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Arnold Harris
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Votes: 0 (Vote!) | | Posted on Tuesday, August 02, 2005 - 09:42 pm: | 
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I have five (5) Voigtlander Vitessa-T 35mm rangefinders. The original built-in Bertram selenium cell exposure meters of two of these need either cleaning, adjustment or outright replacement of the selenium wafers.
All of this can be done at Quality Light Metric in Los Angeles. But they advise that they specialize in light meter repair and not camera repair, with the suggestion that it is easier for them if the meter and not the entire camera is sent to them.
From earlier posts on this forum, and discussions with the shop in North Carolina where I expect to have all these cameras sent for CLAs in the near future, I understand that to get at the meters, the top of the body must be removed.
Which means the tightly-fitted (and reverse-threaded?) knob atop the combi-plunger must first be heated, then unscrewed in a way that does not damage the bright metal.
Then, the two screws which hold the top in place have to be unscrewed from inside the top of the film compartment.
Assuming I can do all that, is the built-in meter a unit that can be disconnected from the camera top, then packed carefully and sent out for repairs? I know the rangefinder itself is mounted in the top of the camera body, and I would not want to damage it.
From other readings online, I have found hints that some selenium cells have been revived by cleaning them with acetone or possibly other chemicals, and that rubber erasers have been used to remove corrosion around the soldered electrical connections to the galvanometer and resistor, which I understand are all that these older uncoupled exposure meters comprise.
Correspondence from Magnetron (UK) indicates they can supply new selenium cell sandwiches cut in the right size (about $31 USD). Although I prefer to fix the originals if feasible.
The only thing for which I need any kind of meter is to provide the exposure value (EV) for any combination of incidental light and film speed. These perfectly lineal EV's are the way we set the combination of aperature and shutter speed on the Compur leaf shutters supplied with the Vitessa-T's.
(I got my first Vitessa-T from a friend in 1971 who had bought his, along with the original auxiliary lenses, at a Chicago hockshop. Aside from an Asahi Pentax K1000 SLR with which I never particularly bonded, Vitessa-T's are all I have used during the succeeding 34 years, and I aim to keep them alive. I buy cameras to use, not to look at. And I know exactly what I like.)
Advice? Information? I'm thick-skinned, so don't be afraid to tell me I'm dead wrong about any of my assumptions, and I freely admit I know nothing about camera repair, other than what I researched for this commentary.
Thank you in advance for any useful information.
Arnold Harris
Mount Horeb WI |
Stuart Willis
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Votes: 0 (Vote!) | | Posted on Saturday, August 06, 2005 - 07:10 am: |
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Arnold ...
I have never personally encountered any Vitessa T which has a left-hand threaded plunger cap. They are all normally threaded but they are usually very tight. The real danger in removing such tight cap is twisting of the plunger-shaft. It absolutely must NOT be allowed to twist under the untorque action of the cap removal - otherwise you create internal problems or damage.
There is a hole in the take-up spool flange for access to one of the two screws which secure the top-plate from inside the camera. Just turn the film-spool until you can align for a screwdriver insertion.
The selenium meter comes off easily as a module.
Selenium cells have a finite service life which largely depends upon the extent of exposure to light (which is why "collection" models on display should have the receptor taped over).
If the cell is generating some degree of voltage it may be possible to simply remove the series resistor/s and end up with a functional meter for which you may need to allow some small compensation. But usually when a forty or fifty year old selenium cell stops working it can be regarded as dead for all time.
Yes - you can buy selenium replacement plates cut to size but make sure the thickness of the plate is the same as the original otherwise you my have installation "ill-fit" or "non-fit" problems.
And you had better make sure that the front surface-coated side has a wire already connected by the supplier because connection is a special process and you cannot solder wires to a selenium surface.
For the price of getting the selenium meter fixed and for the hassles of removing it - a much better option is to procure a really fine separate meter such as a Gossen Lunasix. Your decision of course.
Hope this helps.
Remember what I have written here about the need to avoid any plunger twist when unscrewing the cap - otherwise your problems will compound exponentially.
Stuart Willis |
Arnold Harris
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Votes: 0 (Vote!) | | Posted on Saturday, August 06, 2005 - 11:37 am: |
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Stuart, thank you for the gracious, helpful and timely reply. I had been idly wondering if I owned the only remaining Vitessa-T's in the world, and nobody else knew anything about them.
I just bought a working Bertram Chonos exposure meter on eBay, and I will probably buy an additional separate meter if necessary. My purpose for these is to confirm readings from the built-in exposure meters.
