Hey Tech People- Answer this one

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Archive 2009 · Hey Tech People- Answer this one

lwrnclightner
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p.1 #1 · Hey Tech People- Answer this one

The other night I was testing a new on site printer I bought, and I stopped to take a break and fix a quick bite to nibble on, and while the microwave was on the stobes in use (ab 400's) started having a party of their own (firing randomly).

Just curious as to what causes this, I have noticed that all or some of my strobes will fire occasionally when not triggered, and I could never figure out why. I just blame it on it dumping a charge or something, (trying to sound intelligent, but really not having a clue

Anyway, someone please enlighten me.

Mar 13, 2009 at 06:13 PM

Garry Burton
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p.1 #2 · Hey Tech People- Answer this one

I'd say RF interference.

My work "studio" was located in a fire stair well (yes, a crap spot) but it had very thick cement walls. I work for an online auction house, a bazillion images a day.....
I never had an issue with the cactus el-shito flash triggers I was forced to use apart from, you have to go through 20 to find one that works. DLite 200 kit, so it should be OK.

I've now moved into a gyprock officey-studio. I now have miss-fires constantly. I also set up a shooting table near an area that is used to format 100 or so lappys and the Blazzo 60s (another wonder of lighting) go beserk whenever you get more than a metre away from them (has to be the body sheilding the strobes). Forklifts set them off as well. Got to be interference.

I talked them into PWs now as I trialled mine without any issues with the Elinchrome gear.

I've also found that if I have trigger/sync lead plugged into all of the the cheaper strobes instead of firing one and slaving the rest, they have less miss-fires.

My slant on a similar problem to solve, hope that helps you mate.

PS: I'm thinking of making a bit of shielding with some alfoil, hey it would be the most expensive component on the Blazzos, haha. I'll let you know if it works. maybe with a bit fibreglass insulation.

Cheers Gaz

Mar 13, 2009 at 06:33 PM

bacilonur
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p.1 #3 · Hey Tech People- Answer this one

What triggers do you use? Are you using the optical sensor? If not, put some gaffers tape over the sensors just to rule that out. Next time it starts happening, unplug the radio triggers and see if it continues.

Mar 13, 2009 at 09:54 PM

Gregg Heckler
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p.1 #4 · Hey Tech People- Answer this one

It was the RF from your microwave. Nothing you can do about it unless you put a shield around the microwave or make sure it's not running, or use a sync cord instead of the radio triggers.

Mar 14, 2009 at 05:26 AM

texasruss
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p.1 #5 · Hey Tech People- Answer this one

I'm not sure it's RF.

a) the OP didn't say he was using wireless triggers
b) the strobes would have to be pretty close to the oven, ie. 10'
c) PW's operate at 344 MHz and a microwave operates at ~2450 MHz. There could be some harmonic interaction, but again...he would have to be close. The higher you go in frequency the signal is very line of sight. (Not to say he was using wireless triggers, and not to say they would be PW's, but simply an example).
d) many wireless devices, eg. cordless phones, wireless routers, operate at 2.4GHz. So if that frequency was causing the problem he probably would have seen it earlier.

My guess is a voltage spike in the AC line triggered by the operation of the microwave. You could probably just plug the strobes into a plug strip with surge protection and that would eliminate it.

Mar 14, 2009 at 05:54 AM

mrscott
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p.1 #6 · Hey Tech People- Answer this one

You leave your lights powered on? Bee whisperings...

When I first started messing around with a DIY vagabond using the FRY's inverter and a battery, it did something very strange to one of my 400's as well. When connected to the inverter, it would fire once and then no more. When connected to the wall it would blink out some kind of mayday morse code that was truely disturbing. 5 or 6 attempts later and 120v wall power was still doing the same thing. Two days later and all was well.

I never figured out why it happened, but I'm guessing they were flipping out around 2 or 3 fps. BTW the bad AB400 has worked fine for 3 years on wall or inverter power ever since the abduction.

Mar 15, 2009 at 01:21 AM

BSHuff
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p.1 #7 · Hey Tech People- Answer this one

Could be ground related. Weird things can happen when there is a bad or noisy grounds in power supplies (ground with voltage present). Microwaves are not the cleanest things out there on the power system. I carry one of those plug in outlet testers to check the outlets that I plug my strobes into.

Mar 15, 2009 at 02:57 AM

RDKirk
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p.1 #8 · Hey Tech People- Answer this one

If it were EM interference, I'd junk that microwave toute de suite.

But I also would suspect the microwave oven is actually causing problems with the power lines, and the older it is the more likely it's causing problems. That circuit might also have latent vulnerabilities that are acerbated by the microwave; lots of people are operating barely adequate electrical systems in homes and businesses--especially if they are older systems loaded with a lot of modern devices.

