Group boiler intermittent temperature control problem

[vanceh]

We are experiencing intermittent problems with our S1 V2 that I think may be related.

1. Flashing lights 20-21 alarm, described in the manual as a blocking alarm for "Damaged Group Heating Element Triac." Cleared this by power cycling machine (not unplugging the machine).

Several weeks passed, then:
2. Batch of coffee from our usual roaster that seemed off, burnt. No combination of grinder/tamping/etc adjustment seemed to get the flavor we are accustomed to from those beans. We wrote this off as a bad batch of beans, but it was odd -- a first for us after years of this roaster's beans.

A few days later:
3. Noticed machine making new steam-leaking noise while it was idle. Seemed to be coming from the group side of the machine. Pressed two-cup button and steam came out of group head. Took maybe 10 seconds before steam was replaced by a steady stream of water.

My theory is that all of these issues could be caused by a too-hot boiler due to some failure of the temperature control electronics. Through all of this, the behavior of the temperature lamps has been pretty normal. Holding at 95C, dropping down briefly when drawing a shot, etc.

I took the panels off the machine and grabbed my multitester, hoping that I could troubleshoot when the machine misbehaved again. It has been fine for several days.

Do these symptoms sound familiar to anyone? Any suggestions about how to diagnose?

Cheers,

Vance

[chas]

Vance:

The easiest thing to do first is to either pinpoint it to the triac board or eliminate that as the source of your problem. This is trivial to do since both boiler triacs are identical. Just swap the wires between the two triac boards. If this is the issue then you will see return to normal operation from the group boiler but of course the steam boiler may start exhibiting overheat problems.

However, in that case you can always manually turn off the steam boiler and continue to use the machine for espresso while waiting for a replacement triac board to arrive.

[vanceh]

Thanks for responding so quickly, Chas!

I think I will await until it misbehaves again before I swap the boards. It is reassuring to know that I can keep making espresso even if the triad board fails!

-Vance