Author Topic: micro mill electricals problems, help please!!  (Read 43396 times)

lordedmond

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Re: micro mill electricals problems, help please!!
« Reply #50 on: January 11, 2015, 03:55:11 AM »
Looks like you got the pass jail card , glad at least one part is OK

I also is good that his mistake was admitted to and you had a good outcome , maybe though he should get an appointment with spec savers  :lol:

Stuart

Offline BaronJ

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Re: micro mill electricals problems, help please!!
« Reply #51 on: January 11, 2015, 09:54:57 AM »
Hello Paul,

Sounds like a good outcome.  :nrocks: :nrocks: :nrocks:

If John sorts the controller out for you, you should be good to go.

Best Regards:
                     Baron

Offline John Rudd

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Re: micro mill electricals problems, help please!!
« Reply #52 on: January 11, 2015, 01:47:36 PM »
Could be that the board has arrived.....
I've been in Gateshead all weekend, got home to find the postie had left a card....
Need to collect summat from the PO tomorrow....needs signing for..
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Offline pmdevlin

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Re: micro mill electricals problems, help please!!
« Reply #53 on: January 11, 2015, 03:59:07 PM »
motor is back on mill in excitement, wish I had noted which pulleys the belt was on before I took it off, I have a choice of 3! Need to pay more attention to this machining lark :hammer:

Fire extinguisher is ready, spare fuses, all flammable items moved, Kevlar undercrackers ironed and ready to wear

Offline pmdevlin

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Re: micro mill electricals problems, help please!!
« Reply #54 on: January 15, 2015, 05:06:23 PM »
Looks like the controller could be on way back to me, fixed!! Lets hope postie does not lose it, or break it! and the motor does not damage it when all hooked up. John has done it already, I am sooooo grateful :mmr:

Offline BaronJ

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Re: micro mill electricals problems, help please!!
« Reply #55 on: January 16, 2015, 06:40:44 AM »
Hi Paul,

Looking forward to good news when you get it all rebuilt.  Just one thing, I don't know if you have checked for any leakage to the motor case from either connection.  If not then I would do so before reconnecting the controller board. Simply because we don't know what caused the power FET failure in the first place.

Ideally you would use a megger for this test.  Any electrician worth his salt would have one.

 
Best Regards:
                     Baron

Offline Stilldrillin

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Re: micro mill electricals problems, help please!!
« Reply #56 on: January 16, 2015, 07:38:25 AM »
Having been in the same position myself, Paul.

I've got everything crossed for you....  :thumbup:

David D
David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline John Rudd

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Re: micro mill electricals problems, help please!!
« Reply #57 on: January 16, 2015, 09:09:45 AM »
Looks like the controller could be on way back to me, fixed!! Lets hope postie does not lose it, or break it!
Yup I posted it this morning after a final test.... :zap: All is well...
I wrapped it then put in bubble wrap then put it in its box....
It's gone via parcels and need signing for...should receive it tomorrow...  :coffee:
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Offline pmdevlin

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Re: micro mill electricals problems, help please!!
« Reply #58 on: January 16, 2015, 09:24:26 AM »
I'm afraid, very afraid!, For amusement to all, will post up results :thumbup:




Offline steampunkpete

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Re: micro mill electricals problems, help please!!
« Reply #59 on: January 18, 2015, 07:27:37 AM »
Don't keep us all in suspense!  :poke:

Offline John Rudd

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Re: micro mill electricals problems, help please!!
« Reply #60 on: January 18, 2015, 07:36:00 AM »
Maybe the postie hasnt delivered?.... :coffee:

I hope there's a happy ending to this.... :beer:
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lordedmond

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Re: micro mill electricals problems, help please!!
« Reply #61 on: January 18, 2015, 07:37:41 AM »
Can I take my tin foil hat off yet , I have had my ear plugs in , hang on I am 90% deaf so the bank would have to be in BSL

Good luck hope all goes wel

Stuart

Offline John Rudd

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Re: micro mill electricals problems, help please!!
« Reply #62 on: January 20, 2015, 12:11:38 PM »
So it is now Tuesday....and no news......
I've no finger nails left....
Hope everything is ok...... :zap:
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Offline pmdevlin

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Re: micro mill electricals problems, help please!!
« Reply #63 on: January 20, 2015, 05:39:21 PM »
well here it is, the news, Tonight I ventured out to the man shed, armed with the necessary tools, full of hope 

asbestos gloves, cyno glue, a selection of man hammers, and something to thrash the machine with

Offline John Rudd

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Re: micro mill electricals problems, help please!!
« Reply #64 on: January 20, 2015, 05:43:43 PM »
What a tease....... :)

My repair is sound....you won't need a hammer to beat into submission....Unless you need it for some other reason  :lol:

C'mon we need an update......I'm now down to my elbows... :zap: :dremel: :beer:
 :worthless:

There's more suspense in this thread than a Hitchcock movie..... :coffee:
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Offline Stilldrillin

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Re: micro mill electricals problems, help please!!
« Reply #65 on: January 20, 2015, 05:54:10 PM »
And?  :scratch:

Awwww....... Come on! It's my bedtime! 

David D
David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline steampunkpete

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Re: micro mill electricals problems, help please!!
« Reply #66 on: January 20, 2015, 05:54:49 PM »
I can't stand not knowing any more, the bells, the bells, the sand, the heat, the flies!  :loco:

DOES IT WORK?

Offline pmdevlin

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Re: micro mill electricals problems, help please!!
« Reply #67 on: January 20, 2015, 06:09:06 PM »
sadness abounds, and here is the proof.

yi9-g

so, at first all is well, although a lot of "pot" movement before anything happens. When the first fuse blows, the motor emitted a big spark at brushes end. I did note when running, it was like having a  small misfire in an engine, it wasn't real smooth. It was noisier than before, however the belt was slack, and I don't know if it was on the correct pullies at this time.

