Opening up the Power Pro head

[JPG]

I will be the elephant in the room!

Nothing done in the video proves anything nor does it result in anything useful. The 'probe' is a meaningless device in this context.

Only actual full contact measurements will reveal anything useful in trouble shooting the problem.

[WileyCoyote]

I agree, but he has more information now than he had before. It may not be useful information now, but who knows if it will be in the future. While nothing is revealed as the broken culprit, once he gets his system back from Shopsmith, these basic checks could help someone with the same or similar issue in the future isolate what the problem may be and what the cost could be for the repair. A lack of voltage at one of the components might indicate a different issue, it might not. I would fiddle around with it too before I sent it in for repair and probably would have done the same thing.

[RFGuy]

I agree with JPG on this one. I watched the video. He uses a Sperry non-contact voltage tester. The old ones used to be magnetic induction types, but the newer ones use capacitive coupling to detect an electric field. I believe the model he has goes down to 50V. The test that he does has some value, but beyond proving that the on/off switch works that is probably about it. Without knowing the internals in the control unit and power supply box, it would be hard to gleam any information from the test that he did...with electronic controls like this it isn't enough to simply have voltage present, you need to know if the voltage is the right level, you need to know if the appropriate signal lines are operating as well, whether the microcontroller is alive, whether the LCD is functioning, etc.

I did find it interesting that his tester lit up when he touched the harness to the control (display) unit. I would have assumed the power supply would send power like 5V or 12V to the control/display unit to light up the LCD and power the microcontroller, so his tester should not have lit up on these. I am not sure what the purpose of sending a higher voltage to the control would be, but then these types of testers are not known to be very accurate. His tester could be overly sensitive and picking up any E field it picks up nearby. Knowing that the input power supply is not well shielded (based on past EMI/RFI issues reported on this forum), his tester could be picking up the power supply anywhere he touches nearby. I wouldn't be surprised if touching it to the plywood underneath wouldn't set it off too.

[Ed in Tampa]

Trouble shooting is a process of elimination.
The video did that. It eliminated certain “could be” problems.
We now know he has line power. The switch is opening and closing a circuit. Power is going to the control panel also to power supply. That is far more than any of us knew before.

In my opinion and with the knowledge he has, he has eliminated every thing he could from being a problem. From this point on people that know what voltages should be where need to be involved.

I say well done Poihths!

[RFGuy]

Trouble shooting is a process of elimination.
The video did that. It eliminated certain “could be” problems.
We now know he has line power. The switch is opening and closing a circuit. Power is going to the control panel also to power supply. That is far more than any of us knew before.

In my opinion and with the knowledge he has, he has eliminated every thing he could from being a problem. From this point on people that know what voltages should be where need to be involved.

I say well done Poihths!

I believe all that JPG and I did was to point out that this kind of testing only shows that the ON/OFF switch works. Beyond that, a more detailed troubleshooting is needed. At a minimum the LCD display does not work. It "could be" a) bad power supply, b) bad microcontroller, c) bad LCD display, d) bad LCD driver/control board. Beyond this, once the LCD can function again, there could be secondary failures downstream, e.g. bad motor. Won't know until the LCD is operational, unless you have the schematics and can diagnose further.

[dusty]

I was not going to comment simply because there are so few facts available. However, comments have forced me out.

The test clearly shows that there is switched power to the power supply. When power is applied, nothing happens on the display (control panel). Either the display panel is non-responsive or the power supply has no output (for whatever reason). The motor is non-responsive but that is to be expected if either the power supply or the control panel is inoperative.

Looking at the setup, one cannot say that all of the electrical connections have been made but the setup (laid out on a bench top) facilitates a close inspection of the connectors. Two of those connectors are Molex and those are known to be very unreliable UNLESS properly assembled. On the other hand, if the individual connectors are properly applied to the wires and the then properly inserted into the connector housing the cable is very, very reliable. Based on hear say brought to this forum, I believe the cables remain "suspect".

