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Forum: Pentax K-30 & K-50
11-03-2017, 04:12 AM
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My K-50 suddenly started suffering from dark frames few weeks ago.
I gathered couple old laptop CD/DVD drives in hope I will be able to devour solenoid from one of these.
I have removed bottom and front cover from my camera and located faulty solenoid (as per instruction from first page. No need to remove top cover). Now having clear view on failed part I opened first DVD-ROM drive disc tray, and behold, solenoid used in tray opening mechanism was almost identical to the one in camera. One difference I have notices is that magnet used in DVD drive solenoid is slightly (1mm) higher than the one in the camera but all external/important dimensions were the same.
Using small scissors I cut ribbon cable solenoid in DVD drive was soldered to and gently removed it from enclosure, making sure I do not break tiny wires. Now using precise soldering iron and ‘third hand’ I desoldered what was left of ribbon cable.
Now back to camera. Desoldered two wires going to solenoid, unscrew it and removed from camera. Put new solenoid in its place and solder the wires to it. I have put both covers temporarily back on and tested camera. It was not working any better. After some deliberation I flipped little magnet in solenoid upside down. And camera spring back to life. I have make about hundred test photos since. All well exposed.
HINT ON SOLDERING: Before soldering make sure wires are wetted with solder and put some soldering flux on both soldered parts
HINT TO HINT: if you do not have soldering flux at hand you can use some clear alcohol (Polish vodka is the best and has so many more uses :-) )
Internal resistance (measured using cheap Chinese multi-meter) of both parts :
- Original green Pentax solenoid: 14 ohm
- DVD ripped solenoid: 26 ohm
Btw. I do not recommend soldering wires midway as this is actually more difficult to do and involves way more solder and heat.
Tools I have used:
- precise screwdrivers set (B&Q 6GBP) with proper size handles
Do not use those small all metal chinese made 'precise' screwdrivers.
Those have small handles and are usually made with some soft steel.
- precise soldering iron set (includes some solder with flux, precise pliers) (Amazon 17GBP)
Either but proper soldering iron or do not buy it at all.
Soldering station available from German shop starting with 'L' won't do as it doesn't have right tip.
Soldering irons available in diy shop do not allow for temperature control and don't have right tip.
- soldering flux (Amazon ~2GBP)
- small scissors (wife)
- third hand (Amazon)
Good luck.
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