Gallery, Projects and General > Project Logs
Oh Blimey I bought a CNC Lathe !!!!
awemawson:
I was expecting to find blown up power components in the input side but everything looked (and smelled - don't over look the nose in diagnosis !) ok - It's the usual input stage of the three phases coming in to a bridge rectifier and charging up a whacking great reservoir capacitor, with inrush current limiting by having power resistors in series with the three phases, shorted out a second or so after power on. However all looked well to my trusty Avo!
Then I started looking at the driver board and found this:
awemawson:
There is a bit of pcb track blown open circuit, and a flash mark next to a 180v working electrolytic capacitor. My guess is that the capacitor has gone short circuit blowing the track but yet to prove that theory as it's time to feed the livestock.
vtsteam:
--- Quote from: awemawson on April 29, 2013, 12:00:45 PM ---Today started with a bang. Literally :doh:
--- End quote ---
:zap: :bang: :coffee: :smart: :dremel: :thumbup:
Pete.:
Didn't you say before that capacitors that have been dead a long time have to be started slowly to 're-establish' them or something?
awemawson:
Yes Pete, but this one had been powered up for a long time so I don't think it was a re - forming issue. Anyway the capacitor would seem to be innocent of all charges, not only does that track not connect to it, it tests out ok. This section of the circuit is as far as I can tell (by staring at it !) is a switched mode power supply generating all the internally needed voltage rails for the logic and to drive the 'H Bridge' driver circuits. However they are notoriously problematic to fault find - particularly without a circuit diagram and this one has Meldas proprietary lsi modules on it :(
If I wanted a divorce I could always buy this one:
http://www.ebay.co.uk/itm/360637652653?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
(link to eBay item of similar servo drive for £3,538.18 for those reading after the ebay item expires)
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