# Jet Sander Issues

#### USNPatriot

Dec 24, 2020
5
The circuit board controlling the drive motor (90vdc) which in turn drives the conveyor belt, has a 5 pin Potentiometer that provides speed control for that very conveyor belt. My problem is: This is the device that has failed, as crazy as it sounds, I opened it and sprayed some electronic cleaner in it and it lasted another month, then that was it. Now, the replacement board costs 475.00 and I know this device is all of a buck or two. SO...... how do I go about determining what kind of Pot can take it's place? I'm not dumb electrically but stupid on electronics. there is no Ω rating on the unit all it says is B1k........ would be so grateful for some insight into what can be done.

#### 73's de Edd

Aug 21, 2015
3,366
I thought that you knew . . . B signifies that its a linear resistance change type of resistance element and the 1k is meaning that it is having 1,000 ohms of resistance from extreme end to end terminals.

You should be finding the original pot being of the illustrations 3rd pic, in its having a quite thin resistive plastic membrane as its active element with a rotor dragging around it to effectively abrade it with time and repeated use.
Considering you can physically / mechanically modify the addition of larger and heftier industrial grade unit, in place of the original, why not get a unit that should last a lifetime in the form of one of the ALLEN BRADLEY molded pots of the first two pics.
The original pot likely has a mere 1/4---1/2 watt thin resistance element along with the frailty of the rotor to resistance elements abrasion . . . . as per the 3rd pic..

On the AB unit . . . note the 1st pics HEFTY reddish brown molded ring of the arrow and then, in the second pic, note that a 270 degree arc of a furrow was molded in the bakelite and has been totally filled with a resistance slurry and then furnace fired to leave a resultant DEEP 2 watts of resistance element that the rotor rides around upon. With use . . . . it still has DEPTH of resustance element to still settle down within.

These are getting harder to find . . .expecting a low find of $5 up to 15 . . . with one of a decent shaft length . . . . . but don't buy into the . . . .black cloaked . . . maternally copulating . . . " carpet baggers" that are wanting$50 + for their items.

PICTORIAL SAMPLES . . . . .remember you need 1K linear

E-Bay LISTINGS

Les POTs

https://i.ibb.co/4gPrVhN/POT.png

73's de Edd . . . . .

In our world, there are 3 kinds of people . . . . . those who can count & those who can't.

.

Last edited:

#### USNPatriot

Dec 24, 2020
5
I thought that you knew . . . B signifies that its a linear resistance change type of resistance element and the 1k is meaning that it is having 1,000 ohms of resistance from extreme end to end terminals.

You should be finding the original pot being of the illustrations 3rd pic, in its having a quite thin resistive plastic membrane as its active element with a rotor dragging around it to effectively abrade it with time and repeated use.
Considering you can physically / mechanically modify the addition of larger and heftier industrial grade unit, in place of the original, why not get a unit that should last a lifetime in the form of one of the ALLEN BRADLEY molded pots of the first two pics.
The original pot likely has a mere 1/4---1/2 watt thin resistance element along with the frailty of the rotor to resistance elements abrasion . . . . as per the 3rd pic..

On the AB unit . . . note the 1st pics HEFTY reddish brown molded ring of the arrow and then, in the second pic, note that a 270 degree arc of a furrow was molded in the bakelite and has been totally filled with a resistance slurry and then furnace fired to leave a resultant DEEP 2 watts of resistance element that the rotor rides around upon. With use . . . . it still has DEPTH of resustance element to still settle down within.

These are getting harder to find . . .expecting a low find of $5 up to 15 . . . with one of a decent shaft length . . . . . but don't buy into the . . . .black cloaked . . . maternally copulating . . . " carpet baggers" that are wanting$50 + for their items.

PICTORIAL SAMPLES . . . . .remember you need 1K linear

E-Bay LISTINGS

Les POTs

https://i.ibb.co/4gPrVhN/POT.png

73's de Edd . . . . .

In our world, there are 3 kinds of people . . . . . those who can count & those who can't.

