Mastech MAS830 AND Equus 3300 Digital Multimeters

SEE post #26 for the Equus Meter

I picked this up for $12 + free ship. From a few of the reviews and comparisons, it seems like it might work. I could buy a Fluke, but if I spent $150+ on a meter and it only lasted a few days, due to my stupidity, I would feel really bad. At least these ones I don't feel so bad when I fry them. I have another kind coming, for $8 and I will see how it does too.

This is just an unboxing first view.

I don't have any testing info. I plan to use it for reading amps and when I get a couple builds done, I will test it against my old reliable analog amp meter and see what I get.

I have 12ga wire coming and I plan on soldering short leads right into the meter's terminals.

Good idea on soldering directly to the terminal. My Mastech has a flaky terminal that I have to wiggle to make work, and I'm close to soldering directly to it too.

Those piezo leads don't look like they're soldered very well.

OL…can you test a light prior to replacing test leads…then afterwards? I would be very interested in what difference, if any, it makes.

I got mine at Home Depot, they sell it under the “Commercial Electric” brand. I like it a lot and used to have a “Velleman” that was also the same meter. I left the Velleman out in the rain last year and had to throw it away.

It looks like yours has a backlight and an audible diode tester. Mine has no back light nor the audible portion of the diode tester. HD sells my meter for $20 but I got mine on clearance bundled with af diagonal cutter and wire stripper for $15

Sure, I can do that and see what the difference is.


I tested out the new meter. It's dead now.

First test was with the stock leads. 20ga wire, 24" in length.

Both lights showed to be exactly 5.30 amps with 18650-20R cells and 5.65 amps with 26650VT cells.

Then I put in 12ga wire, 12" in length. I soldered them directly into the meter.

First test was with the 26650VT batteries. The amps rose immediately to 6.95 amps. - POOF! I heard something in the meter pop and zero amps. I imagine it blew a fuse, but my question is, if the fuse blows at 7 amps, how can it be a ten amp circuit? It's supposed to read up to 10 amps.

Sometime I will check it.


It is very common to use a fuse below the meter rating, usual it say it on the front of the meter (Like: 10A for 30 seconds) or in the manual. The reason for the limited time is heat, the shunt inside the DMM will get warm and the reading will change.

For checking tailcap current, it might be a good idea to short the fuse with a thick piece of wire, to get as low resistance as possible.

I think you really should consider getting one of the free Harbor Freight meters. I know I will be criticized again for saying this, but some of the Harbor Freight meters have a direct path from each terminal to the shunt resistor. The Mastech goes through a significant amount of circuit board trace that adds resistance. It also goes through a fuse, which can be a good thing.

Here I have soldiered 14ga wire to the terminals of the 10A terminals of the HF meter.

There is a direct path from the wires to the shunt resistor and back out. Less resistance, less chance of blowing a trace on the board and great current measuring capacity. These meters will read up to 20A on the 10A scale. The question is, will the meter be able to take the abuse. The HF meter, direct path and no fuse, has a better chance.

I am willing to take the heat for advocating the HF meter for just this type of use because I KNOW that they can be a good choice. I make NO apologies for my stance on this issue. People can think what they want of me.

Someday I will post the results of an experiment I would like to do. Hook a thermocouple to the HF shunt resistor and see how many amps my meter can take for an extended time. At 20A that 0.01 ohm shunt will have to dissipate 4 watts, at 10A, only 1.

Ouch! Sorry to hear that. Is it completely dead or can a fuse swap fix it?

HKJ and dchomak already covered the two things I was going to say.

  • The amp-measuring looks pretty clearly to be fused, so I’d just solder a wire in place of the fuse. I’m told not to solder wires directly to the shunt (it changes the length of the shunt, which should really throw off the accuracy of the readings).
  • Or just use the (free with coupon) HF DMM. Solder thick leads on and be done with it. That’s what I’m using.

Ouch! Even at $12 I would be pissed. I hate it when tools break.

For what it is worth...these meters are designed to mimic the Fluke automotive meters which is why the internal circuit runs through a "delicate" board circuitry. Modern automotive computer systems need a certain amount of impedance to avoid pulling too much and "letting the smoke out of the box". The Chinese models often have a lower rated fuse simply because they can get away with it where automotive diagnostics do not tax the circuit and if there where a problem taxing the circuit then the meter quits before a $500 computer.

For these purposes (checking current draw on the lights), and already suggested, it is best to use cheapest $3 meter available because they do not have the high impedance circuitry OR if money is no object an electrician's meter (the skinny ones that have the positive probe built in to the end).

Of course, a high end Fluke would not do this but who needs a Fluke to check current draw on a flashlight?

Curious to hear about the $8 meter.

It’s awesome to see how cheap these things have gotten. I remember how much my dad’s RadioShack model cost in 1994. Ouch!

Instead of buying multiple cheap items and break them, I think it would be wiser to buy something a little bit more expensive but more robust like this clamp meter.

Where OL is located he should be able to get a simple, virtually unbreakable meter from Harbor Freight for either <$10 or for free (no purchase required) if he deems fit to use a coupon. The shunt gives accurate readings with appropriate hookup wire. Will a DC clamp meter reliably give accurate readings? (I don’t know the answer. My question is not rhetorical.)

That clamp is supposedly accurate to 2% +5counts.
Not too bad for flashlight current measurement.
I agree that using an unfused meter is cheaper. I was just suggesting the clamp as it is not intrusive. no need to disconnect anything to measure current. (Well, for tail caps readings you’ll need to place a wire to complete the circuit on the tail.

The meter I saw the HF here in Tyler, at least the one I believe is the same as shown, (they only had two meters in the whole store), was $49.95 here, in the Tyler store. No coupons I know of and never free here in Tyler. Tyler is considered a "retirement community" for rich republican folk from DFW. Everything is higher here. That's why I shop wal-mart exclusively here, or on line mostly. Tyler is too expensive, but it's where my wife owns a home, so we are here, not by choice.

That’s interesting (and annoying). I think you’ve mentioned previously that the buying situation in general wasn’t so hot in Tyler, I’d just forgotten. It’s not an in-store promo though. You need to show up with a coupon in hand. I’m not aware of any HF stores which do not accept the coupons, but I think that they are independent franchises so I think it may be possible for them to refuse coupons. No rainchecks though, so if they really don’t stock the item you’re out of luck. I generally ask a sales associate to look in their system and see if they stock things by item number. There are several item numbers for the free DMM: 98025, 69096, 90899. I don’t have a current coupon for the DMM, it’s typically offered for “free with any purchase” more often than it’s offered “free / no purchase required”. Here is an expired free/no-purchase coupon from earlier in the summer which explicitly allows you to print it and carry it in - this was in the HF email newsletter. Typically good physical/paper coupons show up in auto magazines (all of them - tuner, classic, truck, etc), including “free” stuff coupons. The way the coupons all work is off of a small code at the bottom. The cashier is capable of simply typing the code in if you were to recite the code from memory, and most will do so. Here is a currently valid coupon which does not explicitly allow you to print it (it’s a scan from a flier or magazine).

I definitely don’t think that they can set their own pricing. If an associate can find you the right meter, this is a known good option for us at either price point - Free or $7. Better than continuing to roll the dice IMO…

EDIT: Good Luck!

the H.F. ready to go, $10 or $15.