Amazing amount of custom modding. While I understand little of it, still find it entertaining. I would be heartbroken when it failed after all that time and effort, so I appreciate how far you go in your experiments!
It's for science
P.S. I think the big WW power resistor is needed to help the PTC take the hit.
Carbon comp power-resistors are expensive and end-of-life now, drift is terrible.
How many here or anywhere would take a full day to mod a $20 meter, just to test it to failure, for NO financial compensation? You are far too modest, and way UNDERPAID!
It's for science
P.S. I think the big WW power resistor is needed to help the PTC take the hit.
The Gossen's gas tubes are fast enough?
The Hioki PCB DT4252 layout- a 1,000V fuse with tiny spacing between the trace and clip.
I'd expect an arc there after the fuse clears. Sigh. Engineer's screwup telling PCB CAD guy that both sides of a fuse are at the same potential. Not after it blows...
Fuse holders with fuses intended to be replaceable by an OPERATOR shall not permit access to parts which are HAZARDOUS LIVE during fuse replacement.
101.3.2 Protection by a certified overcurrent protection device
If the protection device is a fuse, it is replaced with an open-circuited fuse. ....
A voltage of two times the highest RATED voltage for any TERMINAL is applied to the TERMINALS of the overcurrent-protected measuring circuit for 1 min. The source of the test voltage shall be capable of delivering 500 VA. During and after the test, no damage to the equipment shall occur.
There is no need to guess about the HIKOI. If you look on page 31 of this thread, we spent some time going over it.
There is no need to guess about the HIKOI. If you look on page 31 of this thread, we spent some time going over it.
Link!
There is no need to guess about the HIKOI. If you look on page 31 of this thread, we spent some time going over it.
Link!Screwdriver drop test!!!
UL 61010 certifiers told me spacings must be met around the entire fuse; (not just the end-bells or clips). Why the mid-section is ceramic.
Their answer:
Because you never know exactly where inside a fuse the link has melted i.e middle, left, right- regulatory consider the entire body of the fuse energized to hazardous live, and carbonized (=conductive).
Additionally, spacings surrounding the overcurrent protection device in the equipment and following the protection device in the measuring circuit shall be sufficiently large to prevent arcing after the protection device opens.
So I had to do placement and PCB layout that leaves a large island around the entire fuse. If parts are too close, you see heatshrink covers used.
It's too bad a 5x20mm fuse could not be developed with a (DMM) 1kV high-interrupt rating. These DMM fuses are pretty huge.
AN8008 CALIBRATION BASICS
I've figured out how to do calibration although I don't have the finer details worked out. Here's what I know...
1. Short out J1 on the PCB (it's at the top right corner as you look at the PCB from the back of the meter)
2. Get your calibration reference ready and connected - in my case a 300 mA DC feed through the mA/A terminal and Common
3. Turn rotary control from off to the resistance position and CAL will appear on the display
3. Now WAIT until you hear a beep and then move the rotary control to the mA/A position - if you turn the rotary control away from resistance too quickly it doesn't show the values you've selected but moving the rotary switch around corrects that
4. Press [Set/Hold] (orange) button repeatedly until you see DC mA and a value will be displayed
5. Now you should see a value close to what you're providing the meter with, around 300 mA DC in my case
6. Press the [Range] (blue) button (quick press) to range down (but it only does it in 0.1 A increments)
7. Press and hold the [Range] (blue) button (long press) to range up (but it only does it in 0.1 A increments)
8. Press [Set/Hold] (orange) button to move off that setting (I think this is when the cal change just made is saved)
9. Move the rotary switch to off
10. Clear the link on J1 and power back on and test
As far as I can tell, the trick is to set the input to an exact value like 300 mA so you can set that value on the display during cal because you can't adjust the display to 303 mA so, for my slight discrepancy, I saw 298 mA displayed, I ranged down - I saw 200 mA, and then ,with a long press of [Range], ranged up and then I saw 300 mA displayed, pressed the orange button again and I was done. Other parameters can be set by pressing the [Set/Hold] (orange) button repeatedly but you'll only see values corresponding to the rotary position selected so you'd leave it in the resistance position to cycle through the measurements associated with that position including resistance.
What I'm not clear about is when it actually stores a new calibration value, I guess that, once you use the [Range] (blue) button, it changes the calibration for that setting, and I think it saves it when - having got the display to show the value you want, you press the orange button once more.
At first I did my above procedure providing 300 mA but ranged down to display 100 mA and couldn't change that value because I hadn't figured out that a long press ranges up by that point. So when I then switched off and removed the link, it had calibrated the meter to display 100 mA when 300 mA was supplied which it did. I had to re-calibrate after I figured out that the long press increases the displayed value.
After I posted a video where I had modified the KZ102 (AN8002) to the capacitance readings were off about 100pF. Someone had wrote me about modifying the contents of the PROM to realign it. Seems like a lot of work. Does anyone know if the above procedure applies to the AN8002 (and others) as well? For capacitance and current, what are the standard values that are required?