Smoked my VOM!

[mbkerk]

I am not sure how much voltage it takes to light up a high pressure sodium lamp, but I wanted to know...! It is over 750 VAC!

I had a starter go bad in my yard light and put in a new starter circuit, but never being able to just fix it and be done with it... I wanted to know what was going on electrically in there. I hooked my VOM to the light socket, hit the switch, heard the meter give it's last pathetic beeeeeeeeep... and now it doesn't measure AC volts any more!:sad_02: It had a range from 0-750 VAC. It still works fine for all other functions. I suspect the microprocessor took the hit.

It was a Christmas gift a few years back... Pretty nice Craftsman digital meter (I know... not a Fluke) so I am kinda bummed about it! It has an RS-232 port on it for interfacing to a computer and software. I never use that part unless I just want to play with it!

I am watching for a replacement on eBay.

BTW... If anyone knows the operating characteristics of a high pressure sodium lamp, please let me know! I'll be staying away from it with my next VOM!

[sixchows]

Mark
That meter could probably be repaired. Any idea who makes it for sears? Do you have the 3 digit prefix of the model number?

[mbkerk]

Mark
That meter could probably be repaired. Any idea who makes it for sears? Do you have the 3 digit prefix of the model number?

Not the prefix... just 82324. I am not sure it is worth fixing Six. I have a friend who teaches electronics at a technical school, and he doesn't think so. It only cost about $80 new. He said he would look at it for me, but not to get my hopes up!

[Greg]

Mark,

Does it work on all other functions?

Since you are considering replacing it, go ahead and open it up. There just may be an AC fuse in there. I have a Fluke and a Sperry, and I believe both have fuses. It might have been a slow blow, so you got the "beep" just before it blew. Worth a try.

Uncle Greg

[mbkerk]

Mark,

Does it work on all other functions?

Since you are considering replacing it, go ahead and open it up. There just may be an AC fuse in there. I have a Fluke and a Sperry, and I believe both have fuses. It might have been a slow blow, so you got the "beep" just before it blew. Worth a try.

Uncle Greg

Did that Greg... Both fuses OK (15A and 2A) I wish I could have been so lucky!

[Greg]

Oh, you didn't find a penny shoved it there? ROF ROF

Sorry to hear, Mark. Well, can you still use it for DC and continuity?

Uncle Greg

[Mark / Ohio]

Might just have smoked a resistor. But good luck reading the color code if you can't find a schematic.

I found this explanation of their operation on the net:

http://www.madsci.org/posts/archives/dec97/879297655.Eg.r.html

[Greg]

Mark, here's the Resistor color code...straight out of AF Tech School! ROF

0 Black -- Bad
1 Brown -- Boys
2 Red ---- ****
3 Orange - Our
4 Yellow - Young
5 Green -- Girls
6 Blue --- But
7 Violet - Violet
8 Grey --- Gives
9 White -- Willingly

Gold and silver which are used to indicate multipliers of 0.1 and 0.01 respectively.

Uncle Greg

[Mark / Ohio]

0 Black = Bad

Yep that one also applies if there is only one color! ROF

[Michael]

The AF did use ways for the GI to remember things. The old gas powered forklifts had a straight six engine in it and to this day I still remember its firing order this way

15-is to young
36-is to old
and 24-is just right

Thats from tech school that I took 32 years ago.

[bobodu]

Did a little research and found this...
"The lamp of power less than 100W can be started with high-voltage-pulse of 2.0-2.5 kV, lamp of 150-400 W needs 2.5-5.0 kV and lamp of 1 kW needs 4.0-6.0 kV."
Pardon the Engrish...I didn't write it.
Makes my hair stand on end... ROF

[mbkerk]

"The lamp of power less than 100W can be started with high-voltage-pulse of 2.0-2.5 kV, lamp of 150-400 W needs 2.5-5.0 kV and lamp of 1 kW needs 4.0-6.0 kV."


Man... I guess that explains what happened to my VOM! It has a range of 0-750 volts! The lamp is a 70 watt lamp. Guess the 2-2.5 KV was a little too much for it! I read the link you posted Mark. That explains a lot! Now I know why the big capacitor in that starter!

I know the color code of resistors for my Ham radio experiences. I think I learned the same way of remembering (Greg) as you did in the AF, except I heard it from an electrician friend of mine.

I will pull the meter apart again tomorrow and see if there is anything obvious, but I really think the microprocessor took the hit.

Thanks for all of the research guys!

[horseman1]

From my days in electronics: The gold and silver bands on the end were for the tolerence (or slop) in the resistor. Gold was 5% and Silver was 10%.

The third band was the multiplier.

Example:

Red Red Orange - 22 000 ohms (or 22K)

Good luck reading them these days. They are all so low power and small they often dont even mark them.

Good luck and sorry to hear about the meter!

[Carl]

There might be a diode or bridge rectifier to convert the AC to DC for the meter. Might have blown that since the DC functions all work.

[jdkubotamurray]

Check the meter fuses internal.

