# Replace Vfd Logic?



## amuller (Nov 11, 2015)

I've been using an old ABB analog VFD to run my unisaw.  It's a big bulky thing and I haven't been able to find any documentation for it.

Recently it's stopped working.  The rightmost of the 4 ("fault") leds flashes and no motor run.

Can anyone give me any guidance on diagnosing this?

Also wondering:  Supposing that the fault is in the analog control side of things, is is possible to rip that out and use one of thte cheap Chinese logic/driver boards to run this?

Thanks.


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## JimDawson (Nov 11, 2015)

If you could provide the model number of the VFD it would help in locating documentation.  Maybe a call to Delta would be helpful, they may be able to provide documentation.  If the problem is with the VFD it's self, then replacing the VFD might be the best way to go.  VFDs are pretty inexpensive these days.  Without knowing what the fault is, the other possibility is a motor fault.

I'm going to say trying to replace the logic board in the ABB VFD with one out of another drive would be next to impossible.
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## chips&more (Nov 11, 2015)

It was clever of you to think of replacing a circuit board in your VFD. But as Jim pointed out, it’s going to be impossible. What is the HP of your Unisaw? If it’s say, 3HP you might consider a Static Phase Converter (SPC). You will lose some HP with this type of unit, that is why I asked about your HP rating. But I think you will have plenty of HP left. I have a 3HP Unisaw, can’t stall it/bog it down. The SPC is cheap enough, but does not offer variable speed. But I do not understand why you would want variable speed on a table saw?...Good Luck, Dave.


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## derf (Nov 11, 2015)

I had experience with 2 AB drives and the fault 4 is "power loss". When you cut power to the drive, it will read this. I had a Power Flex 4 that was giving me a fit, and it would do this after about 10 minutes running. It was determined that it was a bad drive. After all the info I gathered, the concensus was the PF4 was THE most problematic drive that AB ever made, and it was being discontinued.
I opted for a PF 523 and have had no problems so far.
 I would replace the drive and not look back or waste time looking for obsolete parts.


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## amuller (Nov 11, 2015)

chips&more said:


> It was clever of you to think of replacing a circuit board in your VFD. But as Jim pointed out, it’s going to be impossible. What is the HP of your Unisaw? If it’s say, 3HP you might consider a Static Phase Converter (SPC). You will lose some HP with this type of unit, that is why I asked about your HP rating. But I think you will have plenty of HP left. I have a 3HP Unisaw, can’t stall it/bog it down. The SPC is cheap enough, but does not offer variable speed. But I do not understand why you would want variable speed on a table saw?...Good Luck, Dave.



Thanks for the responses.  I used the VFD because the saw was 3 phase and I had the drive lying around.  I agree there is generally not much to be gained by variable speed on a table saw--unlike many other tools where it's a big advantage.  But the saw is only 1.5 hp so I don't have a lot of enthusiasm for a static phase converter.  It certainly is a possibility, though, and I could gin one up.

Alan


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## amuller (Nov 11, 2015)

I don't know how this post ended up in the wrong thread.  Can't figure out how to delete it.

Sorry.....

The original message is unclear.  Do you really mean the motor is "burned up" (windings cooked) or do you have a bearing problem, or both.  The second could cause the first.  Ball bearings are usually easy enough to obtain and install.  Sometimes just relubrication will get you going.  It is possible but not cost-effective to have a small motor  rewound.

My opinion is that the original motors are a big part of the character of an old machine and should be kept if possible.  If not, I would look for an older US-made motor because I have seen too many crappy, lowest-common-denominator Asian motors.  I am not sure that Leeson, Baldor, etc, are still making quality motors in-house.  If they are, a new one will be expensive.  JMO.....


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## amuller (Nov 12, 2015)

Thanks for the feedback.  I decided to scrap the drive.

Alan


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## chips&more (Nov 12, 2015)

amuller said:


> Thanks for the responses.  I used the VFD because the saw was 3 phase and I had the drive lying around.  I agree there is generally not much to be gained by variable speed on a table saw--unlike many other tools where it's a big advantage.  But the saw is only 1.5 hp so I don't have a lot of enthusiasm for a static phase converter.  It certainly is a possibility, though, and I could gin one up.
> 
> Alan


Hi again Alan, I have a 1.5HP and a 3HP Unisaw. And the 1.5HP saw can bog down because of only having 1.5HP. You are correct, that if you used a SPC there would be a HP problem. The good news is, a VFD for your HP needs at todays prices is very reasonable. I would look for a 3HP rated VFD if it’s for a 1.5HP motor (maybe someone could correct me a little on that). I looked on eBay and the price is about the same for a 2HP or 3HP VFD. So I would get the 3HP one. And there’s a ton of controversy on the VFD’s from China. But, I have one of them and it works (the manual sucks)…Good Luck, Dave.


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## Ulma Doctor (Nov 13, 2015)

i would recommend over-rating the chinese drive if you were to go that route, especially if you are going from single phase to 3 phase.
i have 2 machines running the chinese drives , they seem to be doing ok


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## mksj (Nov 15, 2015)

Just about any VFD replacement would work in this setting, you might look at the Teco drives which are just a little more than the eBay Chinese drives, work very well and they have a warranty. Teco, L510-202-H1-N is a 2 HP version or older FM50 in a 2 or 3 HP. http://dealerselectric.com/item.asp?cID=50&scID=182&PID=24448

One other concern with an older motor is the insulation may be going which could have caused a fault error with the VFD, in either case replacing your archaic VFD is probably worthwhile if you are going to stay with a 3 phase motor.


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