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ArTurf
08-08-2008, 12:10 AM
I am dealing with a RainBird PC-506 that has started blowing the fuses that are in the controller, not the house breaker. I cannot get the fuses to blow when I manually turn on the stations but when I check a day or so after I put in a new fuse it is blown. Rainbird help line says it is a short in the wire to the valves but if that is the case why do they not blow when I manually turn on the valves.

bicmudpuppy
08-08-2008, 12:13 AM
How long are you running it manually? My first guess would be that the bad wire is only grounding out after the water runs for the equivalent of a full cycle.

CAPT Stream Rotar
08-08-2008, 07:15 AM
wm solenoids?

AI Inc
08-08-2008, 07:26 AM
wm solenoids?

Or an unwaterproofed field wire geting wet?

FIMCO-MEISTER
08-08-2008, 08:16 AM
Howling PVB?

AI Inc
08-08-2008, 08:25 AM
Howling PVB?

Personal voltage blower?

Mike Leary
08-08-2008, 10:16 AM
wm solenoids?

A solenoid that heats up could blow the fuse.

DanaMac
08-08-2008, 10:18 AM
A solenoid that heats up could blow the fuse.

Yes and sometimes it could take 5-20 minutes before it heats up. Seen it once, and SprinklerGuy mentioned it to me a quite few times.

Mike Leary
08-08-2008, 10:25 AM
Yes and sometimes it could take 5-20 minutes before it heats up. Seen it once, and SprinklerGuy mentioned it to me a quite few times.

I just replaced one where the fuse was blowing, but no "short" warning
showed on the clock. Had to ohm each one out & replaced the one with
the lowest reading, problem solved.

Wet_Boots
08-08-2008, 10:30 AM
You could just install 10 amp fuses, and come back later and install a better controller, after the old one burns out. :p

michigander
08-08-2008, 08:21 PM
Leary gave you the best advice. Ohm out each of the valve wires. Lowest reading will be the most shorted out solenoid. Dig up valve and replace solenoid. Problem should be fixed. :cool2:

irrig8r
08-08-2008, 08:49 PM
Unofficial translation:

To "Ohm out" means to check the resistance between the two solenoid leads using your multimeter set to the "ohms" (or Greek letter "Ω" for omega ) setting. Do this while no power is applied to the valves.

Mike Leary
08-08-2008, 08:59 PM
To "Ohm out" means to check the resistance between the two solenoid leads using your multimeter set to the "ohms" (or Greek letter "Ω" for omega ) setting. Do this while no power is applied to the valves.


After my 521 fiasco, I'm replacing solenoids that show
under/over 20 to 40 ohms. It's failing, might as well
change it out while you can still locate it.

irrig8r
08-08-2008, 09:51 PM
Bill Derryberry has a chart in his book where he lays out some values:

For a one valve circuit:

20-60 Ω is a sound circuit
"∞" is an open circuit
1-5 Ω is a sort
8-12 Ω is a partial short
60-80 Ω is a partial connection

Most solenoids I run across are in the 25 Ω ballpark (measured at the solenoid).
That includes Irritrol/ Richdel/ Hardie, Hunter, Rain Bird and Superior.
Weathermatic M24ESAKs run about 35 Ω.
A few older Toros run at 50-55 Ω.

Bill also says allow one Ohm of resistance per 100 ft. of wire.

BTW, If you are doing this work and don't have a copy of Bill's book, you may be working harder at problem solving than you need to.

Waterit
08-08-2008, 09:54 PM
BTW, If you are doing this work and don't have a copy of Bill's book, you may be working harder at problem solving than you need to.

Great reference for even old hands. Bill figuratively and literally wrote the book.