My APC systems complain constantly about the noisy and poor quality of the mains power in my community.

Mar 16, 2009 at 01:10 PM

cgardner
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p.1 #9 · Hey Tech People- Answer this one

BSHuff wrote:
Could be ground related. Weird things can happen when there is a bad or noisy grounds in power supplies (ground with voltage present). Microwaves are not the cleanest things out there on the power system. I carry one of those plug in outlet testers to check the outlets that I plug my strobes into.

A likely cause. In US residential wiring the neutral and ground are bound together at the circuit breaker panel. So if you have any grounded appliance which is leaking current to ground it will get carried over to the neutral leg. That may be happening when you fire up the MW.

A mis-wired outlet anywhere in the house can be the culprit. If the hot and neutral wires are reversed on a wall outle,t when something connected to the outlet is turned on to complete the circuit it will cause problems. I learned this in the 1970s when an electrician where I worked reversed the hot / neutral polarity on the plug for a fluorescent lamp over work table which had a outlet on the end of it. When a computer terminal was plugged into the outlet on the lamp the ground carried the current on the terminal's connection to the CPU and fried the I/O board. Since that day I've never plugged in electronics without checking the circuit with a tester.

So check the outlet the MW is connected to and all the others in the house...

Chuck

Mar 16, 2009 at 02:52 PM

toddmitchell
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p.1 #10 · Hey Tech People- Answer this one

Chucks probably right, get a outlet tester that plugs right into the outlets that checks. I have a sperry instruments outlet tester HCA300 and it works great.

http://www.amazon.com/Sperry-Instruments-HCA300-Outlet-Tester/dp/B001JI9FOE

I got mine at lowes or home depot and i think it was less money.

If that is not the problem call alien bees and they will walk you through any problem they have great service/support.

microwaves should be on their own circuit per code but often are not.

Mar 16, 2009 at 03:27 PM

davenfl
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p.1 #11 · Hey Tech People- Answer this one

cgardner wrote:
BSHuff wrote:
Could be ground related. Weird things can happen when there is a bad or noisy grounds in power supplies (ground with voltage present). Microwaves are not the cleanest things out there on the power system. I carry one of those plug in outlet testers to check the outlets that I plug my strobes into.

A likely cause. In US residential wiring the neutral and ground are bound together at the circuit breaker panel. So if you have any grounded appliance which is leaking current to ground it will get carried over to the neutral leg. That may be happening when you fire up the MW.

A mis-wired outlet anywhere in the house can be the culprit. If the hot and neutral wires are reversed on a wall outle,t when something connected to the outlet is turned on to complete the circuit it will cause problems. I learned this in the 1970s when an electrician where I worked reversed the hot / neutral polarity on the plug for a fluorescent lamp over work table which had a outlet on the end of it. When a computer terminal was plugged into the outlet on the lamp the ground carried the current on the terminal's connection to the CPU and fried the I/O board. Since that day I've never plugged in electronics without checking the circuit with a tester.

So check the outlet the MW is connected to and all the others in the house...

Chuck

Chuck is dead on right here. A lot of buildings and residential wirings jobs have this problem which is related to the power source and not EM transmission. A cheap and simple solution is to get a power isolation transformer, small box, reasonable priced. A good sized one runs about $120, small one $50 or so. That will clean the power source and should get rid of the problem. I wouldn't be heating up my lunch in the microwave while the strobes are powered on if you are having this problem.

Mar 16, 2009 at 03:47 PM

cgardner
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p.1 #12 · Hey Tech People- Answer this one

toddmitchell wrote:
microwaves should be on their own circuit per code but often are not.

Even if the MW is on a separate circuit it could still cause a problem because all the neutrals an grounds for all circuit breakers are tied together at the breaker box.

Here's an interesting discussion of ground loops:
http://www.dself.dsl.pipex.com/ampins/groundloops/grndloop.htm

Chuck

Mar 16, 2009 at 07:12 PM

ajmichael
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p.1 #13 · Hey Tech People- Answer this one

cgardner wrote:

A likely cause. In US residential wiring the neutral and ground are bound together at the circuit breaker panel. So if you have any grounded appliance which is leaking current to ground it will get carried over to the neutral leg. That may be happening when you fire up the MW.

If that's the case then you've got a wiring problem. The bond between earth and neutral at the distribution board should be a far lower resistance than anywhere else in the circuit, so there's no reason for the fault current to go elsewhere.

Andy

Mar 18, 2009 at 05:02 PM

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