No power to light sources on Leica DMRE

[lxlotl]

Hello all,

This is my first post on the forum, I'm a complete noob when it comes to microscopy.

I recently acquired my first microscope, an old huge Leica DMRE that was destined for the trash.
LeicaDMRE by Linaria Larkin, on Flickr

Presently, the light sources do not work and I don't know why. I was wondering if you all would be able to help me at all diagnose what the problem is.
Probing with a multimeter after turning the light power on, there is no power getting to either light sources.
The microscope does get power, it has a front display for manipulating the z-height that does light up. But I also do not know much of anything about electronics, so I don't know where to even begin!

Thank you all in advance for any advice/help!

[MichaelG.]

I’m afraid this won’t help [or make you happy] : https://www.ebay.co.uk/itm/256205241887

Hopefully, in amongst that lot … you might just possibly find a blown fuse !

… if not, it could be a long investigation.

MichaelG

[Hobbyst46]

How about both bulbs are burnt out, normal end of life ?

[apochronaut]

If you smell around close to the back of the microscope, below where the louvers on top are : do you smell a pungent sort of burnt aroma?

[PeteM]

Your DMRE is potentially a marvelously capable microscope.

And, the worst case for the lamps isn't so bad. If the problem turns out to be more than a burnt lamp or fuse, a loose wire, or just not understanding which switch switches what -- you could simply get an external 100 watt power supply (often available from $50 to $100) and wire it directly to the lamp.

If it's a bad power supply, you also likely have enough room in the base of the scope to get a modern switching power supply and do a replacement if the original power supply board is burnt out or missing.

[apochronaut]

I would go to 150 watts for that but I would rule out the obvious usual culprits first. Fuse, capacitors, switching.Keep the in house p.s. if possible. Remote is a bit cumbersome and matching the microscope's power needs might be a bit tricky.
If the microscope sat for a while without being powered up, electrolytic capacitors can leak or dry up. They tend to fail more unused. A quick check by an electonics guy could find the problem fast. It doesn't have to be a microscope technician. It's just a power supply. No fan in that?

[lxlotl]

How about both bulbs are burnt out, normal end of life ?

I wasn't able to directly probe the plug on the microscope for the light sources with a multimeter, but I was able to probe the connection within one of them, and there wasn't any voltage across them. Not super experienced with a multimeter, so I could've done something wrong, so I suppose it would be worth trying new bulbs.

[lxlotl]

Your DMRE is potentially a marvelously capable microscope.

And, the worst case for the lamps isn't so bad. If the problem turns out to be more than a burnt lamp or fuse, a loose wire, or just not understanding which switch switches what -- you could simply get an external 100 watt power supply (often available from $50 to $100) and wire it directly to the lamp.

If it's a bad power supply, you also likely have enough room in the base of the scope to get a modern switching power supply and do a replacement if the original power supply board is burnt out or missing.

That is not a bad idea, for a worst case scenario! I do have a couple power supplies scavenged from other workplace instruments.
Reading through the manual there was quite a lot of words I had to look up, it seems I have a lot to learn if I want to use it to its fullest potential.

[apochronaut]

How about both bulbs are burnt out, normal end of life ?

I wasn't able to directly probe the plug on the microscope for the light sources with a multimeter, but I was able to probe the connection within one of them, and there wasn't any voltage across them. Not super experienced with a multimeter, so I could've done something wrong, so I suppose it would be worth trying new bulbs.

Since you have a meter, just check continuity across the pins. Sometimes bulb filaments can fry close to the bracket and it is hard to see visually if they are broken.
One other place where those illuminators can give problems over time is in the socket itself. Once a pin loses contact just a little, it heats and oxides build up, causing weaker contact, more heat. Eventually the socket gives out.
Sometimes, a thin point file or emery paper can clean the contacts up and restore the socket but they can be horribly pitted and burned.
It is suspicious that both illuminators are out though. It does sound like a power supply issue.
I found a reference that says 140 watts. It should be on a tag somewhere on the instrument.

[Alexander]

The upper lamp housing looks very much like a HBO which needs a special power supply anyway.
On the picture the lower lamp's power line is not connected to the frame.

Is a bulb installed?
What resistance reads the multimeter on the pins of the lamp housing?