On Thu, 14 May 2009 00:42:16 +1000 Bob Larter
wrote in Message id: :

JW wrote:
On Wed, 13 May 2009 07:51:38 -0400 Phil Hobbs
wrote in Message id:
:

JW wrote:
Let's say you know that a certain point on a data bus has a defective
device that is always trying to drive the bus low; Was wondering if anyone
has any good tricks in finding the defective device, other than
cutting/lifting pins?
Drive the bus high, e.g. with a 1k resistor to Vdd, and use
millivoltmeter. You can see the voltage drops in the traces--where the
voltage drop is changing, current is flowing.

Hi Phil, That sound like a good possibility, thanks. I have a Philips
PM2534 DMM that has a 300mV range with 100nV resolution. The only thing
might be that if the bus is active (changing states) the readings might be
jumping around too much.

If it's stuck low, then the signal won't be changing, will it?

Yes, it can. It's not stuck/shorted to GND, but fighting with another
latch, driver, or buffer.