Adjust R6 accordingly to subparagraph d., (7), (c).
Once this is accomplished there are no further
(e) Should the voltage at terminals 20 and 21
of TB1 remain ON, regardless what position the
750 OHM Rheostat is in, then proceed with the
This also applies if NO voltage is
detected at terminals 20 and 21 of TB1.
Turn OFF Electrical Power
spection and repair.
Step 1. Inspect the circuit board for burned
or broken printed circuit paths. Bridge all open cir-
cuit paths with solid 22 AWG wire, making certain
that adjacent circuit paths are not shorted by
Step 2. If no open circuit paths or loose con
nections of components exist, locate RI, R2, VR1
and VR2. With the 110-120 Volts AC Source con-
nected to TB1, terminals 24 and 27, a reading of 28
Volts DC should be detected with Positive polarity
at R1 to VR1 junction, and Negative polarity at R2
to VR2 junction.
Step 3. If the voltage is lower or higher than
28 Volts DC, check the voltage across VR1 and
If either diode is removed from the cir-
cuit board, do not apply the 110-120 AC
Voltage Source at any time after diode is
removed, until the replacement is con-
nected to the circuit Failure to observe
this precaution could cause the supply
voltage being increased beyond a max-
imum limit for ARI causing complete
failure of the device.
Step 4. After checking the voltage across
each diode, replace either one of the two or both,
that does not regulate the supply voltage to four-
teen (14) DC Volts across each diode.
7 - 4 .
Step 5. After replacing any one of the two (2)
diodes or if there is no voltage detected across
either or both diodes, check the AC Voltage bet-
ween terminal lugs 7 and 8 of TI Power
Change setting of Multimeter to (AC
Volt, 50 Volt range).
Voltage reading between 36-40 Volts AC should be
present. If voltage is not present, T1 Power
Transformer should be checked to make certain
that 110-120 AC input voltage is connected proper-
ly, and all wiring connections to T1 are not loose or
disconnected. If this procedure proves all wiring
connections to be correct, replace T1.
Step 6. After verifying that 36-40 Volts AC
present, locate CR5 and CR9 on the circuit board.
Remove the 110-120 Volt AC voltage and discon-
nect one end of each CR8, or CR9 nine (9) diodes.
Set multimeter on the RX 10,000 OHMS scale. A
good diode will have no meter movement (High
Resistance) with test leads applied, in any direc-
tion and LOW Resistance with test leads reversed.
Remove and replace CR8, or CR9 if any of the two
tests prove defective. Install serviceable diodes.
Step 7. Locate Cl, and C2 on the reverse
side of the circuit board. With one end of each
capacitor disconnected from the circuit board,
check the resistance of each capacitor with the
multimeter set for RX 10,000. Connect test lead of
the multimeter to the POSITIVE scaled end of C 1.
The meter pointer should deflect to the
right half side of scale, then slowly
return to somewhere past mid-scale
toward left half of scale. If capacitor is
shorted or leaky, the pointer will remain
on the right lower half of the scale. If
capacitor is Open there will be no move-
ment of the pointer. Cheek C2 using the
above method. Remove and replace Cl
and (72, if found to be defective. If in
doubt compare the tests of C1 and C2
with a new capacitor, using the results of
the comparison for future tests.