The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
awemawson:
Revival of an old thread - but at last I've got round to doing something that's been on my list for well over a year.
You may recall that the original demise of this machine was due to the lithium 'Tadiran' on PCB RAM back up battery having let out its juices and dissolving much of the Siemens CNC controller, so when I got it all working I mounted a remote battery in a leak proof case away from the electronics. This worked well but a few months (years maybe?) later we had an electrical storm IIRC that took out the little ram card that the battery had been mounted on.
This card backs up many setting and parameters of the machine and is vital to it's operation. However they are rare as hens teeth and come in several incompatible versions. I eventually found one that 'almost worked' - every thing was fine EXCEPT for a look up table that is stored on this card that translates error numbers to plain (ish!) English. Load sequence worked but errors still show as numbers not text. I spent weeks reverse engineering the RAM card - and manually proved that all the addressing and other peripheral logic on the card was fine - but what about the RAM chips themselves - was one faulty.
I then spent several fruitless weeks trying to make a RAM tester using an Arduino but never got a good setup, and the bits have been om my desk in the workshop for well over a year - glowering and nagging me.
Well I decided - hang it, source the RAM chips and change them ! They are four 28 pin surface mount NEC D43256GU-12L -I found a source of the chips - bought myself a cheap SMD rework station and . . . .bottled it ! My eyesight was never good and with anno dominae isn't getting better.
However today I braced myself and made a determined effort using a bench magnifying lens.
To remove the original chips I used loads of flux and Quick-Chip ultra low melting point solder. Strange stuff - extremely brittle and stays molten for a long time allowing the old bits to be removed. However due to this brittleness it is important to remove ALL of it before soldering in the replacements. I used normal Solderwick again with loads of flux, then cleaned up the mess with IPA.
Much watching of YouTube videos told me the virtues of 'drag soldering' - never heard of it before - but essentially you anchor the chip at opposite corners by conventional soldering with a very fine tip iron - then load the tip with excess of solder and drag it across the remaining pis, where the excess of flux and surface tension pulls the solder into the places that it's needed. Amazingly the process seems to work - I had a couple of solder bridges but they were cleared fairly easily.
So after a lot of flux clean up I re-assembled the RAM card with it's retaining handle and umbilical cord, and now I need to find the time / courage to try it in the machine. Lengthy re-load procedure so not today.
Still I overcame the SMD soldering issue and fears :thumbup:
awemawson:
Well that was a fruitless exercise :(
Initially I steamed up my copy of DNC4U intending to talk to the lathe and check its comms as I've not used it for some months. The program said "What Interface?" - my Startech USB to 4 port serial box that's been working for years was only showing two of it's four serial ports and thus the Beaver wasn't connected.
Much faffing about with USB cables USB hubs UPS power sources - PC re-booting and yes at last it found the remaining ports that even still had the correct settings.
OK find a directory with the correct back up to re-load, unplug the RAM card with integral battery, plug in the one where I've changed the RAM chips and not surprisingly it comes up wanting reloading. First step is to power the control down bring it back up pressing the "Eye Key" which is used to get into the set up side of the control. Well it won't come up at all - blank screen - zilch.
Revert to RAM card with integral battery - up she comes and all is well
Try two more times with my 're-chipped' ram - same symptoms - argh we are no better off than we were but at least no worse.
Could be faulty RAMS or more likely forgeries - oh well, slink off and lick your wounds :bang:
hermetic:
You have the patience of Job Andrew! I know what it is like though because once a job is under your skin, it keeps nagging till you fix it! I suffer the same affliction. If you have a go at a fix, and it fails, you have committed the details to the "unconscious computer" and days,or maybe weeks later a solution or strategy just pops into your mind unbidden from who knows where! the UC has been working on it all along and is saying "heres and idea, try this" The human mind is a wonderful thing! AI be damned!!
Phil
awemawson:
The frustration is Phil, I have a perfectly good 6FX1134-2BA01 128K RAM card in the system, but it has the onboard battery, and it was one of these batteries that caused all the issues in the first place.
I don't want to unsolder its battery and connect it to the remote battery until I have a working spare, as if I can't reload it the lathe will be unable to function.
I've fired off an email to a repair company to see what astronomical fee they'd ask to either supply or fix - we'll see what happens !
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