[peter_lille]

Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.

---

Hi all. I recieved my first Pentax earlier this week, an MX from ebay. It functions properly, apart from the light meter. It reads over- or underexposure ramdomly. I've tried changing batteries to no help. Someone suggested I check the connections to the ASA selector.


The problems is I don't have anything in my toolbox that I can use to open the top cover. More specifically for the dial and the winder. I could use pointy tweezers for the winder and loosen it, but the dial is another story.The tweezers are simply not powerful enough and they start slipping, so I'm afraid to chip the two small holes. I set the shutter speed to 1/1000 and ASA on 25, as stated on a service manual I found.

Would dividers like these suffice? link to ebay listing

Suggestions for other tools are welcome!

[Not a Number]

Beside a nice set of slotted screw drivers you would need

- a set of JIS (Japan Industry Standard) cross head drivers. These look like Philips head drivers and screws but have different angular shapes. Using a Philips driver on JIS screws is likely to strip the head of the screw.
- a set of lens spanner wrenches for removing threaded retaining rings (fitted with slots or holes). The best wrenches are the Japan made scissors or compass type vs the crossbar types. The crossbar type have a tendency to slip or twist.

Micro-tools.com has a good selection of just about everything you need but you can find better prices if you shop around.

[aslyfox]

welcome to the forums

you will find friendly members and a lot of information here

I suggest you look at this thread

Those screws that look like Phillips 00 and 000 in Japanese cameras and lenses? They aren't. They're JIS cross-heads and life's a lot simpler using JIS screw driver bits on 'em. . . .

Cross-head screws - a caution: - Page 2 - PentaxForums.com

[Not a Number]

Oh and sometimes the retaining rings around the rewind and winding shaft are reverse threaded - right to loosen vs left to loosen.

[peter_lille]

Thanks. Really appreciate your answers! I was starting to think to abandon this particular camera and get another one, as it was turning out to be quite hard to find the right tools. But I feel it'd feel a lot more like mine, if I can fix it. And how cool is micro-tools.com? Thanks again.

[C_Jones]

This is an older Pentax Forums thread that deals with a similar situation. A shortcut to the thread is below.

Could anyone recommend a good set of JIS screwdrivers and spanner? - PentaxForums.com

[K-Three]

Have you found this yet?
http://www.mammola.net/manuali/Pentax_MX_service_manual.pdf

[c.a.m]

Would dividers like these suffice? Suggestions for other tools are welcome!

Hi,

Welcome to Pentax Forums!

You may be interested in this article: Lens Spanners -- Using the right tool for the job - PentaxForums.com

Pentax Forums has a fairly comprehensive section related to repair and maintenance: Maintenance and Repair Articles - PentaxForums.com

- Craig

[arnold]

Hi all. I recieved my first Pentax earlier this week, an MX from ebay. It functions properly, apart from the light meter. It reads over- or underexposure ramdomly. I've tried changing batteries to no help. Someone suggested I check the connections to the ASA selector.


The problems is I don't have anything in my toolbox that I can use to open the top cover. More specifically for the dial and the winder. I could use pointy tweezers for the winder and loosen it, but the dial is another story.The tweezers are simply not powerful enough and they start slipping, so I'm afraid to chip the two small holes. I set the shutter speed to 1/1000 and ASA on 25, as stated on a service manual I found.

Would dividers like these suffice? link to ebay listing

Suggestions for other tools are welcome!

Get a cheap set of small needle nose pliers, and grind the the point sharp enough to fit.

[Viking42]

Hi all. I recieved my first Pentax earlier this week, an MX from ebay. It functions properly, apart from the light meter. It reads over- or underexposure ramdomly. I've tried changing batteries to no help. Someone suggested I check the connections to the ASA selector.


The problems is I don't have anything in my toolbox that I can use to open the top cover. More specifically for the dial and the winder. I could use pointy tweezers for the winder and loosen it, but the dial is another story.The tweezers are simply not powerful enough and they start slipping, so I'm afraid to chip the two small holes. I set the shutter speed to 1/1000 and ASA on 25, as stated on a service manual I found.

Would dividers like these suffice? link to ebay listing

Suggestions for other tools are welcome!

Peter, please let me know how this works out for you. I just bought another MX to have as a 2nd body (I've owned one since about 1983), and it's showing the same behaviour as yours, plus the meter stays on when the shutter button is depressed halfway. I will open it up at some point this week and clean some of the contacts in there...just waiting for the next rainy day :-) I'd be interested to hear what you did to fix yours, if you manage to get it sorted. Likewise, if I get mine working, I will post back and let you know.

Cheers,
Svend

[peter_lille]

Peter, please let me know how this works out for you. I just bought another MX to have as a 2nd body (I've owned one since about 1983), and it's showing the same behaviour as yours, plus the meter stays on when the shutter button is depressed halfway. I will open it up at some point this week and clean some of the contacts in there...just waiting for the next rainy day :-) I'd be interested to hear what you did to fix yours, if you manage to get it sorted. Likewise, if I get mine working, I will post back and let you know.

Cheers,
Svend

Hej, Svend. I'll certainly do. My tools should arrive in 10 days or so. I also had the other issue with the light meter never turning off. I googled my way to a solution. There's a spring connector underneath the camera that needs to be bent back a little. The original site was dead so here's an archived one

Yours may very well be something entirely else, but this is a quick and simply enough solution to try.

[Viking42]

Thanks for the link! Some really good info there. Interesting that the meter-on problem is at the bottom of the camera -- I would have been looking in the wrong place.

It looks like I might get to working on my MX before you do, so I will post back with my results and any tips.

[ProfessorBuzz]

Hi all. I recieved my first Pentax earlier this week, an MX from ebay. It functions properly, apart from the light meter. It reads over- or underexposure ramdomly. I've tried changing batteries to no help.

Most of the thread discussion has been on tools, not on solving the problem


Can you explain "ramdomly" a bit more specifically?

Have you tried metering off a 18% grey card in sunlight, at various apertures to see if the meter reading steps up/down as expected?
Have you tried changing the ASA/ISO and seeing if you get the correct change. e.g. go with slower film speed, so need wider aperture?
Have you put a roll of film in the camera and shot it?
Have you compared the meter to another camera or a known-good light meter?

Have you tried silver-oxide batteries and checked them with a voltmeter before using? Are the battery contacts and cover clean?

[peter_lille]

And we're up! I got impatient last night and sharpened the tweezers further so I could open the dials. The wires were all connected properly and didn't look dirty. There's a flayed piece of metal in the shutter speed dial assembly. It didn't look to be in contact with the dial so I bent it so slightly that it touched it. Now the meters work as intended.


I did lose the spring and ball bearing for the shutter release lock.Those things are small! At first I thought "F it. I won't need it anyway." But the lock swaying back and forth is gonna annoy me I think. So I'm gonna look for a spare body.

[Not a Number]

From the service manual it looks like a 1.2mm ball bearing, which you can find on eBay. You're on your own for a spring although you can make your own from wire.

https://pentax-manuals.com/manuals/service/servicemanuals.htm