Yet Another LT-40 Forward Feed Problem

[DR Buck]

So now I've suffered one of those mysterious forward feed issues on my LT40 Hyd.    Problem started a week ago or so.   Went out to mill and the head would not move forward.  While it was running I played around with the forward speed control and the forward/reverse drum switch.  It started to work.      So I sawed.   Everything was OK until I stopped and shut the mill down to change a blade.   When I went to start up again, the same thing happened.  After fiddling with the front panel controls it started to work so I finished the job.

Next day.   Same problem.  It only happened when first starting the mill or after I shut it down for a while.

A week later (today).  I had 4 cedar logs to split down the center.   Same issue, no forward motion.      Tap on the speed control a few times and it starts working.     So now I think I have it solved.    After finishing I decide to swap out the speed potentiometer.     Still have the same problem!      Time to get out the book.   Start by checking the LEDS on the motor control board.  They look OK and when I try it it moves forward.   ???   Shut it off and back on the problem comes back, then fixes its self.    Thinking it must be a loose wire I check things out and try again.   No forward motion.  But wait this time the LEDS say there is an overload.  Then while still looking the OL light goes off and the thing works.   

Tried turning it off and on a few times and still get the overload light.    So next I remove the drive belt from the motor.  Still same problem, no forward.   Then it fixes its self again.        Then I start watching the LEDS as I go through start up and try to move forward.  OL comes on and stays on for 5 to 15 seconds, then goes out and the thing works and will continue to work until I shut down and restart.   Then I go through this whole time-out thing and it will work.   I'm thinking I have a control board problem.   Anyone else seen this symptom before?   I tried to call Wood-Mizer, but they were already closed for the day.

[GAB]

DR:
Please keep us posted as to what the problem ends up being.  Owning an LT40 I am curious.
I personally have not had this problem.  Mine drive motor just died period.  One new circuit board later I was operational again.
Gerald

[drobertson]

could be a board, but almost sounds like a broken drum switch contact arm,

[pmatt]

My problem, which still exists, is a fried mosfet board.  All switches, wiring and control boards are fine, the mosfet board took a surge of voltage and went out.  Installed new mosfet and ran about 10 ft and a surge came through and dead in the water again.  No idea where the surge is coming from or why the circuit breaker isn't doing its job but this electrical gremlin will not go away.  Damages so far are about 6 hrs testing, replacing parts, etc., two weeks of down time waiting for parts, and a bunch of cash for parts that don't work.  2001 superhydraulic 42hp kubota.  Great motor.

[DR Buck]

My problem, which still exists, is a fried mosfet board.  All switches, wiring and control boards are fine, the mosfet board took a surge of voltage and went out.  Installed new mosfet and ran about 10 ft and a surge came through and dead in the water again.  No idea where the surge is coming from or why the circuit breaker isn't doing its job but this electrical gremlin will not go away.  Damages so far are about 6 hrs testing, replacing parts, etc., two weeks of down time waiting for parts, and a bunch of cash for parts that don't work.  2001 superhydraulic 42hp kubota.  Great motor.

If the circuit breaker is not tripping, it is either bad, or your 'surge' is more likely a voltage 'spike'.   Voltage spikes are usually a very short duratiion, on the order of milli-seconds which are not long enough to trip the breaker.  I'd look for a loose or coroded connection that may be arcing.  It could even be on the return (ground) side.  Anothe place to look at closely is the drum switch.  Contacts there do tend to arc due to the larger current going through them.

Haven't been back out to look at my problem, but it appears to be a grounding problem or loose connection in the 12 volt circuit.  The control board initially senses low voltage, which causes to OL light to come on and there is no forward motion.  When the voltage recovers, the light goes out and everything works. fine.

[DR Buck]

After explaining the symptoms to Sparks his immediate reply was "Feed control board is bad.   Something is warming up and then it works.  You need a new control board".   

Today I came home from the day job early and decided to install the new control board.   I should have my head examined.  smiley_dizzy  It's COLD out there!   Every time I touched the cold metal parts of the mill I kept thinking about that one scene from "The Christmas Story"....  you kow it   ... " I Double Dog Dare You!" ....   I thought the screws and parts were going to freeze to my fingers.

Anyway,  the the mill is fixed, almost.  ;D     I broke my negative battery clamp when I tightened it up and my feed speed control knob crumbled into pieces.    I've got replacements for both but gave up due to the cold.   Maybe tomorrow.  ;D

[Bogue Chitto]

I have a feed control problem with my LT 40 also.  It seems just to do it when it is warmer out.  When sawing at a normal speed the head will take off going faster forward. I will tap the top of the box and it will slow back down.

[POSTON WIDEHEAD]

I have a feed control problem with my LT 40 also.  It seems just to do it when it is warmer out.  When sawing at a normal speed the head will take off going faster forward. I will tap the top of the box and it will slow back down.

Bogue....you may not have a problem at all with your feed control.  Sometimes when you saw harden dense wood, you will maintain a certain speed. Then the blade will come in contact with some softer wood and it will speed up. And just by chance, when you tap it with your hand, it will slow back down because it is getting resistance from hard wood again....and in reality, your tap did not have anything to do with it.
My speed stays consistent sawing Pine but hardwoods is where I experience it most.

I may be wrong but this is just a my theory.

[Bogue Chitto]

When I say speed up I mean wide open. 

[POSTON WIDEHEAD]

When I say speed up I mean wide open. 

If it speeds up wide open....yes....there may be a problem. Sorry, I did not realize what you meant. Hopefully you can get some help. I have never experienced that. 

[Bogue Chitto]

It does it when it is 65 degrees or more.  say_what

[jcbrotz]

Next time it does it give the wire bundle going into the control box a twist you may have a short in there. You tap on the box may be enough to jar the shorts out of it :D