Post by PeterW on Dec 29, 2006 16:59:45 GMT -5
I've been getting some stuff ready to update my website repair pages but as it may be some time before I get around to the actual updating I thought I'd put one of the items here. Sorry it's a bit long, but if anyone's delving into an early Praktica Nova they might find it useful.
Praktica Nova screen access
This deals with the first of the Praktica Novas, the model with the two speed dials, one for selecting the range and a lower one for choosing the speed. Getting to the screen is quite straightforward except that there are a few things to watch for, and you need a couple of easily made special tools. One is essential and the other is desirable. I didn't take any pictures while I was doing the job but I made some sketches for my own use to guide reassembly. I've cleaned these up and added some notes, and I think you'll find them easy enough to follow, so first of all here they are:
First, the two special tools. Both can be made quite easily by grinding down a couple of old stubby screwdrivers, or for that matter a pair of new cheap ones. Even the ones on the '£1 a time' market stalls are good enough quality for this job. The desirable one is for removing the tubular nut in the wind-on lever assembly. It's possible to remove this with a lens wrench if the legs with screwdriver ends on yours are thin enough, but the tool makes it much easier. I've drawn the tool and called it Praktica special tool 1.
The second tool is essential, at least I think it is. It's for removing the speed indicator which sits under the speed range indicator. This is made from very soft alloy and the slots for the tool are small. On one camera on which I did this job someone had been inside before, and although they managed to get the speed indicator off and back again they chewed up the slots so badly I had to remake them with a 1mm drill before I could get a grip with the tool. I've called the tool for this Praktica special tool 2.
OK, let's start. We'll deal first with the wind lever. At the top is a thin alloy cover plate, stuck in position. Most times you can prise up carefully using the point of a needle held in a pin vice, but other times it may distort or even tear. I think repair men in Praktica dealers must have kept a box full of replacements. Don't worry if this happens, a disc of black leatherette stuck in its place looks quite smart.
Undernerath you'll find a small black screw with a tiny plain washer. Don't lose this washer. The screw and washer don't hold anything but they stop the wind-on segments from lifting up and loosing engagement. Then comes the tubular nut for which you need tool 1. When that's removed you can lift off a plated collar and the wind-on lever. Under the lever you'll probably find one or two shims. They're to stop the lever wobbling but leave it free enough to fly back under return spring pressure.
Moving over to the speed selector group, set the speed to B or some easily remembered position. The top piece is the speed range selector which moves about an eighth of a turn to select the white or red speeds. This lifts off after you remove its screw, and underneath is the speed indicator dial, actually a tubular nut.
This is the one for which tool 2 is essential. WARNING! IT HAS A LEFT-HAND THREAD - UNDO CLOCKWISE. Under that is a washer and a spring and the lift and turn speed indicator which will be loose but won't lift out because there isn't enough clearance underneath. It comes off with the top plate. Over on the other end of the top plate is the rewind crank which comes off in the usual way by wedging the rewind fork inside the camera and unscrewing the knob. Please don't use the little crank handle as a lever to unscrew the knob. You see so many of these levers broken off. If it's tight, a pair of washing-up gloves with a rough non-slip surface to the fingers will give you plenty of grip. Don't loose the little washer under the crank knob.
Now you can undo four small chromium headed screws, two front and two back, and the top plate will lift off complete with the prism and the large black dials, one at each end. The plate is slotted to take the strap lugs so you don't have to remove those. The lift and turn speed selector will either come with it or fall out.
Remember I said set the speed to B or some other easily remembered position? Now you'll see why. There's a dial underneath with holes that correspond to the position of the markings on the speed indicator. A peg on the bottom of the lift and turn selector fits these holes. If you remembered where B was you can locate its hole by comparing the spacing of the holes with the speed indicator and make sure the selector goes back in the correct hole when you reassemble. Remember to postion the selector with its peg in the correct hole as you refit the top plate.
One more point to watch. Next to the wind on lever is the small button which you press to disengage the clutch for rewinding. This sits loose in its position and will fall out if you turn the camera over. Note where it goes and lift it out - and don't forget to replace it before you put the top plate back on.
