[klh]

My K-3 had a failure of the light meter, but everything else appears to be working. I sent in to Precision for repair, and they reported that the top seal failed and water had corroded the main flex circuit and cpu, finder lcd, and photo sensor block.

Read more at: Repair K-3 Silver or buy a K-3ii? (or upgrade to K-1?) - PentaxForums.com.

The $700 cost was more than I could justify, so I had them return it unrepaired. The camera still works, but only in manual mode since the light meter registers zero.

My curiousity got the better of me, and I took the top cover off to take a look. I don't see any obvious signs of corrosion, but I do see five wires that are loose from their solder spots. It is possible that they came loose when I took the cover off. They do not appear to have been very well soldered.

Two (black and yellow) at the top of the prism. Three (orange, purple, and green) under the mode dial.

Does anyone have a clear photo showing these wires so I know where to resolder them? I would like to see if by lucky chance that might fix the camera.

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Last edited by klh; 10-11-2018 at 10:06 AM.

[Adam]

I'd be willing to bet those wires simply came loose due to poor soldering at the time of manufacture. Hopefully someone is able to help you out with a photo!

By the way, I've long been wondering why DSLRs look so archaic/messy on the inside. If you open up a 30 year old Super Program, the wiring is not far removed for what we're seeing here.

[sqrrl]

My take on it is because they tend to be assembled by hand, the slack in the wires gives the technician space to move things around, makes it easier to service also. On cheaper cameras everything just typically clicks together.

[sungibr]

Not a picture, but this might help a little:

You Tube

You Tube

[klh]

I'm not being a wise guy but I haven't used a camera meter in about 9 years. And though I do have a hand held meter ( two actually - one for flash) I rarely use either. I use Sunny 16 as an anchor and guess- timate the Light or Exposure Value. Depending on what I want with motion & depth of field, all I have to know is how may stops I need from EV 15 (I always assume ISO 100).

Thanks Brooke. I learned the Sunny 16 method on my dad's Argus C3, and still use it when the need arises.

I'd be willing to bet those wires simply came loose due to poor soldering at the time of manufacture. Hopefully someone is able to help you out with a photo!

It does appear that the soldering was very poorly done. I wonder if water getting inside could have caused one of the wires to come loose, and the others did when I pulled the lid. I can't know for sure, but I wonder if Precision even opened the camera. I also noticed the foam gasket on the left is folded over which could be how water entered.

Not a picture, but this might help a little:

How to exchange Top cover unit - Pentax DSLR K-3 - YouTube

Very helpful, thanks. It looks like the prism wiring is black to the front, then yellow, then blue and white. Unfortunately I haven't been able to quite see enough detail to be sure of the wiring under the mode dial yet, so I could still use a good photo. I may have to open up my other K-3, but I hesitate to put that one at risk.

[Blue]

On cheaper cameras everything just typically clicks together.

That may hold true on cheap off brands like Nikon and Canon. That isn't going to get it on Pentax as they have been the leader in weather sealed bodies for a long time and set the pace.

[Not a Number]

You could always buy the service parts list. These contain the wiring distribution schematics.

Pentax K-3 Parts List Download USCamera imaging parts listsUSCamera

[klh]

You could always buy the service parts list. These contain the wiring distribution schematics.

Pentax K-3 Parts List Download USCamera imaging parts listsUSCamera

Thanks. I did buy the parts list and the wiring diagram was exactly what I needed.

I also contacted DiGi Service who made the video of replacing a K-3 top and he kindly supplied some photos of the operation which gives me confidence I can resolder it correctly.

Now all I need is a little free time.

[CarMan]

Sorry for late reply, i hope these pics could be still helpful, good luck!

[klh]

Sorry for late reply, i hope these pics could be still helpful, good luck!

Those are brilliant, thanks! That's the exact view I needed to confirm the locations of each wire. I will let you know how it goes.

[Jathys]

This is scary exciting. Hope it works out for you. Still can't believe you hacked open the camera

Anyway, if it doesn't work, keep in mind that there are apps that can essentially turn your phone into a halfway decent light meter to get you a bit closer to the correct exposure on the first attempt.

[LaurenOE]

I'd be willing to bet those wires simply came loose due to poor soldering at the time of manufacture. Hopefully someone is able to help you out with a photo!

By the way, I've long been wondering why DSLRs look so archaic/messy on the inside. If you open up a 30 year old Super Program, the wiring is not far removed for what we're seeing here.

Yep...and THIS is why the K3 replacement is taking so long. Ricoh doesn't make camera internals like that anymore...no one does. Our Pentax cameras have been way too "analog" and it's probably giving Ricoh fits to engineer current standard components.

L.

[klh]

With all the excellent help (thank you!), I was able to resolder the six loose wires properly. Unfortunately, after reassembly the camera still has no signal from the light meter, but all else is working.

My theory is that the wires came loose as I opened the top cover due to poor soldering at the factory combined with my clumsy fingers. I was pretty careful, but that's the only thing that makes sense.

I'm guessing that moisture somehow shorted out the light meter (which I believe is on part J500 "4WDKJ503 photo sensor block assembly"). It was a gradual process as the photos that day become more overexposed over time, and by the next day the light meter showed nothing. I don't know if that means the short can be reversed. If I could figure out how it shorted, it is possible I could correct it. According to the schematics, there is a single connector from J500 to the main circuit board T100, which I may try unplugging, cleaning, and reconnecting if I can get to it easily.

I notice that the LCD display in the viewfinder looks very dim. I suspect that it is designed to adjust brightness based on the reading from the light meter, so I don't think there is anything wrong with that module (O100 "Finder LCD block"). Since everything else on the camera is working, I hope the main circuit board is ok too.

[Not a Number]

My theory is that the wires came loose as I opened the top cover due to poor soldering at the factory combined with my clumsy fingers. I was pretty careful, but that's the only thing that makes sense.

I'm guessing that moisture somehow shorted out the light meter (which I believe is on part J500 "4WDKJ503 photo sensor block assembly"). It was a gradual process as the photos that day become more overexposed over time, and by the next day the light meter showed nothing. I don't know if that means the short can be reversed. If I could figure out how it shorted, it is possible I could correct it. According to the schematics, there is a single connector from J500 to the main circuit board T100, which I may try unplugging, cleaning, and reconnecting if I can get to it easily.

It's also possible Precision un-soldered the connections during testing and did a poor job re-soldering them when the repair job was flagged "no-go" by you.

Removing a short circuit won't undo any component damage that may have occurred . You can try though.

[SamirShah]

Old thread, but did this K3 ever get fixed?