[cck]

My Pentax 645n does not seem to power on at all leading me to believe that it is a failed circuit board not being able to supply power to the camera.

Has anyone had troubles like this before or have a fix for it?

I'm at a loss on what to do and how to move forward.

Thanks!

Caleb

[Alex645]

My Pentax 645n does not seem to power on at all leading me to believe that it is a failed circuit board not being able to supply power to the camera.
Has anyone had troubles like this before or have a fix for it?
I'm at a loss on what to do and how to move forward.
Caleb

This has happened to me many times over the decades, and the cause for me has never been a failed circuit board. Things to check:

a) Are you 100% certain the polarity of the AA cells are correct? + and - are correctly oriented in the holder?
b) Do you have a battery tester, volt meter, or multimeter? Test the batteries. Ideally 1.55V or higher.
c) For whatever reasons, my 645N is more reliable with expensive disposable lithium ion cells and less with the other alternatives.
d) After removing the battery holder and batteries, closely check the metal contacts for any corrosion (On the inner and outer surfaces of the holder and in the battery cavity in the camera too.) Clean with rubbing alcohol, cotton swab stick, or if it's really bad, WD-40 and something to scrape off the oxidation before cleaning.
e) Look for small cracks in the plastic battery holder. At a certain point, they will prevent good contact and should be fixed with glue made for plastic. I used a vise or clamp with Loctite 681925-6 Super Glue Plastics Bonding System with Activator, 2-Gram Tubes.
f) IF you have an external battery pack, try that on the 645N.

How long have you had the 645N? When was the last time you used it? Where do you store it?

[cck]

Hey, Thanks for responding!

A. Yes definitely
B. No, I don't but they are definitely new batteries
C. Good to know
D. Yeah the contacts look really clean and maintained.
E. I haven't noticed cracks or anything. It really is a good looking camera
F. I don't have one, unfortunately

I bought it from FB marketplace a year ago and all was working until a few months ago when I literally died on me mid shot. As far as Ive always owned it, it has been stored on my photography shelf with all of my other cameras. It is really a weird situation.
When it died It sounded like failed electronics.

[Alex645]

A. Yes definitely
B. No, I don't but they are definitely new batteries
C. Good to know
D. Yeah the contacts look really clean and maintained.
E. I haven't noticed cracks or anything. It really is a good looking camera
F. I don't have one, unfortunately

I bought it from FB marketplace a year ago and all was working until a few months ago when I literally died on me mid shot.
When it died It sounded like failed electronics.

A bad solder or shorted circuit is a worse case scenario, so I would trouble shoot with the simplest ideas first.

Not 100% of all new batteries are good. I've had bad cells in the past, so I would try again with a new set of six (or buy a volt meter).

Use a really good light source and look at the battery holder very, very carefully. When mine failed, it was a barely noticeable hairline crack, but enough to stretch the holder so that the battery lost contact.

Do you have the false back that you can put on without the film back? I've reset my camera when it died midroll, by putting on the false back and then getting the power issues resolved.

[gofour3]

I know it's a different camera/format, but I had a similar issue with the electronics in my Pentax Super A.

I loaded a new roll of film and turned off the camera before I left for the shoot, all OK. I turned on the camera about an hour later and the camera was brain dead. Shutter would not trip, nothing. I tried everything Alex recommended and nothing worked.

Sent the camera to Eric and it was a dirty contact on/to the circuit board, that just needed a cleaning. The Super A is working fine five years later. Easy fix and no change, but still requires the camera to be opened up and serviced.

Phil.

[cck]

I was able to take the camera in to get it looked at. He Believes that it is a bad circuit board. It might also have a bad power supply. He said it mostly likely is not worth fixing because they don't make the parts for that camera anymore.
It's too bad because the body is in great shape.

Does anyone know about spare parts out there? Here's hoping!

[rdenney]

I was able to take the camera in to get it looked at. He Believes that it is a bad circuit board. It might also have a bad power supply. He said it mostly likely is not worth fixing because they don't make the parts for that camera anymore.
It's too bad because the body is in great shape.

Does anyone know about spare parts out there? Here's hoping!

Make sure Pentax won't repair it.

But at the cost of these, a replacement body, even though it might have its own issues, might be warranted.

Rick "whose 645N flash sync PC-socket doesn't work--oh, well!" Denney

[Alex645]

I was able to take the camera in to get it looked at. He Believes that it is a bad circuit board. It might also have a bad power supply. He said it mostly likely is not worth fixing because they don't make the parts for that camera anymore.
It's too bad because the body is in great shape.

Does anyone know about spare parts out there? Here's hoping!

I doubt that it's both a bad circuit board and power supply. Spare parts will only be coming from another 645N. But at that point, I wouldn't cannibalize a working 645N, which leads to the question, why is the As Is dead one I'm buying dead?

Here are a few leads where you could inquire if they fix a 645N:

KEH probably repairs and cleans more film cameras than just about anyone:
KEH Online Camera Repair | Digital and Film Camera Repairs at KEH Camera

I grew up in San Diego and Kurt's Camera Repair has been around since the mid 70's.
https://www.kurtscamerarepair.com/

There is one film (and vinyl records) shop in my state and they use LeZot's for all their repairs and CLA. LeZot does work on medium format.
Pentax Service - Complete Camera Center

Personally, I'd rather spend half the cost to fix my gear than to pay twice the amount on new used gear with unknown issues.

[cck]

Nice! thanks so much for the resources! Yeah I would love to get the camera fixed! I'll be reaching out to those places, maybe just maybe they have a Pentax 645n circuit board laying around ��

[Alex645]

Nice! thanks so much for the resources! Yeah I would love to get the camera fixed! I'll be reaching out to those places, maybe just maybe they have a Pentax 645n circuit board laying around ��

Yes, if in fact that's the problem. KEH probably gets a lot of dead "as is" cameras that they move to their repair department. I doubt they are so efficient as to disassemble entire cameras and have parts bins everywhere. They probably just store the donor bodies until parts are needed and then operate.

Others operate in similar fashion but because they are more about repair and less about retail of used cameras, there is less traffic and the possibility of having those parts. Please keep us posted as to what you find and how the story ends. Good luck.

[pdraughon]

My 645N also showed low battery. All I did was open the battery compartment and one of the terminals in the compartment was flat against the wall. I used a screwdriver to gently raise it to the level of the other one & now the camera works!

[Eric Auer]

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