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Registered Member #3124
Joined: Tue Aug 17 2010, 10:25AM
Location: 127.0.0.1, US
Posts: 19
I have an off brand DMM from a company named V&A (Mastech Shanghai). I don't have the fuses for it and I really need them for measuring current. I have been looking all over the net for replacements for it but am unable to find any either exact model or same ratings. Well I did find the 10a one at Digikey but it's like $5 per fuse. If that will work, I'll get it but surely there must be cheaper ones. Can anyone help me locate these?
DMM Model: VA18B
The fuses I need are Ceramic Fast blow 10a 600v 6.3x32 and 750ma 600v 5x20 (from manual). Not sure if they really have to be ceramic or not, I'm kind of unaware about all the technical details on fuses.
Fuse info from old fuses: 6.35x30 H600v ~ gG F10A ZH223 5.2x20 H500v - gG F0.75A ZH217
The 10A one I found on digikey is here I don't know for sure if that will work, but it all looks right to me.
I found some spec sheets on them here ZH223 and here ZH217 but they are both rated for 500v...
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
Ceramic fuses usually have a silica/sand filling that quenches (puts out) arcs, the plain glass fuses are ok for low voltage use but when there's a chance of high voltage and high current the ceramic types are better. HBC (high breaking current) or HRC (high rupture current) fuses are not cheap. Just have to decide how much it's worth to protect your dmm (and you)
European fuses tend to be 20mm x 5mm or 32mm x 6.3mm (length x diameter)
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
Test that it is working correctly on the relevant ranges before spending any money on fuses. In my experience it is not uncommon for multimeters to take damage if a fuse is blown.
For the multimeter to be safe at the rated voltages and safety category you should replace with the exact type of fuse specified in the manual.
Registered Member #3124
Joined: Tue Aug 17 2010, 10:25AM
Location: 127.0.0.1, US
Posts: 19
Thanks for the valuable info Sulaiman and I guess I could test the current measurement capability of the DMM using a source I know the current of and shorting the fuse holder connectors Bjørn... However I am still unable to find the right fuses for the DMM. Will the one from digikey work ok for the 10A fuse? If so I still need to locate the 750ma fuse.
Registered Member #3124
Joined: Tue Aug 17 2010, 10:25AM
Location: 127.0.0.1, US
Posts: 19
Never mind I guess, I tried testing the ammeter on it by just shorting the 10a fuse temporarily while checking current on a circuit with a supply that limits at 200ma but it was over that limit and on a joule thief circuit I built, it was reading all over the place including currents well over the ability of the DMM. Maybe I'm doing something wrong? I know you hook it up in series with the load, and that's what I did... Is there some way to check the accuracy of the DMM, without another DMM of course since I don't have one?
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
You don't need the ceramic fuses unless you're doing measurements on high-energy circuits like wall outlets and so on. They're also known as "HRC" - High Rupturing Capacity - which means that they can interrupt somewhat more current than the cheap glass ones, before they explode and blow your meter into smithereens.
And 5x20 and 6.3x32 (millimeters) are two very common fuse sizes, over here in the UK at least. 5x20 is more common in Europe, but 6.3x32 is the same as the American "3AG" size. I don't know what the situation is in different countries or even what country you are in, but you should be able to go into the local equivalent of Radio Shack etc. and get ordinary glass fast-blow fuses in these sizes for under $1.
It's very common to blow the fuses in DMMs. You do some current measurements, leave the test leads in the "amp" holes, and then go to do some voltage measurements, forgetting to put them back.
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Fuses for DMM
