Mamiya 645 Battery Question

<p>I am on vacation with a PX-28 of unknown vintage in a Mamiya 645 1000S. When I checked the camera last night the shutter fired and the PD-S finder worked. Now the shutter will still fire but the PD-S finder will not show any lit diodes. I have set the shutter speed to the same number on both dials. It's sunny so metering is not a big problem but I have a separate meter with me anyway. Should I be concerned that the PD-S finder doesn't seem to be working or is this just a sign the battery is barely alive? If the shutter stops firing or if I can't find a new PX-28 locally then I have a Canon FTbN with four lenses to fall back on.</p>

<p>Set the shutter speed dial on the body to the little * setting, between B and 1000.<br>

With the PDS Prism you adjust the shutter speed with the PDS Prism while leaving the body dial set at *.</p>

<p>I believe if you do not set the body dial to * you will not get any lights in the finder; at least that is what it does on mine.</p>

 

<p>I second that: The red dot-setting enables power to the PD-S prism. Without it all is dead and timing is via the knob on the left side of the camera body. With a powered prism it takes control of the shutter.</p>

<p>I had tried that before and it didn't work. I tried it again now and the green LED lit up but when I changed the aperture or the shutter speed on the finder, the green light stayed on. I think there is a CVS in town so I will look for a PX-28. If I don't find a PX-28 can I substitute four MS-76s? </p>

<p>Try cleaning the contacts on the prism and matching onesown the body with a pencil eraser.<br>

Use the silver version of the PX28 as the alkaline version voltages drops differently.</p>

<p>CVS was a bust. No PX-28 and no MS-76s. I picked up some pencils with erasers because I thought about cleaning the contacts. I also got a pack of 357 Zinc-Air hearing aid batteries and some aluminum foil. The 357 Zinc-Air batteries have a nominal voltage of 1.4 so four of them in series might work for a little while. The foil would be for making up any space if that is needed. Tomorrow I will go to the nearest Radio Shack which is about 5 miles from here. I should have taken my 645J with a plain prism finder. The 645J was just overhauled. I wanted the higher top shutter speed of the 1000S because I am testing out a 210/4 which I just got. </p>

<p>Is the an ACE hardware near you, they usually have PX-28s.<br>

JD</p>

<p>Here's where I am now. I cleaned everythng wth a pencil eraser and I still had the same problem. The green LED lights up but the meter does not respong to changes in the light level. I opened four Rayovac 675 Zinc-Air batteries and put them in the battery chamber. These batteries are rated at 1.45 volts (they are marked 1.45 volts). As I suspected, some space was left over. I filled the space with aluminum foil. The meter problem is the same. I turned the body shutter speed dial to the red dot and varied the speed on the finder's shutter speed dial. The speeds sound right. If the Zinc-Air batteries can last the week I can meter separately. Tomorrow I will see whether Ace Hardware or Radio Shack is closer so I can find a PX-28 and maybe also some MS-76s. <br>

Taking old cameras on vacation is like driving a classic car on a vacation. In both cases you know something might go wrong but if you didn't think you would enjoy the experience you wouldn't try it. Tomorrow I'll load up the Canon FTbN.</p>

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<p>I turned the body shutter speed dial to the red dot and varied the speed on the finder's shutter speed dial. The speeds sound right.</p>

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<p>I'm a little unclear as to what the status of your problem is now. Is the problem now that the PDS finder does correctly control/fire the shutter at different speeds; but the LED metering display doesn't react to changes in the shutter speed that you make on the PDS finder's dial? </p>

<p>BTW, check that the aperture coupling lug on the lens has "caught" the sprung pin on front of the PDS prism. If it hasn't, that could explain why adjusting the lens aperture had no effect on the meter.</p>

<p>Regarding the battery: silver ones do last (even) longer than alkalines, but I've never had a problem with an alkaline in my M645 1000s bodies.</p>

<p>I got to Radio Shack this morning and bought two PX28As. I removed the Zinc-Air batteries and the aluminum foil spacer and put in the PX28A. The diodes/meter seem fine now. It seems that when the voltage is too low the shutter w still fire but the LEDs will not light up correctly. From now on when I take a Mamiya M645 anywhere I will take a least one PX28 as a spare. I know that a silver oxide battery lasts longer and can work better in cold weather. Can I also use a lithium PX28? The local Ace Hardware store did not have any PX28s. I will keep the dog collar connection in mind for the future. </p>

<p>Glad to hear that everything is now working as it should!</p>

<p>I haven't tried a lithium PX28, but I'm sure it would work very well. I greatly prefer Energizer Ultimate Lithium AAs to alkaline AAs in my Mamiya 645AFD - much lighter (the camera needs 6 of them, so the weight adds up) and much longer lasting. Now for a single small PX28, the weight difference would be pretty negligible, but the long lifetime might be worth considering.<br>

Do keep a spare on you though - I find that when Lithium batteries run out of juice, they do so rather abruptly.</p>

<p>I recently added this on another discussion, it is appropriate here too, I think. Long live blog & thread posterity.</p>

<p>Just FYI...<br>

The lithium and alkaline versions (PX28L and PX28A, respectively) are listed as 6.0 volts nominally (new).<br>

The silver oxide version (PX28S) is listed as 6.2 volts nominally (new).<br>

The lithium is also called - 2CR1/3N, L544, L544BP, V28PXL, K28L, 2CR11108, 2CR1/3H, CR28L, 1406LC.<br>

The alkaline is also called - 4LR44, A544, K28A, V34PX, 7H34, 4NZ13, V4034PX, 4034PX, PX28AB, 1414A.<br>

The silver oxide is also called - PX-28, 4SR44, 4G13, 4SG13, 28PX, 544, KS28, V28, V28PX.</p>

<p>Argh ... gotta luv it! :o)<br>

Jim M.</p>

<p>Great info Jim; thanks for publishing it here.</p>

I have a question on the 645 Pro. (sorry if this is M645 topic, but the batteries mentioned above seems to be similar).

 

Do you still need the teeny battery in the body when you attached the power winder 401? Does the winder only power the

wind motor, or does it also supply power for the meter and shutter circuits?

 

Also how many rolls of film for one set of 4LR44 batteries? Doesn't seem to have this info in the manual.