Where would I be likely to find an AC ammeter trim? - Page 1
Forum section: electronics / projects

author: Ehryk
author_rank: Contributor
timestamp: December 11, 2015, 04:41:09 am
content: I have a power conditioner with a built in ammeter for the AC line.The problem is that with nothing plugged into the unit, it reads 0.5A. I can tell from the lack of heating that it's not constantly dissipating 60W.I'd like to trim out the 0.5A so that it reads 0.0A with nothing plugged in (essentially zero out its own draw, if possible). If there were to be calibration device available (trimmer potentiometer, variable capacitor, etc.), what components would it likely be connected to, and what might it look like?

author: Jeroen3
author_rank: Super Contributor
timestamp: December 11, 2015, 06:25:12 am
content: What happens when you short the input?

author: Ehryk
author_rank: Contributor
timestamp: December 11, 2015, 07:59:57 am
content: Short the input to what, the AC main input to the unit itself? Then there wouldn't be power on the display, so I don't know.

author: ConKbot
author_rank: Super Contributor
timestamp: December 11, 2015, 09:11:09 am
content: Not sure what exactly they have going on inside of there, but with all those caps pictured, if they are across line to neutral (Certainly cant be line to ground, wayyyy too much leakage current) Half an amp really could be flowing. Can you get an ammeter in series (or use a clamp on type) with the AC input?

author: Jeroen3
author_rank: Super Contributor
timestamp: December 11, 2015, 11:10:52 am
content: Hard to see on the image. But it's just an plug box with current sensor?Then you can't short the input to create zero volts over the shunt. Which often elimates such noise you have.

author: Delta
author_rank: Super Contributor
timestamp: December 11, 2015, 12:23:08 pm
content: In what way does it condition your power?

author: Dago
author_rank: Frequent Contributor
timestamp: December 11, 2015, 12:58:04 pm
content: Quote from: Delta on December 11, 2015, 12:23:08 pmI think this is the type of a product which mainly conditions your wallet to a state preferred by the manufacturer.

author: Fungus
author_rank: Super Contributor
timestamp: December 11, 2015, 02:06:13 pm
content: Quote from: Delta on December 11, 2015, 12:23:08 pmAccording to the web site it swallows up spikes and surges.It looks like an expensive way to add a $1 MOV to your equipment but then again, it's made by the people who make monster cablesandit's purple inside, so who knows. You'd think they'd at least get the calibration right, though.I wonder what the 'volume' knob on the front does. What could you possibly need to twiddle on a mains filter?Quote from: Ehryk on December 11, 2015, 04:41:09 amI'd start by looking on the board that's connected to the display, ie. the part that's half-hidden in the photograph.It would probably look like the thing labelled "VR1" in the middle of the board above it. "VR" could be "Variable Resistor".Thereisanother one of those half-visible at bottom-left. That might be it.nb. They're both covered in red gunk to lock them down after factory calibration. You'll have to break that seal. Adjust it with nothing connected. If the display doesn't change when you adjust it then put it backexactlywhere you found it before applying any load to the unit.

author: Ehryk
author_rank: Contributor
timestamp: December 11, 2015, 03:31:04 pm
content: They're fairly expensive new, (these are going for $400 new), I bought it for $90 shipped with a broken circuit board (just the corners by the mounts, no traces) and I like having a nicer looking and feeling central unit to plug my components into, and I like the voltage/amperage display, so I find $90 worth it. It certainly *feels* of quality, even if it's not doing anything that useful other than displaying things and makes my power routing nicer and shorter.Quote from: Fungus on December 11, 2015, 02:06:13 pmThe front panel doesn't have a volume knob, the center one switches between the voltmeter/ammeter on the display, then going to the right there is a potentiometer for dimming the display, then 'on' then 'off' for the switched outlets.I'm not under the illusion that it's doing anything great for my sonic output, I just can't hear the difference if it's doing anything negative, either, and enjoy the unit for non-sound based reasons, and I didn't come close to paying full price.Quote from: Fungus on December 11, 2015, 02:06:13 pmI'm curious for learning layout reasons - why would the trimmer be on the display board, rather than near the shunt? And how do you know it would be a VR, not a variable capacitor or other device?