Tankless Paloma Water Heater Igniter Problem

Hi guys,

Are you familiar with tankless water heater igniter control board ?
The problem is it won’t ignite electric arc.
I tried recaping the electrolyte capacitors, 100uF 10v which was faulty measured by ESR reading.
I measured the elco 10uF 16v, ESR reading is fine. So I let it alone.

I did replace the 3 micro switches.
2 of them are short circut, I tested the connectivity while they’re still soldered to the board.
But strange thing is, when I desoldered the 2 of them.
These 2 micro switches are fine, nothing is wrong with them.
But I replaced all of them anyway.

The igniter still is dead silent.

My suspicion is these little diodes are shortcircut or faulty.
I can’t find its schematic (tankless Paloma water heater PH5-WX)
to find out what are these diodes.
Anyone knows what these diodes are or has any ideas of how to fix it ?

RogMar:
2 of them are short circut, I tested the connectivity while they’re still soldered to the board.
But strange thing is, when I desoldered the 2 of them.
These 2 micro switches are fine, nothing is wrong with them.

That’s not strange, it just teaches you that you can NOT measure a single component while it’s part of a circuit (i.e. soldered on the board). Same for the capacitors, without removing them from the board first you can’t properly measure them.

Don’t mess around with dangerous stuff you’re not familiar with. An error here may cause the gas valve to remain open, and puts you at risk of gas explosions. Get a qualified technician to have a look at your board - maybe the board is broken, maybe the igniter, maybe something else: they should be able to fix it or if not fixable replace it, and keep you safe in the process.

I checked elcos and 3 diodes with ESR readings.

They are in good condition.