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HELP!!! Finding a short to ground when nothing gets hot on the board

supamodz

supamodz

Member
Hey guys this is a general question about finding shorts. This problem happens to me from time to time and i have no clue on what to do.
From time to time i will get a board where i find a short to ground, so i then would inject voltage in that circuit, but when voltage is injected the voltage drops on psu but amps do not drop. When i check around board using a flir thermal camera nothing gets hot which makes the short almost impossible to find. How do you find a short when this happens? This annoys the shit out of me when i come across these types of shorts looking for suggestions.
 
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dukefawks

Administrator
"the voltage drops on psu but amps do not drop" What does that mean?
If you have a short and you inject the maximum voltage on that rail lets say 1.5V and there is no current draw then there is no real short. If you have a full hard short injecting any voltage will pull maximum current from the PSU.
 
supamodz

supamodz

Member
dukefawks said:
"the voltage drops on psu but amps do not drop" What does that mean?
If you have a short and you inject the maximum voltage on that rail lets say 1.5V and there is no current draw then there is no real short. If you have a full hard short injecting any voltage will pull maximum current from the PSU.
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then my question is if you don't have a full hard short how do you find whats causing the connection to be missing finding these issues are nightmares to me how do you handle a situation like this duke.
So i guess this is why its better too look for resistance to ground instead of using diode mode to find shorts because that what I've been doing to look for shorts.
 
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dukefawks

Administrator
How do you define "short"? Anything over a few dozen Ohm will not cause enough current draw to heat something up.
 
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