Author Topic: Hydro-Hot circuit board  (Read 5537 times)

Roland DuBree

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Hydro-Hot circuit board
« on: September 01, 2015, 07:43:49 PM »
Anyone have a hydro-hot board go bad?  My board displays "RED Emergency cutoff" light.  Cannot get it to go off.  Supposed to indicate low antifreeze level in tank.  Have checked - not problem - even by passed float switch.  Hydro hot says bad board, new is $416.60 + fgt.  Cannot explain what might have caused board to fail.  Almost afraid to replace and something external caused board to fail and another board goes down in flames.  Present board shows no damage that I can see of any kind.  Any suggestions?
May try to bypass board to get electric solenoid the pick up to at least get electric hot water.

Orman Claxton

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Re: Hydro-Hot circuit board
« Reply #1 on: September 01, 2015, 11:57:13 PM »
Roland DuBree,
Where did you check the coolant level, Coolant tank or under the Radiator cap?
« Last Edit: September 02, 2015, 01:53:18 AM by Orman Claxton »

Darrell Terry

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Re: Hydro-Hot circuit board
« Reply #2 on: September 02, 2015, 02:28:24 PM »
Roland,
I found a Main Circuit board for my HH-500 at Northwest RV Supply in Eugene, OR. for $150. That was about two years ago but they had a box of them. Might be worth a call.

Darrell Terry 2004 Monterey
2004 Monterey
350 Cummins ISC

Joel Ashley

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Re: Hydro-Hot circuit board
« Reply #3 on: September 02, 2015, 10:30:51 PM »
Orman-
I know many failures are due to a bad hose to the expansion tank or a bad hose connector weld atop the boiler tank, and many owners don't check the boiler tank level, just relying on the expansion tank.  However, if the float switch is in the boiler and not the expansion tank, and Roland bypassed the switch with still the same result, would that not imply something else wrong?

If it is the board itself, and the switch is a normally open one that closes when the level is okay (which is why you can jumper its board connections to bypass it if it's faulty), then I'd first suspect a short on the board along that printed circuit.  But I commonly find micro-cracks (nearly invisible splits) in solder points to be a culprit on all kinds of pcb's;  a cursory exam won't reveal those - I have to carefully check each solder point with my OptiVisor magnifier.  I used to think micro-cracks only occurred on pcb's that heat and cool cyclically, but I've found them in things as inocuous as a wireless mouse.  A simple remelt of the cracked solder point is a cheap fix... if you can find the break.  I'd start from the board connectors for the float switch and work from there.

Nevertheless, it certainly could be something else.

But, Roland, did you reset the unit after you jumpered the switch connections, flipping the inside switches off for a minute, then back on?

Joel
« Last Edit: September 02, 2015, 10:37:04 PM by Joel Ashley »
Joel and Lee Rae Ashley
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36.9 ft. 2006 Monterey Ventura IV, aka"Monty Rae"
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Roland DuBree

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Re: Hydro-Hot circuit board
« Reply #4 on: September 15, 2015, 10:14:52 PM »
Have jumped float switch at JP-3 board and red light goes out. Have turned electric heat switch on and 120 VAC reads at heat element terminals, but NO heating.  Here I sit in Branson (site 103) at the BAC rally with no hot water and no heat. Any one here have experience with Hydro HOTs?

Orman Claxton

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Re: Hydro-Hot circuit board
« Reply #5 on: September 16, 2015, 02:24:02 AM »
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