short circuit after soldering my AVRcam

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short circuit after soldering my AVRcam

Postby Jan Valcke » Tue Jan 11, 2005 1:47 pm

Hi,

After i soldered my pcb with al the components i have done the test before inserting the IC's. I have found a short circuit. Then i have checked my soldering points and all components for any errors but i can find anything.
Are there people that have also this problem, or have found the solution.
I breaking down my pcb when i desoldering the components so i do more wrong than right. I really can't find the short circuit.

Thanks
Jan Valcke
 

Postby Guest » Fri Jan 14, 2005 8:08 am

Hi Jan,
As per our off-forum email exchange...there haven't been any reports of anyone else who has seen a short on the PCB. This is the first reported case of this type of thing. The short was found after all the components were soldered down, but before the mega8 and tiny12 were inserted. It sounds like, after our email exchange, that you think the short may have been internal to the LM2937 itself.

Has anyone else seen a short on their board between Vcc and Ground (other than an accidental solder bridge, of course :-) ? In this case, the short was found before the ICs were ever inserted in the board. Has anyone seen a defective LM2937, where the voltages aren't at 5V?

Post back if you have seen similar peculiarities...
Guest
 

I've cooked parts until they were shorted

Postby hamjudo » Sun Jan 16, 2005 10:36 pm

I've never shorted an LM2937, but I have cooked other parts enough that they've developed shorts. I do ok if I use a good soldering iron set at the right temperature and good solder. I've made enough bad solder joints that I can now tell by looking when I'm making bad solder joints. This is a sign that it's time to change something. Did I pick up the wrong solder? I'm used to old style rosen core, it's harder to solder with "no-clean". "lead free" solder is much harder. Plumber's or jewelers solder is right out. Is my soldering iron falling apart? Does it need cleaning? Does it still work? etc...

Anyway, if it takes too long to get the solder in the right place, then you destroy the chip or the transistor. Sometimes you destroy the connections, sometimes you melt everything together, sometimes, the chip still kind of works, it's just way out of tolerance.

Desoldering is difficult without the right tools. Google will probably find a better description than what I could write. The most important thing to do is practice on some circuit boards that don't matter. For example, this would be an excellent time to take apart an obsolete modem. Once you can reliably desolder junk, then you can try to desolder something that matters.
hamjudo
 
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