On Tuesday 24 December 2002 22:18, somebody wrote Thanks for the reply and the ideas, on which I have some comments. Sorry if I don't sound too enthusiastic. > > Technique one: Pulse your unit on and off at 1000 Hz. Probe every > node with a high gain FET input audio amplifier digital probe and > listen for anomalies.
I can write software to do this - It's an idea. I don't have the fet amplifier, but I'll try a 'scope. > > Technique two: If the nodes are lined up like an IC, then swipe the > digital probe so it hits each node in rapid succession. This will > cause the digital probe to make a chirping sound. If any node is > drawing more current than the other nodes, it will color the chirp > sound at that node. I learned that this is called voodoo > electronics. This is impractical - and that's the worst of messers talking at this end :-/. It's a small smt pcb, not a xylophone! > > Technique three: Make a shielded test probe with two tiny points > less than 0.1 inches apart. Connect the test probe to a high gain FET > input AC and DC amplifier. The test probe shield should be grounded > at the end connected to the amplifier ground input only. The test > probe shield should not be grounded to the circuit under test. A > separate ground lead should connect the amplifier ground input to > common bus of the circuit under test. Connect the output from the > amplifier into a scope or meter. Poke the circuit board traces until > you find a voltage anomaly. The higher the current passing through a > circuit trace the higher the meter or scope reading will be. If I gather the substance of this correctly, you are telling me to amplify the voltage drop across the traces. Fine, except it's a four layer board, and those traces are in the middle. I may well try to amplify the voltage between devices if the worst comes to the worst. > > > > -----Original Message----- > Here's one to tease yourselves over. I have a board to fix and for > once, I do not know how to go about it. > > Good luck' > Jeffrey Meade > [EMAIL PROTECTED] -- Regards, Declan Moriarty. -- Author: Declan Moriarty INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
