Film-Tech Forum ARCHIVE: Volt Meter Help

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Posted by Matthew Stevens (Member # 2167) on 12-30-2004, 02:16 PM:

I just installed a new mxl-20 bulb in my back lamp house, and I wanted to make sure the watts are correct for this bulb, however, the lamp house doesn't have a volts reader, but it does have Amps. I can't figure out which symbol on my damn volt meter I need to use (and what range) is it the omega symbol the V with a ~ over it or V with a ---? Thanks for helping.

Posted by Monte L Fullmer (Member # 2797) on 12-30-2004, 03:31 PM:

You don't need the "omega" symbol. Just look for VDC.

Are you tapping across the recitifer lead outs to check for voltage, and is this on a Christie lamphouse being the "mxl-20" a Christie bulb (wonder if the bulb should be a CXL-20)? Easy way for proper wattage is to have the console's ampmeter, with bulb on between 65 and 75 amps for a 2000w bulb.

the "~" is the VAC, and the "--" is the VDC. good luck - Monte

Posted by Richard Fowler (Member # 893) on 12-30-2004, 04:29 PM:

mxl is the letter code used by the Xcel xenon bulb company...same dimensional type as a CXL. These where distributed under the Marble name in the USA.

Posted by John Hawkinson (Member # 1135) on 12-30-2004, 05:36 PM:

Be careful when working with a meter inside a lamphouse. It's not particularly safe.

Also, please ensure that your meter is not connected when the lamphouse igniter fires -- the high voltage pulse will fry your meter.

--jhawk

Posted by Randy Stankey (Member # 64) on 12-31-2004, 12:00 AM:

The Ω symbol is for measuring resistance. (Ohms)

DO NOT connect the meter to any source of electricity when it is in resistance mode! You will likely blow the meter all to hell! You also risk getting hurt. (The risk is proportional to the amount of voltage & current you are working with.)

Some meters have fuses. Others have internal electronic gizmos that prevent damage.

Some meters just go "Pffft!!"

It would be a smart thing for you to study your meter to find out if it has fuses and/or a protective circuit. You would do well to go get yourself a handful of spare fuses and put them in a safe place. You never know when you'll need them. It'll probably be right when you need the meter to fix a blown diode or something when you discover it's got a blown fuse from some OTHER idiot putting the meter to a power source when its in "Ohms"!

If you can find the manual for your meter, I suggest putting it in the bathroom. If you can't find your meter, see if the company that made it has a website where you can download it. Then print it out and put the hard copy in your bathroom.

Posted by Thomas King (Member # 2745) on 12-31-2004, 10:23 AM:

Just set the rectifier so that standard running current is right. As a constant-current supply, the rectifier's going to range the voltage to whatever's nesscary.

Posted by Michael Schaffer (Member # 1204) on 12-31-2004, 04:22 PM:

quote: Randy Stankey
If you can find the manual for your meter, I suggest putting it in the bathroom. If you can't find your meter, see if the company that made it has a website where you can download it. Then print it out and put the hard copy in your bathroom.

I meditated on these mysterious words, but I just couldn't figure out why you should keep your manuals in the bathroom. I keep mine on a shelf next to my desk.

Posted by Mark Gulbrandsen (Member # 72) on 12-31-2004, 04:40 PM:

Michael,

Manuals are usually kept in the bathroom because for many its used for the longest period of concentration out of the 24 hour day. Good time to study and no one to annoy you(hopefully anyway! [Eek!]

).

So you DON'T have manuals in your bathroom.....? You keep yours by your desk.... you mean to tell us that you can actually concentrate by your desk [Cool]

. Hey I wanna come to work for your company!

Mark

Posted by Oscar Neundorfer (Member # 458) on 01-01-2005, 07:12 AM:

I quite agree, Mark. I daresay most of my education has come from many happy hours of bathroom reading.

Posted by Richard Hamilton (Member # 321) on 01-01-2005, 08:39 AM:

Is Penthouse considered a manual?

If so, I graduated summa cum laude!!!!

Rick

Posted by Gordon McLeod (Member # 33) on 01-01-2005, 10:59 AM:

Matthew my advice is get someone who knows how to use a meter safely come in and do it and show you at the same time

Posted by Steve Kraus (Member # 476) on 01-01-2005, 11:55 AM:

Eek Richard...that's usually a girl thing: Sum Cum Laud

But hey, different strokes...

Posted by Michael Schaffer (Member # 1204) on 01-01-2005, 01:37 PM:

I actually didn't get the reading on the toilet association. Probably because I never read on the toilet myself. My pale ass gets cold, I don't like that. I prefer to read in bed.

Posted by Mark Gulbrandsen (Member # 72) on 01-01-2005, 06:41 PM:

quote: Michael Schaffer
I prefer to read in bed.

If I read in bed about 6 pages in I always fall asleep. I sometimes read in the bathtub..... very relaxing and I don't fall asleep!

Mark

Posted by Randy Stankey (Member # 64) on 01-01-2005, 07:49 PM:

Seriously? You DON'T read in the bathroom?! [Wink]

Right now, in my bathroom, I have the latest copy of Scientific American, a copy of Uncle John's Bathroom Reader and an old copy of the ARRL Handbook given to me by a friend to encourage me to take the test some day.

Most people I know do their best studying in the BR! [Big Grin]

Posted by Mike Babb (Member # 1379) on 01-01-2005, 09:55 PM:

These days with wireless network laptops you can get some reading done...

I second the observation about getting into trouble with a meter, I saw someone measuring DC volts on a rectifier, then try DC amps without knowing the meter was not capable and created a dead short. Amazingly it didn't kill the meter but it burned his leads down and he jumped back about 6 feet, plus his vision was a little screwy for a few minutes.

Posted by Thomas King (Member # 2745) on 01-02-2005, 09:04 AM:

I wouldn't say it was the meter that wasn't capable, I'd say it was the engineer. Anyone who tries measuring the output current of a rectifier with a standard multimeter managing to go across the terminals deserves a bit of a scare.

Posted by Steve Kraus (Member # 476) on 01-02-2005, 09:17 AM:

Probably vaporized the typical 10A shunt. The rest of the meter remains functional but don't expect it to work in the high (relatively speaking) current range again.

Posted by Mike Babb (Member # 1379) on 01-02-2005, 02:51 PM:

It was when I had first started and watching him do it was a nice learning experience for me as well as a scare for him. I got a clamp meter soon after which does the job. He doesn't work for the company anymore but his meter does, I'll have to pull it out at the shop and see if Steve's theory is right.

Posted by Matthew Stevens (Member # 2167) on 01-02-2005, 04:24 PM:

I have not touched the lamp house yet with the volt meter, I have scheduled a booth tech to come down someday from Denver and he can mess with it.

Thanks for the information about volt meters and your "bathroom reading matterial" (gross)

Posted by Randy Stankey (Member # 64) on 01-02-2005, 05:07 PM:

Gross?! Not at all!
Just put a copy in the John and leave it there. You'll thank me some day.

Some day you'll figure out what the REAL reason for the Copyright page, inside the front cover was REALLY meant for! [Big Grin]