WM Power Feed Problem

Tobacco Plug · January 27, 2005, 01:19:01 PM

The power feed on my 94 model LTHDG24 is not working right. It works fine in reverse. It works when the blade is not engaged. But when I try to saw a board, it stops working. I have checked the contacts on the drum switch, turned the power feed regulator knob up and down several times while it was not running, checked the connections and cannot determine the problem. It ran fine this morning, but started acting up this afternoon. Day before yesterday (the last time I ran the mill) it did pretty well, with only one or two episodes. I called Wood Mizer and the technician said I need a new circuit board ($250). Any ideas from any of y'all about this that could perhaps save me some money? Thanks.

isawlogs · January 27, 2005, 01:28:07 PM

I had a simelar thing happen to mine and changed the variable speed control switch and solved my trouble .... My mill would work fine in reverse and then be iratic when sawing ... but if the blade was out of the log and then put in forward it would run ok .... Prety much like yours ...
Maybe you should talk to you rep again and see what he thinks of this ....

VA-Sawyer · January 27, 2005, 01:55:49 PM

Is it possible the drive belt is slipping? Try to hold the head back with your arm, put it in foward and slowly increase the feed speed. You should be able to feel the difference between a slipping belt and a complete loss of voltage to the feed motor.
VA-Sawyer

Kevin_H. · January 27, 2005, 03:33:46 PM

I just replaced the speed controller on my 97 WM this morning, following the same kind of problems.

It would work fine in reverse but in forward the head would stop and start,

When the head stops while in forward, try gently tapping on the speed control with your finger tip and see if it will start again.

27.50 for the speed controller is a heck of alot better than 250.00 for the new board.

DR Buck · January 27, 2005, 03:57:04 PM

I agree with VA Sawyer. Check the drive belt. We had a very similar post just a few weeks back. Also, before replacing the variable speed control, try a little contact spray cleaner into it first. It might just be dirt in the control.. You can get it at Radio Shack for a couple bucks a can. Spray it in and work the control a few times.

Randy · January 27, 2005, 04:52:12 PM

My Sawmill (LT40)did the same thing---Took the cover off next to the battery box, tighten the belt-------Works Good now. Good Luck! Randy

WH_Conley · January 27, 2005, 06:23:37 PM

Only 2 things I can think of to add, cause these have zeroed in on the main problems.

(1) With my 97 lt40 when board went bad it would not go in morning, when first started, condensation problem. I would not think it would be a problem later in the day. However to cure this problem I put a fog light in the control panel, turn it on a few minutes, problem solved, cost-0, salvage.

(2) when top rollers went out, mill would stop when cutting, scratched my head a half a day before figured it out. New sharp blade was worst than a dull one, only thing could think of was more agressive the blade the more pressure it put on the rollers. Who knows?

I would try everyone elses solutions first, they are more reasonable. I think # 2 would be the least likely to happen.

Just a guess on my part, lotsa luck.

gmmills · January 27, 2005, 06:44:48 PM

Well guys add me to the list. Mine has been acting up since the first part of this week. First thing I did was check belt tension. It was fine. Checked electrical connections and drum switch . All were ok. The potentiometer, variable speed control, came today. Going to replace it in the morning. Mine would act fine in reverse. It would act up starting from dead stop going foward. Get it to move by rotating the knob above half way . By this afternoon it was hard to get it to move from a dead stop and getting worse. What lead me to think it the potentiometer was this. As the blade exits the cut I always have turned the knob up faster while raising the head so the board return will drop off the end of the cant and get the board back to me. When i turned the knob up quickly the head would come to an abrupt stop. It was really getting on my nerves today.

Kevin_H. · January 27, 2005, 07:02:05 PM

I have to sit and laugh a little, When I got my new controller the pick list had it on back order, The backorder stamp was scratched with an ink pen. I guess now I see why it was back ordered.

The parts guys at WM have got to be thinking something weird is going on with the speed controllers...

job security sparks...job security. :D

GF · January 28, 2005, 06:06:12 AM

Just curious as to why Woodmizer uses electric feed and electric speed controllers instead of hydraulic with flow control valves etc?

Jason_WI · January 28, 2005, 10:03:22 AM

Potentiometers will only last so long. Vibration, continous use will cause them to fail. Most are made with a carbon track on a circuit board and a set of copper berillium spring contacts that make contact with the carbon track. Over time the carbon track will be worn away and cause a dead spot.

Replacing with a high quality wire wound poteniometer is one solution. These usually cost 10 bux on up verses the .99 cent carbon pot.

Jason

isawlogs · January 29, 2005, 10:07:34 PM

QuoteReplacing with a high quality wire wound poteniometer is one solution.

