The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
awemawson:
THE RFI suppressor capacitors arrived this morning, so no excuses - replace them !
Firstly - definite mains isolation - this thing takes no prisoners with high voltage DC - so not only turned off but unplugged as well. I was surprised to see that the front control panel hinge pins are self tappers - seems crude.
Then it was just a case of marking anything that might confuse on re-assembly, and un-bolting and un-screwing everything until finally the board could be removed from the power semiconductors that it mounts on
awemawson:
Then it was a case of un-soldering the old capacitors, cleaning the board up, and soldering in the new. The old capacitors were very degraded, with blobs of I presume solder escaping from the cracks in them. These could not have been left unchanged safely I think.
The gunge that escaped took a devil of a lot of cleaning. Carburettor cleaner, and IPA didn't touch it. It was slightly soluble in acetone with vigerous rubbing so that's what I used.
So, cleaned up, repopulated, bolted back in and tested with the power on. It goes to the ready state as it did before, but this is no real proof that it's functional - just that it's not dead !
Anyway then I was dragged away to unload a pallet from a lorry. All those problems the other week with my hydrovane showed me how vulnerable I am to loss of compressed air - so this one, a three phase '502' on a 90 litre tank , was liberated from eBay and travelled down from Norwich - best go and test it's OK
PekkaNF:
Good job with RFI capacitors.
How do those MOV:s feel?
awemawson:
Thanks Pekka :thumbup:
The MOV's don't seem to have suffered.
I received a text this morning from the chap who used to operate this lathe telling me that there was an issue changing to low gear which they never got round to fixing, and if run in high gear for too long 'something in the back got very hot and had to be left to cool'
Now the 'something' can only really have been the KTK Mentor spindle drive so maybe those poor RFI suppression capacitors died from heat stroke :scratch:
Pete.:
Knew I'd seen one somewhere, just took me a while to remember where and get round to finding it...
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