M
Myauk
- Jan 1, 1970
- 0
Hello..
I found a strange problem while working on a typical PCBA.
It is a kind of pneumatic control PCBA. The PCBA uses 24V power supply
from which it draws current from 1 to 3A.
Before its operation, normally we check the resistance measurement
between 24V and Gnd, which should be around 2 kilo ohms.
For a particular PCBA, the measurement showed 30 ohms, we rejected it
for further analysis.
After a week or two, I study the PCBA to determine what was causing
the problem. Accidentally I supplied 24V to it and found that it was
working normally.
When I disconnect the powersupply and measure again, I found that it
showed higher than 2k ohms at that time.
I visually checked it thoroughly to see if there were any defective
capacitor along the pcb traces but found no problem at all.
I kept it for at least three weeks, I have tested it in operation for
more than 5 times, and until now there is no problem in the operation
of that particular PCBA.
I wonder what could cause the resistance measurement to 30 ohms and
then higher than 2 k ohms after supplying voltage to it.
Any idea?
Regards
I found a strange problem while working on a typical PCBA.
It is a kind of pneumatic control PCBA. The PCBA uses 24V power supply
from which it draws current from 1 to 3A.
Before its operation, normally we check the resistance measurement
between 24V and Gnd, which should be around 2 kilo ohms.
For a particular PCBA, the measurement showed 30 ohms, we rejected it
for further analysis.
After a week or two, I study the PCBA to determine what was causing
the problem. Accidentally I supplied 24V to it and found that it was
working normally.
When I disconnect the powersupply and measure again, I found that it
showed higher than 2k ohms at that time.
I visually checked it thoroughly to see if there were any defective
capacitor along the pcb traces but found no problem at all.
I kept it for at least three weeks, I have tested it in operation for
more than 5 times, and until now there is no problem in the operation
of that particular PCBA.
I wonder what could cause the resistance measurement to 30 ohms and
then higher than 2 k ohms after supplying voltage to it.
Any idea?
Regards