Home page of the microscope service parts, repair and spare parts online catalog - Sermik-Oplatek Mikroskopservice Dresden f.n.n.Z

Description of this part for the microscope.

the following microscopes:
- Olympus CX30 / CX31
- Olympus CX40 / CX41 / CX43
- Olympus BX40 / BX41 / BX43
- Olympus BX50 / BX51 / BX53
- Olympus BX60 / BX61
- and probably others

This is a black housing made of cast metal. Metal, cast or injection-molded parts of Olympus carry their own numbers. This microscope element bears the number AB8931.

Because this is a brittle casting, the housing can crumble, crack or break. The remedy is then to replace the complete head or just this part of the housing.

In the compatibility section you will find an example list of microscopes the U-TR30 fits, although that list is not complete.

Description of this part for the microscope.

removed from an Olympus U-TR30 trinocular head.

The Olympus U-TR30 / U-TR30-2 photo-trinocular heads are most often used in the following microscopes:
- Olympus CX30 / CX31
- Olympus CX40 / CX41 / CX43
- Olympus BX40 / BX41 / BX43
- Olympus BX50 / BX51 / BX53
- Olympus BX60 / BX61
- Olympus MX40 / MX50
- and probably others

Olympus offers a whole range of tubes with a 42.1 mm mounting diameter, so such mounts are fitted not only to the U-TR30 head.

The female mount for adapters with a 42 mm dovetail (more precisely, according to the manufacturer specification: 42.1 mm) is found, among others, on the following microscope heads and tubes:
- Olympus U-TR30
- Olympus U-TR30-2
- Olympus U-TR30H
- Olympus U-TR30IR
- Olympus U-TR30NIR
- Olympus U-TTR-2
- Olympus U-ETR3
- Olympus U-ETR30
- Olympus U-ETR-4
- Olympus U-SWTR
- Olympus U-SWTR-2
- Olympus U-SWTR-3
- Olympus U-SWETR
- Olympus U-SWETTR-2
- Olympus U-SWETTR-5
- Olympus MX-SWETTR
- Olympus U-CTR30-2
- Olympus U-TRU
- Olympus U-TRUS
- Olympus U-MPH
- Olympus U-TLU
- Olympus SZX-TR30
- Olympus SZX2-TTR
- Olympus SZX2-TTRPT
- and probably others

Important: as of now (2026) the microscope brand "Olympus" has been replaced by "Evident". Evident microscopes (e.g. Evident BX53) still keep the previous standard, so the 42mm mount is also found in products carrying that brand.

Metal, cast or injection-molded parts of Olympus carry their own numbers. This microscope element bears the number AB8980.

Because this is a brittle casting, the mount can crumble, crack or break. The remedy is then to replace the complete head or just this part - fortunately this mount is a separate component, fixed to the head with three screws.

And this implies another important matter: the diameter of the mount is standard, but I cannot guarantee that a mount fixed with exactly three screws fits every one of those heads and tubes, and even if it does - whether their hole spacing is the same in each of those models. The user should check that for himself based on the photos in the gallery.

Where the descriptions quoting a 51 mm diameter come from?
On the website of "Martin Microscope" and in many other descriptions available online, exactly the same (sic!) mount is described as having a diameter of 51 mm. That is the internal diameter of the ring, measured without the seat of the dovetail taper. So the 51 mm at "Martin Microscope" refers to the same mount into which a 42 mm dovetail is inserted.

This is not a part for one specific microscope model. As listed above - such a mount can be found in many heads and tubes, and these in turn in any microscope the user fits them into.

In the "compatibility" section there is an example list of microscopes the U-TR30 head fits, although it is not a complete list.

Description of this part for the microscope.

is fastened to the condenser holder with two screws.

Because the rack of the condenser height adjustment mechanism is made of plastic in this microscope model, it is a part that gets damaged very often.

Description of this part for the microscope.

marked AB4317)
- steel shaft
- plastic pinion (sometimes simply called a gear) fitted onto this shaft

It is this rotary movement of the knob that is transferred to the toothed rack (https://www.microscopeparts.eu/part/92011), which in turn produces the vertical up and down movement of the condenser (the focusing of the microscope condenser).

Because both the knob and the pinion are made of plastic in this microscope model, it is a part that gets damaged very often.

Description of this part for the microscope.

together with the nosepiece carries the manufacturer's catalogue number AW019700 and the name "CX31 arm ass'y". I am not offering the complete microscope arm here. What I show and offer here is only the nosepiece itself (the rotating turret disc), together with the click-stop latch spring. The part offered here should be treated as a service part used to repair the nosepiece when it gets damaged.

On the arm from which this particular nosepiece was removed, the manufacturer placed the casting number AD7858 - but I do not know whether this is the permanent number of this component or merely the number of the mould in one particular factory. Based on my experience with other, similarly marked Olympus parts, I lean towards it being the permanent numbering of this component.

The set offered here consists of:
- central screw together with bearing balls - it forms the rotation axis of the nosepiece and fastens it to the arm casting
- silver-plated brass turret disc with four objective seats with RMS thread
- set of bearing balls around the turret disc
- thin brass sliding washer
- click-stop latch spring with ball - for stopping the nosepiece in a given position while turning it
- rubber grip ring around the nosepiece that makes it easier to hold

Important: this nosepiece does not fit the polarizing version of the Olympus CX31 microscope, that is the CX31-P. The nosepiece in Olympus CX31-P microscopes allows the objectives to be centred, and the one shown here does not have that function.

Description of this part for the microscope.

the vertical movement (raising / lowering) of the microscope stage, that is the mechanism responsible for setting the sharpness (focusing). It is located behind the microscope stage, on the inner side of the microscope arm. This cover is screwed to the housing with three screws (they are included in the set I offer here). These screws have their own Olympus part number: CUTB3X8SA, which is very interesting, because the cover itself has no commercial part number of its own.

In the service manual for the Olympus CX31 / CX41 microscopes the manufacturer uses the official name "guide cover" for this part. The number AD7856 is placed on the part itself. Based on my experience with other, similarly marked Olympus parts, I believe this is the permanent numbering of this component and that the number can be used for identification.

The part is so delicate that it could even be described as "very thick foil". As a result, it is highly susceptible to mechanical damage.