by lostmarbles » Wed Feb 21, 2018 11:17 pm
I had similar problems when starting out. I have a perforated plate 4" modular.
Turns out i had 2 plates leaking, mine are soldered so easy fix, and 2 of the 3/4" J down-comers leaking,again more solder.
It helped somewhat but I was still plagued with a random plate or plates drying up, sometimes fogging on any one of the sight glasses but usually one or two of the bottom ones, flooding and less than stellar product take off/ quality / smearing.
I tried different power levels, different take off rates, I even added more holes to the plates and then less holes by soldering them up.
It was on about my tenth run when I realised i had stuffed up and set my down-comers (Bath depth) to 26 mm above the plate, and the J cups could only hold 17 mm static height below the plate, net result was vapour was flowing up the down-comer, plate or plates above would be flooding, plate or plates below dry or partly full and not much real liquid movement down.
Fixed it by reducing bath height to 15 mm by chopping the down-comers off 15 mm above the plate so the vapour has a positive head pressure liquid seal in the down-comer. Everything now works as it should with no effort. Plates fill from the top down, stay full and are very even.
Maybe that story might be useful to someone.
It sounds like as others have said here, its either leaking on that plate or the down-comers aren't working right.