Trying again...pressure problems.

[brandon]

Posted this problem a couple months ago and has yet to be resolved. I've only lightly used the machine because: a) I don't want to cause further damage, if in fact this in indicative of damage; and b) the coffee tastes like crap because it is too acrid from the low pressure. Anyways, I've taken a new video with better lighting and sound. Notice how quiet the machine gets and how the pressure drops off. Yes, there is a bit of channeling early on but the pressure issues seem to have no correlation to that (i.e. I've pulled much better shots with much less channeling with no effect on pressure).

http://www.youtube.com/watch?v=zZ9ZFr0-3Rk

[rhinoevans]

I am not questioning your barista skills, but to me sound like chocking the machine because of way to fine grind and tamp pressure. What does it do with a loser grind and tamp. I have choked mine before with to hard a tamp and very fine grind. Takes for ever and very bitter. Just a thought.
Although it does get very quite and I do not remember that with mine.

[chas]

My first recommendation is to disassemble the group pressure adjustment valve. It could be getting stuck partially open.

The Mini uses the same part for group pressure control as is used in the "Maxis" as the expansion valve. There is a spring with a rubber plug on the end. This spring tension holds the plug against the end of a copper pipe to block the water flow. When set to 9 bar. It will open as soon as the pressure hits 9 bar to allow water to pass from the output of the pump back to the input. This lowers the pressure and the spring immediately stops the flow, the pressure instantly builds back to 9 bar opening the valve again, etc.

When you disassemble the valve you will see the impression of the end of the copper tube on the end of the rubber plug. Be sure it is centered and not right on the edge of the plug. Also be sure there are no hairline cracks in the rubber plug and that, in general, there is no debris of any kind inside the valve. If the rubber plug doesn't look right or the spring seems bent at all, you should probably order replacements.

If everything looks OK, reassemble, readjust pressure to 9 bar and see if it still happens. If so, it could be the pump.

Feel free to call CCS tech support and run the problem by them, too. AFAIK they don't charge for phone advice even if you didn't buy the machine from them or it's out of warranty.