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General Forestry => Sawmills and Milling => Topic started by: halcyon on July 28, 2017, 07:13:52 PM

Title: Help on a 1985 woodmizer lt40
Post by: halcyon on July 28, 2017, 07:13:52 PM
Great site,sure hope you can help me out. I bought a 1685 woodmizer lt40. The variable speed for feed is not working. Called woodmizer and they said I need to upgrade . How do I put a potentiometer on it ,what all do I need to do this job. Can I buy a pot on Ebay that will work ,wiil the variable speed control they sell at Harbor Freight work. It already has the single feed chain so I don't have to do that upgrade.Thanks for any help you can provide me
Title: Re: Help on a 1985 woodmizer lt40
Post by: Kbeitz on July 28, 2017, 07:59:52 PM
You will need to know the ohm's of the potentiometer. Sometimes they are stamped on the back.
Title: Re: Help on a 1985 woodmizer lt40
Post by: pineywoods on July 28, 2017, 08:52:07 PM
Just about any generic 5K ohm or so pot will work BUT, that ain't likely to be the problem. A pot like that will handle no where near the current needed by the feed motor. So,, use a small pot to control an electronic circuit that will. It's mounted on the back cover plate of the control box. Woodmizer is correct, you will need to upgrade to a later version speed controller. The old one is no longer available. The new version is not an exact replacement, but properly installed, works just fine. A detailed set of installation instructions is included.
Title: Re: Help on a 1985 woodmizer lt40
Post by: KirkD on July 28, 2017, 10:53:07 PM
Quote from: halcyon on July 28, 2017, 07:13:52 PM
Great site,sure hope you can help me out. I bought a 1685 woodmizer lt40. The variable speed for feed is not working. Called woodmizer and they said I need to upgrade . How do I put a potentiometer on it ,what all do I need to do this job. Can I buy a pot on Ebay that will work ,wiil the variable speed control they sell at Harbor Freight work. It already has the single feed chain so I don't have to do that upgrade.Thanks for any help you can provide me

Do you have nothing at all or only in certain spots on the dial of the pot? Mine had flat spots when it would not work and I was able to take the pot out and open it up and clean the contacts, greased with dielectric grease and it is working fine now.
If it is dead you will need to do further troubleshooting to make sure it is not the motor or circuit board / wiring and then decide if you need to replace with the upgrade.
Title: Re: Help on a 1985 woodmizer lt40
Post by: Crossroads on July 29, 2017, 02:13:24 AM
I was having trouble with mine and it was nothing more than a loose wire that feeds the circuit board. I hate working on electronics and I stink at it, but a few min. With a test light and I had it figured out.
Title: Re: Help on a 1985 woodmizer lt40
Post by: Kbeitz on July 29, 2017, 05:04:21 AM
Another way that you can maybe go is to replace the board with one off e-bay.
I have no idea what voltage or amps you need but I can buy a board off E-bay
that takes 12/24v input and puts out 12/24v out for under $20.00. The board
come with the pot.
Title: Re: Help on a 1985 woodmizer lt40
Post by: Darrel on July 29, 2017, 07:58:11 PM
My 92 wood-mizer has developed few flat spots in its feed control pot so this may be a good thread to pay attention to.  :P
Title: Re: Help on a 1985 woodmizer lt40
Post by: halcyon on July 30, 2017, 10:06:45 PM
Thanks for all the input. If I can get the right potentiometer on Ebay I would like to go the way. I have bought two on Ebay so far but apparently I got the wrong ones. The woodmizer I have is a 1985 lt40 with the original power electric feed motor. If anyone could tell me the a potentiometer that will work with this motor I will order that one so I don't make another mistake.  Thanks so much for the help.
Title: Re: Help on a 1985 woodmizer lt40
Post by: Kbeitz on July 30, 2017, 10:29:04 PM
Can you look at the back of the pot and get any info off of it?
Title: Re: Help on a 1985 woodmizer lt40
Post by: halcyon on August 01, 2017, 10:43:50 AM
Any controller I tried to use ,all from Ebay,I fried. the original feed speed control that came with the 1985 woodmizer does not use a pot. the motor on the feed drive doesn't have any info on it. I am sorry I haven' been able to provide the info you need. I am wanting to buy a potentiometer on Ebay that will do the job. I hope any info I gave help out. thanks for the help
Title: Re: Help on a 1985 woodmizer lt40
Post by: Kbeitz on August 01, 2017, 02:58:48 PM
Most pots will work... It might go to fast or to slow with the wrong one.
Also some will ramp up faster or slower.

