Archived from the Tools In Action forum (Power Tools). This thread is read-only.
In my previous post, circuit board # 270264001 fixed the variable speed problem. I inspected the bad board that I had pulled out and found that the MOSFET was short about 10 ohms between Drain and Source, pin 2 and 3. In diode check mode with a multimeter, with the negative lead on pin 2 and the positive lead on pin 3, you should read about .589 ohms and infinite with the leads in reverse. I ordered a couple of MOSFET’s PN# IRFZ44N from Mouser electronics with one being a spare. A $ 1.12 ea. I bolted on a small piece of aluminum fin to the tab to help dissipate heat and replaced the component on the board, then disassembled the caulking gun to replace my new board with the one I just repaired for an actual test. The repaired board worked, so I’m leaving it in. Now I have a spare new board and a spare MOSFET. Browsing the Net just didn’t show much information about this model. The caulking gun and chord less circular saw are the only 2 power tools I have from RIGID. Both have come in handy. I paid a lot for this caulking gun at the time, so felt the need to repair it. Hopefully, if there is anybody out there that is still using this tool and they have the same failure, this info can get them back to a variable speed function with the exact fix for the cost of the part and ground shipping, approx. $12.00.
