My Leitz Orthoplan

What equipment do you use? Post pictures and descriptions of your microscope(s) here!
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Hobbyst46
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Re: My Leitz Orthoplan

#31 Post by Hobbyst46 » Mon Dec 17, 2018 3:53 pm

The resistance of the alligator/crocodile clips (more signs are needed to identify the species) seems OK.

I do not have a halogen bulb that I could test, but a resistance of 0.4 Ohm feels too low.

Because the initial current will be 12V/0.4 = 30A. This would be an overload of the power supply. The power supply ammeter can only reach 10A.

Of course, as the lamp filament heats up, its resistance rises and the current drops, say by a factor of 10. But the initial current is too high.

That does not solve the problem yet.
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Re: My Leitz Orthoplan

#32 Post by janvangastel » Mon Dec 17, 2018 4:00 pm

Exactly the meter on my power supply. I didn't know that I shouldn't turn it up only to the red lines. And I didn't know whether a 50W or 100W lamp was installed. I noticed though that the meter didn't go up till 10 but stopped somewhere half way and most of the time I did not turn it all the way up. If it was a 50W lamp, could I have blown up the power supply? I would think the lamp would be blown up but that wasn't the case.

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75RR
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Re: My Leitz Orthoplan

#33 Post by 75RR » Mon Dec 17, 2018 4:13 pm

Might be an idea to purchase some new bulbs. Ones that are either 12v 50w or 12v 100w
That way you know where you are starting out from.
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Re: My Leitz Orthoplan

#34 Post by desertrat » Mon Dec 17, 2018 4:28 pm

More rambling here, with limited information. A .4 ohm cold filament doesn't sound bad for a high current bulb. If it increases by a factor of 10 when at operating temperature, that would be 4 ohms. With 12 volts, that would be 3 amperes, or 36 watts of power dissipation. The initial low resistance is replaced by full operating resistance in a small fraction of a second, and that typically won't harm a power transformer that isn't working into solid state rectifiers on the output side.

If the power supply output is AC, it probably doesn't have any solid state rectifiers like a DC output supply. It may just be a variable transformer. Overloading these, unless by a direct short circuit, doesn't burn them out very quickly. Putting a 50% current overload on a transformer will typically heat it up over a period of several minutes.

A problem in your power supply might be a very bad, highly resistive connection in the wiring somewhere. Since the multimeter draws only a tiny amount of current when measuring voltage, taking a reading from a terminal with a very bad connection behind it somewhere usually gives a full voltage reading. But when using that circuit to drive a bulb drawing several amps, the bad connection causes the voltage to drop to almost zero and the bulb doesn't light.
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Re: My Leitz Orthoplan

#35 Post by janvangastel » Mon Dec 17, 2018 4:35 pm

Might be an idea to purchase some new bulbs. Ones that are either 12v 50w or 12v 100w
The two new bulbs I used (and tested for resistance) are 12V 50 W (just checked to be sure). Brand is sensys.

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Re: My Leitz Orthoplan

#36 Post by Hobbyst46 » Mon Dec 17, 2018 4:38 pm

desertrat wrote:A problem in your power supply might be a very bad, highly resistive connection in the wiring somewhere. Since the multimeter draws only a tiny amount of current when measuring voltage, taking a reading from a terminal with a very bad connection behind it somewhere usually gives a full voltage reading. But when using that circuit to drive a bulb drawing several amps, the bad connection causes the voltage to drop to almost zero and the bulb doesn't light.
So, if I understand correctly, all the voltage drop falls across other components of the circuit, rather than on the bulb itself. Since the cables show very low resistance, that means that the fault lies within the PS itself? Or, as suggested by 75RR, that the bulb was not pushed sufficiently into the socket, so poor contact?
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Re: My Leitz Orthoplan

#37 Post by Culicoides » Mon Dec 17, 2018 4:48 pm

It may be that there is a bad connection to the bulb, and the pins may not be making contact in the socket. I think that John B uses 50 watt g4 bulbs, but these will not work on my Orthoplan; I use 100 watt gy6.35 bulbs; there is a slight difference in the pins of these ( I think the pins of the g4 bulbs are a bit thicker than gy6.35). If the power supply works, this is worth a try. Good luck!

