Sanwa EM7000 Analogue Multimeter Review 

if first scale was let's say zeroed, it showed 1k, then moving the scale, it showed 900 ohms which is 10% not accurate, so he should've thought why is that, because that multimeter is not that much wrong. Of course you need to do zeroing for each magnitude/scale.

So he was using a megger to trace faults in a circuit board? That’s interesting. I’ve actually seen other people do this, obviously must be a bit complicated because if you just hooked it straight up… It would pretty much blow everything I think. I think it can also be used to test capacitor leakage in some cases if you have a dropping resistor. But I’m not really sure how that would work. I use power supplies all the time to find bad components. When quickly diagnosing a fault, I start with my FLIR thermal camera, but if that doesn’t work… I use a current limited supply with a resistor in series. So that I can push a low-voltage and controlled current through the board, and look for the heated traces or other signs of fault.. Most commonly shorts or heat… which has caused or is generating internal board faults, component faults, heatsink bonding faults, current overload faults, or even shorted faults hidden beneath multi pin components due to solder balls etc. Probing around all those small parts for faults can be very tedious. But with the constant current supply… I can quickly probe around and look for the lowest dropped voltage… Usually a pretty fast process but the flir thermal camera is always my first choice! Sorry didn’t mean to ramble, I’d be interested to hear how your dad used the insulation tester to find faults. analog meters are so important, most people don’t know how useful they really are! can easily see what’s going on in real time instead of super fast updates, with numbers flashing and speeding by on the new digital meters

Is normal practice in the electrical industry to use them on circuits that have potential wiring or equipment faults. They arent used on electronic equipment. Most experienced electricians know not to connect to live supplies that will potentially damage themselves and the equipment. They are never used on sensitive equipment only on circuit wiring and appliances that cant be damaged. On most mains powered equipment faults it isnt safe to start putting power in to the circuit. As may risk fires and potential other issues. They are never used on circuit boards on insulation resistance voltage. Finally the Megger name is a brand name that seems to be used on any insulation resistance tester.

The black case was purchased from the store in Akihabara, it was about 1500 yen from memory. overseas.sanwa-meter.co.jp/products/accessory-fuse/c_ca.html

Edit: I was a bit quick on my previous reply and put my foot firmly in my mouth :P In this case, for voltage, the specification does say a +/- 3% of full scale on the DCV range. So the most accuracy is near the top end of the range. That means only the last division is within 3%, it actually gets WORSE the lower you go, reducing to 3.75% at around 80% of the scale, 5% at 60% of scale, 6% at 50% of the scale, 7.5% at 40% of the scale, ballooning to 15% at 20% of the scale, 30% at 10% of scale. As the pointer approaches zero, the meter error is constant but the percentage of error increases until the over-all error reaches and exceeds 100 percent at the very low end. An example for your DC reading on the 30V DC scale, if you are measuring 15V (verified by some other source) the meter could read anywhere from 14.1V to 15.9V and be within spec. I'd recommend checking out the PDF I linked to below for more about it. For resistance, however, they give a specification of +/- 3% of arc which means the arc on the range selected. If you want to know how to read the resistance properly, check out this old Electronics World magazine from 1966. It shows how to read the resistance properly for different types of meters. On the magazine scan it'll be page 82, but it's page 78 of the actual PDF. worldradiohistory.com/Archive-Electronics-World/60s/1966/Electronics-World-1966-04.pdf

@@redemptusrenatus5336For what it's worth, the movement in this meter is *way* more accurate than the FS error specs indicate. The one I got is well within +/-0.5% on the movement linearity. It was hard measuring it to begin with - had to use machine vision to read out the pointer angle. The analog front-end could be made to match the movement if one wanted to. The FET front-end is probably where a lot of the error originates from. A jellybean CMOS op-amp should take care of that - even the lousiest op-amp is more linear than the movement. If someone wanted to design an alternate PCB for that thing, it could be a pretty good upgrade. With a good nanovoltmeter front end it's possible to use the taut band as a torsion strain gage, although that's of academic interest mostly. It requires resolution and stability that costs so much you could just slap a resolver in there and have a meter with a mechanical accuracy good enough to read out with a loupe :)

I could do a trimpot swap, but then I'm up against the inaccuracy of reading an analogue gauge anyway. I've swapped trimpots out on other gear before for the exact reasons you mention (like my Yokogawa 2554 volt/current standard I made a previous video on), but I don't think the improvement in accuracy would have much effect when the display isn't digital. Plus it is still under warranty, so it'll have to wait before I start modding it anyway. :D

Ah yep, you are correct. :)

You just did. :) What's up?

@@NearFarMedia Two things, I have something to send to you for review and perhaps use. Just a little electronic project. Not so soon as the current situation not okay yet. The other thing, I wish to communicate through email. my email is yusdiytechATgmaildotcom

Nothing from the manufacturer unfortunately.

Yeah, I couldn't believe my luck! The boxes were a bit expensive, but the free stuff inside made up for it in the end. :D

The adjustment is to allow you to zero the ohms scale in each range before taking a measurement.

A Sanwa for $11? If so, it won't be genuine... If it's another brand, I wouldn't trust it to be safe or accurate as far as I could throw it. :)