STFA20 - 10-1-2020 at 06:02
I mixed up my wall warts somehow and plugged in a mysterious 9v AC, 15 A power supply to my Accumet pH meter. I don't own anything that uses 9V AC but
it found its way into my life anyway.
There's no visible signs of cookage to start replacing parts but I figure there wouldn't be much in the circuit to protect against AC, so the IC's are
likely gone and the board is scrap.
I'm trying to reduce waste and repair as much as I can, and realized that many of these instruments these days are just a board and
sensor/display/output, and if you could source the PCB, you could have the instrument without paying for the box.
For example, with this board and a Weller pen, you have a fancy Weller soldiering station that could be added to a panel if you're offended by open line voltage.
Point is, there's no difference at all between that and the one from Weller except for the price.
Anyone have a line on OEM boards for scientific instruments that don't require much else? like a Fisher Accumet 15 for example? *cough*
Thanks
Twospoons - 10-1-2020 at 14:29
Your link looks like a pulled board from a defunct weller soldering station.
For something as specialised as a bench pH meter, the only thing you might find is another junked meter of the same type, but with a working board.
Being an EE myself, I'm surprised your meter doesn't include protection on the power input. I would design that sort of thing in as standard,
especially for an expensive piece of lab gear. Are you sure you haven't just toasted a fuse? A common ( and cheap) method of polarity protection is
a fuse and a diode, such that the diode shorts the reversed power and blows the fuse. It may not look like a fuse either - it could be a soldered in
fuse, that looks like a black cylinder or small plastic box around 10mm in size.
[Edited on 10-1-2020 by Twospoons]