Pro Planer speed control box problem

[tdubnik]

I don't see anything that I recognize as a diode (rectifier) but there has to be one. With amount of heat developed, the current through that diode would have been significant. The diode would therefore be suspect also.

The diode might be the form around which the coil is wound.

Would it not be the small rectangle attached to the metal bracket?

The part # is 0973

[Ed in Tampa]

Would it not be the small rectangle attached to the metal bracket?

The part # is 0973

Tdubnik
That would be my guess that the diode in the black component in the heat sink which makes sense. I don't know the status of it but I think the blown land pattern acted as a fuse and hopefully burned through before the other components totally fried.

We don't know but I would make the repairs I suggestted and see. It is very possible both the coil and or the diode got cooked but without taking everything apart and checking each component you can't tell.

I suspect one of two things happened. One the drive motor stalled and sat there cooking or the DC motor got shorted. You say it is working so I would guess something made it draw enough amps to cook the board.

Was it possible to dial the pot until the motor stopped turning or turned very very slowly? If so the machine might have been run that way until the pot got so hot that coil began to melt down. Then things started to change value and in fact the diode might have cooked too and then the board finally blew.

I think the planner motor actually plugs into the bottom of this unit. Is it possible the plug was pulled and the planner switch left on with the pot turned down to the point the motor wasn't turning and then left that way for a loooong while? If so that may be the problem.

I would like to see SS build this speed control using electronics that would cause the motor to recieve pulses instead of regulating the voltage to the motor. Bad bad design these days.

[tdubnik]

[ATTACH]2361[/ATTACH]

[ATTACH]2362[/ATTACH]I've annotated all of the parts as best I can. There are no hidden parts that I can find. What you see is what we have.

[tdubnik]

Tdubnik
That would be my guess that the diode in the black component in the heat sink which makes sense. I don't know the status of it but I think the blown land pattern acted as a fuse and hopefully burned through before the other components totally fried.

We don't know but I would make the repairs I suggestted and see. It is very possible both the coil and or the diode got cooked but without taking everything apart and checking each component you can't tell.

I suspect one of two things happened. One the drive motor stalled and sat there cooking or the DC motor got shorted. You say it is working so I would guess something made it draw enough amps to cook the board.

Was it possible to dial the pot until the motor stopped turning or turned very very slowly? If so the machine might have been run that way until the pot got so hot that coil began to melt down. Then things started to change value and in fact the diode might have cooked too and then the board finally blew.

I think the planner motor actually plugs into the bottom of this unit. Is it possible the plug was pulled and the planner switch left on with the pot turned down to the point the motor wasn't turning and then left that way for a loooong while? If so that may be the problem.

I would like to see SS build this speed control using electronics that would cause the motor to recieve pulses instead of regulating the voltage to the motor. Bad bad design these days.

The planer had actually been sitting idle for several years. As far as I know the last time I used it everything was fine. I started a new project and needed some 1" stock and was going to plane down something thicker. I plugged the planer in and turned it on and it tripped the breaker. I unplugged the planer and checked everything out and couldn't find anything wrong except it felt a little stiff. I would guess that the V-belt had set. I turned it by hand a few times and then plugged it back in. This time the planer worked but wouldn't feed the stock and you know the rest.

[johnm]

The "diode" is the four terminal block seen in the photo 026 (right above the power cord on the left). The DC from the rectifier is fed to the circuit board which basically contains a high voltage transistor (mystery part 0973) and potentiometer which controls the voltage fed to the "base" (control terminal of the transistor) so that the output voltage is controlled (somewhat). The whole circuit on the board is in series with one of the leads to the DC motor. Things probably fried when the DC motor stalled.

[dusty]

Yup, very observant of you John. I was engrossed with the circuit board while knowing there had to be a rectifier somewhere.

Therefore, the circuit board is nothing more than a bit of a filter and a means of varying the DC to the motor.

Yes, I think you have a keeper as long as you are willing to put in the effort to repair/replace the board.

[dusty]

I am a bit of a tinkerer and took apart the control box. I used a volt meter to test inputs and outputs and know that the problem is in the brown box that contains the circuit board and speed control dial. There is power going into the box but no power coming out at any speed setting.

I know that the feed motor works when I connect it to a DC power source. I guess if I have to I could buy a DC variable power supply and hook it up external to the SS box. This means that I would have to control the power seperately from the planer motor but I think I could make it work.

I just hope there is a better way.

You say here that there is power going into the box. Is this an AC voltage or a DC voltage that you are reading.....and exactly where are you metering for this test?

[johnm]

Yup, very observant of you John. I was engrossed with the circuit board while knowing there had to be a rectifier somewhere.

Therefore, the circuit board is nothing more than a bit of a filter and a means of varying the DC to the motor.

Yes, I think you have a keeper as long as you are willing to put in the effort to repair/replace the board.

Given enough time (and beer) to stare at the photos of the top and the bottom of the board, I could probably draw a schematic of what's there.

A simple DC supply that would work would be a variable AC transformer (trade name Variac, Staco or Powerstat) driving one of those "block" rectifiers; take the DC out of the rectifier and connect to the feed motor. The problem is that the variable transformers are pretty pricey ($200+) unless you can find one cheap at an electronics flea market.

But it looks like the feed motor requires high voltage DC, so a model train controller won't do...

[tdubnik]

When I try to bridge the gaps on the board per Eds suggestion; is there any special kind of wire required?

I have some single strand bell wire that I can use if it will be OK.

[johnm]

[quote="tdubnik"]When I try to bridge the gaps on the board per Eds suggestion]

The wire should be of approximately the same gauge as the black and white wires going to the board.