How to find Short point between VCC and GND on PCB ?

[vikasveshan]

Hi all ,

Is there any better way to find Short between Vcc And Gnd on PCB ??

Regards !!
V V

 

[ckshivaram]

At the time of manufacturing they do a test called BBT test, ( bread board test) which tells about short between any 2 tracks , or supply and ground.. they charge you extra for that...

If it is not done the we need to do manually before mounting the components.....

 

[lurchman]

Vikasveshan,

There are a number of ways you can find the fault on a PCB and the simplest is to make a low frequency current tracer. It puts 100mA of AC at around 1KHz into the board trace, you then use a magnetic probe to follow the signal around the board.

Basically you can make a probe with a short iron nail with a few hundred turns of fine enamled copper wire around it connected into an audio amplifier.

If for some reason (like a multilayer board) you can't get at the short you can if you are lucky "blow it out". That is some shorts are "whiskers" and pulsing a very high current through the trace will cause the "whisker" to behave like a fuse. However you may be unlucky and have to "drill cut n wire" around the short.

 

[Hussainb]

Vikasveshan,

There are a number of ways you can find the fault on a PCB and the simplest is to make a low frequency current tracer. It puts 100mA of AC at around 1KHz into the board trace, you then use a magnetic probe to follow the signal around the board.

Basically you can make a probe with a short iron nail with a few hundred turns of fine enamled copper wire around it connected into an audio amplifier.

so please can you explain what happens next, i mean how the short can be detected after making the probe and the low freq tracer ckt?
i think the tracer has to be connected to the faulty pcb and the probe has to be moved over the pcb? so what responses do we get so as to identify the short.
thankyou

 

[embeddedlover]

What you can do is connect the output of audio amplifier to a speaker....which gives small beep sound (constant freq)
When you follow the trace if any short is present in the path, after that node you will not be able to listen the beep as entire signal will be grounded...

Is there any better way to find Short between Vcc And Gnd on PCB ??

If you can't afford the BBT as sivaram was mentioning, go for the tradition way of continuity test with multi....

 

[Hussainb]

oh ok ok...i understood now.. thankyou