My only real interest in light meters is getting correct EV values, because these are the primary means of setting both aperatures and shutter speeds on all the lenses used with the Vitessa-T, and these more or less are the only cameras I use; setting aperatures by f/stop readings is cumbersome on the Color-Skopar, Skoparet, Dynaret and Super-Dynaret lenses, because their f/stop settings are printed on the underside of the aperature rings, and the EV setting are on top of the aperature rings.
I am too much a purist to ignore or de-commission any built-in meters as a substitute for repairing them. I keep no cameras at all just for show, and I want no equipment whatsoever that cannot be operated for its original purpose.
I intend to send the meters, and if necessary, the tops of the camera bodies in which they are mounted, to Quality Light Metrics, Los Angeles, who are noted specialists in repairing exposure meters and where necessary, replacing selenium cells and recalibrating the galvanometers that they power. Some refocused questions:
1) How would you suggest simultaneously gripping the shaft with one tool and the cap with another, without damaging either part? I was told it would be advisable to heat the screwed-on cap. What tool would use useful for that?
2) When the selenium-based exposure meter comes off the camera top as a module, do all its vital compenents come off with it for easy and safe shipping? These components include the cell, its wiring, the resistor, the galvanometer, and the rotary drum with the metering scale imprinted on it. From examining the attached camera top, it appears that the drum is attached to the top by a shaft that the user rotates to line up the exposure range appropriate for a given film speed. But without that drum, there is no gauge against which the repair shop can recalibrate the galvanometer.
3) Are there any other wires that come off when the top of the camera is loosed and removed? Particularly, is their a wire connection between the shutter assembly and the flash mounting shoe on top of the camera body? If so, is that wire cut and resoldered whenever the camera top is removed?
4) What other questions about this topic ought I to have asked, but do not have enough information even to know that I should raise the question?
Some time in the near future, I hope to buy a low-cost junk/parts Vitessa-T solely upon which to gain experience dismantling, performing my own CLA jobs, and reassembling this particular camera model.
I appreciate any further helpful advice you can offer.
Arnold Harris>br>
Mount Horeb WI |
Arnold Harris
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 06, 2005 - 11:53 am: |
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Stuart, I stand corrected. Re-examination of the top of the Vitessa-T shows that the black and white marked areas of the scale are separate from the drum which has only the numeric values which pertain to a specific film speed.
Therefore, I assume that the meter unit can be detached from the camera top with the black and white scale, implying that the repair people at Quality Light Metrics can recalibrate the meter based on those markings. (Hopefully.)
Based on your experiences, how long can a replacement selenium cell be expected to last as many decades as these old ones, assuming the light meters, if not the cameras, can be kept covered when not in use?
Arnold Harris
Mount Horeb WI |
Arnold Harris
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 06, 2005 - 07:15 pm: |
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Stuart, yet another question. Is the cap located on top of Vitessa-T combi-plunger a nut or a bolt? In other words, is it screwed INTO a threaded hole in the combi-plunger, or is it screwed ONTO the outside of the combi-plunger? The answer to that question tells me whether to heat the cap or to heat the combi-plunger in order to unscrew it more easily. I.e, what part do we want to expand with heat, the combi-plunger or the cap?
Arnold Harris
Mount Horeb WI |
Tony Duell
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 12, 2005 - 04:35 am: |
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I was fiddling with my Vitessa-T last night...
The cap is the male thread, it screws inside the plunger. But more interestingly, it appears that there is a trim disk glued on top of the cap, under it is a conical screw which expands the threaded part of the cap to lock it into the plunger. It's hard to remove the trim without minor cosmetic damage, but personally I'd rather do that than risk damaging the threads on the cap/plunger or worse still damaging the advance mechanism by twisting the plunger. |
Arnold Harris
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Votes: 0 (Vote!) | | Posted on Friday, August 12, 2005 - 12:55 pm: |
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Interesting, Tony, interesting. This is one discovery that should be brought to the attention of all owners of the old Combi-plunger Voigtlanders. Some of them apparently have scarred either the plungers or the caps over the decades, trying to remove them by grip and main force.
You didn't happen to make a small sketch of showing exactly where on that cap is the separation point, did you? And what kind of cement should be used to re-attach the trim disk to the rest of the cap, (with the thought in mind that it may require future removal)? And what tool can be inserted between the trim disk and the cap, to break the cemented bond without damaging either piece of metal?
Thanks again for this timely information.
Arnold Harris
Mount Horeb WI |
Tony Duell
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Votes: 0 (Vote!) | | Posted on Friday, August 12, 2005 - 12:58 pm: |
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I'm working from memory...
I think the trim is a thin metal disk _inside_ the top of the cap. Try working a sewing needle round the edge and under it to get it off. I suspect there will be minor cosmetic damage, but I care more about the functioning of my cameras than the appearance.
