The Forestry Forum
General Forestry => Sawmills and Milling => Topic started by: stavebuyer on May 24, 2012, 05:00:43 AM
Started sawing yesterday morning and the LT70DCS "stopped" moving forward half way through the opening cut on the second log. A small chunk of thick stringy water-soaked white oak bark basically wrapped around the sprocket and chain of the power feed gearbox. It tripped the circuit-breaker but still fried the h-bridge first. This is the 2nd h-bridge in 3 months. Still under warranty and Wood-mizer is overnighting the parts. The tech tells me it's usually a ground issue and the h-bridge I just burned is an upgraded version with a daughterboard thats supposed to keep this from happening. It was a wet misty morning and I am wondering if condensation on the contacts and lower rail contributed to this as the contact strip and buttons appear to tight and adusted properly.
The lower ground block is for the hydraulics only. If it has a bad connection then the hydraulic system will search for a better ground somewhere else on the mill. To check the connection, place a volt meter on the block and the other lead on the rail it touches. Operate the hydraulics. If you have more than a volt draw it is not making a good connection. Condensation has nothing to do with the failure of the bridge itself.