Power Pro Power Supply

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Shawn
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Power Pro Power Supply

Post by Shawn »

Checking to see if anyone else hears a crackling noise from their power supply when power switch is engaged? Sounds like a static/arcing. It is not very loud, but can be easily heard even when enclosed in the headstock housing. It does this for me when just turning on the main power switch. It does it whether it is tied into a GFCI or non-GFCI outlet.

Unit under warranty so I took video and submitted to Shopsmith and sent back the power supply. They did not detect the issue and had me send the rest of my headstock back due to another issue which I will also list.

My headstock was not running at a consistent speed between 500-1350 RPM. It was fluctuating randomly, with the screen stating it was fluctuating by multiple hundred RPM (while it appeared to be fluctuating, it did not actually seem it was fluctuating that much).

Anyway, I received my headstock back, it appears they changed the motor. I still have the static noise. While the fluctuation has gone away at low speeds, now it sounds like I have a bearing/belt noise at the higher speeds...which doesn't shock me as the new bearing kits are from China. Just wondering if anyone has had similar motor/power supply issues. I have already been without my unit almost 2 months, so not in a hurry to send back to Shopsmith.
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DLB
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Re: Power Pro Power Supply

Post by DLB »

I don't have a Power Pro but I have a lot of electrical/electronic experience. The noise could come from arcing in the mechanical power switch, the one I think you are calling Main. I would try to isolate that by plugging the SS into a switched power strip if you have one with sufficient power rating, probably 15 Amps. (Or other method to externally switch power.) You want to remove power from the SS but leave the main power switch on, then use your external switch to apply and remove SS power. If the arcing goes away, the main switch is the culprit.

That is not a fool proof method, just a test. Inrush current could also be a factor and could still be a switch problem. Or, as you say, a Power Supply problem. The switches are on SS's list of 17 most frequently ordered service parts, presumably a relatively high failure item. (I'm assuming the Power Pro switch is the same as the switch in late model traditional headstocks, 556089).

- David
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reible
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Re: Power Pro Power Supply

Post by reible »

When you turn on the main power switch the machine boots up and while doing so plays a little tune. Is the noise you hear different then that?

Ed
{Knight of the Shopsmith} [Hero's don't wear capes, they wear dog tags]
Shawn
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Re: Power Pro Power Supply

Post by Shawn »

DLB wrote:I don't have a Power Pro but I have a lot of electrical/electronic experience. The noise could come from arcing in the mechanical power switch, the one I think you are calling Main. I would try to isolate that by plugging the SS into a switched power strip if you have one with sufficient power rating, probably 15 Amps. (Or other method to externally switch power.) You want to remove power from the SS but leave the main power switch on, then use your external switch to apply and remove SS power. If the arcing goes away, the main switch is the culprit.

That is not a fool proof method, just a test. Inrush current could also be a factor and could still be a switch problem. Or, as you say, a Power Supply problem. The switches are on SS's list of 17 most frequently ordered service parts, presumably a relatively high failure item. (I'm assuming the Power Pro switch is the same as the switch in late model traditional headstocks, 556089).

- David
Thank you David. The engineer that was helping me at Shopsmith asked if I could bench test it to verify it was the power supply, which I did. I ended up pulling out the components, laying them on a table, and then supplying power. I listened to each component and isolated noise to the power supply.

As for the switch, it was brand new as this was supplied with the DIY PowerPro kit. Shopsmith actually sends 2 versions of the switch with the kit - the metal toggle switch and the removable "safety" switch. That does not mean it wouldn't be bad out of the box, but it appeared to be OK.
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Shawn
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Re: Power Pro Power Supply

Post by Shawn »

reible wrote:When you turn on the main power switch the machine boots up and while doing so plays a little tune. Is the noise you hear different then that?

Ed
Hi Ed. Yes I do hear that noise, but I also get "static" coming from the power supply. It stays constant as long as the main toggle switch is on.

Full disclosure, this is from the DIY PowerPro kit and it is from their "Reman" line (I was trying to save some money and they had that marked down 30% from the already discounted price from the normal DIY cost.)

So, essentially I have used product but still covered by a 1 year warranty by Shopsmith for those interested in this option.
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RFGuy
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Re: Power Pro Power Supply

Post by RFGuy »

Shawn,

Just to confirm, the static noise is coming from the PowerPro itself, correct? Only reason that I ask is that the PowerPro can disrupt any tv, stereo, clock radio, etc. in the vicinity due to its EMI/RFI output. Is it possible that you are hearing the static from another device, even though the PowerPro is causing this noise? See previous PowerPro threads below that discuss this:

http://shopsmith.com/ss_forum/woodworki ... view=print

https://www.shopsmith.com/ss_forum/wood ... view=print
📶RF Guy

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Shawn
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Re: Power Pro Power Supply

Post by Shawn »

It's coming from the power supply for the PowerPro. If there was some insulation or ferrites or something to add maybe that would help, I don't know. But it is coming from the power supply. Doesn't appear to affect the performance as far as I can tell so far, but I have not put it through the ringer yet. Been doing upgrades and maintenance.
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RFGuy
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Re: Power Pro Power Supply

Post by RFGuy »

Shawn wrote:It's coming from the power supply for the PowerPro. If there was some insulation or ferrites or something to add maybe that would help, I don't know. But it is coming from the power supply. Doesn't appear to affect the performance as far as I can tell so far, but I have not put it through the ringer yet. Been doing upgrades and maintenance.
Shawn,

I am hesitant to give advice here, because
a) I don't own a PowerPro
b) I don't know the internals of the PowerPro so I am just guessing on limited information
c) I only dabbled in switched mode power supplies (SMPS) during my career and it was DC-DC SMPS...so I am no expert in this area of AC SMPS

Okay, with those disclaimers, here goes...Putting an input filter on would only prevent PowerPro EMI from getting back into the power lines and affecting other equipment (hence my questions about nearby radio, tv, etc). Another function of this filter is to prevent any high frequency coming in on the power line from affecting the output voltage of the SMPS. So, you could try this, but I am doubtful it will "fix" your static issue because I have my doubts this would cause an auditory component emanating from the PowerPro itself, but it could.

So, what else could it be? I need to stress that the PowerPro is a black box with very limited documentation shared outside of Shopsmith. Striatech designs and builds it and is actually quite helpful if you contact them for information. Unfortunately though, Shopsmith licenses their particular DVR motor from Striatech so I think Striatech is limited on what they can share on the PowerPro product with customers. Still it could be worth a shot to contact them and just see what they say regarding this static noise issue. My guess is they will tell you it is time to change the power supply. Again, the PowerPro is a black box, but we do know that it is a switched reluctance DVR motor design. The most common way to power a switched reluctance motor is through an asymmetric bridge converter, which typically has a capacitor on its output to limit electrical and acoustic noise. If the PowerPro skipped putting a capacitor here, or if the cap is old and degrading this could explain the problem you have. I wouldn't advise trying to implement a fix yourself. Even with full schematics, a SMPS can be a dangerous thing with high voltages stored even when turned off. If this is the cause of this noise, it is likely not causing any damage so you could just live with it. On the other hand, if you want to fix it, perhaps go the Striatech route to get their opinion. Then with all information, try to convince Shopsmith that they need to replace the power supply on your PowerPro. Below are a couple general documents related to switched reluctance DVR motors if anyone is bored and wants to read them related to this:

https://en.wikipedia.org/wiki/Switched_reluctance_motor

http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf
📶RF Guy

Mark V 520 (Bought New '98) | 4" jointer | 6" beltsander | 12" planer | bandsaw | router table | speed reducer | univ. tool rest
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