More parts I need to replace on the VT100

Dwight K. Elvey dwight.elvey at amd.com
Wed Nov 30 20:31:42 CST 2005


Hi
 I looked at the schematic and the parts you'd indicated.
It looks like one of them was one off and was R55 and not
D11. From the looks, it might be that you have other failures
in the supply. You've indicated R11, R21 and R55. These
are all part of the circuit that drives the primary switcher
transistor through T3.
 You might check D11 to make sure it isn't shorted. You
might want to run the supply separately to check outputs.
A short in T3 to the mains would also cause a lot of troubles
and burn these resistors( taking may other part with it ).
Other parts to look at would be:
Q2, Q3, Q4, E5 and D4
These are parts that could also be involved.
 It does look like there is something other than the
resistors blown in the supply.
Dwight





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