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Author Topic: Its a sad day... destroyed my favorite test meter  (Read 7814 times)
KE4JOY
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« on: July 26, 2013, 02:37:46 PM »

Yup blew up my favorite multimeter a radio shack 22-175. Not your top of the line stuff but it did a lot of things diode, capacitor, even transistor checking. The voltmeter sill works but the resistance, cap check, and diode check are all gone. So I am left with a voltmeter than can check transistors   Sad

I did the unthinkable, applied 240V AC across the ohm input. Meter let out a horrible buzz and I knew instantly it was a goner!

So long old friend!  Angry  Sad

ps: No the fuse did not go  Tongue

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AC5UP
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« Reply #1 on: July 26, 2013, 04:14:14 PM »


Last fall I perma-zapped a Centech (Harbor Freight) cheapie doing the same thing. Except it was only 120 vac across the Ohms scale.

Which is one reason I prefer Harbor Freight to Duh'Shack. Achieved the exact same result at a fraction of the cost with only half the voltage......................   Tongue
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AA4PB
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« Reply #2 on: July 26, 2013, 05:07:05 PM »

Did you open the case to let the smoke out?   Grin
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KE4JOY
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« Reply #3 on: July 26, 2013, 05:20:46 PM »

LOL funny thing is I later borrowed (another) harbor freight meter to check things out once I realized my faith full friend had gotten toasted.

Why I was using my bench meter to check line voltages I will never understand... oh wait, yes I do, because the harbor freight meter that I borrowed from my dad had met the same death previously.

I had that Radio Shack meter for decades, it was a familiar comfortable unit I trusted and understood... What a shame.

Almost feel guilty replacing it with a 20 dollar meter from Chinese junk is us.  Cheesy

ps: no smoke just an angry loud buzz. I popped it open and saw a resistor with a scorch on it but I am pretty sure its toast.
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WB5TFV
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« Reply #4 on: July 26, 2013, 06:26:31 PM »

Years ago I acquired a RS multimeter from a guy at work who had tried to "measure the amps in his house." Apparently he had set the meter to the 10A current setting or some such thing, stuck the probes in a 110VAC receptacle and pow.

I opened it up, found a scorched precision resistor, went to the lab and had the tech dig up a replacement. Changed it out and the meter worked again. You might try replacing that fried resistor and maybe get your old friend back in the game.
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AD7VB
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« Reply #5 on: July 26, 2013, 09:32:56 PM »

What to look for in a Multimeter

http://www.youtube.com/watch?v=gh1n_ELmpFI&feature=player_embedded

Example of a cheap Multimeter

http://gossenmetrawatt.com/english/seiten/cautiondangerousmultimeters.htm

Todd
AD7VB
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KA4POL
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« Reply #6 on: July 26, 2013, 09:59:02 PM »

Sooner or later you just got to accept Murphy's Laws.

Any system which depends on human reliability is unreliable.
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G3RZP
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« Reply #7 on: July 27, 2013, 01:03:53 AM »

My old fashioned Avo 8 with a moving coil meter has a mechanical trip protect it......My quite good German DVM has burned resistors a few times - although rated for 750v DC, it can't take it. I don't believe it can take the 20 Amps current rating that it has, either.
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KA4POL
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« Reply #8 on: July 27, 2013, 02:20:34 AM »

I don't believe it can take the 20 Amps current rating that it has, either.
There is an easy way to find out  Grin
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AC5UP
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« Reply #9 on: July 27, 2013, 05:44:35 AM »


Read the back panel on this...............

http://www.shopgoodwill.com/viewItem.asp?ItemID=13797197
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G3RZP
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« Reply #10 on: July 27, 2013, 06:40:36 AM »

KA4POL

I don't intend - or need - to find out! I have a beautiful old meter that will read up to 100 Amps by attaching the appropriate shunts, and I have shunts for 5, 10, 50 and 100 amps. The last one is formidable chunk of metal!

For AC, it's not hard to make and calibrate a current transformer.

I do have some voltage standards and I'm somewhat surprised and rather pleased with the way the DVMs maintain calibration.
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KE4JOY
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« Reply #11 on: July 27, 2013, 10:00:30 AM »

The burnt resistor (as well as many other resistors) has an odd color code on it with 5 bands.

Red, black, black, black, red

I assume its a 20 ohm looks to be 1 watt don't really know.

Oh and it reads any resistor from 100 ohms to 10K ohms as zero ohms.
« Last Edit: July 27, 2013, 10:06:50 AM by KE4JOY » Logged
TANAKASAN
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« Reply #12 on: July 27, 2013, 01:48:52 PM »

Way back when I was just out of university I was working in a shop that repaired TV sets. Needing two meters for a particular repair I borrowed a very expensive Fluke bench meter and set everything up. With the TV set displaying a picture the positive probe of the Fluke just brushed the EHT cable and there was a loud crack. The poor Fluke let out a single beep and just died.

That was not a happy day.

Tanakasan
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K0IZ
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« Reply #13 on: July 27, 2013, 06:42:26 PM »

Shop for a used Simpson 260 (series 5, 6,7 preferred).  Probably about $35-40 on ebay or hamfest.  So nice that you will start to forget your old friend.
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AD7VB
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« Reply #14 on: July 27, 2013, 10:09:33 PM »

The burnt resistor (as well as many other resistors) has an odd color code on it with 5 bands.

Red, black, black, black, red

I assume its a 20 ohm looks to be 1 watt don't really know.

Oh and it reads any resistor from 100 ohms to 10K ohms as zero ohms.

200 ohms 2 % http://www.digikey.com/us/en/mkt/5-band-resistors.html

Todd
AD7VB
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