PM 3520B: replaced inverter, still not working

Re: PM 3520B: replaced inverter, still not working *LINK*

Clifton C

Aage,

Doc Green has an incredible write up on his web site, cannot remember if we passed that on. Here's the link. I have been remiss in not sending him thanks as it has saved me on more then one occasion...

cc


PM 3520

Re: PM 3520B: replaced inverter, still not working

john lucas

Sounds like it still might be the VFD. I would call Powermatic back and keep at them until they help solve the problem.

Re: PM 3520B: replaced inverter, still not working

John K Jordan

Aage, I forgot exactly what was in the earlier thread and unfortunately don't have time to read it today.

The chances are very small of getting a new VFD with exactly the same electrical or logical problem as the old one.

This can be figured out. It may take 15 minutes if a person with the right experience looks at it. However, it may require a 100 guesses by people who cannot look at and put their hands on it. Even the right guess might never fix it if you do not have the same experience.

Where do you live? Any PM3520b owners nearby?

- Any error codes on the LED display on the back of the VFD when it shuts down? (What exactly is displayed when first powered up and what is displayed when it shuts down?

Guesses without any diagnosis:

- Motor issue

- Physical problem

-Intermittent/bad connection in the low voltage control circuit? (swtiches, speed control)

- Incorrect wiring to VFD

- bad speed control

- 220v supply circuit

Diagnosis needs to be specific and each component and connection should be tested, one at a time. For example, to test for loose or incorrect connections on the VFD and in the motor I might do this: turn off power, one at time disconnect each wire from the VFD, turn on power, try again. If you get the identical symptoms with any of the wires disconnected that wire and the components it leads to should be examined further.

Do you know anyone who is good at electronics who can diagnose this? Provide a wiring diagram for them or show them Doc Greens web site. (Note that the B version is wired slightly different than the A). If mine did this I would pull out my meters and oscilloscope if necessary and hunt for the problem. The things that could cause this should be tested for and eliminated one at a time.

Do you know anyone nearby who is willing to let you substitute test the VFD on their lathe and make sure it works? This would be easy and fairly quick.

Do other 220v machines work on this circuit? Do you have another 220v line on a different circuit (on a different breaker) you can plug into? Better yet, pull off the entire headstock and carry it to a friend's shop and see if it works there. That would eliminate all problems with your shop wiring.

You said when you turn the speed control "the spindle does not turn". Does it turn freely by hand or is it locked up or tight at this point?

I would be glad to work through this with you, but unfortunately my suitcase is packed I'm headed out the door. One thing you might could do is photograph and write down each wiring connection along with the color of the wire and post it here. Someone could compare that to their machine.

JKJ

Re: PM 3520B: replaced inverter, still not working

Braden

Start with your power source. Can you verify you have 220v where you plug the lathe in? Some 220 powered electronics will function somewhat with only one leg of power.

Can you verify the resistance across the potentiometer (speed dial)? These are usually 10Ohms at the zero setting.

The digital readout on this lathe gets its info from a sensor on the spindle (right?). If so, with the lathe plugged in but not running, can you spin the spindle by hand and record a small RPM on the digital readout?

Does the inverter have a display window? There may be an error code readable on this display when the abnormal behavior occurs.

Was the original VFD and lathe configuration working originally? This questions tells us if there is a miswiring available or just a loose wire in the event that there is not a source or component failure.

John and Braden

Aage Rendalen

1. The lathe worked fine from 2007 to this summer.

2. The error code on the inverter looks like lower case "lu" or "6u"

3. Rotating the spindle results in rpm readout

As John says, it seem unlikely that the inverter is the problem given that the old and new both behave the same way.

Powermatic has a service representative 10 miles away so I will probably call him to come over. Otherwise I shall have to depend on the illustrious Dick Hines, a fellow club member and friend here in Richmond.

Thanks all of you for pitching in. I greatly appreciate your willingness to help out.

Check all connections, even in the breaker box

Dick Coers

With a lot of years, and heat in the wire, sometimes the screws on the breaker will not be remain tight. No idea if VFDs are that sensitive.

Re: Perhaps LV - Low Voltage code *LINK*

Dave Paine

The link below is for the VFD-S inverter from Delta Products.

In the troubleshooting section 7.4 are the steps to check for Low Voltage.

I hope this helps.

A variable to eliminate is to check the voltage at the outlet which the lathe is using. It is possible this may not be 220V. Easy for a screw in a breaker to come loose at the panel.


http://www.shopbottools.com/ShopBotDocs/files/VFD-S_manual_en.pdf

240 volts at socket/plug

Aage Rendalen

My volt meter is not the greatest, but it reads 220 at the socket (three feet away from breaker box).

Two Simple Tests . . .

Doc Green

Aage, you can do two simple tests with only a shorting wire and nothing else to verify that the problem is in the control circuitry and not the inverter.

One is to bridge across the OFF -ON switch to make sure it is not the problem. That switch has a history of failures.

The other is to bridge across ALL the control circuitry to verify that the inverter is good. This is done at the inverter by shorting the blue and white wires in the row of control terminals.

These tests and more are described in Part 2 of the article on my website. Photos there show you exactly where to put the shorting wire.

Feel free to email me directly if you have questions. I recommend Dick Hines - he can provide moral support if you don't feel comfortable doing the tests by yourself.

Good Luck! ~Doc

Re: 240 volts at socket/plug

John K Jordan

Aage,

Reading the voltage at the plug with a meter does not always tell the whole story. Without going into the technical issues, understand that even if the meter reads 220v at the plug, IF there is a problem somewhere with the wiring or breaker the act of turning on the lathe can pull the voltage down low enough that the lathe may not work. This can be due to a loose connection anywhere (inthe wall or in cord or the lathe, resistance somewhere, bad breaker, or something else.