Jason
How much bigger are these I would like to change over to these if they will fit in the space that is left inside of the box ...

Brucer · January 31, 2005, 01:25:47 AM

Marcel:
I've got one in my hand. The body is 29 mm (1-1/8") diameter and 14 mm (9/16") high. The bushing
and shaft are the standard size. This is about 6mm bigger in diameter and 4 mm thicker than a
typical carbon potentiometer. The one I've got here is only 50 ohms and I suspect that's way too
low for what you need.

gmmills · January 31, 2005, 09:03:52 PM

To update my power feed trouble. The potentiometer was the problem. Changed it out and works great.

The pots that WM uses are not just common off the shelf Radio Shack components. WM had an article about them a while back. I just can't remember which issue of the WM News it was in. Yea, I"ll admit it , old age creeping in. :D I'll agree that they will only last so long. I really can't be upset about having to change it. It was the original and lasted 3762 hrs.

Tobacco Plug · February 06, 2005, 01:45:01 PM

Well, I talked with another technician at WM last week and decided to order a new pot. Got it and put it in yesterday so I will see it that fixes my problem. I didn't mention earlier that the problem seems to present itself only after the mill has been running for a while. Guess I won't really know until I have run things for a few hours. :

Kevin_H. · February 07, 2005, 10:33:59 AM

Hey Lewis

Keep us up to date, let us know if that fixed the problem...

sparks · February 07, 2005, 04:10:46 PM

There are some easy checks for the power feed. If the power feed board has LED lights on it, write down what the lights are doing when you try to go forward. Call and we can use those lights to troubleshoot. If the board has no LEDs, then you can check the output of the board using a voltmeter. The variable feed switch (potentiometer) has 3 wires, brown/brownstripped, red/redstripped and violet/violetstripped. The brown is on one outside terminal and the violet is on the other. These are the outputs from the board. One outside terminal should read approx 1vdc. The other outside terminal should read approx 3.5vdc. If either one of these are wrong it is a bad board or a bad connection on the variable feed switch brown and violet wires.
If these voltages are good, then the center terminal should vary between 1vdc and 3.5vdc. If it does not vary it is a bad switch. If it does vary then it is a bad board or a bad connection of the variable speed switch red wire.
Sorry, didn't want to write a tech bullentin. ;D

sparks · February 08, 2005, 08:18:44 AM

Slabs, the schematics are proprietary. The pot is linear. Thanks

Jason_WI · February 09, 2005, 11:12:51 AM

QuoteSlabs, the schematics are proprietary.

With an ohm meter and about an hours time I could retrace you a schematic ;D

To get the value of the POT measure the two outside terminals. Or if there are markings on it that read 103 then it is a 10 K (k = 1000) ohm POT. The last digit tells how many zeros there are. Sometimes just 10K is stamped on the POT. Sometimes sneaky engineers sand the part numbers off....

To determine if a POT is linear or audio taper turn the pot to the mid point. The reading with an ohm meter between the center terminal and one of the outside terminals should be about half of the total value of the POT for a linear taper POT.

Resistor color code table:

Tobacco Plug · February 10, 2005, 10:11:50 PM

Today was the first chance I had to run my mill after replacing the pot. It seems to be running fine after that repair. Hoo Ray!
8) 8) 8) 8)

Kevin_H. · February 11, 2005, 04:11:20 PM

Good Deal there TP...Glad ya got it going. Few things as fustrating as a sawmill not running right. ;)

Tobacco Plug · February 11, 2005, 10:33:07 PM

Quote from: Kevin_H. on February 11, 2005, 04:11:20 PM
Good Deal there TP...Glad ya got it going. Few things as fustrating as a sawmill not running right. ;)

Ain't it so. Today was the second of no problems with the power feed so I guess the problem has been solved. Thanks to all for the advice.

logman · February 15, 2005, 09:40:02 AM

I am having a feed problem also. The troubleshooting light is showing
overload when I turn the rheostat up. It isn't the feed motor, mechanical
binding or feed switch. Any ideas?

sparks · February 16, 2005, 12:26:37 PM

Logman, is it a Wood-Mizer? If so what year? Are the lights on a black box labeled pwr. out, in, ol, ov?

logman · February 16, 2005, 01:36:01 PM

Yes, it is a 2000 or 2001 (can't remember which) LT30. My carriage will
return but when I try the forward feed the light on the module inside the
control station marked OL comes on. The morning that it did it I had to
jump my battery to get it started. I don't know if that caused the problem
or not. I know it isn't the feed motor or the feed switch because I tried
new ones. Thanks for any help you can give me. I was going to call
WM again if I didn't get any help here.