CreativePart: If you kept your old circuit board, it would be interesting to know know if you can find a "cold solder joint" under magnification? Why?
...So you can get to the root cause.
BACKSTORY
I'm guessing you will find a "cold solder joint" where your diodes are located on your circuit board, but I don't know why diodes joints seam to "brake" more than others?
* I know these diodes are there to block (suppress) AC transients, among other things.
For reference information you can go to this website:
https://components101.com/articles/h...ge-suppression
* What I have noticed is that when you have a cold solder joint -- to a diode -- then I would say some transients get through; and the circuit is not stable. I.e., sometimes it works and sometimes it doesn't. And sometimes a cold solder joint may cause "open" circuit.
* The interesting part, is that these diode cold solder joints located in one part of the circuit board, can affect the function of a device on a completely different part of the circuit board,
because they share the same ground!
==> And the simple fix is just reflow the solder in the joint that is already there.
HOW DO YOU SPOT A COLD SOLDER JOINT?
* Simple. Just look with a high power set of reading glasses (maybe) or use a magnifying glass.
QUESTON: Can someone explain why diode joints crack when resistor and capacitor solder joints don't?
Do diodes "vibrate" and add stress to the solder joint? IDK. I just don't buy the problem is in the wave solder pass when the board was made, because several times now, when I paid a TV repair shop to repair several circuit boards in my RV, he always finds cold solder joints where the diodes are located... and occasionally a weak capacitor.
And when you think about it, in every RV, there are these little circuit boards, that are subject to heat and vibration and time. So I hope it's comforting to know, that if you can remove the CB you can also get it repaired for $50-$100.
Further, when you own an RV that is more than 10 years old, you often have to repair your old CB, because a replacement CB is not available.
...Then you learn there is an upside: I.e., you can save a lot of money by bringing your old circuit board to a repair shop.
... And when RV ownership is more affordable, it's also more fun!
Note: It turns out a TV-Satellite-Radio repair shop does NOT need to have a circuit diagram to repair your old circuit board. In fact, they don't care how it was designed. Why? ...Because they can do a component-to-component check and find the problem areas using a bunch of tips and tricks... and in the end, the fix may just come down to reflowing a bad-cracked "cold solder" joint.
Just a simple fix! ...Your mechanic will not mention most of the time, unless there is no other choice, because he is on the other side of the trade. I.e., he may not be the most objective tool in the shed.
On the other side, where would be if there was not a resident RV repair expert where you live? And in this case, when you pay for a diagnose you also get a complete system check-up, cleaning and adjustment, so you have the assurance your heater will be there when you need it.
In fact, I have never performed any maintenance on either of my 2 Suburban heaters, and I'm not sure I want to do it myself? The question then becomes: Do do I pay to get some preventative Suburban maintenance now; or do I wait until my heater starts acting up?