The motor, the AC power source, the power cable are now unlikely causes for the obvious failure mode.

The suspect list (for me) includes the control panel, the power supply and internal wiring harness (IN THAT ORDER).

The OP did what he did to convince Shopsmith that there was a problem and to have them recommend a course of action that they would approve of. He certainly has shown that "the system" is unresponsive when power is applied. Apparently, Shopsmith is also "unresponsive".

It has also clearly demonstrated that without detailed documentation of the wiring harness, the power supply and the control panel users are at the mercy of either Shopsmith or Teknatool (Striatech) and this needed information is being held hostage (some might call it proprietary secrecy).

[RFGuy]

Looking at the setup, one cannot say that all of the electrical connections have been made but the setup (laid out on a bench top) facilitates a close inspection of the connectors. Two of those connectors are Molex and those are known to be very unreliable UNLESS properly assembled. On the other hand, if the individual connectors are properly applied to the wires and the then properly inserted into the connector housing the cable is very, very reliable. Based on hear say brought to this forum, I believe the cables remain "suspect".

Well said, Dusty. I forgot about the Molex connectors and you make several good points. Going back and watching the video again, one curious finding that he makes is towards the end of the video (2:48 to 3:20 in video). There are two different wiring harnesses to the motor. One is clearly the power to the windings, but on the far left is a smaller (two lead?) connection that is probably a sensor (spindle speed/position) being fed back to the microcontroller. The curious thing is he shows power on this sensor line whereas the power connections (3 twisted pair) do not show power. This makes sense on the one side because the motor is not spinning so these should be off, but the important thing is that the sensor connection seems to be powered. Just a wild guess here and we have limited data to go on, but it looks like some portion of the power supply and microcontroller are alive. We are all shooting in the dark here, but I suspect the round display/control module is bad. To confirm, does anyone know where the microcontroller resides? Is it in the power supply (rectangular module), or is it inside the display/control (round module)?

[dusty]

Looking at the setup, one cannot say that all of the electrical connections have been made but the setup (laid out on a bench top) facilitates a close inspection of the connectors. Two of those connectors are Molex and those are known to be very unreliable UNLESS properly assembled. On the other hand, if the individual connectors are properly applied to the wires and the then properly inserted into the connector housing the cable is very, very reliable. Based on hear say brought to this forum, I believe the cables remain "suspect".

Well said, Dusty. I forgot about the Molex connectors and you make several good points. Going back and watching the video again, one curious finding that he makes is towards the end of the video. There are two different wiring harnesses to the motor. One is clearly the power to the windings, but on the far left is a smaller (two lead?) connection that is probably a sensor (spindle speed/position) being fed back to the microcontroller. The curious thing is he shows power on this sensor line whereas the power connections (3 twisted pair) do not show power. This makes sense on the one side because the motor is not spinning so these should be off, but the important thing is that the sensor connection seems to be powered. Just a wild guess here and we have limited data to go on, but it looks like some portion of the power supply and microcontroller are alive. We are all shooting in the dark here, but I suspect the round display/control module is bad. To confirm, does anyone know where the microcontroller resides? Is it in the power supply (rectangular module), or is it inside the display/control (round module)?

NO, I do not know but I have concluded from previous conversations (on the forum and otherwise) that there are two microcontrollers; one that manages motor speed and one that manages the processes unique to the PowerPro (not Nova processes).

[JPG]

IIWM, I would be sending SS both the control panel and the power supply.

I would guess the controller is in the power supply package.


BTW I consider that 'probe' to be only one level above a divining rod.


What Dusty posted re controllers makes sense. Motor controller and operator interface.

[RFGuy]

BTW I consider that 'probe' to be only one level above a divining rod.

LOL. Too true. Back in college, I took one of these non-contact voltage testers around with me (neon one, not like the new Sperry unit in this video). I walked by a small power sub-station on campus. I was at least 100 yards away from it and the voltage tester started lighting up...