[Wild Bill 83]

Mark, If the wiring scematic sticker is still on the ballast, it should give the open circuit voltage on it.

It's fine to check the input voltage in High Pressure Sodium, Metal Halide, Mercury Vapor, and flourescent lights.....but checking output voltage on any type of fixture with a ballast (which is actually a transformer) is hard on a VOM.... ROF

Most flourescent light fixtures have output voltages in excess of 600v.

Some friendly warnings about light fixtures.....

When installing/removing flourescent light tubes, never touch a bulb end with the other end in the socket.....it will buckle your knees........

When working on HPS, MV, and MH fixtures,> always disconnect power before fiddling with anything <.....ignitors, and especially the capacitors. Make sure to 'ground out' the capacitors -put a screwdriver across both terminals- before handling them. A 24Uf capacitor found in a typical 400w Metal Halide fixture will really blast you if you touch both of the terminals while it is still charged!!

In the past 15 years of doing electrical work, I have gotten in a hurry, and forgot/skipped doing it right....trust me, the electricity WILL remind you...and it is also an 'Equal Opportunity Killer'...it doesn't care how old you are, who you are, what color your skin is, what country you are from, or if you are man or woman...if you aren't careful, and respect it --- you will pay the price!

[LPBOLENS]

:ditto: :ditto: I work for a ballast manufacturer; the starting pulse is MUCH higher than the operating current. Fluorescents, HID's, Metal halides may seem to be harmless, after all we are used to regular old lightbulbs, but they operate quite differently from regular old lightbulbs.

[mbkerk]

In the past 15 years of doing electrical work, I have gotten in a hurry, and forgot/skipped doing it right....trust me, the electricity WILL remind you...

Bill... You must be an electrician? Nice to have you as a resource here! I know a little about the simple stuff (general home wiring), but in my second life I want to be an electrician! I should have done that to begin with!

Roy, AKA "chipmaker" built a phase converter that you can see on his web site. I want to build one (just because I can) but I need to find a 3 phase motor for the project. I don't even have a need for one, I just like to try things like that.

I might "bounce" some questions off you from time to time Bill!

[Wild Bill 83]

Well......that's what some people call me......and then again some other people call me different things ROF

Yeah, I'm a 'Sparky'...started soon after high school, and went through 4 years of apprenticeship, and trade school to get my Journeyman Certificate.

You see phase converters in small shops...mostly out in the country...where the power co. doesn't provide 3 phase. Most machinery comes with 3 phase motors on it, and if there is no 3ph. available, you 'can' convert the machine to single phase, or get a phase converter and make your own 3ph.

I forget the mathematical equations used to figure the amperage draw for a 1ph to 3ph converter........it's been probably 8 years since I had to figure that in trade school :fing20:

Uhhh......you might want to reconsider the career change. Residential and light commercial work isn't bad...but res. does involve a lot of crawling...attics, and crawl spaces... Commercial/Industrial electrical work is pretty physical, and a lot of times is hot, especially in foundries!! Man, talk about sweating!!....

You are sore and worn out, at the end of the day. Running 3" and 4" rigid conduit, and pulling 500mcm wire (or it's new fangled name 500kcmil) will truely wear a man out......the wire is about 2lb/ft....most pulls have 4 of the 500's along with the ground wire (3phase 4wire services or machine hook ups)

The longest pull I have been in on was 675 ft. We used 1000' spools, set up on adjustable jack stands...we never took the spools down off of the trailer (except to 'swap' them for full spools for different pulls). There were 3 500's, and the 3/0 ground wire....1 guy was on each wire pulling it up to the disconnect, 1 guy collected the wires, 1 guy fed them in the 4" conduit, and 1 guy was using a 5 gallon bucket of soap (Ideal Yellow 77 pulling lube) to help the wires 'slide' in the conduit....at the other end was 1 guy running the 'chugger' (Greenlee wire puller) that was chained to the forks of a huge towmotor, and another guy helping manage the rope... That is 9 guys, and around 4,000lb of just the 500's (I don't know what 3/0 weighs)...just in that 1 pull!! We did that pull, and 4 other slightly shorter pulls that day, to power the overhead cranes in a new factory that slits (cut to a specified width) steel rolls.

Needless to say, my butt was dragging that night!

[Kbeitz]

Question... How good does the power nail gun work for hanging conduit off cement ??? How good does the stud hold over time???

[newjerseybt]

"It's fine to check the input voltage in High Pressure Sodium, Metal Halide, Mercury Vapor, and flourescent lights.....but checking output voltage on any type of fixture with a ballast (which is actually a transformer) is hard on a VOM...."
-------------
Whenever I am not sure how high the voltage can go I use the high voltage adapter that TV repairman used to use to measure the 2nd anode picture tube voltage which could be 25KV. Once you smoke the meter movement, you can put a fork in it cause its well done. :(

I would rather use an old Simpson 260 over the newer digtal meters for residential use. You place a higher load on the line which eliminates those crazy false phantom voltages that are due to capacitive coupling.