Tool Tip: Repair a Circuit Board
Replace or Repair?
A friend has a Grizzly G0459 12” baby drum sander on which the conveyer belt stopped moving. A little troubleshooting revealed that the speed control board failed. A replacement board is $62 plus shipping from the manufacturer. Once he popped the new one in, he was back in business. But what would it take to repair a circuit board?
Troubleshoot the problem
I asked him to let me take a look at the old board. When I got it, the first thing I noticed was that the circuit board is single-sided. That is, there are copper traces on one side only. A single-sided board is not as robust or reliable as a double-sided board. Therefore, I did a thorough inspection for bad solder joints.
Solder to Save
A solder joint can be weakened when the soldered-in wire or terminal is moved, causing the solder to fracture. A bad solder joint does not make a good electrical connection and causes the circuit to fail. As expected, there was a funny looking circle on one of the .250” spade terminals. A quick hit with new solder and the soldering iron and the board is once again functional.
Repaired Circuit Board
The pictures below show the repaired board. The offending terminal is circled in red. It turns out that the mechanical design of the board could be better. When the mating terminals are pushed onto the board connectors, a lot of force is required. That force can cause the solder connections to weaken. Plus, normal vibration from the sander’s operation can damage the connection over time.
What have you got to lose?
If you have a similar failure of a piece of equipment in your shop, before you spend money on a replacement circuit board, take a good look at the solder joints on any terminals on the defective unit. If you see any indication that the joint has failed, reheat the joint with a soldering iron and apply some new solder. Be sure to clean the flux off the board using alcohol or flux remover. If the problem is not a bad solder joint, you can order a new board!
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