SERVICE MANUAL
Medi-Therm II
w
w
w
.g
aymar
.com P/N 10187-000 7/98
TROUBLESHOOTING CHARTS
*
*
*
*
No
Yes
Is it
opened or
shorted
?
Measure resistance
of heater. Refer to
power supply board
schematic (fig. 21)
for heater
resistance.
No
Yes
Yes
No
Yes
No
No
Yes
No
Yes
Yes
No
Yes
Yes
No
No
No
Yes
Is pin 7
ref to pin 10
of U51
0 VDC?
Suspect
control/display
board.
Repair/replace.
Suspect
board-to-board
connection.
Repair.
Suspect
control/display
board.
Repair/replace.
Disassemble
solenoids. Clean,
inspect seats,
repair/replace.
Suspect Q3 or U1.
Repair/replace
power supply
board.
Is
optocoupler
U1 input
low?
Is pin 11
ref to pin 10
of U51
0 VDC?
Replace
heater.
Suspect cold
solenoid SV1 may be
stuck open, or hot
solenoid SV2 may be
stuck closed.
Suspect
base-to-power
supply board
connection.
Repair.
Line
voltage at
output of
Q3?
Is
optocoupler U8
input pulled
low?
Line
voltage at
terminals 11
and 8 of
TB1?
Line
voltage at output
of Q9?
Check heater
(it should be on)
Line
voltage at
terminals 1
and 3 of
TB1?
Check
cold solenoid SV1
(it should be off).
See
"CHECK WATER
FLOW alert is on"
(figure 6I)
Is
there
adequate
flow?
pulled too
Figure 6K—Blanket Won't Heat in Auto or Manual Mode, Page 2 of 2
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