heated shield not working

Johnnysrx

Johnnysrx

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Joined
Oct 5, 2004
Messages
183
Age
52
Location
SE WI
Hi guys I have a question about my friends heated shield. We were out today and his shield was not working. So I jumped on his sled and it was working for me and his was not working on mine. So we figured that it is in the shield. So Im not a electrinan but I know a little. So I thought to try a Ohm meter on it. Tryed my shield and we got a reading of about 9.9, tried my brothers and his got a reading of 12.4 then we tried his and we got a reading of 54.3. So im not forsure but I think 54.3 is a bad reading. So then there is a plug inside the shield so we unpluged it took some readings and all the wires gave us readings of 0.0. Pluged it back in and we got a 54.3. So then we think the little plug is bad so we cut the plug out and tie the wires together. Now we get a reading of 0.0 so we think we are okay. Plug it into the sled and the sled head light goes super dim and the sled all most shuts down. Unplug it and the sled fires up and the light gets bright. What are we doing wrong? What can go wrong with the shield? Is there any other test we can do? Thanks
 
Tying the wires together creates a dead short=very bad. 54.3 sounds high compared to the other two but I'm not too clear on what you did at the shield. There should be some resistance as thats what creates the heat. Too much resistance and it acts like an open(cut wire). Need a little more info to finish the trouble shooting.
 
How many wires are there in your shield? I'm guessing you have several loops through the shield and your reading of 54 ohms was the reading of a single loop and the others are broken or not connected. If you had 5 loops in parallel you'd be around 10 ohms and draw 1 to 2 watts. Sounds reasonable for a shield.

You do not want to be at zero ohms! Your resistance then, is only the resistance of the wires and you'll melt something.
 
Okay, We pretty much figured putting them all together was very bad! There are two loops in the shield. So from the hook up on the out of the shield (rca looking plug) we got a reading of 54.3. Then we took apart the shield and found another little plug where the two wires split and went to the loops that are inside of the clear plastic. We took the little plug apart and took some reading. First from the rca plug to the little plug we got 0.0, then from the little plug to the loops inside of the clear plastic we got 0.0. So we figured that the wires and connections were all good. So we figured the problem must be in the little plug. We cut the plug out and hooked up the wires to each other (one wire to one wire) and got a 54.3 reading. Then we hooked all the wires together and got a reading of 0.0 (bad) So is the little plug bad? But with out the plug we still got a 54.3 reading. What could be wrong? Thanks
 
Can you post a picture? I'm having a hard time picturing the little plug and the wiring through the loops. Are you able to measure resistance in each loop separately?
 
I will try and post some pictures. I tested the wire from the little plug to the rca plug on the outside and got an 0.0 reading so that lead me to believe that the rca plug was okay. How and where does the resistance come into play? I thought it was the little plug but when I cut the plug out and hooked up the wires to each other I still got a reading of 54.3. So im confused!?!? LOL Thanks for your help
 
I have two HJC's.
Old shield was 9 Ohms
New one is 13 Ohms

I didn't take them apart but I did meassure between the two 'rivets' where the wires go into the clear part of the shield and got the same meassurements.
 
thanks, that is the same as we saw on the other two helmets we have. So we figured that the one with a 54.3 must have something wrong.
 
I hate to say this but it is TOAST. when the resistance goes way up you have a problem and you should replace it. and if they read 0 you could get an electrical fire from the insulation on the wires melting.

HJC is 12.8 and the AFX is 10.1
 
Yes I understand I have a problem but I would like to know why? It looks like there is nothing to it. Just two plugs and some wires.
 
There are VERY fine wires in the shield and some are melted that is the reason for the hi resistance. I see this all the time with our heated winsdshield on our aircraft. all you can do is replace it.
 
I guess if you think about it like this:

Compare your shield to a rear window defroster in a car, if one or more of those lines go open(break/crack) the overall resistance goes up some(less parallel circuits). Eventually the resistance will get to high and the thing will stop working.

To explain the parallel thing a little better, two 4 ohm speakers wired in series=8 ohm load. Two wired in parallel=2 Ohm load. If you break a speaker wire to one of the speakers in parallel, the load will jump to 4 ohms. Each speaker in parallel reduces the resistance even more. I'm a little rusty on my electronics theory but i think four 4 ohm speakers in parallel gets you down to either .5 or 1 ohm. Apply all that to many small 'wires' and you should see why going grom 10 ohms to 50+ is not good, speakers stop working. :)

Hope I didn't just confuse the issue.
 
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