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Help With Jet 16-32 Drum Sander

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Forum topic by dgrant posted 01-20-2016 05:15 AM 715 views 0 times favorited 17 replies Add to Favorites Watch
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dgrant

47 posts in 1178 days


01-20-2016 05:15 AM

I had an unfortunate incident with ugly side effects tonight. I was using a wooden brush to sweep the rubber from the belt cleaner off the belt as it was rotating. Done it a hundred times. I looked over to talk to someone and the brush knocked up against the drive belt motor housing and the belt immediately stopped. The drum still works. The person I was talking to said a bright flash came out of the motor housing. So the assumption is that something blew. I have looked at parts for the machine trying to narrow it down. The only two possibilities are the control unit, 350 bucks, or the motor, 239 bucks. I need to figure out which problem I have. The parts web site I looked at addressed a similar question to someone else, telling them to test the motor first before buying the part. And that is the problem. I work with wood, not electricity. How do I go about testing the motor? Any help would be appreciated.


17 replies so far

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splintergroup

827 posts in 684 days


#1 posted 01-21-2016 06:42 PM

I’ve rebuild the conveyor speed controller on my Performax 16-32 twice now 8^)

Since you don’t seem to have much experience with electricity/electronics, you may be limited with what you can do.

I’d start first with removing the conveyor motor/controller assembly.
This requires removing the cover (4 screws I believe) and then loosening one of the set screws on the coupler between the motor shaft and the belt roller. Either way, it should be fairly obvious what needs to be done to free the assembly from the sander.

With the controller cover off, you should be able to see anything that got shorted out. I doubt the motor was hurt since you wouldn’t see a flash emanate from the motor housing (it’s sealed). Best guess is one of the power cord leads shorted to the case. The power cord runs to the conveyor speed controller where the power gets switched by the speed knob. The wires also pass onto the outlet for the big drum motor.

There really is no point in guessing further until you at least open the controller and report what you see.

My controller originally had a problem that the conveyor would begin ‘surging’ when the feed rate was low. The controller is basically the same as a light dimmer circuit. I replaced the primary component (the TRIAC) and it’s associated DIAC, everything was great again. About a month later, the unit refused to turn on. Turns out the speed control switch was broken, it was far easier just to bypass it with a new switch then to actually replace the speed control/switch.

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dgrant

47 posts in 1178 days


#2 posted 01-21-2016 08:53 PM

Thanks for the info splintergroup. It’s a really good thing I checked around first because I was tempted to just plug in the motor from the black and white wires and see if the motor came on. An engineer friend told me I would have been replacing the motor too since its 90v DC and I would have blasted it with 120v AC. He agreed with your conclusion that the flash must have come from the board, rather than the motor. This is one of those Sandsmart units that sensed the drop in voltage to slow the feed down. He thinks that when I knocked my wooden duster into the housing I shook the board enough to damage something and short it out. I already have a new board on the way so hopefully that will solve the problem. I got the whole thing apart with no problem so this will give me an opportunity to clean it up. I’ve run a whole lot of stock through it.

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MrUnix

4216 posts in 1661 days


#3 posted 01-21-2016 09:00 PM

If there was a flash, you should be able to determine what ‘flashed’ pretty easily just by looking :)

It’s a really good thing I checked around first because I was tempted to just plug in the motor from the black and white wires and see if the motor came on. An engineer friend told me I would have been replacing the motor too since its 90v DC and I would have blasted it with 120v AC.

Yeah, AC wouldn’t be a good idea, but If it’s a DC motor, you can use a car battery to test it. It won’t run fast, but should be enough to determine if it runs at all.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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dgrant

47 posts in 1178 days


#4 posted 01-22-2016 03:44 PM

Here is a surprisingly good iphone pic of the only damage I was able to find on the board. It looks like something arced across the two silver tapes. I have no idea what it might have been. I must have dislodged some little bit of debris inside the box causing it to lay across the tapes and cause the short. I will be much more careful in the future. This must be a pretty delicate board.

