Pentax Spotmatic SP: opening a jammed battery compartment

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Thomas78

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Hello,

I was lucky to get a nice Pentax Spotmatic SP recently:


DSCF0651 von thomas.78 auf Flickr


Unfortunately I am not able to open the corroded battery compatment, because it is jammed.

So I unmounted the base plate:


DSCF0653 von thomas.78 auf Flickr


DSCF0654 von thomas.78 auf Flickr


DSCF0655 von thomas.78 auf Flickr

Do you have any ideal how to open the battery compartment?

Thanks and best Regards,
Thomas
 
My old repairman used to drill two tiny holes on opposite ends of the metal battery cover, then insert a spanner wrench and twist it off. A little penetrating oil can also help.

PS: I see you already have two tiny holes in the coin groove.
 
Maybe try soaking it in a little Baking Soda mixed with water to see if that will eat away at any left over battery acid...
Anyone else in here ever try that...???
And BTW my battery cap has one hole drilled in it...must be a factory thing...
 
Now that you have the plate off, I'd heat that baby. Hair dryer, paint gun, or even put it in boiling water.
 
Paint gun might be a bit much, but hair dryer and boiling water should be fine. I'd run it through a couple heat-freeze cycles, and that should loosen the bonds enough.
 
There must be plenty of parts cameras, or parts even.

Igor is very busy, but will mention it to him, though he often gives parts collections he finds to well known repairmen, so he may be out.

As I recall, I've seen more than a couple with some serious corrosion inside.

If I were going to heat it, I might use a soldering gun/pencil on low wattage.

Regards, John
 
Flood the cap with acetic acid (household white vinegar, working strength stop bath, or 28% Acetic Acid - Glacial Acetic Acid may be a bit strong). The acid will react with the alkaline deposits left by the leaking battery.

Let it soak for 5-10 minutes and then try to remove the cover. Try a mint condition US nickle held in the jaws of a ViseGrip plier as a tool. Repeat the acid treatment as necessary.

The great thing about the Spotmatic design is that removing the baseplate lets you do this without risk of damaging the rest of the camera with the liquid.
 
+1 on the household vinegar application.

Apply with a small artist's paintbrush around the rim of the cap.

Safest when done with the bottom plate removed from the camera, as you have already done.

You will see some bubbling/foaming action as the vinegar does its job. Keep trying the coin in the slot inbetween applications of vinegar until the cap loosens. You don't have to force it, the cap will loosen.

I used this technique recently on a Spotmatic just like this, and it worked beautifully.

A great camera!
 
Thank you for your tips!

Finally I was able to unscrew the cap.

First, I applied some acetic acid (25 %) at the thread and the two holes. Some bubbles were formed and the solution got a bit green.
After some time the black paint at the cap dissolved and the chrome vanished at some small spots.

But I was not able to unscrew it.
I washed the acid away with water, applied some penetrationg oil (?) and heated it with a heat gun. Then I put it in the freezer, heated the base plate with the heat gun.

I put a washer in the vice, filed it down that it fit the slit in the cap perfectly and was able to unscrew the cap via rotation the base plate. 🙂


Best Regards,
Thomas
 
Wow, that was some procedure just to unscrew the cap. I'm glad you were successful. I have the same problem with one of my Spotmatics. I also tried the vinegar and lighter fluid technique but non of them worked. Fortunately the battery is still working so I don't need to unscrew the cap just yet. I have to remember what you did when it's time.
 
Thomas78 said:
...and the chrome vanished at some small spots.

...
Click to expand...

This happens when the corrosion from the battery leakage has attacked the brass under the chrome lifting the chrome from the brass. When the alkali salts are desolved by the acid the chrome that had been lifted by the corrosion is free to wander off. The acid itself didn't separate the chrome from the brass.
 
I've used that stuff we have to clean the espresso machine ... it's an acid of some sort, sulphuric I fancy, that certainly won't damage the chrome as I've used it on La Pavoni for years
 
Glad you got it fixed Thomas. Having used the spotmatic and old kmount pentax before I hope you enjoy it as much as I enjoy mine.😀
 
You can contact Spotmatic repairman Eric Hendrickson. He has lots of Spotmatic parts should you ever need some in the future. I think if you google pentax repairs you'll get his email address.
 
Dwig said:
This happens when the corrosion from the battery leakage has attacked the brass under the chrome lifting the chrome from the brass. When the alkali salts are desolved by the acid the chrome that had been lifted by the corrosion is free to wander off. The acid itself didn't separate the chrome from the brass.
Click to expand...

Yes, that is true. The chrome at the baseplate is almost untouched. As my adapter to replace the mercury cell by a silver cell is formed as a battery cap, I don't mind the "damage" at the original battery cap that much.

Compared with my gossem digisix, my first impression is that the TTL meter shows about 1/3 stop to much light, giving minimal under exposure.


it'sawhat? said:
Glad you got it fixed Thomas. Having used the spotmatic and old kmount pentax before I hope you enjoy it as much as I enjoy mine.😀
Click to expand...

It is a nice campera to use, I like it much more than working with my brothers Canon EOS 1 or EOS 3.

A SLR is a nice additon to a RF.
 
Thomas78 said:
I put a washer in the vice, filed it down that it fit the slit in the cap perfectly and was able to unscrew the cap via rotation the base plate. 🙂


Best Regards,
Thomas
Click to expand...

That's primarily what did the trick. I just snap a nickel in vice grips so the handle is parallel to the baseplate, hold it down with one hand while turning with the other. Works like a breaker bar.
 
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