This is the reason I asked about a possible error code. Write down exactly what is on the LED display. Look it up in your VFD manual. If you lost the manual, you can find it online.

If it does indicate low voltage:

Do you have something else you can plug in and test the power at the outlet?

Use your meter and measure the voltage across the power lines inside the VFD. It should read 220v (or so). Then have someone turn on the lathe and rotate the speed control while watching the meter. Does it change?

I'm traveling today but I'm sure someone else will respond with what to do next based on what you find.

Again, if you can get someone experienced to look at your lathe it might be very quick to find the answer. (Or not!)

JKJ

Re: John and Braden

Braden

Great info Aage! From looking up the fault codes in the manual of the delta s1 inverter the code "Lu" corresponds to a low voltage error:

----------------------------From the manual--------------------

Low voltage

The AC motor drive detects

that the DC bus voltage has

fallen below its minimum

value.

1. Check whether the input voltage falls within the

AC motor drive rated input voltage range.

2. Check for abnormal load in motor.

3. Check for correct wiring of input power to R-S-T

(for 3-phase models) without phase loss.

-----------------------------------------------------------

If you can confirm 220 volts with a multimeter at the input terminals of the inverter you can rule out #1.

You can do this with the meter set to Volts AC "~" and compare:

- leg one to ground equals about 120

- leg two to ground equals about 120

- leg one to leg two equals about double the above readings (~240)

#3 should be checked as best you can as well. Can you describe the motor wiring?

Thanks, Doc

Aage Rendalen

I just read your article 2. You write with great clarity and I will go ahead and see what I can find out. But first I should buy a decent volt meter.

Tests negative: nothing happened

Aage Rendalen

Doc, I circumvented the on/off switch as you laid out in your article. Nothing happened. I turned on on/off button after plugging in power so that should not be the problem, and the speed was in the mid range.

Then, with on/off button off, I connected inverter posts 10 and 4 and then 10 and 5. Nothing happened.

I get no RPM readout by spinning the spindle manually.

Instead of wearing out everybody's patience on this forum, I believe I should turn this over to the PM service guy. I'm afraid that further attempts on my part will push me into territory that I'm not equipped to handle.

Re: 240 volts at socket/plug

Michael Schneider

Do you have any other 240 tools beside your lathe that you could plug into the socket and try?

Mike

No, I don't have any other 240 appliance

Re: No, I don't have any other 240 appliance

Braden

It sounds like the only wise move forward is to purchase a large power tool that runs on 240V immediately. I see no other way. If powermatic is already coming over for a visit, see if they can bring a 24" planer or something like that. Wisdom is knocking.

Low or uneven voltage was the problem

Aage Rendalen

The Powermatic service guy was here today and finally, after three hours, concluded that the problem--as I suggested to him--might be low or uneven voltage. That was also, unfortunately, how long it took me to remember that I had nicked the insulation on the power cable leading to my woodshop when I built a wrap around porch early in the summer. I had wrapped it in electrical tape and left it shielded under the deck, but apparently humidity got to it so as to make it leach voltage.

Do I need to replace the entire four twine cable or can it be bandaged properly? My natural inclination would be to seal the nick with thick superglue or silicon and then wrap it. What do you say?

Re: Low or uneven voltage was the problem

Dick Coers

Based on the result of your first fix, and the aggravation it has caused, I vote replace the wire.

Re: Low or uneven voltage was the problem

John Veerkamp

There are several insulation repair wraps out there. Remove your old fix and make sure the damaged area is dry. Get a wrap that is specified for under ground and/or damp environments. Many of these are heat shrink, some are self fusing. Any electrical shop can fix you up. You shouldn't need to replace the whole wire.

It Depends

Brad Vietje

If you nicked the wire, replace it. If you nicked only the insulation, and not the copper, you should be able to repair it.

What sort of wire was used? Standard 12-3 Romex is not rated for outdoor use or for under a porch. That should be done with code-compliant wiring, ideally run in conduit if exposed anywhere to possible abrasion, moisture, or critter damage. In my area, porcupines and squirrels often damage exposed wires, and tragedy can be the result.

Remember that a lathe that won't run is annoying, but no big deal. Burning your house down could ruin your whole day. Wiring is not a place to scrimp.

Safe spinning,

Brad Vietje

Newbury, VT

Re: It Depends

mikeee12345

A heat shrink repair is your most reliable repair.

There are several companies that make URD repair kits for multi-conductor cables.

It might be wise to pull a new cable and not have to worry about the splices down the road.

Re: It Depends

Jerry Maske

Actually, since the voltage irregularity is showing up inside your house, your best bet is to tear your house down and replace it!

Seriously, I had a sun room added onto the back of my place on the second story, and in the process of drilling the foundation, they drilled right through the 220 pump line. Fixed it with the Shrink Wrap. That was about five years ago and the pump still works.

Re: It Depends

mikeee12345

Raychem makes an RT-555 series heat shrink tape.

You can use this to wrap around a skinned cable to seal it, a heat gun is used to seal the repair.

3M also makes a cold shrink seal that you roll over the splice, but you have to cut your cable and

roll it down the cable and then make your splice repair and then roll the seal over the repair.

3M also makes a liquid mastic that can be brushed onto the repair and then tape applied over the

splice. Any splice outdoors needs to be sealed or you will have problems later on.

Re: Low or uneven voltage was the problem

Dennis in Southern Oregon

Aage, the nicked insulation IS a problem but not the source of voltage variation you are concerned with. If the insulation "leaked" enough current to pull the line voltage down significantly, a breaker upstream would trip instantly or the cable would disappear in a puff of smoke.