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splintergroup

827 posts in 684 days


#5 posted 01-22-2016 05:43 PM

Your guess sounds right.
My best guess is you shorted the output of the AC to DC rectifier bridge. Chances are you only blew a $1 diode (there are 4), probably the components directly on the reverse side of the right edge in your picture.

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cracknpop

194 posts in 1811 days


#6 posted 01-22-2016 07:16 PM

Curious if you found the board and its housing filled with dust or debris. or have found what shorted it out.

Owning a Jet 16/32 myself, I appreciate your sharing your experience and am wondering if this is something that should be periodically cleaned out.

-- Rick - I know I am not perfect, but I will keep pressing on toward the goal of becoming all I am called to be.

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MadMark

977 posts in 915 days


#7 posted 01-22-2016 07:47 PM

Lets talk about the other issue, the cause of the accident:
The tool grabbed a foreign objest that got too close.
It got close because the operator looked away from the tool.
The operator looked away when interrupted.
From reading the description the brushing of rubber bits was what the operator was attempting.
Was it NECESSARY to brush the little rubber bits off? Probaby not.
Thus a sloppy attempt at an unneeded operation was the root.
Why were the nubs important, since they cause no damage?

Pay attention to both what and why you are doing. Do not try to interact with others while machinery is running or spinning down.

M

-- Madmark - Madmark2150@yahoo.com Wiretreefarm.com

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splintergroup

827 posts in 684 days


#8 posted 01-22-2016 08:12 PM

My 16/32’s controller box is sealed up tight, actually quite dust proof. The only thing I could envision causing the short dgrant experienced would be a loose solder blob. Certainly it is about the only thing that could vaporize, leaving nothing behind.

I actually do the same thing, I’ll spin the drum while using my rubber cleaner (with the dust collection running), then run the conveyor an brush off the rubber nubs. These nubs tend to stick to the belt and if left in place, they can get trapped under a piece of wood, causing a defect to get sanded into the top surface.

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splintergroup

827 posts in 684 days


#9 posted 01-22-2016 08:15 PM

EDIT: removed double posting (oops!)

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Kazooman

625 posts in 1414 days


#10 posted 01-22-2016 09:40 PM



Lets talk about the other issue, the cause of the accident:
The tool grabbed a foreign objest that got too close.
It got close because the operator looked away from the tool.
The operator looked away when interrupted.
From reading the description the brushing of rubber bits was what the operator was attempting.
Was it NECESSARY to brush the little rubber bits off? Probaby not.
Thus a sloppy attempt at an unneeded operation was the root.
Why were the nubs important, since they cause no damage?

Pay attention to both what and why you are doing. Do not try to interact with others while machinery is running or spinning down.

M

- MadMark

Do you own and use a drum sander? I think not.

I did not read anywhere in the OP that the machine grabbed the brush. That is your speculation. The OP stated that the brush knocked into the belt drive motor housing.

” a sloppy attempt at an unneeded operation was the root” That’s what would lead me to think that you do not own a drum sander. You DO need to clean the belt occasionally or residue will build up on the abrasive and cause burning on the piece. You do the cleaning of the abrasive belt with one of those rubber blocks. They work great. However, they will leave a residue of the “nubs” as you would call them, and those will REALLY cause burning of the piece if you do not get them off.

I know that you hold the opinion that every problem in the wood shop is caused by someone “looking away”. Some are, some are not. I would call this a “sloppy attempt at an inaccurate explanation”. The OP told us what happened. He hit the motor control box with the brush he was using. As far as I can tell from what he posted the machine didn’t grab it and cause the problem. You DO need to clean the belt and you DO need to remove the junk that is created in the process.

To the OP: can you post a picture of the component side of the circuit board? Do any of the components look like they got fried? You can GENTLY probe the components to see if there is an issue that is not immediately apparent. A diode can be split in two and not really show up.