I'm wondering if you need a reostat type Power Wirewound Potentiometer instead.
These are for high power. Do a search for one on E-bay and see if yours looks like that.

A picture of what you have would help.
Title: Re: Help on a 1985 woodmizer lt40
Post by: Ga Mtn Man on August 01, 2017, 04:30:44 PM
 
Quote from: halcyon on August 01, 2017, 10:43:50 AM
Any controller I tried to use ,all from Ebay,I fried. the original feed speed control that came with the 1985 woodmizer does not use a pot. the motor on the feed drive doesn't have any info on it. I am sorry I haven' been able to provide the info you need. I am wanting to buy a potentiometer on Ebay that will do the job. I hope any info I gave help out. thanks for the help

If the original speed controller didn't use a pot, how did you vary the speed?  Are you wanting to replace the speed controller with a potentiometer?
Title: Re: Help on a 1985 woodmizer lt40
Post by: KirkD on August 01, 2017, 06:00:29 PM
In my 1989 it says this on the back of the Pot
rv4naysd102a
type J
1k-ohm k5
But I know for a fact they are not sending all the voltage or amperage through the pot because the specs on that one if you google it is only 2 watt.
Title: Re: Help on a 1985 woodmizer lt40
Post by: paul case on August 01, 2017, 06:43:30 PM
That k5 may mean that Kevin has 5 of them in his shed.

PC
Title: Re: Help on a 1985 woodmizer lt40
Post by: Kbeitz on August 01, 2017, 08:27:18 PM
Quote from: paul case on August 01, 2017, 06:43:30 PM
That k5 may mean that Kevin has 5 of them in his shed.

PC

For real I got a whole coffee can full of them...



 (https://forestryforum.com/gallery/albums/userpics/39553/Dsc06310.jpg?easyrotate_cache=1501633626)

Only $0.38 each on E-bay... Free shipping...
Title: Re: Help on a 1985 woodmizer lt40
Post by: Larry on August 01, 2017, 09:36:45 PM
The rheostats that take full current are about the size of a large donut and wire wound using a porcelain base.  A common brand name is Ohmite.  The small rheostats control an electronic circuit which controls the motor speed.  They will burn up with full motor current.

You can find many rheostats on ebay for less than a dollar but they are Chinese junk.  If you put an ohmmeter on the leads and turn the knob you will see dead spots, and spikes as you turn the knob.  If they pass the first test they fail within a couple of years.  If you need this kind look for something made in the USA as they are quality and usually run $10 or more unless you get lucky.  I like AB the best.
Title: Re: Help on a 1985 woodmizer lt40
Post by: Kbeitz on August 01, 2017, 09:46:20 PM
Quote from: Larry on August 01, 2017, 09:36:45 PM
The rheostats that take full current are about the size of a large donut and wire wound using a porcelain base.  A common brand name is Ohmite.  The small rheostats control an electronic circuit which controls the motor speed.  They will burn up with full motor current.

You can find many rheostats on ebay for less than a dollar but they are Chinese junk.  If you put an ohmmeter on the leads and turn the knob you will see dead spots, and spikes as you turn the knob.  If they pass the first test they fail within a couple of years.  If you need this kind look for something made in the USA as they are quality and usually run $10 or more unless you get lucky.  I like AB the best.

