Water Heater problem

[whit]

Need some opinions guys,

My 1995 Atwood water heater is acting up. It would not fire up. I replaced the hi-lo sensors and the fusible link thinking the sensors might be the problem. Still wouldn't fire. In fact it does nothing. No sparking, no solenoid opening.
I got out the voltmeter and checked everything. It's getting 13.3 volts to the circuit board. So I figured it must be a bad ground or the plug isn't making good contact.
Redid the ground, cleaned everything, checked the little prongs inside the plug.
Tried it again. Nothing. Unplugged, replugged, unplugged, replugged, boom it fired.
I took the circuit board to the RV store and they tested it. Said it is good.
They said if it is getting good voltage to it, it should spark and the gas solenoid will open. I told them it does nothing. They said it has to be a bad ground or plug because the board tests ok. (When unplugging and replugging I'm talking about the circuit board)
I returned home and made absolutely sure it had a good ground and the plug contacts were clean, circuit board contacts clean. I turned it on, nothing. I unplugged, replugged 3-4 times boom it fired up. I wiggled the connector and the wires to check for a bad connection and it continued to fire, no problem. I unplugged it and it shut off as it should. I replugged it and it fired again. I unplugged it and replugged it again and it wouldn't fire. I kept doing this and sometimes it would light and sometimes it wouldn't.
I'm convinced it's the circuit board because there's no consistency when it works and when it doesn't. Although the RV guy said the circuit boards usually work or they don't.
Is that true or can they work intermittently as they go bad? Anything else I'm not thinking of? Thanks

[Old-Biscuit]

whit wrote:
Thanks guys,

Just received my new circuit board and installed it.
Fired right up 3 times in a row.
Pretty sure problem solved. If any of you have a problem with your circuitboard and you take it to have it tested just be careful if they tell you it's fine that's what they told me.

That's the problem with an 'intermittent' problem......it CAN test OK.

Sometimes you just have to do 'process of elimination' (trying everything else prior to replacement)

[whit]

Thanks guys,

Just received my new circuit board and installed it.
Fired right up 3 times in a row.
Pretty sure problem solved. If any of you have a problem with your circuitboard and you take it to have it tested just be careful if they tell you it's fine that's what they told me.

[j-d]

I had a friend's TC with Atwood WH in it, to a good repair and parts shop. First thing they did was clean and re-spring the contacts on the edge connector to the control board. The problem had been intermittent. The WH worked fine after that, but I don't know if the indeterminacy returned.

[Gjac]

Do you have the potted circuit board? What I have found over the years that was baffling to me also is that just because you have that correct voltage does not mean the correct amps are getting through. I would try a jumper wire directly from your battery to the fusable link the next time it won't fire and see if it consistently fires it should be the brown wire. You can compare the amp reading with the jumpered wire to your original wire this will tell you if you have corrosion somewhere or a failing switch. After playing with my WH for 10 years my board finally failed the test Old Biscuit posted and I replaced it with the Dinosaur board and it now lights every time. I also installed a new wire and switch.

[Old-Biscuit]

Test the 'Power Track' & 'Valve Track' on circuit board. Simple ohms test using multi-meter

See pg. 23...........HERE

Also good info concerning 'Intermittent Firing Issues' pg. 21 & 22

Dinosaur Electronics Board for replacement....get the cover also.

[whit]

Yes, I cleaned everything, male and female. 320 grit, lifted the female pins in the plug, etc.
Riddle me this. If when I connect it and it finally lights, I wiggle the plug, wires, etc, it does not shut off. If the contacts were bad or dirty or corroded, it would lose contact and shut off, but it doesn't. Thus the connection has to be solid right?
All I am doing is unplugging and replugging, sometimes it fires and sometimes it doesn't. If it had to do with the switch or other connections wouldn't it either work or not? The switch doesn't move once it's on. I don't get it. I'm going to clean and check ALL connections just in case.

[newman_fulltime]

If the shop can plug into it and it test fine then that tells me it's in the wiring.Did you pull the switch and clean those contacts?
Look at the wires there selves it could be corrosion try firing it without the heat link

[DAWg134]

Try thoroughly re-cleaning the power contacts once again.

I had a similar situation with a 12 Vdc power connection recently. Wire harness continuity measured okay on my DMM and open-circuit voltages were present at all pins. However, whenever I tried to pump amps through the cable, the voltage would immediately disappear. Wiggling the cable would make the voltage re-appear intermittently.

Turns out the culprit was some tarnish on one of the brass pins of a brand new marine grade connector. Although I had inspected the connection repeatedly, the brass appeared to be bright and untarnished and so the connector remained low on the list of suspects. It wasn't until I removed one of the connectors from the cable and "re-installed" the connector directly onto the DMM probe that I was finally able to isolate the cause.

In my case, I successfully brightened up the brass male contacts using fine steel wool, but a pencil eraser or emery cloth should work just as well. If the problem is in the female contact, you may have to squirt some de-oxidizing chemical (e.g., DeOxIt) to clear up any latent corrosion.

Afterwards, I was explaining the problem to someone and pulled out another brand-new-in-the-box connector to show them. On this particular connector, three of the four pins were visibly tarnished, but the fourth pin was bright and shiny... just like the four pins of the connector I had actually installed. It's just bad luck that I randomly chose the "good" connector. Had I installed the other connector, the visible tarnish would've been a dead giveaway.

Dale