How do you fix a mosquito magnet?

Answer 1

Depends on what's wrong right? The most common problem is the flame constantly blowing out. The orific that supplies gas to these magnets is very tiny and over time can accumulate enough residue to clog sufficiently to start going out. With a little know-how and a few simble tools the orifice can be removed and cleaned with acetone or alcohol. You may need to drip some into the hollow portion of the orifice and then blow it through given the tiny size of the hole. Don't try stick pins or anything though. The size of the orifice is important to the correct flame size.

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Recommend reading through all the responses to synthesize your own troubleshooting methodology.

There is a good overview of MM operation at http://gra.midco.net/jmanley/.

A forum devoted to fixing MMs is at http://mosquitomagnet.freeforums.org/.

Here is how I fixed My Mosquito Magnet Liberty Plus: I charged the battery full, shot 3 CO2 Cartridges one after another, gave it a try. It would not start. I then attached a more robust power supply and attempted to start with the power supply plugged in (jump start). This worked in just a few seconds. The next gas run-out I tried the normal start, no luck after several tries. I tried the "Jump Start" again with the 12 volt power supply and it started right up in less than a minute. I used a 12 volt supply designed for a 12 volt TV. I cut the wires off the old supply and connected white to white, black to black. I used my Multi Meter and read 8.9 volts off my charged battery and 15 volts off the power supply. I suppose that since the fan and igniter is rated 12 volts it works fine. I unplug the supply immediately after I feel heat coming from the black emitter tube where the Octonol is. I talked to a tech that was trained by Applied Biophysics and he said not to leave the power supply plugged in more than 40 minutes. I think this is to protect the battery from too much charging power.

Based on a little net searching, the MM has a tendency to stop working after a few seasons. (My MM Defender stopped in the middle of its 3rd season. Had to disassemble several times before I could get it to run.)

If you consider the circuit board as a single component, then there are only a handful of components to a MM. There is the power supply, liquid propane (LP) connector, LP 1-way valve, LP hose, LP mixing chamber, Schrader valve, LP solenoid valve, LP sprayer, ignitor, thermocouple, catalytic converter, fan, combustion chamber, and circuit board.

In simple terms, when you power on the unit, it's supposed to turn on the fan and get good airflow through the combustion chamber. After that's established, the igitor is energized, the solenoid valve is engaged, and the LP is released into the sprayer. The sprayer sprays the LP into the combustion chamber where the ignitor burns the LP. A thermocouple is there to provide feedback on the combustion. Any CO from the reaction gets converted to CO2 by the catalytic converter before exiting the head. The Schrader valve (which is normally closed) is there to allow you to put some compressed CO2 through the sprayer to clear any clogs (of course, with the unit off and unplugged from the LP).

For thorough troubleshooting, you may need a multi-meter, #2 and #3 Phillips head screwdrivers, a handful of wrenches, some high-temperature silicone adhesive, a 12-volt DC power supply, pipe-tape and other miscellany.

The power supply converts power from a standard outlet into 12-volt DC. If you turn on your MM and nothing happens, maybe the power supply is dead. (I ran over my cord with a lawnmower in its 2nd season.) To test, plug in the power supply and use a multi-meter to see if 12-volts DC is coming out of the end that plugs into the MM head. If not, unplug the supply and check for shorts/opens in the cords. If no shorts/opens, then you might need to replace the whole power supply (which I think can be purchased from the manufacturer). If the power supply is OK but nothing goes on, then it probably is bad news as the circuit board or switches/lights may be fried. You can try to troubleshoot and substitute parts, but you might also need more. If the power supply is OK, lights are going on, but something else isn't working, you probably need to dismantle the head.

Remove the head from the LP tank, stand, and power supply. (#2 and #3 Phillips head screwdrivers worked for me.) Advice: Dismantle this outdoors, as insects can take up residence in the head unit and may infest your home if you repair indoors! (Yes, I did this by accident!) To remove the innards, you'll have to use a wrench and remove the 1-way valve from the hose.

Inspect the LP connector, 1-way valve, and hose for damage. My guess is that these parts are robust enough that they shouldn't give a problem, but if they are dirty, you should be able to clean them out (e.g. with alcohol or mineral spirits and a bit of compressed air to dry).

Unplug things from the circuit board. Bravely now, dismantle the combustion chamber (i.e. the big, heavy metal thing which is most of the head unit) by unscrewing the 4-5 screws holding the 2 halves together. There is some silicone adhesive holding the 2 halves together, so this may take a little leverage and some elbow grease. Once apart, use this as an opportunity to clean the inside of the unit, including the cylindrical catalytic converter, with mineral spirits.

The LP hose, mixing chamber, Schrader valve, solenoid valve, and LP sprayer should still be together as a unit. Using a wrench, unscrew the LP sprayer from the mixing chamber, and soak the sprayer in mineral spirits for ~60 min and dry thoroughly. (The sprayer is a little sensitive, and can get clogged with impurities from the LP tanks.) If need be, you should be able to unscrew the Schrader valve with a wrench and replace with a new valve from an auto parts dealer. Once you clean the sprayer, put a little pipe tape on the threads and reassemble the LP hose, mixing chamber, Schrader, solenoid, and sprayer. You can test the solenoid valve by applying 12 volts DC to the plugs and listen for the valve to 'click'. Am not sure of the best way of testing these other parts, but you can theoretically connect it up to your LP tank, trigger the solenoid valve, and see or listen for the spray. For the brave, you could even use a lighter to check for the spray.

