Accidentally ran mill DRO on 50Hz power, what do I need to replace?

Thread Starter

LL2

Joined Oct 4, 2017
5
Hello all, first post here so apologies if I have this in the wrong place or if this has been touched on elsewhere. I tried searching for similar posts and while I learned a good bit, I think I could still use a bit of help.

So today I messed up by accidentally running our small shop that is set up for US 60Hz power off a generator outputting 60Hz for probably 30 minutes. We were lucky and we came out of it pretty unscathed. The biggest loss waas the Digital Read Out (DRO) for our mill which didn't survive. It would be great if I could fix it, but at this point I'm just trying to figure out what component(s) need replacement or if I need to order an entire new setup. I'll try to summarize what I know/have found out. Feel free to tell me I am terribly wrong on something as I haven't had much electrical experience since I graduated and as an ME we only covered pretty rudimentary mechatronics/ESys material.

The DRO consists of:
  • The display/control panel

  • Three position sensors (X, Y and Z axes, they are optical encoders set up on a rack & pinion)

  • The AC Adapter

The AC Adapter has the following information on it:

Input: 120VAC 60Hz 200mA
Output: 7.5VAC 1000mA

(I don't want to violate any forum rules but I can link to the exact brand/model if that would help and isn't against the rules.)

As far as I know, the voltage and amperage should have been correct with the only issue being the wrong frequency.

I know the AC Adapter is likely fried/overheated since it was warm to the touch for probably a good 10 minutes after unplugged. From what I've read it is common for newer adapters to lack a margin of safety large enough to handle the wrong frequency, especially if it is marked with a VAC and specific frequency like this one is. If it is all that was damaged I would be very happy though.

I have no idea on the status of the display/control panel. This is where the bulk of the circuitry is and well beyond my abilities to repair if it has more than minor damage. If the damage stops there, though, then it will still save me from having to replace the entire assembly.

I was hoping the sensors would be purely resistive and thus OK, but after looking up optical encoders, it doesn't look like that is the case (however, I have zero familiarity with the working of this type of sensor beyond a little googling). If the damage has gone this far, I will simply have to repurchase the entire system.

Thanks in advance for any help and let me know if there is anything else I should look into/provide!
 

MaxHeadRoom

Joined Jul 18, 2013
21,443
I am quite suprised that those devices would suffer damage running on 50Hz.
Are you sure there was nothing else going on, higher voltage for e.g.?
The vast majority of it would just be converting the AC to DC.
Max.
 

RichardO

Joined May 4, 2013
2,271
The adapter may or may not be dead. All adapters of this type normally run a little warm.

Do you have a DVM? If so, measure the voltage on the adapter plug. I would expect it to be 10 to 12 volts AC.
 

ian field

Joined Oct 27, 2012
6,539
I am quite suprised that those devices would suffer damage running on 50Hz.
Are you sure there was nothing else going on, higher voltage for e.g.?
The vast majority of it would just be converting the AC to DC.
Max.
Universal mains input rating more or less goes with the territory on anything with an electronic PFC front end.

That may not be the case with permanent installation equipment.

Anything with SMPSU won't care if the mains is 50 or 60 Hz.

A big contrast to the old iron cored transformers - 220V 50Hz into a 110V 60Hz primary usually lets the magic smoke out.
 

Thread Starter

LL2

Joined Oct 4, 2017
5
Wow! Thanks for all the quick replies, I really appreciate it.

I am quite suprised that those devices would suffer damage running on 50Hz.
Are you sure there was nothing else going on, higher voltage for e.g.?
The vast majority of it would just be converting the AC to DC.
Max.
50hz generator = 220VAC?
There may have been higher voltage, I will check with the generator mechanic tomorrow and see if he can let me know exactly what the settings were. I do remember none of our breakers tripping (so AFAIK this means it wasn't a straight amperage issue) but about half of the GFCI outlets had to be reset, if that means anything.

The more I think about it, the more likely it sounds that this was an overvoltage problem.

The adapter may or may not be dead. All adapters of this type normally run a little warm.

Do you have a DVM? If so, measure the voltage on the adapter plug. I would expect it to be 10 to 12 volts AC.
I will do this first thing tomorrow.

