Right. I enquired because when Pentax made the original 645 they included a big booby trap that can render the camera non-functional if it is incorrectly handled. More below.
I just pulled out my 645 to compare
well - after a few years of no use, there's something up with my camera
there's no BC as far as I know, there is a tiny window under the ME winder on the side that will show red if the shutter is cocked and mirror down
there's also a manual wind port on the side , you detach a knob from the bottom and attach to the side to manually wind/ cock the shutter - the battery can die and leave the mirror up or shutter not cocked.
in my case the LCD is lit when off, when I turn the power switch on and touch the shutter, the LCD blanks and nothing happens.
there also an internal CR1220 battery that stores the settings when the AA batteries are out or detached. mine apparently needs to be replaced, but I'm not sure that would prevent the shutter from firing...
good luck
I acquired an original 645 a few years ago. It was a freebie, which was good, because nothing came of it.
The owners manual mentions the presence of the two battery systems: the AAs in the grip, and the memory battery under the hatch in the bottom of the body. If the memory battery needs to be changed, they instruct you to take it to a service centre.
I wasn't going to do that when I got mine. How hard could it be to change a battery, right? Well, not very hard, at all, actually. But...
I replaced the memory cell easily enough. But afterwards the camera wouldn't function. The reason why wasn't easy to find, but after a fair bit of googling I found some leads via photonet.
Here is one relevant thread. Note, please, the second post particularly.
The memory chip used by Pentax to store the software for the camera functions has to be powered, either by the lithium cell or the AA cells in the grip. If it is de-powered, it's wiped, and your 645 will become a paperweight. This is why the manual advises taking the camera to "an authorized Pentax service facility" for replacement of the memory battery.
Maybe Pentax agents can still reprogram your 645 for you (or maybe they can't, so many years after manufacture). In my case I didn't look into it, but I wouldn't assume it's possible without first investigating. If you do happen to follow it up, though, I'd be curious as to how you get on, just for future reference.
Given the age of these bodies I'd not be at all surprised if some of them are non-functional. If your 645 won't respond to activation of the control buttons etc. even with fresh AAs installed, this
might be why. I'm not suggesting that this
is the case for either of the original 645 owners who have posted above, but merely mentioning this issue for their information and to caution them.
It is possible to replace the memory battery yourself but it is critical—repeat—critical, that the body is powered up with fresh AAs in the grip and the power switch is turned "ON", prior to removing the memory cell. Doing this will power the chip directly from the AA main power supply, during the process of removing and replacing the CR1220. (See this thread at MFLenses Forum for reference to the importance of the switch position).
In my case I was not aware of the significance of this. I removed the memory cell to replace it. Whether I: simply didn't have any batteries in the grip; didn't have the power switch set to ON, or; had no AAs installed with the switch set to "ON"; the bottom line is I wiped all the programming (we are going back a few years, now, hence my inability to be specific). It was only after the camera wouldn't function that I eventually worked out what I'd done.
I have read of a couple of owners who actually had all batteries (AAs and lithium cell) removed simultaneously and replaced them without incident. So I suspect the circuit includes a capacitor that stores a limited amount of power from the batteries. Perhaps their capacitors stored enough juice during the period there was no battery supply connected, and they simply didn't turn the main power switch on, and, thus, avoided tapping the capacitor? Maybe their capacitors were simply in better condition that other owners'? I don't know—I am not an expert on the Pentax 645 circuitry—I'm simply describing my experience with one. I suspect that I may have had both battery types removed with the power switch "ON", exhausted the capacitor, and de-powered the memory. In any case, it was fatal to this older model camera that I had zero interest in getting professionally serviced.
It was an annoying lesson, but being a 645 camera (not a format I've ever really clicked with) and not having a mirror lock up or pre-release, the 645 wasn't a camera that greatly appealed to me even though, in general, I rate Pentax products highly. I scored it in a box of sick or dead bodies and lenses, so it was a challenge to try and get it working again. One which, obviously, I failed dismally! I'm sure the SMC-A 80mm f/2.8 Pentax lens it came with would have been an excellent performer, and I certainly would have run a roll or two through it had I got it going, but would have then moved it on. Ah well.
Please note the lesson I learned the hard way, lest you inadvertently repeat it. If you do change the lithium cell, keep the power switch "ON", ensure the grip is correctly attached, feeding power from the AAs to the body, and then, take great care not to bump the switch to "OFF" during the replacement process. And if you bugger your 645, please do not blame me—all care taken, but no responsibility accepted, etc—I'm simply passing on this information for your attention as it seems an easy trap to fall into. 😉
Cheers,
Brett
