waterheater intermitten ?

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The fuses are supposed to protect the board from damage, but if someone used a larger-than-specified fuse, or simply continued to replace it, there could be damage to the boards wiring traces. Older circuit boards are notorious for failing intermittently, and many people replace them with a Dinosaur-brand board. There is probably a diode in series with the thermostat and over-temperature switches. If open, that could be your problem. It should be visible; inside a small, clear plastic sleeve. You can check it with a meter. Disconnect it from the circuit and measure the resistance. It should read a high resistance when you have the positive and negative meter leads hooked up one way, and a low resistance when you reverse the meter leads. If it shows high resistance OR low resistance both ways, the diode is bad. If it reads low resistance both ways, chances are good that it also damaged the circuit board by letting a high inductive voltage from the solenoids get back into the circuitry.
 
thanks karl i will check that tomorrow and repost. yes it did keep blowing fuses and my friend did replace a few before i got involved. he had removed the board and had it tested at gamblers it was good then i checked for 12 volts at solenoid i had 12 volts. removed valve and 1 sol. had gotten wet and was rough getting off the peg i bench tested both 1 was bad . gamblers said that the valve had to be replaced could not get just sol. i asked about used,they said to look out back i found 2. put 1 on and both worked on bench after putting back together igniter would fire as before but no 12 volt to sol. rechecked all connections and used eraser on board connections but still no 12 volt to sol.
 
Check for 12V where it comes out of the board, then follow it along through the diode, thermostat, and over-temp thermostat. Obviously, if you don't have power coming out of the board, that's probably where the problem is. Some boards have two fuses. Test by swapping in known good ones. Recheck the connections. Sometimes the wires will pull back slightly in the connectors when you remove them from the board, especially if you tugged on the wires themselves, causing an open. Push them back in all the way. 
 
as always thanks for the expertise. we will check these today, my friend had to go to Blythe today, but will work on it upon his return, and will re post. i see this has been read many times and may help others. this forum is great and i would like to thank all who lend their help.
 
karl we had the board retested at lifestyles it was bad bought a dinosaur board $105.00 with tax  {quartzsite tax ouch} installed board and it work now.  my question is does anyone have a schematic for for the board that came in it.
 
my question is does anyone have a schematic for for the board that came in it.
Probably not, and thankfully so! They fail intermittently as you've found out, and aren't worth the time and effort to diagnose and repair them - if that's what you were planning on doing. You can bet Dinosuar didn't copy the design (again, thankfully), and $105 including tax is about right.
 
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