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Mitre saw laser guide resistor

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davetupps

New Member
Hi folks new to the forum with my first post here. I've got a mitre saw with a faulty laser. I've replaced the laser and know thats working. Having traced the circuit board out (i think) I came to a burnt out resistor. I'm pretty sure this is the problem. I have tried to read it but not sure I'm doing it right. I've come up with 1000000 ohm with -/+2% tolerance. Underneath it written on the circuit board it says 25R / 1W. Can someone tell me what resistor I need (i.e. what i need to type into ebay) cheers for any help you can give.

I've attached a pic. if you cant see it to well, its a light blue cover with a brown band (burnt section) black band green band red band.
 

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davetupps

New Member
hi mate, thanks for the reply. So if i where to go in to an electronics shop and ask for a resistor I would request a .25 watt???? or 25 ohms? or a 1w or etc... I have near enough no understanding of electronics.
 

Torben

Well-Known Member
hi mate, thanks for the reply. So if i where to go in to an electronics shop and ask for a resistor I would request a .25 watt???? or 25 ohms? or a 1w or etc... I have near enough no understanding of electronics.
In order to match what the PCB says, you would walk in and say that you want a "1 Watt 25 Ohm resistor".

I think you read the color bands backward; if you start with the red one, the value you wind up with is 25 Ohms. I suspect that the "brown" band used to be gold (i.e., 10% tolerance) but I could be wrong about that. If it burned and failed open (as opposed to failing shorted) that would explain the very high resistance you measured.


Regards,

Torben
 
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