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Re: My Leitz Orthoplan

#38 Post by janvangastel » Mon Dec 17, 2018 4:54 pm

Or, as suggested by 75RR, that the bulb was not pushed sufficiently into the socket, so poor contact?
After reading 75RR's message I bought a new lamp socket, which gave the same results as the old one. I am sure I pushed the lamp pins sufficiently far into the holes. So I don't think poor contact is the problem. I also use gy 6.35 bulbs, because that's what the original lamp - that worked initially - had.

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Re: My Leitz Orthoplan

#39 Post by Hobbyst46 » Mon Dec 17, 2018 5:00 pm

if the issue is not solved by Wednesday, I might be able to talk it over with a friend expert electronics engineer, which element of the PS to suspect, if any.
janvangastel wrote: 3. I also tried with the halogen lamp pins directly connected to the output of the power supply (where I measure 12V), so without the lamp socket and without the cable connecting the power supply to the lamp socket. To do this, I used two cables with crocodile clips (or whatever they are called in English) as shown in the image. I measure 12V between the crocodile clips on each end of the yellow and white cable , but as soon as I connect the lamp pins to the crocodile clips the 12V goes to zero while the lamp stays dead. So probably the socket is OK.
this indeed supports the notion that the problem lies inside the PS. Perhaps between the secondary solenoid and the downstream components.

BTW - searching "Orthoplan" in this forum brings about hundreds of found references. Here is one about light bulbs:
viewtopic.php?f=28&t=5160&p=49384&hilit ... lan#p49384
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Re: My Leitz Orthoplan

#40 Post by Hobbyst46 » Wed Dec 19, 2018 12:46 pm

I found a fresh-from-the package Philips 12V-50W halogen bulb, type GY6.35, and measured its resistance. It is 0.4 Ohm, so the halogen bulbs that Jan tried are OK, just as desertrat explained above. The fault is not within the lamp.
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Re: My Leitz Orthoplan

#41 Post by 75RR » Wed Dec 19, 2018 1:29 pm

I wonder if the time has now come to take the Power Supply to a local appliance repair man.

These are not complicated instruments, which is why they last practically forever, but they do need someone who knows what they are doing when they need fixing.
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Re: My Leitz Orthoplan

#42 Post by janvangastel » Wed Dec 19, 2018 1:48 pm

I wonder if the time has now come to take the Power Supply to a local appliance repair man.
A friend of mine works in electronics. I will ask him to take a look at it when he has time. I also bought another one from forum member mrsonchus. It's on his way and hopefully it will arrive soon. Nice to have a spare one. But probably the new one will last for ever.

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Re: My Leitz Orthoplan

#43 Post by Hobbyst46 » Wed Dec 19, 2018 1:55 pm

I have just discussed the issue with an expert in power supplies. He claims that indeed, it is possible that the PS provides the expected voltage, but not sufficient current to light up the bulb. He suggested to try and connect, instead of the 12V bulb, a weaker lamp, say a 6V bulb. If that one responds then it is certainly a problem inside the PS. Although, if it is an AC PS, he does not know apriori what to suspect.
However, if this is a DC PS, the first suspects would be capacitors near the output. Electrolytic capacitor deteriorate over time and may become faulty.

@janvangastel: if the reason for the PS failure is revealed, please publish it so we all know!
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Re: My Leitz Orthoplan

#44 Post by janvangastel » Wed Dec 19, 2018 8:49 pm

Thanks for the info.
if the reason for the PS failure is revealed, please publish it so we all know!
Yes, I will.

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Re: My Leitz Orthoplan

#45 Post by janvangastel » Thu Dec 20, 2018 5:31 pm

Today John B's Leitz power supply arrived in mint condition. So one big step closer to a solution. Only thing now is to find another connector for the cable from lamp house to power supply. The old one had 5 pins, the new one only two. The local shop here didn't have one so I will look on ebay. It looks like the photograph's (outside and insice the ps.).
ingang.jpg
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binnenkant plug_2.jpg
binnenkant plug_2.jpg (253.07 KiB) Viewed 10049 times

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Re: My Leitz Orthoplan

#46 Post by janvangastel » Fri Dec 21, 2018 6:21 pm

Looked at more then 1000 connectors but didn't find the right one. Neither on ebay, nor else on the internet. So I will go for another solution and another plug type. Maybe I use the connector from the broken PS.

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Re: My Leitz Orthoplan

#47 Post by mrsonchus » Fri Dec 21, 2018 6:35 pm

Hi Jan' - yes, I'd just use a different 'cabinet fixing' connector that will screw onto the back panel as the original does.