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dgrant

47 posts in 1178 days


#11 posted 01-22-2016 11:11 PM

Here is the best pic I could get with my iphone. It blows up surprisingly well. To answer a few of the questions, the housing for this board is fairly well sealed and it was clean except for a light dusting of sawdust. As far as that tool grabbing the brush, that is not what happened. It would be difficult if not impossible for the sanding drum to grab the brush. unless you had the drum way up off the belt, which it wasn’t

. I had just cleaned a belt with a crepe bar, dust collection on. The junk it leaves all over the belt even with the collection on would cause problems if you put your stock on it and ran it through. It really needs to be cleaned off. I agree that getting distracted in the shop is a huge issue and I do everything possible not to allow that to happen. My daughter knows not to interrupt me when a machine is running. The feed belt poses no danger that I can see unless you laid your hand on it and really got careless since it moves pretty slow. I will just need to be careful in the future not to be knocking the side of that housing with the brush. All things considered, this is about the safest machine I have.

I still have no idea what might have caused the arcing. One thing is for sure and that is the housing itself did not deflect far enough to touch the board. It’s at least 3/4 of an inch away. The solder blob theory works for me.

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Kazooman

625 posts in 1414 days


#12 posted 01-22-2016 11:51 PM

Thanks for the second picture. I can’t see anything obvious, but I would have to say I love the big gobs of hot melt glue used to retain the settings on the trim pots. Especially the one with the tail of glue stretched across the board.

My experience with using the crepe bar to clean the abrasive sounds exactly like yours. You clean the drum, then you wipe the junk off the abrasive and the dust hood, and then you need to clean the stuff that lands on the drive belt. If you don’t remove the junk that landed on the drive belt it will stick to the bottom face of the piece and then will burn when you flip it over to sand the other side. The drum, work piece, and drive belt ALL need to be kept clean or you are headed for trouble. I have learned through experience that you will get a bit of residue deposited on the surface of the work piece as it exits from the sander, even with a large dust collector drawing through the dust removal hood. A quick swipe of a brush to remove this before the next pass goes a long way towards minimizing burning.

I use a typical hand held broom like you wold use with a dust pan. I sweep it back and forth across the drive belt with the belt running on the top speed. I must have hit that housing hundreds of times. Based on your experience I will change the last step a bit.

Please post again when you figure out what went wrong. I do not believe it was any “sloppy attempt” on your part. You were using the machine the way we all do.

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splintergroup

827 posts in 684 days


#13 posted 01-24-2016 03:38 PM

I see an ‘F2’ designation right of the current sensor (wire wound object in the upper center). ‘F’ usually designates ‘Fuse’ of some sort (could be soldered on).

My controller is the old style, not the load sensing type you have. When mine blew the first time, I considered upgrading, but the cost was just too steep compared to what the machine cost.

Be sure to check out your new part for any solder dingle berries!

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dgrant

47 posts in 1178 days


#14 posted 01-28-2016 06:09 PM

I got the new board in and it seems to be working nicely. I made sure the housing for the board and switch were spotless before installing and I made sure there was no loose debris or solder leftovers on the new board. I have to say the new one seems more neatly made than the original. At least the silicone application was much cleaner. In conclusion, I think this is a great tool and I use it almost every day but the lesson is to be careful around delicate electronics. Still no idea what shorted out the other one.

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MrUnix

4216 posts in 1661 days


#15 posted 01-28-2016 07:08 PM

Glad you got it working… that’s the one thing I hate about machines with proprietary electronics though, it’s not if, but when they will go bad. I can replace a broken pulley, but trying to get an obscure electronic board can sometimes be difficult :) Hopefully, you kept the old one, which may be fixable. Could be something as simple as a blown varistor (why do they use those stupid things?!?) or diode, and a fairly cheap fix. That would give you a backup should anything happen to the new one (and replacements may not be available years from now). Just a thought.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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