Rheem RTG2-42 Troubleshooting Manual page 43

Is there
voltage thru
the 3 amp
fuses?
Yes
Is there power
to the Printed
Circuit Board
from the
transformer?
Yes
Is there power
to the Printed
Circuit Board
thru the PCB
fuse?
Yes
Unit appears to be OK. Try to restart.
Did the
unit go to
main
burner?
See next page
No
Check fused power leads next to junction box.
Check and verify the fused leads next
to the junction box on the black and
white wires are OK. Replace with 3
amp fuses if needed.
Measure the voltage of the wires
inside the junction box of the water
heater between the black and white
wires at 108 – 132 VAC
No
Replace transformer
Measure the voltage of the two red wires on
the bottom right of the PCB @ 90 - 110 VAC.
Second Generation 4.2, 5.3, and 7.4 series
have black and white wires for this test. You
will also see a true 120 volts. The second
generation 4.2, 5.3and 7.4 series units don't
have transformer.
No
Replace 5 amp fuse
Measure the voltage thru the fuse located on the board. Measure
both sides of the fuse to ground @ 100 VAC.
The second generation 4.2 and 5.3 units do not have a
transformer; you will see 120 volts.
42
SVC 810 Tankless Troubleshooting Manual