How about something like this, it'd easily handle the 12V and it seems 15A, more than enough for 100W.
Capture.JPG
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Capture2.JPG
Capture2.JPG (38.58 KiB) Viewed 10012 times
Probably better than the original.

Maybe a solution my friend, regards, John B. :)
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Re: My Leitz Orthoplan

#48 Post by janvangastel » Fri Dec 21, 2018 7:35 pm

Thank you, yes, I can try that. For the moment I have a solution that works. Now I can actually use the microscope until I have a definitive solution.
new solution.jpg
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Re: My Leitz Orthoplan

#49 Post by mrsonchus » Fri Dec 21, 2018 7:49 pm

Hey, that looks just the job - I'd call that a good solution, good enough to keep, nice and robust.

A blue filter will be very handy for you also, to counteract the yellow-ish tones of the halogen a little.
I have a large-diameter blue filter mounted in the spaces between the lamphouse and 'scope-back, but a smaller one over the field-light port is every bit as good.

Good job! :D

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Re: My Leitz Orthoplan

#50 Post by janvangastel » Fri Jan 18, 2019 7:18 am

I have a problem with opening and closing the field iris of my orthoplan. Rotating the close/open knob is very difficult and only doable using both of my thumbs. Even that way it takes much effort. The problem exists since I have the microscope, but I would like the movement to be a lot easier. Does anyone know a way how to accomplish that? I have already found an extensive thread about this problem on this forum. Maybe I will have to get the iris assembly out of the microscope. When placing the assembly back, will it automatically be alligned?

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Re: My Leitz Orthoplan

#51 Post by mrsonchus » Fri Jan 18, 2019 10:47 am

Hi Jan, hmm, as you say a common enough scenario but pretty easy to overcome I think. I too had some resistance to the operation of the field-iris with my big-O. It would also buckle as it reached the nearly closed position as the blades weren't moving smoothly over each other.
An early piece of good advice - don't whatever you do apply any sort of liquid to the blades!

I simply turned the mighty beast onto it's back, after removing the removable parts of course, including the head, nosepiece etc. The assembly is easy enough to remove and does indeed go back into the same position, it certainly did in my 'scope. I found very fine but clearly present traces of rust on the blades, which I carefully cleaned away with I think it was alcohol and cotton-buds. I chose alcohol as it's very quick to evaporate.

After this bit of maintenance it worked, and still does, perfectly.

There are also a lot of very experienced and skilled folk here that restore and repair microscopes so you would do well to remove the assembly then post close-up images here as they will be able to give you very good advice indeed with this. Your problem may have a different cause or severity to mine so I would post a separate thread titled something like "Orthoplan Field Iris Jamming" and wait for their expert response/s.

Hope this helps Jan.

John B.
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Re: My Leitz Orthoplan

#52 Post by MicroBob » Fri Jan 18, 2019 11:13 am

Hi Jan,
I don't have an Orthoplan but I have repaired several camera and microscope irises. The problem is often that lubricant from the mechanism finds a way onto the blades. I haver had a case where I could repair it without fluids. A proven camera repair techician method is flooding with lighter fluid/Waschbenzin, letting soak, taking up as much of the fluid with cotton buds or tissue, repeat procedure, move blades frequently. The goal it to solve old grease, moved it where it can be reached, and remove it.
In some cases very fine graphite can be added to the last load of lighter fluid to lubricate the blades. I have also repaired several irises where it was necessary to take the blades out, but it is fiddly to get the last ones back in.
Until you repair it I wouldn't move it with force. It is easy to destroy the blades this way.

You might be able to remove the glass cover over the iris and all optics below it and clean the iris while the microscope is in vertical position.