When you've got the disk off, loosen the screw under it, and then try to unscrew the cap. |
Arnold Harris
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Votes: 0 (Vote!) | | Posted on Friday, August 12, 2005 - 07:47 pm: |
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Tony, is there some way of chemically dissolving the bond between that thin metal disk and the top of the cap? What about heat applied to it? (Not enough heat to warp or scorch the metal, just enough to loosen the cementing agent.) Also, what about soaking the cap in a solution of some sort that might loosen or dissolve the glue?
Among other considerations, none of these possibilities would involve even cosmetic damages.
I have yet to locate the disk within the top of the cap. I have not yet examined it under magnification, but that's next.
I wonder how anybody ever serviced the Vitessa units which had Combi-plungers. Presumably it is necessary to remove the cap in order to completely remove the top of the camera body from the rest of the main assembly. My guess is, the loosened the top sub-assembly by removing the long screws accessible from the film compartment, put the Combi-plunger in raised position, found a handy place lower on the shaft where scratch marks would not show, then gripped the shaft with one tool and the cap with another, and turned it until it came off. They probably had to heat the top of the shaft to do this, in order to expand it just enough to unscrew the male-threaded cap with the hidden set-screw still inside.
Let me know further what you think of all this.
Arnold Harris
Mount Horeb WI |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 13, 2005 - 10:36 am: |
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I would have thought that any official repair notes would tell you to remove the trim disc and loosen the lock screw,before unscrewing the cap by finger pressure.This type of thread locking does not require the cap to be tightened hard down.You would just run it down until it stopped and then tightened the conical lock screw.Pipe wrenches and blow torches are not required.
The use of trim discs in this situation is quite common on photographic equipment,Canon Auto Bellows' rack knobs and Gossen Lunasix dial screws to name but two. |
Arnold Harris
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Votes: 0 (Vote!) | | Posted on Saturday, August 13, 2005 - 03:24 pm: |
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I agree. But is there some way to remove the trim disk without some sort of metal-to-metal prying? It doen't take much to leave scratch marks on such a highly-visible part as the cap on the Combi-plunger.
What about dipping the cap in some chemical solution that will dissolve whatever adhesive material was used to cement the disk to the top of the cap? Has anyone tried that? Or what about heat on the cap, maybe just enough to loosen the glue?
I haven't yet located any kind of official factory repair manual for the Voigtlander Vitessa-T. I know there are repairman's notes sold by Nikon Dave that cover all the Vitessa models, and I expect to buy a set soon.
But the first I had ever heard of an expansion screw hidden in the cap of the Vitessa Combi-plunger was on this forum.
Arnold Harris
Mount Horeb WI |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 13, 2005 - 07:43 pm: |
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The only experience I have of the Vitessa-T is using my late father's example, before he traded up to a M2.
I have modified two electric soldering tools to deal with glued name/data plates etc.One is just a normal 100watt thermostatic soldering iron to which I attach copper bits that are shaped to cover the plate or disc in question.ie in this case it would be a cylinder of solid copper,the same diameter as the disc.However that still leave you with the problem of lifting the disc.The second device is more useful.It is basically like a pair of pliers with electrically heated copper jaws.It was originally used to melt the solder in Yorkshire fittings for copper pipes.(A ferule containing rings of solder is used to join two pieces of copper pipe.The heated copper jaws are place around the ferule and the solder melts).The heated jaws come in various sizes for the different diameter copper pipes.These jaws can be easily modified to accommodate any diameter.
I would glue a lifting tab onto the disc with high temperature epoxy( safe to 200C),then I would place the jaws around the cap and apply heat.The disc adhesive should fail before the epoxy,allowing you to pull off the disc.Soaking in methylene chloride will weaken the epoxy and allow it's removal.
The disc may not be glued in however, but may be held in place by a slight chamfer on the edge of the counter bore.Rolex watch bezel inserts are held in this way and it is very secure.As in the case of Gossen,I suspect that at official repairs the disc would have be sacrificed and a new one pressed/glued in place.
I would remove by drilling a small hole and running in a tap to force out the disc.Turning up a new disc out of stainless,alloy or even plastic is a simple job.I would rather have an unmarked none original plunger than one with scratch/gouge marks. |
Arnold Harris
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Votes: 0 (Vote!) | | Posted on Sunday, August 14, 2005 - 06:35 am: |
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How about heating the cap with a copper tip soldering iron or similar tool to loosen the bond, and using a powerful magnet to suck out the small disk, which, hopefully is fabricated from a ferrous metal.
Has anyone gotten the disk off a Combi-plunger that way?
Arnold Harris
Mount Horeb WI |
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