Cascade lamp and Coral interlock are broken

John Shott shott at stanford.edu
Tue Nov 16 16:26:02 PST 2010


Cascade folks:

The problem is not with the Coral interlock but with the microscope 
light or power supply.  Here is the report that I filed with Mihir after 
my investigation of the Coral interlock:

Mihir:

I've taken a look at this and believe that the problem is NOT with the 
Coral box.  The reason that the orange light on the interlock box wasn't 
on or the Coral "ON" light didn't turn on was that the interlock box 
(which is powered by the microscope power supply) was getting no power.  
Why? Because the fuse in the microscope power supply was blown.  My 
belief is that something is wrong in the microscope light assembly 
itself.  My guess is that there is either a short in the projector bulb 
or something in the bulb socket assembly is shorting to ground.

Here is what I did to test things:

1. Got replacement fuses ... this thing uses 2.5 A fast fuses in the 5 
mm by 20 mm size that are stocked in Physics Stores.  The little fuse 
holder beneath where the power plug goes has room for both the fuse in 
use and a spare.  There is currently a good fuse AND a spare.

2. With Coral disabled, I could power this up, which then caused the 
orange light on the interlock box to come on. However, as soon as I 
tried to enable the tool to turn on the microscope light, it promptly 
blew the fuse.

3. I replace the fuse and repeated the experiment ... but this time I 
left the projector bulb assembly pulled out of the box.  In this case 
enabling caused the "ON" light to come on and doesn't blow the fuse.  Of 
course it doesn't turn the microscope light on either because of the 
interlock in the microscope light controller that removes power from the 
bulb when the light assembly is pulled out.  This leads me to believe 
that there is a short in the lamp itself or in the socket.

So, your problem is not fixed, but I believe that it is back in your 
court and likely caused by either a failed bulb or a bulb socket problem.

Good luck,

John




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