This camera was originally released in 1976 as an up-market lightweight manual camera for the commercial market. The camera was at the time the smallest and lightest SLR on sale. (Until the ME, released a little later that year!)
The design incorporates a mechanically timed cloth horizontal-run shutter, with three colour LED TTL exposure meter using five LEDs, with shutter speed, and aperture displayed in the viewfinder, depth-of-field preview.
What follows is the basic disassembly of the camera into it's major sub-assemblies. The camera illustrated had been used in South Africa for about ten years. (Or so I was told.) The heat and dust had taken it's toll, and it simply did not work. These usually respons well to camera repair, but this seemd much worse than generally encountered, and I had to disassemble further than I would normally have to in order to clean all the parts thoroughly.
I picked it up for the price of the lens, but after stripping, cleaning, and reassembly, bench testing showed perfect shutter timing, and the meter calibration was bang on. Not at all bad!
I'm not going to show all the fine details of that. It's all a bit too much to take in at one go, and I suspect that you won't have to go that far in any case to sort any problems with your own camera.
Disassembly.
Before starting, make sure that you have provided yourself with a notebook and a pencil. There are a number of variants of the internal wiring, and these may not correspond with the camera shown here.
Also, make sure that you have a tray for small parts, and be prepared to spend several hours on the job.
If during the procedure after releasing a part it is stiff, or difficult to remove, stop and check that all the screws, wires etc' have been removed. Remember the golden camera repair rule: Never try forcing a part, you risk permanent damage if you do.
If you start to get tired, stop and come back to the job. You will make mistakes that you will regret later, and you are much more likely to lose your temper with stubborn fixings if you allow yourself to get too tired. (I am speaking from experience here!)
Also, it is likely that your camera has not been disassembled for servicing since it first left the factory. If this is indeed the case, all the internal light seals will probably require replacement. As this disassembly will expose all of the seals these should be replaced at this time. Deterioration of the seals will not only increase the risk of film fogging, but they actually fall apart and crumble.
The resulting particles consists of a sticky black goo which gets into the viewfinder and shutter, it is difficult to clean off and corrosive. If you have paint flaking off the film door margins, the cause is the door seals dissolving the paint! If it gets onto the focusing screen, the only way to get it off is to use an ultrasonic cleaning bath. Don't be tempted to try solvents. (Some household bleaches can be useful for breaking up the goo deposit, but unless you are sure.... ) That will completely ruin the screen! Small ultrasonic cleaners can be bought for less than £100 these days, or you could take it to your local jewelers who will probably have one and perhaps could clean it for you.
Suitable seal kits can be had from a number of internet camera repair vendors, and are not expensive. Shop around for the most comprehensive, a wide range of types and thickness of material may be encountered in a single camera.
Procedure.
Before starting any disassembly it's as well to get an idea of what might need doing, and if there is anything in particular to watch out for.
The mirror cushion shown here has deteriorated, which is indicates that the internal seals are in poor condition, and so I know that I'm going to have to strip out the main assemblies to access those.
A fair bit of brassing here. This just shows that the camera has been used a lot. Examination of the lower part of the case showed very little brassing. That suggests that it was kept in it's leather case a lot of the time. In my experience the two factors of lot's of use, and in the case most of the time suggest a one time cherished possession. Which is a good sign!
It's also worthwhile examining screw heads under a magnifying glass. These collect a good sample of much of the muck that the camera may have been exposed to. (I just stripped a K1000 that had been dunked in a good strong cup of very sweet coffee. Once dried that really jammed it up good!) This one was well bunged up with caked dust. To make sure that your screwdriver gets a good purchase you want to clean any muck out before attempting removal. It also can show if the camera has had any clumsy maintenance!
In this case I removed the bottom cover before I started, as I already new the camera needed a good internal clean, and a quick squirt of lighter fluid freed the shutter to the point of allowing shutter release albeit with crazy shutter speeds, and squealing noises!
We'll start by removing the film-advance lever. This is easier on this camera than others in the Pentax range, as there are holes in the cap. Beware though, this is a left handed screw. So make sure you don't break it by turning it the wrong way!
You can also see some of the fine dust still adhering to the outside of the camera.
The advance lever is retained only by the cap in this model. (The shiny round object in the foreground is a blob of solder, not a part of the camera!)
Then remove the collar shown.
Next remove the selector. This can be done with the improvised tool described elsewhere. The Pentax service manual recommends setting the speed to 1/1000, and selecting 100 ISO for reference.
Take care that you don't lose the film selector locking stud. Take careful note also of how it fits into the selector assembly.
The position of the selector coupling, and potentiometer should be noted.
And remove the trim collar.
The selector parts removed.
To remove the rewind knob, lock the rewind shaft with a screwdriver.
Once the rewinder is removed you can remove the retaining bush.
(You might want to unclip the film-door at this point. If the winder drops into the body opening the back will be quite difficult.)
The top cover should lift off easily now.
With the top removed, take a good look around. You will need to be sure you have a good idea where everything goes, especially the wires. (You can't test-fit these to see if you have it right!)
Note the large foam seal here. This is only just holding together, and will soon become crumbly, and disintegrate. If you can imagine how much particulate muck this will generate, you just about got the reason why we need to check these out!)