Bob

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Re: My Leitz Orthoplan

#53 Post by Hobbyst46 » Fri Jan 18, 2019 11:26 am

janvangastel wrote:I have a problem with opening and closing the field iris of my orthoplan. Rotating the close/open knob is very difficult and only doable using both of my thumbs. Even that way it takes much effort. The problem exists since I have the microscope, but I would like the movement to be a lot easier. Does anyone know a way how to accomplish that? I have already found an extensive thread about this problem on this forum. Maybe I will have to get the iris assembly out of the microscope. When placing the assembly back, will it automatically be alligned?
I suggest to avoid WD40 or similar fluids.
You might find this thread helpful, although about a Zeiss Standard not Leitz:
viewtopic.php?f=5&t=6255&p=56289&hilit=aperture#p56289
Since I managed to clean and dry every leaf, and assemble without any lubrication, so it is dry, it works like a dream.
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Re: My Leitz Orthoplan

#54 Post by janvangastel » Fri Jan 18, 2019 3:33 pm

Thanks for all advice. I disassembled the eyepiece head and the objective nose and turned the Orthoplan at his back. I am not sure which screws/bolts I should remove to get the iris block out and I don't want to parts to fall into the scope. I see for larger and two smaller bolts to be removed with a scew driver and one central allen bolt. If I remember correctly, no need to remove the two smaller ones (but I am not sure).
iris blok.jpg
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Re: My Leitz Orthoplan

#55 Post by janvangastel » Fri Jan 18, 2019 3:59 pm

OK, its out. And the iris works perfectly when not in the microscope. So it must have binded somewhere. What I already saw in the FOV, I also saw on the 45° morror: some scratches or dirt (below/left). I suppose it is a mirror like secondary mirrors in telescopes (it lookes exactly the same): accurately polished glass and an aluminum caoting. I will try for a moment to remove it, but not easy, I let it be.
iris blok_2.jpg
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Re: My Leitz Orthoplan

#56 Post by janvangastel » Fri Jan 18, 2019 5:45 pm

Its not dirt on the 45° mirror, but it's damaged. Not a big problem, because I know from astronomy (I make and test mirrors myself) that scratches are most of the time cosmetic and have little and non-visible influence on the image quality. Furthermore, it is only visible when not focused on the specimen and only at low magnification. I can't see well if it is damaged glass or only damaged coating (I think the first). But like I said: not a big problem. And more importantly: the problem of the stuck iris is solved! Kohlered for a minute or two and everthing works well again. And I learned something about my Orthoplan again.

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Re: My Leitz Orthoplan

#57 Post by mrsonchus » Fri Jan 18, 2019 6:09 pm

Nicely-done Jan, great to hear it's OK.

As you say, every problem's an opportunity to learn more!

John B. :)
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Re: My Leitz Orthoplan

#58 Post by janvangastel » Sat Jan 19, 2019 7:11 am

Two last things that could be of interest/importance.
1. The iris blades looked a little wet, so I think they were oiled with very thin oil. I have not removed that, because it workes fine.
2. With the ortoplan on its back, the iris assembly tends to shift to its lowest position when placing it back. Fastening the bolts in that position makes that the iris will bind somewhere and get stuck, as I experienced when putting it back. Lifting the assembly a little bit while fastening the bolts, maybe a millimeter or so, prevents it from binding.

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Re: My Leitz Orthoplan

#59 Post by 75RR » Sat Jan 19, 2019 2:54 pm

janvangastel wrote:Two last things that could be of interest/importance.
1. The iris blades looked a little wet, so I think they were oiled with very thin oil. I have not removed that, because it workes fine.
2. With the ortoplan on its back, the iris assembly tends to shift to its lowest position when placing it back. Fastening the bolts in that position makes that the iris will bind somewhere and get stuck, as I experienced when putting it back. Lifting the assembly a little bit while fastening the bolts, maybe a millimeter or so, prevents it from binding.
re-1) That will attract dust so make sure to cover the microscope up even for short periods of time.
re-2) Good tip for Orthoplan users - nice !
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Re: My Leitz Orthoplan

#60 Post by gastrotrichman » Sun Feb 17, 2019 12:25 am

I just finished cleaning the field iris on an Orthoplan following the procedure suggested above by MicroBob. Three thoughts. (1) There may be shims under the iris/mirror housing screw holes, so beware when removing the housing and note the location of any shims so they can be replaced in the right spot. (2) The solvent (lighter fluid) lubricates the leaves, so one must be sure the solvent is completely removed before concluding that the iris is fixed. (3) Notwithstanding a number of "washes" with solvent and many operations of the iris with solvent in place, I found that the iris would still bind once the solvent was removed. I ended up polishing the exposed parts of the leaves with dry cotton stick-swabs. After going through dozens of swabs, the iris worked like a charm. The used swabs initially picked up additional dried lubricant … evidenced by brown residue on the swabs. The residue was not showing up when I ended the polishing.
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