PULL OUT THE DETECTOR CARD
This is another (last) difficult step. Also, you will need to be
creative and careful one more time: when we free the detector card from
the back of the box (instructions below) it will drop to the bottom of
the box, carrying the thin wires with it. Having the box tilted helps,
but horizontal is better or use small pliers (the kind that presses by
default) to hold on to the card so that it doesn't drop when you free it.
Now the detector assembly is tied to the G10 plate, but free from the box.
Either now or in the following
Unscrew the upper cold strap from the back of the box.
Unscrew the 4 screws that tie the the G10 plate to the back of the box.
Those are labelled A, B, C, D in Drawing 4. Remember which
set of four holes at each corner is being used, since that determines which
quadrant is aligned on the optical axis.
step is when the detector card will want to drop down if you are holding
Now, that thing at the center of the card is the NICMOS3. It is sitting
in its socket, and is covered by the "detector cover". The detector cover
is in turn being pushed down by a copper squared-ring spring held by
Unscrew the 4 more inner screws in that same G10 plate, labelled 1, 2,
3, 4 in Drawing 4. Keep one of these screws handy, you may need it shortly.
Now you can tilt back the G10 plate somewhat, and gain access to the screws
that attach the lower cold strap to the cold finger. Remove them.
This is a pain, and putting it back is a bigger pain even, but you'll manage.
Then, you can separate the G10+cold strap and set it aside.
The next step is to pull out the detector card. Note that it is permanently
attached by the red thin wires to the connectors in the cross-brace,
so it will not go very far. My trick is to flip it as I pull it
out so that the front (incoming light) faces up, and set it on the back
of the box itself. This is again why being horizontal
helps. Be careful not to pull on the cu-c wires as you take the card out,
and not to press on them when you set it on the back of the box.
That way it won't wiggle around, or fall off. But this may not be worth
it if you are not going to do a lot of work on the card.
Eliminate the 4 screws that hold the copper square-ring spring. Do them
so that the spring doesn't fly into your eye and back down
on top of the detector. Another trick at this point is that you can use
one of the free holes on the detector card from this last step to actually
secure the card to the back of the box using the screw that you kept
handy in (5-c), and one of the holes in the back of the box.
That's it. Go take a shower.
Now simply put the replacement detector cover in place, being careful to
properly align the inner recess with the detector and
Then, put the spring back in place. Turn the screws until the spring is
pushing on the cover nicely, and symmetrically.
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