Now, at last, we can get to the screen. On top of it is a three-sided open-ended box of soft foam which just lifts off. In most cases you'll find this in good condition. Note that it fits snugly over the screen retaining plate and has one of the long sides thinner than the others. This thin side goes to the front. Inside the foam box is a three-sided thin shim brass support plate to support this thin side and stop it drooping over the screen. Be careful not to bend it. Under the foam is the screen retaining plate which just clips into position. Remove this and you can lift out the screen for whatever reason you needed to get to it.
One more point I ought to mention. If you look in the front with the lens off you'll see at the top a black fabric light baffle which is pushed upwards by the lens barrel as it screws in. In most cases this will be in perfect condition, but on the Nova I took apart it wasn't. Someone had been inside, and though the camera worked perfectly there was something obscuring the top of the viewfinder. Either that person, or someone later, thought wrongly that the light baffle was causing this, and cut it back. When this didn't clear the viewfinder they gave up.
When I took the top off I found that the obstruction in the viewfinder was part of the foam box over the screen. Whoever put it back had forgotten the brass shim support, and the thin front edge of the foam had squashed down over the screen. I made a new support from thin shim brass to cure this, but I also had to take out the light baffle to renew the mutilated fabric. The baffle comes out after you take off the front plate - two screws at the bottom - and the lens flange. This flange has stagered holes so you can't get it back in the wrong position. On one camera I dismantled the light baffle was held by two screws, but on another it was just held in with a touch of adhesive and the front plate. I renewed the fabric with a piece cut from thin black fabric from the local fabric shop and ran a thin smear of adhesive over the cut edge to prevent it fraying. I trimmed the fabric back by trial and error till it was just clear of the viewfinder.
If by any chance you have to make a shim support for the foam it's from 0.15mm shim stock by 5mm deep, not so deep as the foam so the foam can squash down slightly when you put the top plate and prism back on.
Reassembly is pretty much the opposite of disassembly, to use the time honoured phrase. I can't remember any special points to watch.
The Nova B, B for Belichtungsmesser, or light meter, is almost identical. The whole meter lifts off with the top plate.
My sincere thanks are due to Robert - Toolmaker 48 - of the Praktica Users Group Worldwide for making freely available to me his extensive knowledge of Praktica cameras together with copies of the relevant pages from the workshop manual and his notes.
PeterW
Praktica Nova screen access
This deals with the first of the Praktica Novas, the model with the two speed dials, one for selecting the range and a lower one for choosing the speed. Getting to the screen is quite straightforward except that there are a few things to watch for, and you need a couple of easily made special tools. One is essential and the other is desirable. I didn't take any pictures while I was doing the job but I made some sketches for my own use to guide reassembly. I've cleaned these up and added some notes, and I think you'll find them easy enough to follow, so first of all here they are:
First, the two special tools. Both can be made quite easily by grinding down a couple of old stubby screwdrivers, or for that matter a pair of new cheap ones. Even the ones on the '£1 a time' market stalls are good enough quality for this job. The desirable one is for removing the tubular nut in the wind-on lever assembly. It's possible to remove this with a lens wrench if the legs with screwdriver ends on yours are thin enough, but the tool makes it much easier. I've drawn the tool and called it Praktica special tool 1.
The second tool is essential, at least I think it is. It's for removing the speed indicator which sits under the speed range indicator. This is made from very soft alloy and the slots for the tool are small. On one camera on which I did this job someone had been inside before, and although they managed to get the speed indicator off and back again they chewed up the slots so badly I had to remake them with a 1mm drill before I could get a grip with the tool. I've called the tool for this Praktica special tool 2.
OK, let's start. We'll deal first with the wind lever. At the top is a thin alloy cover plate, stuck in position. Most times you can prise up carefully using the point of a needle held in a pin vice, but other times it may distort or even tear. I think repair men in Praktica dealers must have kept a box full of replacements. Don't worry if this happens, a disc of black leatherette stuck in its place looks quite smart.
Undernerath you'll find a small black screw with a tiny plain washer. Don't lose this washer. The screw and washer don't hold anything but they stop the wind-on segments from lifting up and loosing engagement. Then comes the tubular nut for which you need tool 1. When that's removed you can lift off a plated collar and the wind-on lever. Under the lever you'll probably find one or two shims. They're to stop the lever wobbling but leave it free enough to fly back under return spring pressure.