.
You are terrific,I did reply from my phone yesterday to thank you again for jumping into this problem and helping me, and I sincerely thank you, but it looks like that post didn't make it. while you are obviously right at home with this problem, I'm an old salt and haven't dealt with this kind of thing regularly....so forgive me for "catching up"...... as I look at the board where I unsoldered the old Pot, there are 5 connection points, the 3 you normally see on all Pots and the other two which must be incoming voltage. However when I look at some of the AB pots, i'm not seeing 5 connection points. I did read, after I sent the original post that B meant Linear, and thanks to you I'm catching up on the 1K value. So based on what you just sent to me, I'll make one of the Industrial units work if it means simply extending the "dial" shaft... that needs to be about 1.5 inches.... the original board achieved that by putting LONG ears on the POT so it extended away from the board and reached the hole in the Panel so one can rotate the POT handle. BTW, you are right on, the Third picture is exactly the JUnk they used!!

#### 73's de Edd

Aug 21, 2015
3,366
Sir USNPatriot . . . . .

When you mentioned five . . .count 'em FIVE . . .terminals, I looked up what I thought might be your units speed controller. One was being rectangular and about 2X 3 in and had only small trim pots and any large pot would have to be wire lead remoted into the board.
HOWEVER . . .the one depicted below, looks more in order as to its being your unit.

The three pot tabs would be my RED mark-ups and the extra two "mystery terminals" would be for a SPST switch mounted on the end / bottom of the pot.
I showed the one switch connection that I could see, as being the BLUE dot on the left pic, with the other dot being hidden directy behind it.
These are on the component side of the board and pass thru to connect to the two BLUE dots of the foil side of the board on the right pic.
S o o o o , I interpret that you must have to rotate the speed down until the switch clicks off to power down / off and click on the switch.
Or click the switch on and set up to desired operating speed when you turn the unit on.
Now I don't know your techno-mechanical accumen . . . . . so could you just use a SEPARATE stand alone SinglePoleSingleThrow switch to the two BLUE dots for fulfilling your power switch aspect.

BECAUSE I may have seen only 4 switch versions of that hermetically sealed AB pot within 60 yrs.
If it was my situation and I just HAD to have the same scheme of the max CCW positon of the pot turning a switch off.

I could accomplish that with a round bakelite disc and a cut out divot that rests at CCW position to let a MICROSWITCH button pop out to its power off condition.
Then at first CW rotation of the pot shaft/disc, the disc has its periphery then holding the MICROSWITCH tab in, to its power on condition.
OR I could use the same procedure with an epoxy ramp built onto the back of the control knob that engages the MICROSWITCH button that is facing into it.

HOW 'BOUT THE OUTRAGEOUS PRICE OF THAT SIMPLE UNIT ! . . . . . . .Price: $293.67 . . . . . . now thats either being " product marketing " or PIRACY . . . . . PIC MARK UP . . . . . 73's de Edd . . . . . A proven . . . . . . factoid The hardness of butter is being in direct inverse proportion to the softness of the bread you're trying to spread it upon . . Last edited: #### USNPatriot Dec 24, 2020 5 Sir USNPatriot . . . . . When you mentioned five . . .count 'em FIVE . . .terminals, I looked up what I thought might be your units speed controller. One was being rectangular and about 2X 3 in and had only small trim pots and any large pot would have to be wire lead remoted into the board. HOWEVER . . .the one depicted below, looks more in order as to its being your unit. The three pot tabs would be my RED mark-ups and the extra two "mystery terminals" would be for a SPST switch mounted on the end / bottom of the pot. I showed the one switch connection that I could see, as being the BLUE dot on the left pic, with the other dot being hidden directy behind it. These are on the component side of the board and pass thru to connect to the two BLUE dots of the foil side of the board on the right pic. S o o o o , I interpret that you must have to rotate the speed down until the switch clicks off to power down / off and click on the switch. Or click the switch on and set up to desired operating speed when you turn the unit on. Now I don't know your techno-mechanical accumen . . . . . so could you just use a SEPARATE stand alone SinglePoleSingleThrow switch to the two BLUE dots for fulfilling your power switch aspect. BECAUSE I may have seen only 4 switch versions of that hermetically sealed AB pot within 60 yrs. If it was my situation and I just HAD to have the same scheme of the max CCW positon of the pot turning a switch off. I could accomplish that with a round bakelite disc and a cut out divot that rests at CCW position to let a MICROSWITCH button pop out to its power off condition. Then at first CW rotation of the pot shaft/disc, the disc has its periphery then holding the MICROSWITCH tab in, to its power on condition. OR I could use the same procedure with an epoxy ramp built onto the back of the control knob that engages the MICROSWITCH button that is facing into it. HOW 'BOUT THE OUTRAGEOUS PRICE OF THAT SIMPLE UNIT ! . . . . . . .Price:$293.67 . . . . . . now thats either being " product marketing " or PIRACY . . . . .