You can see what happens after that. I have put a 60w bulb on the output of the control board, its gone back to how it was prior to Johns repair (real sorry John, I wanted it to work as much for you as for me!). With pot turned off, bulb is very bright, turn up pot, brightness stays constant, John tested this and he has a proportional brightness with the pot.

So back to square one unfortunately, and I have probably blown Johns repair, however, I can solder John, and thanks to you sending the part back, could probably change it out again.

So peeps, I don't know what is the cause, change motor, its not motor and keeps blowing board, change board, and its the motor??? I stripped motor again, cant see any sinister goings on.

I am thinking change the thingy John did, and the pot? try again, hopefully the video will give up a clue, now where is the thrashing thing, this machine needs a dammed good John Cleese style thrash :D

PS..., Just watching video back again, when first turned on, you here the motor, but see its not turning, so no real slow drive, then up to 0.34 you can here the speed isn't exactly constant. For reference, when it first went bang last year, fuse just blew, I had slowed the motor down

Offline John Rudd

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Re: micro mill electricals problems, help please!!
« Reply #68 on: January 21, 2015, 02:32:18 AM »
Sparking from the com like that is indicative of either an adjacent short or open circuit.......there should be little or no sparking....assuming the brushes are in good nick...

So, to the controller,advancing the pot quite a way before anything happens points to the motor...(I'm not trying to exhonerate myself here... :( ) the lamp I used lit more or less straight away...albeit at reduced brightness, which is what you'd expect...
If you attempt a repair, unscrew the bolt securing the heat sink to the mosfet(an IRFP450  you can get them from Ebay at reasonable cost), remove the heat sink from the board, then cut the mosfet legs with side cutters, then remove the remains from the board gently.....don't overheat the copper pads on the board else there's a risk of it delaminating.....reassemble, test with a lamp bulb to see all is well....decide what to do about the motor...
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lordedmond

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Re: micro mill electricals problems, help please!!
« Reply #69 on: January 21, 2015, 02:48:17 AM »
That motor has released its magic smoke  :zap:

As John said its looks like a short , windings or comm I cannot be sure.

If it was me in your place I would repair the board as per Johns post and get a new motor .

Stuart

Offline steampunkpete

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Re: micro mill electricals problems, help please!!
« Reply #70 on: January 21, 2015, 03:21:41 AM »
Or possibly sticky brush(es).

f you live anywhere near St. Albans and could drop the motor off, I could give it a going over for you (within the limitations of the equipment I have). In the far distant past I did some design work on PM brushed motors, some with (what were then) exotic magnetic materials.

I did notice the unusual label on one of the lamps on the control box - "unnormal".

Offline BaronJ

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Re: micro mill electricals problems, help please!!
« Reply #71 on: January 21, 2015, 10:55:41 AM »
Hi Paul,

Sorry to learn the sad news.  :hammer: :hammer: :hammer:

I wonder did you do the insulation of the motor windings to case check as I suggested ?  You never said.

Best Regards:
                     Baron

Offline Bluechip

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Re: micro mill electricals problems, help please!!
« Reply #72 on: January 21, 2015, 11:23:13 AM »
Metering/ Meggering to deck may not show the fault if it is an inter-winding fault.

My WM16 motor went pop about 18months ago and meggering from a brush to the casing while turning by hand showed nowt at all ...  :thumbup:   but ......

Stuck it on my Variac via a bridge rectifier and it was fine until some 40V r.m.s. then  the  arcs tracked around the commutator ... amusingly  :zap: but not helpful. If I let it cool off for a bit it would run for several minutes OK below the 40V mark. New motor fixed machine, it  didn't kill the KB board ( the thyristor version).

Maybe some winding had chafed in the slot and was shorting to adjacent turns ??? Hoo nose ???

Commiserations to Paul ..  :(

Dave
I have a few modest talents. Knowing what I'm doing isn't one of them.

Offline pmdevlin

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Re: micro mill electricals problems, help please!!
« Reply #73 on: January 21, 2015, 11:39:16 AM »
ok all,

just so I have not mislead you, the sparking wasn't/isn't constant, it was more a flash as the first fuse blew. Motor was stone cold, brushes are perfect.
Bluechip, thanks for input but have no idea what you are talking about, remember, I am thick!

Baron, same sorry, I thought you guys might get fed up of me! so didn't reply due to embarrassment :doh:

Pete, many thanks for very kind offer, but I am Wirral, so miles away

John, I will try to get back to what you had, can you please post an ebay link for the right fet, I had a quick look, and there seem to be different specs for that part number. Ill get a pot from arc euro also, for that price it is worth it, then if all agree its the right course of action, at least get back to a proportional bulb as John had it. If I have a spare fet, then  I can try on the motor, if it blows again, change the fet again, and with a new pot it must be the motor?
I would have thought the motor would give a clue, such as smell of electrical death, burning, burnt wires etc. As the motor could have been the original fault, I have no way of going back to our "expert", he had it running for a while on 60vdc, I take it when it starts to get up to 230vdc that is when things go wrong!

Paul

Is there a very simple test I can do on the comm, such as a test light on each segment to establish anything worthwhile!


lordedmond

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Re: micro mill electricals problems, help please!!
« Reply #74 on: January 21, 2015, 12:05:39 PM »
Paul yes there is a test

It's simple when you have the required DC source it's called a volt drop test but that motor has a thick winding in relation to its size you would need to measure about 0.1 volts and a current limited 2 volt source

Stuart