This seal will be replaced with new material once we have cleaned is all up!(Back to top)
The leatherette trim should now be removed. To do this first remove the self timer lever. First the screw cap should be removed.
Then the Leatherette can be carefully peeled off. Start the edges with a dental probe.
Note the metal plate beneath the right hand side.
This covers the shutter release adjustments. It's a good idea to leave this well alone for the time being.
The bottom cover is retained by three screws.
Don't lose this plastic bit. All that keeps it in place is the bottom cover.
Take a minute or two to explore.
Note especially the location of all the springs.
If you're thinking that this all looks a bit complicated, you're right.
The reason is that unlike the older Spotmatic and K' cameras, a good part of the shutter mechanism is under the bottom cover.
The low-speed cams, and escapement are all accessible from under this cover, as well as the mirror priming gear.
If you are having problems at low shutter speeds, often a good washing out of this lot with lighter fluid or similar solvent, and lubricating with a couple of drops of shutter or watch oil will fix it.
(Always use as little oil as you can. Apart from it being a bit on the expensive side(!), too much oil causes problems elsewhere. It isn't total immersion lubrication system!)
With the top, bottom covers, and the leatherette out of the way the front standard can be removed
Try not to disturb these washers, or at least get them mixed up. These are used to set the lens registration distance essential for accurate focusing, and they are not all the same.
Check that there are no washers stuck underneath the standard.
The easiest way to avoid losing these washers (and indeed the screws themselves) is like this!
Now you want to remove the electronics.
Start by removing the speed-resistor.
Unsolder both the brown wires, and remove the two screws holding it to the speed selector assembly.
The resistor removed.
Unsolder any other wires connecting the to the board from the camera. Be sure to record the location of each wire. The pictures shown here may not correspond exactly to your own camera!
With the wires disconnected proceed by loosening the clamp screw, and remove the screw securing the LED PCB.
The hot-shoe contacts should be removed to free the photocell board.
Once this is done you should be able to remove the meter board.
If you haven't already done so, remove the focusing screen before proceeding. Keep it somewhere safe.
It will be easier also it the prism and associated parts are removed at this stage.
This is most easily achieved by loosening one of the set-screws at one side of the prism. Leave the other in place as a reference.
Alternatively removing the two screws holding the viewfinder lens will allow removal of the viewfinder frame complete.
Do not disturb the small set screws fixed with lacquer, or glue unless you want to spend the rest of the day setting the screen focusing up again!
In order to remove the mirror cage, you will have to disconnect some more wires, and remove the transfer gear that operates the shutter speed indicator dial.(You will have a jolly time setting this up again, so it's worth considering wether you really need to remove the cage at all!)
The cage itself is secured by two screws accessed from underneath.
Before lifting the mirror cage out, check that all the wires are disconnected, also check that the mechanical linkages are free. This usually means that the shutter should be charged before removing the cage.
with the cage removed it's easy to see how the mirror mechanism works.
Servicing the cage is simply a matter of cleaning away all the old oil and grease, and replacing any corroded light seal foam etc.
I find that the easiest way for me is to remove all the foam, wash the moving parts liberally with lighter fluid (total immersion in a jam jar works well!)and after mopping up the excess I drop the whole lot into an ultrasonic bath with water and a good detergent will get all the remaining dirt off. (It also cleans the mirror at the same time!) Washing the whole assembly in clean water is then required to remove all the cleaning fluid.
The mechanism should be dried immediately (You can use a hairdryer!), and lubrication applied.
Light oil should be used for each of the pivots, but a thin smearing of grease should be applied to the release catches where they bear against spring loaded levers. (Note: Thin means very thin. Too much may prevent the catch from setting properly.)
You should now have access to the shutter itself, the shutter mechanism and the shutter rollers.
Carefully washing the moving parts with lighter fluid while operating the shutter mechanism will wash out the old oil from the mechanism. Don't forget the shutter rollers.
Try not to get lighter fluid on the shutter blinds. The rubberisation won't like it much, and the longer it is before you need to replace the shutter cloth the better. It is not an easy task!
Once the mechanism has been cleaned, you should replace any foam seals, before lubrication, as you will find that however careful you are, you will get some oily stains just where you would like to put a seal, and they won't stick!
Now re-lubricate the mechanism. You should obtain specialist shutter oil, or watch oil for this purpose. These are especially light oils, and other heavier oils may just gum everything up. Also they are designed to last a long time without needing replacement, which is not the case with general purpose or cycle oils.
Slow moving parts such as winder gears etc. should be lightly greased. I find that dissolving a little grease in a solvent will allow even application of the minimum amount of grease, and help distribution throughout the gear train.
Re-assembly is largely the reverse of disassembly, but if you have removed the transfer gear you will have to temporarily fit the selector knob, to show which speed you have selected.
With the prism in place, you will have to adjust the position of the transfer gear so to obtain the correct indication of the selected speed between the index marks at all speeds.
If you have not done this before, this could take some time, so be prepared for a long frustrating session! (It gets easier with time.)
Take care that you don't allow the activating cord to become dislodged from it's pulleys, as this also can be a pain to get back on track!
