So I called in sick today to play with my new 14g and 18/21g baskets I ordered. I see the wife off to work, and fire up the machine. I come back about 30 minutes later. Grind some [Unicorn Pony], tamp it down, and run a cooling flush. Something doesn't sound right. I do it again, no steam. WTF.

Sure enough I touch the water, cold. Okay, now I'm not happy. I rip the side off of the machine to start looking for problems. I power cycle the machine, and the correct LEDs are lit. I rip apart the other side and top, and probe the heating element. (0VAC). Power-off.

I unplug the +120V lead, power on, and probe the supply for the heater. It shows as +120V. Power off.

I connect the lead back to the heating element, power on and get 0V again. Power off.

This is when I start checking the wiring. I find this:


The pins / wire in question is the supply for the heater element. I remove the offending pins from the connector and re-crimp the wire. Okay, maybe it was just a really bad connection... Nope, still got 0V at the element. This is where I start to dig deeper.

I finally get to down to the only remaining items. The triac that controls the element. I find a supplier (Jameco) that has a replacement in stock. I order 3. My motherboard has room for 3 groups, but only one is used. So I only replace the one triac connected to my one heater. I power on the machine, GFI trips. CRAP.

I was given a similar spec'd triac, except for one VERY IMPORTANT item. My machine uses BTA24600WB triacs, but was given a generic Q6025R6. The tab used for heat dissipation on the new triac is connected to MT2 (+120V when on). The old triacs are isolated. Now I know why the GFI snapped.

Okay, so the $7 I spent on triacs is worthless now. I now give up and steal a triac from another group's circuit. I only have one group, so group 2 or 3 won't miss their triac, right? So I get all of the put back together, and fire up the machine. This time NO power to the element. The motherboard is not even trying to power the triac. Back to the diagrams.

I'll wrap this up. After moving a few jumpers around on the board, I get the heater to go. The pressure stat seems like the problem. After returning all jumpers to normal, and a power cycle, I had to adjust my pressure stat WAY WAY up to get the heater to turn on. Once at 1.1 bar, I have to fine tune the pressure stat over and over to keep the machine stable. If I don't keep adjusting, the pressure is all over the place.

So, now I wait on espresso parts to ship a thermister retro-fit kit.

To Be Continued...

Okay,
I removed the old bendy tube pressurestat combo and installed the Thermosistor retrofit. Machine immediately powered on and filled the boiler. It's nice to note, on initial startup, the motherboard will not engage the heater until the boiler fill cycle completes. The machine came up to about .6 bar and stopped. I adjusted the trim-pot higher until the machine stopped at 1.1 bar.

I ran the machine via group head, hot water tap, and steam wand. Every time, the heater turned off at 1.1 bar.

YAY! I have a machine again!

Now, if I want to replace the stolen triac (from the other (unused) group circuits), I will need to order in the special isolated models... :(

Infact, the triac is mounted to an aluminum block, mounted to a metal body panel (firewall?) that separates the boiler from the motherboard. When I removed the old triac and block, it was liberally coated in a thermal compound. upon motherboard re-installation, I used my good computer thermal compound to connect the triac and aluminum block. It gets pretty hot on initial startup. I'm wondering if I should add a heatsink to the back of this panel to help keep the triacs cool?

Okay, well, nobody seems to have an opinion about adding a heatsink to the back of my triacs, so I'll be doing that tomorrow. I am expecting a +15 horsepower gain.