PIC MARK UP . . . . .

73's de Edd . . . . .

A proven . . . . . . factoid
The hardness of butter is being in direct inverse proportion to the softness of the bread you're trying to spread it upon .

.
Sir USNPatriot . . . . .

When you mentioned five . . .count 'em FIVE . . .terminals, I looked up what I thought might be your units speed controller. One was being rectangular and about 2X 3 in and had only small trim pots and any large pot would have to be wire lead remoted into the board.
HOWEVER . . .the one depicted below, looks more in order as to its being your unit.

The three pot tabs would be my RED mark-ups and the extra two "mystery terminals" would be for a SPST switch mounted on the end / bottom of the pot.
I showed the one switch connection that I could see, as being the BLUE dot on the left pic, with the other dot being hidden directy behind it.
These are on the component side of the board and pass thru to connect to the two BLUE dots of the foil side of the board on the right pic.
S o o o o , I interpret that you must have to rotate the speed down until the switch clicks off to power down / off and click on the switch.
Or click the switch on and set up to desired operating speed when you turn the unit on.
Now I don't know your techno-mechanical accumen . . . . . so could you just use a SEPARATE stand alone SinglePoleSingleThrow switch to the two BLUE dots for fulfilling your power switch aspect.

BECAUSE I may have seen only 4 switch versions of that hermetically sealed AB pot within 60 yrs.
If it was my situation and I just HAD to have the same scheme of the max CCW positon of the pot turning a switch off.

I could accomplish that with a round bakelite disc and a cut out divot that rests at CCW position to let a MICROSWITCH button pop out to its power off condition.
Then at first CW rotation of the pot shaft/disc, the disc has its periphery then holding the MICROSWITCH tab in, to its power on condition.
OR I could use the same procedure with an epoxy ramp built onto the back of the control knob that engages the MICROSWITCH button that is facing into it.

HOW 'BOUT THE OUTRAGEOUS PRICE OF THAT SIMPLE UNIT ! . . . . . . .Price: \$293.67 . . . . . . now thats either being " product marketing " or PIRACY . . . . .

PIC MARK UP . . . . .

73's de Edd . . . . .

A proven . . . . . . factoid
The hardness of butter is being in direct inverse proportion to the softness of the bread you're trying to spread it upon .

.
I'm dealing with 9" of snow here on Christmas day...... oh well, we've been lucky for several years...... nevertheless...... I'm going to RE-Read your latest post, AND I'm going to shoot a pic of the existing Pot, and board so we can see exactly what i'm dealing with. I hate to admit that I needed to buy a board, but if i can find a Pot and the existing board is still repairable I'm going to send the new one back. I hate like heck paying 500 for a device I KNEW was fixable if I could just locate the right item. I really cannot see anything else on this board that might suffer from age...... as you mentioned the POT is the achilles heal of this whole thing, which really kind of makes me PO'ed that MFG's throw this kind of junk in a decent tool .

#### USNPatriot

Dec 24, 2020
5
I'm dealing with 9" of snow here on Christmas day...... oh well, we've been lucky for several years...... nevertheless...... I'm going to RE-Read your latest post, AND I'm going to shoot a pic of the existing Pot, and board so we can see exactly what i'm dealing with. I hate to admit that I needed to buy a board, but if i can find a Pot and the existing board is still repairable I'm going to send the new one back. I hate like heck paying 500 for a device I KNEW was fixable if I could just locate the right item. I really cannot see anything else on this board that might suffer from age...... as you mentioned the POT is the achilles heal of this whole thing, which really kind of makes me PO'ed that MFG's throw this kind of junk in a decent tool .

#### USNPatriot

Dec 24, 2020
5

73 Just to answer one question you did have, YES there is a SPDT switch component in the POT, as it does have a "clickable" switch when turned to 0 voltage. However that item no longer works, and interestingly enough the NEW pot on the NEW board does not act like the old one, no clickable switch??? Oh well. Also, If I need to Mount the POT independently of the board and lead wire it.... so be it.

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