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07-15-2019, 07:11 PM - 1 Like   #1
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Pentax 645 Won't Turn On

Hello All. I'm having a problem with my Pentax 645. As the saying goes, no good deed goes unpunished! I had not used this camera in a while and decided to charge up the 6 AA batteries before taking it out for a shoot. As I was replacing the fully recharged batteries, I started to smell something burning and the battery holder got really hot along some of the contacts. Obviously, I had the batteries mounted incorrectly, or something! BTW, I had not put the battery holder into the camera at this point. I immediately removed them. I couldn't see any issue with the holder or the batteries. I reinserted the batteries in the proper orientation and then inserted them into the camera and it won't turn on. As another aside, I had recently (~6 months ago) replaced the internal battery, so I don't think that's an issue. I could see the display light up before removing the AA batteries for charging. So, did I fry the batteries, or did I fry the holder? I sure as heck hope it's not the latter, because I can only find one for sale on ebay and it's from Japan for $75! Any help or critique (aside from letting me know I'm an idiot!) would be helpful. I'm going to see if recharging the batteries will help. Totally frustrated at this point!! Another FYI, I did try cleaning the contacts on the holder with an eraser!


Last edited by photojunkie; 07-15-2019 at 07:20 PM. Reason: Additional information
07-15-2019, 08:53 PM   #2
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Chin up. You still have the camera and most of your wits. Sending good thoughts. c:
07-16-2019, 12:14 AM - 1 Like   #3
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Hi,

I know with my 645n that it will not fire up with rechargeable batteries as there is not enough voltage even if they are fully charged.
I doubt if you would have damaged the battery carrier.
Do you have a multi-meter that you can put something across the two terminals inside the carrier and just check the terminals on the outside for continuity, for starters.
I am more inclined to think that you have a battery problem.

All the best,
Gordon.
07-16-2019, 12:59 AM   #4
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QuoteOriginally posted by gordon_l34 Quote
Hi,

I know with my 645n that it will not fire up with rechargeable batteries as there is not enough voltage even if they are fully charged.
I doubt if you would have damaged the battery carrier.
Do you have a multi-meter that you can put something across the two terminals inside the carrier and just check the terminals on the outside for continuity, for starters.
I am more inclined to think that you have a battery problem.

Gordon.
+1 on Gordon's thoughts. With age, both my 645 and to a lesser degree my 645N are extra sensitive to lower voltage, but since switching to disposable AA lithium cells, they both run well. The 645N Owner's Manual specifically states to only use AA Alkaline or Lithium batteries. Rechargeable batteries just don't have high enough voltage, even when fully charged.

However, I just noticed that in the 645 manual (not 645N) they mention you can use manganese disposable or Ni-Cd rechargeable batteries. Although that my be theoretically correct, I've always used alkaline and as the camera has aged, I find it more reliable with lithium only.


Last edited by Alex645; 07-16-2019 at 09:28 PM. Reason: correction
07-16-2019, 01:01 AM   #5
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The battery holder was in your hands and it got hot, right? Check your battery holder. It shortcuts (if that is a valid verb) somewhere. The heat you're feeling is from a high current due to the shortcut.
07-16-2019, 07:14 AM   #6
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QuoteOriginally posted by Alex645 Quote
+1 on Gordon's thoughts. With age, both my 645 and to a lesser degree my 645N are extra sensitive to lower voltage, but since switching to disposable AA lithium cells, they both run well. The 645N Owner's Manual specifically states to only use AA Alkaline or Lithium batteries. Rechargeable batteries just don't have high enough voltage, even when fully charged.
Thanks to both of you for the suggestion regarding the battery. I just inserted some fresh alkaline batteries and still no go. Nothing even on the screen. Unfortunately, I don't have any kind of meter to see if I'm getting juice from the grip to the camera. The other odd thing here is that as soon as I removed the battery grip, the LED screen went blank. I don't know if that was supposed to happen or not. I think I just have a fairly expensive paperweight at this point!
07-16-2019, 12:33 PM   #7
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I'd recommend you get a multimeter to check both continuity (on the battery pack) and the actual voltage on the batteries you're using. Process of elimination. Short circuiting those batteries could have damaged the holder. Not sure why your LED screen is blank if you had a new internal put in recently. Also, your paperweight does have a manual advance feature which I've used to shoot all manual with manual advancing. It's slow, it's cumbersome, there's only one shutter speed (1/50"), but it's better than a brick.

http://www.cameramanuals.org/pentax_pdf/pentax_645.pdf

Last edited by Alex645; 07-16-2019 at 07:03 PM.
07-16-2019, 04:55 PM   #8
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Hi,

I go along fully with the above post from Alex645 as I do not believe that there is a fault in the camera at this point in time.