So this adaptor may be an iron-cored transformer version. Please post model and manufacturer (it's not against the rules).
Thanks for the clarification, I didn't want to step on any toes as some forums I've been to are very strict about any outgoing links to products. The DRO is a Shooting Star BT-3 (http://www.star-techno.com/INFO.HTM). Here is a picture of the adapter's markings.

20171004_225803.jpg

I assume you mean the generator was outputting 50Hz?
Yes, apologies. The generator was outputting 50Hz.
 

Reloadron

Joined Jan 15, 2015
5,646
I would start by replacing the AC adapter. That said I also ask:
So today I messed up by accidentally running our small shop that is set up for US 60Hz power off a generator outputting 60Hz for probably 30 minutes.
Now did you mean to say 50 Hz? I doubt a line frequency of 50 Hz verse 60 Hz would matter. I see you just posted as I type this. Should there have been an over voltage as in a severe over voltage I would expect you would have seen more things go wrong such as 120 V lamps (incandescent lamps) burning out in short order as well as other problems including some breakers tripping. Talk to your power guy and see exactly what the generator output was. Again, I doubt a change of 60 to 50 Hz would do much, if any damage.

Ron
 

AlbertHall

Joined Jun 4, 2014
10,413
As it's an AC output adaptor, it's a fair bet that it uses an iron-cored transformer and may have suffered from the lower frequency - especially if the voltage was high too.
 

JohnInTX

Joined Jun 26, 2012
4,292
It is OK to post links to products that you are having trouble with. That helps our members be helpful. We draw the line at links with commercial intent benefiting the poster - links to your companies' products etc.

Welcome to AAC!
 

Thread Starter

LL2

Joined Oct 4, 2017
5
It is OK to post links to products that you are having trouble with. That helps our members be helpful. We draw the line at links with commercial intent benefiting the poster - links to your companies' products etc.

Welcome to AAC!
Makes sense, I just wanted to be sure. Thanks for the welcome! I'm digging the helpful people and good attitude. I just wish I discovered AAC under better circumstances!
 

Thread Starter

LL2

Joined Oct 4, 2017
5
Alright so I got a chance to revisit the setup and it turns out it was indeed a voltage issue. The generator mechanic and I had a bit of miscommunication during the setup. Me, being unfamiliar with split-phase power, told him we needed 240V. He took that as having 240V across each leg of the generator, so set it up for 240/480V instead of 120/240V. The frequency was also wrong, but was the (far) lesser of the problem in retrospect.

So there it is, my poor little DRO received double what it bargained for voltage-wise. Is there any way to tell if it is totally toast through and through, or will I need to incrementally replace components to find out?
 

MaxHeadRoom

Joined Jul 18, 2013
21,443
Anything is possible, but I would have thought the P.S. would have suffered only, but if it is in fact a linear type supply as opposed to SMPS, then it could well have received over voltage.
What are the details of the DRO make etc? and if possible a photo.
Max.
 

tranzz4md

Joined Apr 10, 2015
310
Alright so I got a chance to revisit the setup and it turns out it was indeed a voltage issue. The generator mechanic and I had a bit of miscommunication during the setup. Me, being unfamiliar with split-phase power, told him we needed 240V. He took that as having 240V across each leg of the generator, so set it up for 240/480V instead of 120/240V. The frequency was also wrong, but was the (far) lesser of the problem in retrospect.

So there it is, my poor little DRO received double what it bargained for voltage-wise. Is there any way to tell if it is totally toast through and through, or will I need to incrementally replace components to find out?
Yes.

Double voltage, certainly for 10-30 minutes will toast plenty.
 

philba

Joined Aug 17, 2017
960
Over voltage, that's what it sounded like to me.

OK, first thing to do is look at the adapter. Does it still put out 7.5VAC (though unloaded, it will probably do about 10-11VAC). If it doesn't, that may be all there is to replace. If not, look at the power supply for the DRO. You might get lucky and see that it just cooked a regulator, cap or diode or some such. I would guess that in trying to keep the output voltage stable (5VDC, I'd think), it gave up. Open up the readout box, find where the power connects. Look for something near there that is burnt or bulging. Really nice sharp pictures would help. Too bad they didn't use a newer DC wall wart as those are universal and would have handled the situation just fine.

I bet there is a linear regulator in there and the over voltage caused it to cook out. Probably didn't damage the rest of the circuit. Replacing it might be all that's needed.
 
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