fieldp wrote:30 minutes warm up. Let steam bleed. I did not see a pressure drop though
Did you bleed the pressure just after the machine reached pressure or after 30 minutes?
Your version is equipped with an ani-vacuum overpressure valve,
Which means it will vent some steam when coming to pressure, this can be enough to prevent a massive pressure drop during the bleed. Also if you bleed after 30 minutes the cold headspace will also have heated up a bit more so you'll get less of a drop.
fieldp wrote:When I tried the late lock-in, I got no water even at the very top and with pressure gauge showing 1 bar. I had to re-lift the lever twice to get anything coming through.
You mean with the portafilter locked in?
If so, you have fine ground fresh coffee in a tightly packed puck, this will hold the water back quite some time. I've even had the lever up for a few minutes in a test before any coffee came through the puck without applying pressure.
fieldp wrote:Maybe I choked it but after the second lift there was only moderate pressure. In the eventual shot, there was almost no crema
Almost no pressure in the first part of the pull? This means you'll have to do a fee more wiggles at the top to get the air out of the group. (You can search the forum for 'spongy pull' to get more tips and tricks on this)
fieldp wrote:I noticed the puck was a bit cracked. Also it seemed dry.
the dryness happens if the last bit of your pull is mostly air
fieldp wrote:I see lots of people saying 20Kg of pressure but no idea how to measure that.
Try doing the tamping on the bathroom scale to get a feeling for how much pressure that is. People also did this trick to feel how hard you have to pull the lever to get close to 9 bars of pressure.
fieldp wrote:The shot had an extremely acidic finish. Maybe not quite so bad as the previous but really pretty bad. But again, it could be me and the method
Light roasts have more acidity than darker roasts, if it is just at the finish, you probably have a cup that is higher than it is wide.
This prevents mixing if the espresso while you drink it resulting in a physically layered shot. (See also Are cup size and shape too often everlooked factors?
To prevent this you can stir or swirl the cup before tasting.
Again you may have to get the grouphead a bit hotter, try one or two lever strokes without letting water out before you raise the lever to lock in, this will raise the grouphead temperature.
fieldp wrote:I am only using tap water. Not filtered. Will do that, but not sure this is likely to be a factor?
Not likely unless the water has a strong taste by itself. It will mean you have to descale the machine much more often (depending on the hardness of your water) if you want to change that search the forum for rpavlis water (a recipe using distilled water and sodium bicarbonate to create neutral buffered water with minimal hardness)
fieldp wrote:One additional question, when the green light goes out, does that mean it thinks it's up to temperature or up to pressure or both?
On a pressostat regulated pavoni (such as yours) the light goes out when the pressure setpoint is reached, the heating element is then switched off. Boiler pressure has a linear relation to the water temperature, if the air above the water has the same temperature (hence the bleeding of pressure at the start).