When a TSOP flash goes bad (R7R3/R7R4)
Here we have a (very) brief write up of a repair I've done for an attempted TSOP flash gone bad. Fairly straight forward repair and only three pictures. Hopefully this is useful to anyone whose damaged R7R3/R7R4 on the bottom of their board.
|When I received this board I was wondering why people do TSOP flashes. I mean chips can be had for only a few bucks (I sell one for $15, nearly ready to go). Well so what does it matter, people do TSOP flashes and periodically mess them up. This was one of those times. Not only had they damaged one of the pads they needed to short together, they removed a rather important component as well.|
|Here is a wide shot of the area to help you get your bearings. The damage is located between the Alternate D0 and the LPC header.|
|A close-up of the damaged area shows the faulting. The trace that is pulled away should be connecting to R7R3 (A 10Kohm 0402 resister) and R7R4 (an empty spot, shorted to enable TSOP flashing). Well it would appear that in the process of attempting to short out the required points, far too much heat was applied long enough to loosen the pads from the board. Something I can never repeat enough: Once a pad or trace starts moving STOP. If you are not skilled in SMT re-work and repair you will only make the problem worse. Send the board to someone with skills in this arena and pay for the work to be finished. Often times if no damage is yet done, finishing the job is far cheaper that repairing the damage. At least this person quit before digging a giant chasm in the board.|
|All in all the repair was successful, if not time consuming. Placement of the replacement resister was the most difficult, as the components are designed to be supported by two pads, not one. I broke a couple trying to properly position the wire for the repair point.|