Correct, what i measure with my multimeter is equal to the boiler result of test 5 (both are now around 4V ).hvxl wrote:To make sure we're not chasing ghosts, can you measure the voltage on IC1 pin 18 with a voltmeter in the same situation where you run diagnostics test #5? So, IC1 installed, OK1 removed and power applied. The results should be similar to what test #5 reports for the boiler, so around 3.3V.
I measure still around 4V.hvxl wrote: If that is the case, let's narrow down where it's coming from: Disconnect the gateway power, remove IC1, and reapply power. Now measure the voltage on IC1 pin 18 again. If you still find 3.3V, it's coming from somewhere outside IC1.
I don't know if it is still relevant (because i measure 4V and not 0 V) but did this test also.hvxl wrote: If you now measure 0V, the short-circuit must be to some IC1 pin. In that case, remove the power from the gateway and measure the resistance from every IC1 pin to pin 18. You should see infinite on most pins, although a few may give a reading. Any reading below 330 ohm needs further scrutiny.
*between pin 18 and pin 5 of IC1 I measure 316 Ohm (R4 also measures 316 Ohm but it's in the 5% range so I assume this is ok).
*between pin 18 and pin 14 of IC1 I measure 407 Ohm but it looks like the value isn't stable... I checked the soldering around pin 14 and resoldered it on both sides but it is not always stable......When I measure between pin 14 of IC1 and pin 6 of OK1 there is no resistance.