Moving over to the speed selector group, set the speed to B or some easily remembered position. The top piece is the speed range selector which moves about an eighth of a turn to select the white or red speeds. This lifts off after you remove its screw, and underneath is the speed indicator dial, actually a tubular nut.
This is the one for which tool 2 is essential. WARNING! IT HAS A LEFT-HAND THREAD - UNDO CLOCKWISE. Under that is a washer and a spring and the lift and turn speed indicator which will be loose but won't lift out because there isn't enough clearance underneath. It comes off with the top plate. Over on the other end of the top plate is the rewind crank which comes off in the usual way by wedging the rewind fork inside the camera and unscrewing the knob. Please don't use the little crank handle as a lever to unscrew the knob. You see so many of these levers broken off. If it's tight, a pair of washing-up gloves with a rough non-slip surface to the fingers will give you plenty of grip. Don't loose the little washer under the crank knob.
Now you can undo four small chromium headed screws, two front and two back, and the top plate will lift off complete with the prism and the large black dials, one at each end. The plate is slotted to take the strap lugs so you don't have to remove those. The lift and turn speed selector will either come with it or fall out.
Remember I said set the speed to B or some other easily remembered position? Now you'll see why. There's a dial underneath with holes that correspond to the position of the markings on the speed indicator. A peg on the bottom of the lift and turn selector fits these holes. If you remembered where B was you can locate its hole by comparing the spacing of the holes with the speed indicator and make sure the selector goes back in the correct hole when you reassemble. Remember to postion the selector with its peg in the correct hole as you refit the top plate.
One more point to watch. Next to the wind on lever is the small button which you press to disengage the clutch for rewinding. This sits loose in its position and will fall out if you turn the camera over. Note where it goes and lift it out - and don't forget to replace it before you put the top plate back on.
Now, at last, we can get to the screen. On top of it is a three-sided open-ended box of soft foam which just lifts off. In most cases you'll find this in good condition. Note that it fits snugly over the screen retaining plate and has one of the long sides thinner than the others. This thin side goes to the front. Inside the foam box is a three-sided thin shim brass support plate to support this thin side and stop it drooping over the screen. Be careful not to bend it. Under the foam is the screen retaining plate which just clips into position. Remove this and you can lift out the screen for whatever reason you needed to get to it.
One more point I ought to mention. If you look in the front with the lens off you'll see at the top a black fabric light baffle which is pushed upwards by the lens barrel as it screws in. In most cases this will be in perfect condition, but on the Nova I took apart it wasn't. Someone had been inside, and though the camera worked perfectly there was something obscuring the top of the viewfinder. Either that person, or someone later, thought wrongly that the light baffle was causing this, and cut it back. When this didn't clear the viewfinder they gave up.
When I took the top off I found that the obstruction in the viewfinder was part of the foam box over the screen. Whoever put it back had forgotten the brass shim support, and the thin front edge of the foam had squashed down over the screen. I made a new support from thin shim brass to cure this, but I also had to take out the light baffle to renew the mutilated fabric. The baffle comes out after you take off the front plate - two screws at the bottom - and the lens flange. This flange has stagered holes so you can't get it back in the wrong position. On one camera I dismantled the light baffle was held by two screws, but on another it was just held in with a touch of adhesive and the front plate. I renewed the fabric with a piece cut from thin black fabric from the local fabric shop and ran a thin smear of adhesive over the cut edge to prevent it fraying. I trimmed the fabric back by trial and error till it was just clear of the viewfinder.
If by any chance you have to make a shim support for the foam it's from 0.15mm shim stock by 5mm deep, not so deep as the foam so the foam can squash down slightly when you put the top plate and prism back on.
Reassembly is pretty much the opposite of disassembly, to use the time honoured phrase. I can't remember any special points to watch.
The Nova B, B for Belichtungsmesser, or light meter, is almost identical. The whole meter lifts off with the top plate.
My sincere thanks are due to Robert - Toolmaker 48 - of the Praktica Users Group Worldwide for making freely available to me his extensive knowledge of Praktica cameras together with copies of the relevant pages from the workshop manual and his notes.
PeterW