BREVILLE BES 920 – TRIAC FAILURE

This is a common failing of the Bes 900 and 920 Breville Coffee Machines. The symptoms include; the machine going over temperature and the machine continuing to heat while turned off. In fact even before we look at the error logs I can plug the machine into a watt-meter or current meter and with the machine switched off, but obviously still plugged in and on at the wall, the machine draws amps. Any machine drawing 0.9 Amps or more in standby has an issue. The one that came into that has prompted me to write this post was drawing over 5 Amps in standby mode and I could hear the steam boiler heating the water.
On inspection of the error codes, error code number 11 read 99. This indicates the steam NTC sensor has gone over temp 99 times. We have a problem Huston and a potentially dangerous one. What do we do.

Amp Meter, showing 5.06 amps with machine turned off.

The first thing you need to do is purchase a replacement Triac board here. Yes I know we could just replace the Triac and I usually would. However I have done this a few times and it’s often more than just the Triac faulty on these boards and they are not of great quality. So its is easier to replace the entire board. It’s not difficilt, there are 3 wires to the 3 heating triacs and the neutral wire to cut. So 4 main power wires to deal with and make sure you connect correctly. I say this as the new board may have different coloured wires, so make sure you connect the correct Triac to the correct wire. And we have the control wires as well, but these simply unplug on the main board, so you can not go wrong. You will need heat paste, purchase that here.

A Brief Pictorial Follows;

Remove the back panel and locate the power wires – of course unplug the machine. They are behind the while sleeve.
remove the plastic cap and cut the 4 power wires
Now locate the triac board on the lid and remove the plastic case and unscrew the 3 trials from the heatsink. The PCB comes away. See below.
New Heat Paste Applied, yes liberally, heat paste is a better heat conductor than air.
New Triac Board installed, refit the case and its just the wiring to go.
Join the 4 power wires. I solder them to a tab of the old wire and then heat shrink.
Now locate the port for the control wires harness on the main board and connect it.

That’s all there is to it. Also note it is good practice to replace the NTC Sensor associated with the faulty boiler. So in this case the Steam boiler NTC. Sensor.

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