I agree 100 percent.  The one I collect comes out of militarily equipment.
Title: Re: Help on a 1985 woodmizer lt40
Post by: halcyon on August 11, 2017, 08:10:39 PM
I want to thank everyone for the great replies on my question. I think I am going to try an get a rheostat to see if it would work. Could anyone give me the spec's on which one I should get. It has the original motor for feed that the 1985 lt40 came with. I looked on the motor but it does not show any spec's so I hope someone knows what size it is. Thank again for all the help
Title: Re: Help on a 1985 woodmizer lt40
Post by: Kbeitz on August 11, 2017, 08:50:14 PM
Quote from: halcyon on August 11, 2017, 08:10:39 PM
I want to thank everyone for the great replies on my question. I think I am going to try an get a rheostat to see if it would work. Could anyone give me the spec's on which one I should get. It has the original motor for feed that the 1985 lt40 came with. I looked on the motor but it does not show any spec's so I hope someone knows what size it is. Thank again for all the help

If you could take whats left of the old one and get an OHM'S reading that would help. Inside probe from one end
of the windings to the other.
Title: Re: Help on a 1985 woodmizer lt40
Post by: halcyon on September 07, 2017, 09:14:54 PM
I want to thank everybody for the input given for my problem on the feed control on my 1985 woodmizer lt40.I finally tried an ohmite rheostat I bought off ebay. It worked good for a little while but finally got hot and quit working. I need to find the right rheostat to put on then I think I will have the problem solved. Eventually when I get the money I will try and buy the speed controller assembly that woodmizer sells. It will convert from the old rheostat speed controller that came on it from factory to the new with a pot and circuit board. Thanks again.great site for info.
Title: Re: Help on a 1985 woodmizer lt40
Post by: Magicman on September 07, 2017, 09:37:13 PM
I have no idea what the motor circuit looks like but a quick answer is that since the rheostat worked but got hot, the amperage rating was too low.  Measuring/knowing the amperage draw of the motor would be necessary before you could determine which rheostat to get.
Title: Re: Help on a 1985 woodmizer lt40
Post by: KirkD on September 07, 2017, 09:56:30 PM
If you go back and read my post again you will see the original one is only 2 watt. WM is not sending all the amperage through it. It has to be something on the board causing it to send more than it should.
Title: Re: Help on a 1985 woodmizer lt40
Post by: Magicman on September 07, 2017, 10:31:10 PM
True but halcyon's unit is already broken and WM advises that the only fix that they offer is an upgrade.  The only thing that he stands to loose now is already lost.  Something may loose it's "magic smoke".   :o
Title: Re: Help on a 1985 woodmizer lt40
Post by: Kbeitz on September 08, 2017, 06:41:46 AM
I'm thinking you got another problem with high amperage draw.

Your going to need a bottle or two of this around...



 (https://forestryforum.com/gallery/albums/userpics/39553/Luquid_smoke~2.jpg?easyrotate_cache=1504486656)
Title: Re: Help on a 1985 woodmizer lt40
Post by: sparks on September 12, 2017, 04:40:42 PM
Remember the pot can only do what the circuit board gives it to do. The output of the board on the brown wire is 1vdc. The output on the purple wire is 3.5vdc. The red wire is and input back to the board. Make sure these voltages are correct. If they're to low the pot will not work right. if they're to high it will fry the pot.The machine uses a 1K pot and it must be a 1K pot. If you get a pot that uses a coil for the resistance it will be very jerky.
Title: Re: Help on a 1985 woodmizer lt40
Post by: halcyon on September 12, 2017, 09:13:56 PM
Quote from: Magicman on September 07, 2017, 09:37:13 PM
I have no idea what the motor circuit looks like but a quick answer is that since the rheostat worked but got hot, the amperage rating was too low.  Measuring/knowing the amperage draw of the motor would be necessary before you could determine which rheostat to get.
Thanks for letting me know that I need a rheostat with higher amp capability. I can't find any info on the motor so I am at a loss of how many amps it takes. At least I know I need a rheostat that can handle more amps.Thanks again for the info
Title: Re: Help on a 1985 woodmizer lt40
Post by: Magicman on September 12, 2017, 09:22:54 PM
I would concentrate on Sparks' reply above.  He is quite familiar with this power feed circuit.