Lt30 power feed

HPPDRoss · August 07, 2015, 09:34:11 PM

Hey guys, just purchased a 1988 lt30 to go along with my old circle saw. Everything works great but the power feed speed adjustment. It wants to run wide open. I bought a new power feed unit from woodmizer but its doing the same thing. I called tech support, they said take the two wires off the motor and put a test light on them. He said turn the speed knob and the test light should dim and brighten but it stays bright. Any suggestions would be great.

Rougespear · August 07, 2015, 10:03:02 PM

Sounds to me like the potentiometer circuit (or its equivalent) is defective... I would start there. Probably best to revisit the issue with WM tech service though.

pineywoods · August 07, 2015, 10:53:09 PM

Ross, what part did you change? If you swapped the little round module that the speed control knob attaches to, that's not the actual speed control. That's the input to an electronic circuit board mounted inside the control head..To get at that circuit board, pull off the back cover. That module is a fairly common failure on older mills. They don't like excessive heat, water, or mouse pee..

HPPDRoss · August 07, 2015, 11:07:52 PM

I bought the box from woodmizer that has the circuit board and drum switch as one whole unit.

MartyParsons · August 08, 2015, 07:14:45 AM

Hello,
The power feed control in simple terms the Power Feed ( PF) motor has 12 volt to the motor as soon as the drum switch is pushed forward. The control pulses the ground, the more it pulses the faster the motor runs forward. On reverse there is no control the motor has 12+ and 12- to both wires as soon as the drum switch is pulled back.
So the questions are.
Does the PF motor run back at full speed? I am assuming this statement is yes
Does the PF motor go forward? Yes
Does it run full speed? Yes
Open the box 1988 would have the control mounted to the PF assembly You should see a green printed circuit board and wires running to a mosfet module ( aluminum block with three terminals) One terminal will go to the ground one terminal will go to the PF motor through the drum switch. The third terminal comes from the printed circuit most times this wire is blue. If the power feed runs full speed forward. remove this blue wire. ( you may want to remove the PF belt for safety) If the PF motor stops running. The problem is in the control side. Either the control module is faulty or the feed control pot is bad. If the motor still runs at full speed with the blue ( blue wire has a male and female spade ) wire disconnected then the mosfet module is shorted to ground. There is also a free running diode that should be checked before you order parts.

Hope this helps.
Marty