Author Topic: Broken CNC milling machine  (Read 420 times)

Offline AdeV

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Broken CNC milling machine
« on: February 07, 2019, 03:59:37 PM »
Well... I think I've found the problem with my main CNC milling machine....


There are 6 capacitors, and whilst only one of them has actually caught fire, all of the others are in an advanced state of decay, or have already burst. So... 6 new caps it is. Off to Farnell I go!

I'm just grateful it's not the computer board that's let go... although I need to check it for fire damage, as it sits right over that capacitor, and there's a properly big sooty mark on it... plus I found some blobs of solder on top of one of the orange components (you can actually see it in the picture, 2nd one along), which doesn't bode well.
Cheers!
Ade.
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Offline awemawson

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Re: Broken CNC milling machine
« Reply #1 on: February 07, 2019, 04:50:20 PM »
Well at least you found it before the shop burnt down  :clap:

It all looks horribly familiar.

The orange components are triggering (pulse) transformers driving the thyristors. Are the burnt capacitors Rifa ones like these? (RFI suppressors)
Andrew Mawson
East Sussex

Offline AdeV

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Re: Broken CNC milling machine
« Reply #2 on: February 08, 2019, 07:01:59 AM »
Hi Andrew,

Yep - they're identical in every way!

I've got 10 on order from Farnell (12.70+VAT)... unfortunately I missed the cut-off for next-day delivery, so it'll be next week before I can fit them. However, I'll pull the board out tomorrow for a good clean up.

I'm just hoping the burnt one didn't take out the resistor above it, as I can't find a like-for-like replacement, nor can I find any reference to the existing part(s) to buy an equivalent...
Cheers!
Ade.
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Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
Skype: adev73

Offline awemawson

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Re: Broken CNC milling machine
« Reply #3 on: February 08, 2019, 07:20:37 AM »
When I was replacing mine, I dug about on the internet investigating the failure mechanism. Apparently these things are designed to 're-heal' after break down discharge from spikes, and can be expected to be subjected to many many spikes in their life time.

I've gone though all the circuitry in the Beaver lathe and replaced every one of them, even if they look pristine.
Andrew Mawson
East Sussex

Offline AdeV

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Re: Broken CNC milling machine
« Reply #4 on: February 09, 2019, 11:32:27 AM »
I've gone though all the circuitry in the Beaver lathe and replaced every one of them, even if they look pristine.

I will probably do the same to the Bridgeport now... although before I do I'll get it back up and running.

Removed, after much unscrewing, the drive board, unsoldered the caps. The burnt one has taken its trace off the back of the PCB, but fortunately its very simple, so a straight wire bridge will replace it easily. The blackened resistor, remarkably, is still pin on 33.3 ohms! So I'll re-use that, after cleaning the soot off it.

Now I just need to wait for the caps to show up, and it can all go back together again  :thumbup:
Cheers!
Ade.
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Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
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Offline AdeV

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Re: Broken CNC milling machine
« Reply #5 on: Today at 01:25:01 PM »
Mutter grumble...  :(

So - replaced all the caps  :thumbup: cleaned up the boards  :thumbup: returned and re-wired  :thumbup: and things lit up kinda like they should do  :clap: - but no spindle action  :scratch:

When I powered up this time, the first thing the machine requested I do was replace the buffer batteries... so - whilst I had it all powered up, I did exactly that: 3 shiny new Duracells to replace the ones which are 8 years past their "best before" date  :clap:. And now the damn thing has lost all its parameters & switched to German! Argh! It's not a disaster, I have the parameters saved on the computer, but buggered if I know how to switch it into English until I find the manuals. Annoyingly, I think the spindle problem MAY be the phases are out of order in the plug - this is the first time I've tried to use it (well, excluding the time it caught fire a few weeks ago), and I recall I had to switch wires in the plugs of both the normal mill and the lathe, in order to fix a phase difference between my old & new workshops...

So... once I work up the Round Tuits to figure out the parameter re-load... I'll have a go with the phase wires the other way around. Oh, and try to figure out why the shiny new batteries have decided not to work properly.

TBH, I'm getting closer to think it's time to re-fit this mill with some updated electronics/controller.
« Last Edit: Today at 02:33:23 PM by AdeV »
Cheers!
Ade.
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Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
Skype: adev73

Offline awemawson

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Re: Broken CNC milling machine
« Reply #6 on: Today at 04:24:50 PM »
Parameter 92 for most early Heidenhains
Andrew Mawson
East Sussex

Offline AdeV

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Re: Broken CNC milling machine
« Reply #7 on: Today at 05:31:21 PM »
Hi Andrew -

I discovered that earlier, reading a post on the CNC Zone forum + downloading the TNC151 service manual. It's hardly obvious about the setting!

I suspect I'll have to type them all in this time, as I can't find my serial cable, or the laptop with the TNC Server program on it (!), so that should keep me busy for an hour or so tomorrow!
Cheers!
Ade.
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Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
Skype: adev73

Offline awemawson

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Re: Broken CNC milling machine
« Reply #8 on: Today at 06:36:41 PM »
TNC server is downloadable from Heidenhain or I can send you a copy

The cable is straightforward and again I can send you details, and if you've lost your back up there are default values for most Interact versions floating about on the web.
Andrew Mawson
East Sussex