Resistor Question

M

macrospect

[H]ard|Gawd
Joined
Nov 22, 2004
Messages
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I have a quick question about a dead resistor I have. It came out of a heat gun that I was using, and I found out that the resistor burnt off on one of the ends and was fried (it is OL on a multimeter) I need a new one but dont know what the ohm rating was on it. There are NO colored stripes on it, its all blue and there is a little number written on it.

The number is 103, and written below the 103 is M5C.

I would greatly appreciate it if someone knows what the ohm rating is. :confused:
 
Heres what I am talking about:

resis.jpg
 
Actually I didnt think of that. WHat it came off of in the heatgun is the 2 wires that go to the motor that powers the blower fan. It was soldered between the red and black wires going to the motor. A fuse sounds like it may be it, I dont know why a resistor would be in a place like that, heres another pic if anyone has an idea of what I need to get as a replacment part.

The part above was on the motor just like this, if it is a fuse does anyone have any idea what kind to get? If I cant get any answers here maybe ill just call Wagner up.


heatgun.jpg
 
From that picture it is clear that it is not a fuse or a resistor, since a fuse needs to be in series, not in parallel, and a resistor wouldn't make any sense. Typically motors use a filter capacitor across its terminals and that is what your blue component is.

From the markings it appears to be a 10nF high temperature capacitor but I'm not sure what its voltage rating is. However, this isn't likely a problem as I don't think the capacitor is actually broken.

You said that you tested it with an ohm meter, but that won't work for testing a capacitor. From the look of the picture the capacitor seems to be undamaged. There are no burn marks or anything else out of the ordinary. What exactly makes you think it is broken?
 
yea dude.. i think it's a cap.. caps usually have markings lik that on them..


and the fact that it's between power and ground suggest it's a cap.. caps are can be used between power and ground to help filter noise, helps keep a more consistant DC flow.. as i'm sure that's a DC motor you got there

I would solder that badboy back on.. and let her rip

it's an odd looking cap i might say though..

EDIT: actually.. a lot of times people use electrolytic caps.. but i guess teh heat from the gun would make that hard to use.. and unsafe..
 
RancidWAnnaRIot said:
.....and the fact that it's between power and ground suggest it's a cap.. caps are can be used between power and ground to help filter noise, helps keep a more consistant DC flow.. as i'm sure that's a DC motor you got there....
Click to expand...

Yep - your photo / diagram rocks....:cool: I'm betting it's a cap, too.

Believe it or not, it may be there for the sole purpose that the gun can pass emissions testing....like, FCC type of emissions. Everything sold to "a consumer" has to pass "some" type of certification.

I'll bet the motor will run just fine without it. If you want to replace it, I'd try a 0.1 or a 0.01 uF (micro farad) ceramic cap. Make sure the "working voltage" is 3-4 times the DC voltage of the motor. Electrolytics are usually used as filters on the output of power supplies, and this isn't the application this is in. That and to start really big motors, but again, that's not this app.

Good luck - B.B.S.
 
Thank you for all the replies ! :)
Actually to tell you the trut hthe gun runs fine without it on there, I just didnt know if it is safe for it to be running like that. Maybe ill take a trip to radioshack to see what I can find there. If I cant find anything then ill just put the gun back together and run it like that. It must have been running years without that cap. in place anyway.

Ill measure the voltage ratings on the motor later, time for school ;)

DaRkF0g
 
I'd go with safe..... heck if no smoke came out and you didn't trip a breaker by now. just kidding tho its fine. Caps are normally used like this to cut down on noise (electronic noise not the sound my fans are making) that is generated by the motor.
 
Just for reference, this is how to read capacitors:

A = first digit
B = second digit
C = third digit

[(10 x A + B) x 10^C] x 10^(-12) Farads
 
Teancum said:
Just for reference, this is how to read capacitors:

A = first digit
B = second digit
C = third digit

[(10 x A + B) x 10^C] x 10^(-12) Farads
Click to expand...

... that's the hardest way i've ever seen... lol
 
plot said:
... that's the hardest way i've ever seen... lol
Click to expand...

As far as i know.. that's the only way i've seen.. at least for the monolithic caps... in my experience electrolytic caps usually just have the value printed on it...
 
It's right...just not particularly easy to undertand. I'll try again:

take the first two digits. Add X zeros after that, where X is the third digit. That gives you the number of picofarads. So a cap labelled 102 is:
10
tack on two zeros (the third digit), and you get 1000 picofarads = 1 nF.
 
RancidWAnnaRIot said:
As far as i know.. that's the only way i've seen.. at least for the monolithic caps... in my experience electrolytic caps usually just have the value printed on it...
Click to expand...

flat out memorization is alot easier then that IMO

i do this:

Teancum said:
take the first two digits. Add X zeros after that, where X is the third digit. That gives you the number of picofarads. So a cap labelled 102 is:
10
tack on two zeros (the third digit), and you get 1000 picofarads = 1 nF.
Click to expand...
 
using my referece we can go on to say

M5C

Tollerance +/-20%
Temp Rating 85C+/-2.2%
 
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