So I'm going on again.

 

[Andreas Thaler]

… that old electronics may sometimes not become just more e-waste.

Thank you, I see it that way too.

This technology doesn't deserve to end up in the trash without a fight.

 

[Andreas Thaler]

If you don't mind me giving some advice... I'm quite experienced at writing stuff that few find intersting and even fewer respond. It was a profession. Self-motivation and self-satisfaction is all that keeps one going at times.

Thank you, that is certainly correct.

 

[Andreas Thaler]

I don't have anything else to say, except that I got the Canon T70 up and running again

Report to follow.

 

[Andreas Thaler]

Canon T70 back among the living

A solid camera from the 1980s, the first SLR for Canon's FD system with a built-in motor.

A screw in the base plate was corroded and could not be removed. Drilling into it and removing it with the screw extractor did not work. So I removed the screw head with a diamond burr on the Dremel.

One should never forget about batteries in devices.

After I had scraped the cap free, I was able to pull the battery out of the battery compartment using the Nejisaurus pliers, the specialist for all rounds.

I couldn't get the pliers to the second battery, so I cut a hole in the battery with the tungsten carbide cutter and pulled it out with a hook, which required some strength.

A rough job and unappetizing.

I cleaned the battery compartments with plenty of Durgol descaling solution and distilled water on cleaning sticks.

 

[Andreas Thaler]

Here too, Durgol dissolved the encrusted electrolyte residue completely and in just a few minutes. Then rinse with clear water.

Electrolyte filled the screw head profile, only after I dissolved the hard residue with Durgol could the screw be unscrewed.

Quite a dirty job. I cleaned all the tools in Durgol and water.

I should have let the camera dry longer, but impatience got the better of me.

I put in two AA batteries and the T70 worked as if nothing had ever happened

 

[gorbas]

Good work Andreas! Thank you for all your efforts to restore and share knowledge about this old good cameras!

 

[Andreas Thaler]

Conclusion

• Even if it looks bad years later when batteries have leaked, the situation is not hopeless. As long as the battery contacts are not corroded by the electrolyte, you can carry on. This type did not attack the metal.
• It would be important to check behind the battery compartment to see if the electrolyte has reached the electronics. I will do this later.
• I don't know if it was a good idea to drill into the rotten battery, but nothing happened to me. Maybe someone can say something about this.
• In my experience, steel screws often cannot be drilled any deeper. The drill obviously rotates freely due to the bevel in the screw head. The only thing that helps is the diamond burr or tungsten carbide milling cutter.
• I am always amazed at what SLRs (have to) put up with

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All information provided without guarantee and use at your own risk.

 

[Andreas Thaler]

Good work Andreas! Thank you for all your efforts to restore and share knowledge about this old good cameras!

Thank you!

If only for the great engineering achievements from Japan, which I deeply admire

 

[gorbas]

Andreas, your extraordinary works gives us, ordinary guys with minimum technical knowledge, hope that we also can fix some of our cameras so they not become E waste. Thank you!