Hi,
I bought a VT420 from a neighborhood garage sale ($5) that
turned out not to work. Turn it on and I saw nothing happening.
Only heared a faint "fip ... fip ... fip ..." kind of sound,
you know that one "fip" when a screen comes on, just a little
softer and repeated about 1 per second and no screen came on.
Opened the box and powered on, the kathode in the tube didn't
seem to glow. More inspection turned out that what seems like
a ceramic capacitor was exploded or fried, all black and
crummy, impossible for me to identify its specs. Can someone
help me out with a schematics or databook or something?
Again the terminal is DEC VT420
the blown-up capacitor is C621.
What kind of collateral damage do I have to expect? I mean,
does a fried capacitor normaly cut short? Here are some
hints:
- That C621 is in close proximity to C617, another sizeable
capacitor. However there are no marks left on that one after
cleaning the explosion site :-)
- A diode D603 is also in that neighborhood, doesn't look
bad, but I didn't test it yet.
- I do see suspicious brown-coloration in an area farther off
around D607 and R649. I wouldn't be surprized if R649 was
fried.
- R650 is in next to R649 but looks fine to me, though I
didn't test it. It's always a problem to test components
while in the circuit, don't know what I should expect.
I appreciate any help.
thanks,
-Gunther
--
Gunther Schadow, M.D., Ph.D. gschadow_at_regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistant Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org
Received on Tue Jul 17 2001 - 11:08:52 BST