Ignoramus19508 wrote:
On 2008-01-31, Don Foreman wrote:


In fact, this is what I like about these boards, they are 1) very low
tech and 2) easy to repair due to good part placement 3) easy to
identify components, which look mostly off the shelf.

My repair was, obviously, the most trivial kind, but I appreciated
repairability of these boards.
I had to dig into my 800+ Pound Lincoln square-wave TIG 300 machine, and
old-school
transformer AC/DC constant-current power source with SCR phase control.
Well, the power components are mostly brazed, welded, etc. and then
everything bolts together. But, there are several fairly large circuit
boards in it. There is a main control board that pretty much covers the
entire back of the control panel, and then a power supply board, a phase
controller board and a safety board, as I recall. Yes, everything is
off the shelf, resistors, caps, ICs, pots and switches, etc. The shield
gas post flow timer was bad, and I had to trace the wiring and replace
it. As the damn boards are all conformal coated, I DID use my Pace tool
to desolder it, it does a much better job when the going gets rough.

Jon