To check the ignitor, carefully unscrew it from the combustion chamber, and plug it and the power supply into the circuit board. After turning on the unit and waiting a short time, the ignitor should turn bright, hot red. If it doesn't, you can replace with more robust units that are sold on eBay.

To check the thermocouple, carefully uncrew it from the combustion chamber, and connect the terminals to a multi-meter. As you heat the thermocouple (with say a lighter), the ohms should decrease significantly. This should be a simple thing to replace, but am not sure where to purchase replacements if it's not working. Note that the thermocouple is held in place by a flimsy nylon screw. Replacement screws can be purchased at just about any home store. Have heard of others replacing it with a ceramic screw.

You should be able to test the fan by applying 12 volt DC to the terminals. If it doesn't turn on, you can probably find a replacement at DigiKey.

Once you've cleaned and tested everything, you can reassemble the combustion chamber by using high-temp silicone adhesive (found at auto parts stores). Be sure to apply the adhesive ONLY in the same areas as where the previous adhesive was applied.

Once the combustion chamber is back together, you can plug everything back into the circuit board, reassemble, and screw everything back. (Again, use a little pipe tape on the threads of any of the LP lines.)

Haven't tried this yet, but to prevent future clogging, I'll try to use the compressed CO2 cartridges with the Schrader valve (as recommended by the manufacturer) to try and keep the sprayer from clogging.

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I have been struggling with MM Defender that won't start.

How do you get the orifice out? Does the gas feed part simply unscrew from the burner casting, or do I need to split the two halves of the casting apart? I have been tempted to port and polish the part...maybe it needs some higher gas flow to burn with more vigor?

From a technical perspective, I have figured the whole thing out, cept how to get the thing to light and stay lit. I have taken apart the gas valve and carefully fed a thin copper wire on through to inside the combustion chamber and forced air through the whole thing. I have tested the ignitor, the gas valve, and the thermistor. I have even created my own spark-ignition system to replace the hot suface ignition (and ironically, stood there getting bit by mosquitoes as I continually pull the trigger on my piezo lighter gizmo). I also connected a second thermistor to the burner case so I can monitor the temperature of the burner with the case on.

Inside parts: There is a control board which has connections for the 12V AC power supply, the fan, the gas valve, the thermistor, the ignitor, and the power switch/lamp assembly.

The startup sequence runs the fan for about 2 minutes, then the 12vdc gas valve opens (the fan is slowed for about ten seconds when the valve opens). The 12V hot surface ignitor then powers up (goes cherry red) and stays on for the remainder of the 'trying to start' time which is something like 3 or 4 minutes until the unit either goes steady-red (running) or goes to fast-blink (failed to start) and closes gas valve and shuts down ignitor. The fan runs for awhile then shuts off. The control board has all the timing logic on a couple of chips, rectification circuitry to convert AC to DC, transistors to switch power on/off for the ignitor, fan, and valve, as well as the sensor input from the thermistor.

Closer to the gas valve is a 12V hot surface ignitor module (thicker wires) that glows nice and red when it's supposed to. At the rear of the burner casting is a thermistor (skinny wires) (temperature-variable resistor) that connects to the control board so the unit knows if it started or not. Of course there is a 12V fan in there, which is a three-wire fan (which either means it has a tach lead or it's a variable-speed fan). On the input side there is a 12V solenoid valve. (Note for parts: you can get a replacement ignitor on eBay...it's a 12v glo-stix from www.crystaltechnica.com. The valve is made by Peter Paul Electronics)

My next project is to try to take the orifice all the way out, perhaps inspect the catalyst directly by splitting the casting apart, and possibly going full-manual (running gas valve, fan, and ignitor with 12VDC source) and monitoring temp with the thermistor I bolted to the burner casting. I have also thought about drilling an inpection hole in the casting so I can see if the catalyst lights or not.

On the lighter side, I have considered adding a liquid-oxygen auxillary ignition system (this is a joke), or adding some other starting enhancement like ether, carbon tetrachloride, or gasoline. (these too are likely to kill more than just mosquitoes). I have also considered adding a gas guage to the unit so I can tell if propane gas is flowing or not, and if it is flowing at correct rate.

And here is mystery of the universe: How the heck do you tell if a propane tank needs to be purged of air?? Won't it just purge itself if I let it leak out by leaving the gas fitting loose??? Is there a fuel-air meter for propane I can buy?? (Heated oxygen sensor may not work properly---hee hee). I've got two propane tanks that the supplier says have been purged...but how can you tell???

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After trying all of these things unsuccessully, I scoured through Google to find more information. I needed my mosquito trap repair done. Not that the above info is not good, it just didn't work for my liberty. After what seemed like weeks of research, I was weighing my options. Keep messing with it and possibly never get it going................ or send it in to have it repaired. Well another week went by and after calling ALL, and I mean ALL of the service places on the web, the cheapest I could find was mosquito control technology. They had a $19 tuneup special. I had to pay return freight of course, but after sending it to them I found out it was only a faulty ignitor. It cost me 20 extra bucks to have it installed and they shipped it out. Pretty painless soprisingly. Only out about 50 bucks or so, anymore and I'm not sure I would have done it. oh yah go to www.mosquitomagnetrepair.com that's where I went.

Steven in VA

skwanto@lavabit.com