DexterMccoy
New Member
Why does a plug in bench DVM meter short out when measuring VCC and VDD at the same time?
VCC is +30volts and VDD is -30 volts
The Bench DVM meter shorts out the burns the circuit board, but why?
How do you prevent this from happening?
I had my red dvm meter probe on VCC +30 volts and my black meter probe on VCC -30 and it shorted out the power supply diodes and fried the board
But why?
Why would this create a short if the DVM meters negative input is connected to earth?
-30 volts VDD and + 30 volts VCC = 60 volts potential difference
Is the Bench DVM meter chassis ground connected to the meters probes?
The meter probes would have to be internally inside the bench DVM meter connected to earth or chassis ground of the DVM meter
If a circuit boards power supply earth or chassis is different then the DVM meters chassis ground or earth ground can this cause a ground loop or short when measuring from VCC to VDD rails?
When can a SHORT occur when measuring from VCC to VDD supply rails?
The grounds would have to be different how so?
VCC is +30volts and VDD is -30 volts
The Bench DVM meter shorts out the burns the circuit board, but why?
How do you prevent this from happening?
I had my red dvm meter probe on VCC +30 volts and my black meter probe on VCC -30 and it shorted out the power supply diodes and fried the board
But why?
Why would this create a short if the DVM meters negative input is connected to earth?
-30 volts VDD and + 30 volts VCC = 60 volts potential difference
Is the Bench DVM meter chassis ground connected to the meters probes?
The meter probes would have to be internally inside the bench DVM meter connected to earth or chassis ground of the DVM meter
If a circuit boards power supply earth or chassis is different then the DVM meters chassis ground or earth ground can this cause a ground loop or short when measuring from VCC to VDD rails?
When can a SHORT occur when measuring from VCC to VDD supply rails?
The grounds would have to be different how so?