- Thread starter jateu
- Start date
the snooper
getting older by the day
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- 21,078
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- Hull UK
is it just a small resistor ? if so probably just around 0.6 watt
the snooper
getting older by the day
- Messages
- 21,078
- Location
- Hull UK
if its physically the same size as a .25 try it you will know because it will heat up if its too small
the snooper
getting older by the day
- Messages
- 21,078
- Location
- Hull UK
if it was destroyed that fast you have another problem on the board
most small resistors are carbon
most small resistors are carbon
Metal film are better quality with tighter specs, better stability and better noise figures, but in a circuit like this it hardly matters. 0.6W metal film from Maplins are maybe 15p. There aren't that many run of the mill circuits where you need 1% or better metal film types and carbon won't do.
I'd guess the original was carbon composition, 5% tolerance.
You could even put in a 2 or 3 W resistor with a bit of fiddling, and if you are having problems it makes sense.
As others have said, you probably have a fault somewhere else in the circuit causing the resistor to be subjected to a higher voltage than anticipated.
Have you tried measuring the voltage across the resistor? If you do that you can work out the current it's passing, then the power it dissipates is the square of the current times the value of the resistance.
Yeah originally I had added the non PSU motor update to mig and I think the high current load of the two extra 2200uf caps might have cause an extra current feedback to PCB because I tested motor but not while welding ! This may have made relat to blow , the motor still working and going to replace res with .5w and remove extra caps to see what happens ?
the snooper
getting older by the day
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- 21,078
- Location
- Hull UK
i would agree there
the snooper
getting older by the day
- Messages
- 21,078
- Location
- Hull UK
look at maplin or cricklewood electronics , farnels
Maplin is the easiest if there's a local one and if it isn't anything odd like a wirewound.
http://www.maplin.co.uk/standard-potentiometers-2205
RS, Farnell, Digijkey etc will have a better range and probably better quality ones, but they're more of a pain to deal with.
Somewhere on the body of the old one there should be a value, 4.7K Lin (linear) or like that.
Why have you decided that the pot is shot? Is it open circuit or doing strange things when you test it with a meter?
http://www.maplin.co.uk/standard-potentiometers-2205
RS, Farnell, Digijkey etc will have a better range and probably better quality ones, but they're more of a pain to deal with.
Somewhere on the body of the old one there should be a value, 4.7K Lin (linear) or like that.
Why have you decided that the pot is shot? Is it open circuit or doing strange things when you test it with a meter?
