MX woes


george_in_georgia

Link Posted 05/05/2019 - 03:24
I have three MXs. One I bought used over 20 years ago, and a really rough example bought for parts (perhaps) and a lovely black example. The oldest worked well for many years until it started eating cells, a set every one month or so. Before cell life was over a year. A local supposedly good shop worked on it - I told them to keep it long enough (a month or so) to see if they'd found the problem, no joy. The Black Beauty has the same problem. I've removed the base plates to check the wind lever switch, it does interrupt the circuit. Yes, I used a digital VOM. I guess a trip to Eric in Tennessee is the next step, perhaps send all three with the rough one as a donor for Eric's use.
BTW, for those contemplating the winder, be careful with the little toothed wheel securing the battery compartment cover. From what I can see it would be all to easy to strip the threads in the winder body, or lose the tiny cover itself. Bad design by Pentax, IMHO.
I like the MX. It is fast to use (although the stiff shutter dial is a downer) and the meter is visible in bad light. With a fast 50 or wide angle and the winder it is a fine street camera, but I'd like the meter to work more than a few weeks.

JAK

Link Posted 05/05/2019 - 13:43
Which cells are you using? Some of the older cells used mercury which is now banned due to environmental issues and many of the current equivalent alkaline LR44 or AG13 simply aren't as efficient. Try sourcing some better batteries for it (eg silver oxide versions.)
John K
Last Edited by JAK on 05/05/2019 - 13:50

Jonathan-Mac

Link Posted 05/05/2019 - 15:13
Alkaline batteries are by far the most common but they don't maintain their voltage over their lifespan - voltage decreases steadily (which is why alkaline AAs are poor in the older Pentax DSLRs which can take AAs). Silver oxides are harder to find and much more expensive, but work far better.
Pentax hybrid user - Digital K3 & K200D, film 645 and 35mm SLR and Pentax (&other) lenses adapted to Fuji X digital
Fan of DA limited and old manual lenses

george_in_georgia

Link Posted 05/05/2019 - 15:47
JAK wrote:
Which cells are you using? Some of the older cells used mercury which is now banned due to environmental issues and many of the current equivalent alkaline LR44 or AG13 simply aren't as efficient. Try sourcing some better batteries for it (eg silver oxide versions.)

The MX never required mercury cells, IIRC; indeed the Spotmatics will work fine with silver oxide cells if they physically fit, since the Spotties use a bridge circuit metering system, which is tolerant of voltage variations. I've always used silver oxide because of their longer life.

johnriley

Link Posted 05/05/2019 - 16:46
The silver oxide G13 cell is the one to use for the MX - it takes two of them. Lithium cells should not be used, even if they fit. Not sure why, but that was put in the instructions of later MX cameras when lithium started to appear.
Best regards, John

george_in_georgia

Link Posted 05/05/2019 - 16:52
johnriley wrote:
The silver oxide G13 cell is the one to use for the MX - it takes two of them. Lithium cells should not be used, even if they fit. Not sure why, but that was put in the instructions of later MX cameras when lithium started to appear.

Thanks for that info! Being a cheapskate I wouldn't consider them because of the cost, but now I have justification.

barkin

Link Posted 05/05/2019 - 18:15
johnriley wrote:
Lithium cells should not be used, even if they fit. Not sure why

Lithium cells are 3V, rather than the 1.5/1.6V of alkaline/silver oxide cells.

Algernon

Link Posted 05/05/2019 - 18:34
The Lithium cells came in as a cheap alternative to silver when it shot up in price in the late 70's. One cell was equivalent in size to two G13's stacked on top of one another.

There was also a 6v version for Canons that replaced 4 x G13

They should be cheap to buy, but the makers later decided to charge higher than the silvers.

--
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

johnha

Link Posted 06/05/2019 - 10:28
Doesn't help that most SR44's advertised online are actually LR44's. Only a few specialist suppliers seem to get it right.
PPG Flickr

Algernon

Link Posted 06/05/2019 - 11:04
I always buy the Swiss made Renata 357 (SR44W)
https://www.renata.com/industrial-products/silver-oxide-coin-cells/

Most jewellers sell Renata, but will be expensive in the shops.

I used to buy them from a jeweller on ebay in boxes of 10, but they don't have anything listed at present..... hope it's just holidays.

--
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

doingthebobs

Link Posted 06/05/2019 - 20:40
Lots of SR44 silver oxide batteries available.

Amazon uk https://www.amazon.co.uk/Energizer-Silver-Oxide-Button-Battery/dp/B000IX2GXI 3.34 for two inc post. lots of other sellers on there.

lots of other suppliers are available if you search.
Bob

JAK

Link Posted 06/05/2019 - 23:14
Don't forget the person asking is from Georgia!
John K
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