Du Pont SORVALL RC-5 Service Manual page 106

So
rva
I Is CentrifugesDrive
System
CircuitTable
4-10.
Troubleshooting Chart,
Automatic
RateController
Sheet
2 of
4PROBLEM:
Incorrect slow mode
operation.Completed
run produces
non-resolvedsamples.System
Conditions:1.
SLOW
switch
ON.2.
"Speed"
control set to more than
1000
rev/min.Door
closed.4.
START
switch
ON (START
lamp
lit).Remove
power.
Check
continuitybetween
the following
points:P200-2
and
J305-8J200-2
and
K210-5K210-5
and
9K210-9
and
J109-9Repair
open
circuit as
required.Remove
power.
Remove
silencer.Restore
power and commence
aslow
start. Observe
brushes.Are
they
retracted?NONOCheck
for
11 5 V ac
betweenP305-8
and
gnd.
Is
voltagepresent?YESYESNORemove
power.
Check
continuitybetween
J305-8
and
gnd.
Iscircuit
open?Faulty
brush lift
mechanismin
motor
assembly.
Repairor
replace.YESUse
test tachometer to
observespeed
at point of transitionto
RUN.
If transition
pointis
below
1000
rev/min,
adjustR14
slightly
counterclockwiseuntil
transition occurs
at1000
rev/min.Replace
brush lift
motor.8/79RCS'1504-25