Regards,
Gordon.

07-16-2019, 07:38 PM   #9
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Thanks to all for these suggestions. I'll see if I can't locate a meter to check out the voltage. The really odd thing about this is that the LCD screen is blank. That's supposed to be powered by the internal battery. To be sure about this, I also replaced that today as well, and still no dice. If it was just the batteries in the grip, the LCD should still display something and it's just a total blank. Is there any way to "reset" the entire system?
07-16-2019, 09:44 PM   #10
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QuoteOriginally posted by photojunkie Quote
Thanks to all for these suggestions. I'll see if I can't locate a meter to check out the voltage. The really odd thing about this is that the LCD screen is blank. That's supposed to be powered by the internal battery. To be sure about this, I also replaced that today as well, and still no dice. If it was just the batteries in the grip, the LCD should still display something and it's just a total blank. Is there any way to "reset" the entire system?
The 645 has a lot of electronics and is also an 'old' camera that's been around for decades. It's finicky, especially when left dormant. For example, mine hates sudden temperature and humidity changes.

I do not know of any reset options other than taking all the power out and then reinserting the lithium internal and the battery grip. Maybe once I was able to kick start mine by shooting with manual advance. Your first issue to address is power. Brand new or almost new doesn't matter: one bad AA cell in the group? A short in the grip or bad contact where it connects to the body? Before you look into other solutions, you have to make sure (with a volt meter or multimeter) that you're getting at least 1.5V per battery. Then you want to check that the entire grip is feeding the camera 1.5V x 6 = 9 volts. Might as well check that your CR1220 is outputting at least 3 volts.

After all that is checked, then we can all have darker thoughts that your reversed polarity fried something in the camera. Page 7 in the owner's manual does warn that incorrect polarity can cause damage "to your equipment". For now, think positive unless you can actually smell a new odor; something burned coming from the camera.
07-17-2019, 06:32 PM   #11
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Again, thanks to all (especially Alex645) for the suggestions. I'm convinced that it's the battery holder. I didn't gauge each battery, but I've put them in other devices and those work just fine. It has to be the holder. I didn't have the batteries installed when I smelled that odd odor and I actually was holding the battery holder when I felt it get really hot. I must have fried something in the connections. I've looked at it pretty intensively and I can't see anything obvious, but, by the process of elimination, it just has to be that piece. The bad news is that i can't find one for sale anywhere. I've looked for 645s for sale for parts, and just about all of them have some issue with the battery holder (corrosion, cracked, etc.). I'll keep looking. If anyone on this forum has any insight as to where I might find one, just let me know. I really like that camera and I'll probably look for another if I can't find a part soon. This group has been very patient and helpful. I really appreciate the comments and input.
07-17-2019, 09:49 PM - 1 Like   #12
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QuoteOriginally posted by photojunkie Quote
I can only find one for sale on ebay and it's from Japan for $75!
The Achilles Heel of the 645 is that holder and if you can get one in good condition for $75, it's worth it. Not sure if Achilles' Heel is the right term as mine lasted at least 25 years before the plastic started to suffer.

On this forum, there is a map that shows where all the members are (if they chose to disclose it) and if you do a bit of research, you may find another 645 owner not too far from you. You can PM them and see if they are willing to meet up so you can try a good battery holder in your camera.
07-18-2019, 01:52 AM   #13
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The big problem with Alkaline batteries in cameras is that the voltage decreases steadily while the batteries discharge. Other types of battery maintain a more consistent voltage until they are almost exhausted. So while alkalines may hold more power than most other types, they are not the most suitable for high-drain devices.
07-19-2019, 11:37 AM - 1 Like   #14
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QuoteOriginally posted by Alex645 Quote
The Achilles Heel of the 645 is that holder and if you can get one in good condition for $75, it's worth it. Not sure if Achilles' Heel is the right term as mine lasted at least 25 years before the plastic started to suffer.

On this forum, there is a map that shows where all the members are (if they chose to disclose it) and if you do a bit of research, you may find another 645 owner not too far from you. You can PM them and see if they are willing to meet up so you can try a good battery holder in your camera.
Just to close the loop on this, I have discovered that my battery tray is the culprit. I was able to find a used 645 in very good condition (sans lens) for ~$160. When I loaded the batteries into that tray and placed it in my current 645..........voila! It turned on. Now all I need to do is to find another battery tray for my 645 and I'll have 2 fully functioning bodies. If anyone has ideas or suggestions for locating the tray or has an idea for swapping something, let me know.
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