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The object lens current control box.
Object lens current control - overview. Notice the two tubes for cooling water to the left and the
lid of the oil tank to the right of the relays.
On the left side are all the contacts and on the right side is the fuse and a
control lamp to indicate a blown fuse.
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The transistor side.
All transistors ans some of the resistors are mounted on a plate with an integrated cooling pipe.
Either there have been a reconstruction of this card or some of the transistors have been removed.
I can't find any traces (loose wires) of any more transistor so it's probably been rebuilt in 1996.
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The power resistor side.
These resistors are connected together, forming the R10 - R14 resistors connected in serial with
the lens.
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Side view.
Here we can see the tube for the cooling water that goes around the transistors.
The emitter resistors (R1-9,46-53) are mounted on small plastic towers. Some of the towers
are broken but it probably doesn't affect the functionality.
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Lens serial resistors.
A close up of three of the RWH40 resistors that makes up the serial resistance for the lens.
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Resistor ladder.
This is part of the resistor ladder (R15-R44) and some other resistors.
I don't know what function the ladder fills, the different voltages goes away to the
control box.
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Possible failure.
The mounting pads for the resistor ladder seems to be too weak and it ought to have at
least one more screw to hold it to the cooling plate. As it is now I suspect that when
it get hot the plastics expands more than the cooled plate and forces the mounting posts
down into the plate, shortcircuiting the transistors.
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Thermo guard and transistors.
Here we have three of the transistors and the 50° thermal switch.
The transistors are of type BU126, NPN, 700V / 3A / 30W. In the original drawing the
transistors were 2SC792, NPN, 300V / 1.5A / 50W. The manufacturing date of the transistor
is 1996.
That tells me that this is probably a refurbished unit.
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Relays and feedthrough.
A closer look at some relays and the signal feedthrough into the oil tank.
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Cooling tube.
The cooling tube, seen from the bottom.
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Contacts.
These are the connections for control, powersupply and the lens. Two of the contacts have
been removed, but they were lying together with the unit.
OL - Object Lens, OLPS - Object Lens Power Supply, OLC - Object Lens Control.
RO1 goes to the Right Control Panel Housing and RO2 goes to the Left Control Panel Housing.
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The object lens.
The lens consists of a couple of copper windings on a water cooled iron drum. There are two
separate (?) cooling circuits and the four water tubes are clearly visible in the picture.
This lens was an old replaced, possible broken one that lay beside the TEM.
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