The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)

[AdeV]

Which tube would that be? 
John

The London Underground system, I'm guessing?

[awemawson]

Yes many of the Underground lines had their power distribution controlled from Long Acre (just round the corner from Stringfellows !) by our computers and remote telemetry kit, but those were the next generation on from the ones the chap wanted to scrap!

[russ57]

Graham, I rarely resent buying spares for these things when they are available and the price is sensible. It makes diagnosis so much easier in the future. A case in point is the little battery backed RAM card that seems to have succumbed to the lightning storm - I had it because it had flitted by on eBay about a year ago. Without that spare I'd still be scratching my head 


Other examples: I have a complete set of electronics and servos for my H425 Spark Eroder in a crate in my container alongside another with virtually all the bits of a Fanuc Wirecut wire eroder.

I suppose it comes from a lifetime career supporting obscure equipment in critical applications.

Years ago we were taken over by an organisation more accustomed to supporting commodity PCs where there were usually many substitute spares available at short notice from dealers at low cost. Seeing some exceedingly rare CPU modules on the books at well over £50K a piece the new MD wanted them written off pronto to make the books look better. When I pointed out that they supported a fair proportion of the National Grid infrastructure including Nuclear Power Stations that we had very tight contractual commitments to, and that they could no longer be made his face was an absolute picture

. Seeing some exceedingly rare CPU modules on the books at well over £50K a piece the new MD wanted them written off pronto to make the books look better. When I pointed out that they supported a fair proportion of the National Grid infrastructure including Nuclear Power Stations that we had very tight contractual commitments to, and that they could no longer be made his face was an absolute picture

My brother has some stories about stores. 
Item value 50k. Min stock level 2, , max stock level 2. Item required for urgent maintenance, but 'can't have it, stock would be below minimum...



-russ

[Sea.dog]

That sounds like a scenario that Douglas Adams or Joseph Heller could have come up with.

[awemawson]

It's actually remarkably similar to the maximum rpm parameter that caused me all this bother by reverting to Max = 0 

[awemawson]

So one of the 'post lightening strike' issues that I need to sort out is that back in 2018 I had made some alterations to the PLC code, and although the vast majority had been saved, my last alteration hadn't.

This is just to drive a solenoid valve to depressurise the coolant system when not being pumped, to allow the parts grabber (which is coolant powered) to open. I have hard copies of the minor change - it only involves two PLC segments - but not in a format that allows me to upload it as part of the normal reload procedure.

So today I took a trip down memory lane, re-learning how to connect my Win XP powered Toughbook running 'STEP5' to the  PLC. Amusingly, the correct version of the PLC code is still showing within the program, but I've not yet rediscovered how to upload the local copy to the PLC. If all else fails I can edit the code within the PLC to match my printout, but that's cheating!

Now I have to say that having uploaded masses of screen shots when I was doing it back three years ago, it has been a very handy resource to set me on the right path, as believe me STEP5 is not at all intuitive !

 

[awemawson]

This morning I managed to upload the PLC program file image from the Panasonic Toughbook via STEP5 to the PLC on the Siemens 820T controller. I did try directly editing the code in the PLC but it kept slapping my hand. I tested the coolant depressurisation, which was the modification that hadn't been backed up, and it works fine.

Back ups downloaded and put on two separate PC's in separate buildings along with a copy blown to CD and placed in the pocket inside the machine door - don't want to have to jump through these hoops again.

Still got the mystery of the error code numbers not being translated into text from the PCA file but that's not a show stopper. Conceivably it could be that little battery backed RAM card that I had to replace - maybe an oddity with the replacement. A further spare has arrived with my son in Houston yesterday and will be coming by shanks pony in due course.

[hermetic]

"Shanks pony" yer can tek the lad outa Leeds etc etc!! Favourite phrase of my dad and grandad!!
Phil

[awemawson]

And there was me thinking the whole world would understand, Phil, not just you 

[hermetic]

Damn, not Yorkshire, but Scotland, first written reference to it in 1729,
"This phrase seems to be of Scottish origin. It is first recorded in The Tea-Table Miscellany: Or, a Complete Collection of Scots Sangs, published in 1729 "
I had assumed its "wezzy" origin because I have seldom heard it used in East Yorkshire!
Phil, Arm deep in Fordson hydraulics!

[vintageandclassicrepairs]

Hi Andrew & Phil
Funnily enough "Shanks Mare" was commonly in use here in Cork (Ireland) when I was a youngster back
in the sixties

John

[awemawson]

I’d never appreciated that the reference was to your own thighs or shanks, so Shanks Pony was really saying that you have to walk!

[mattinker]

I thought like Andrew that it was universal, it was definitely used in West Wales when I was growing up!!

[PekkaNF]

....
So today I took a trip down memory lane, re-learning how to connect my Win XP powered Toughbook running 'STEP5' to the  PLC. Amusingly, the correct version of the PLC code is still showing within the program, but I've not yet rediscovered how to upload the local copy to the PLC. If all else fails I can edit the code within the PLC to match my printout, but that's cheating!

Now I have to say that having uploaded masses of screen shots when I was doing it back three years ago, it has been a very handy resource to set me on the right path, as believe me STEP5 is not at all intuitive !

 

First PLC programming language I learned and it was still not intuitive....even though I has suit case full of reference manuals, I had attended few lessons, I had been reading the manuals (in German, that time all the newest were in German and programs were in german too) and I had tagged along senior programmers. Ladders, timers etc. I go pretty familiar with, but assembly math and smart bit operations on tight control loop always raised my blood pressure. When making changes on running PLC while the machine was running production my blood pressure was off the chart and I was swatting bullets right when I pressed the <> key on old programmer to send out the to PLC.....hold my breath for few seconds and usually it went fine, but sometimes PLC stopped and everything went into safe mode with all noise and cacophony and signal lights went off....I could feel every eye trying to bore holes trough me....check error code, deside how to proceed and put the system up and running before whole plat goes down....don't miss it any more. I don't wake up at night on nightmare and start to think that did I checked the code right and make sure that everything is documented to last bit....all few thousands of I/O points and relevant programs. No one can do it alone, bit if you are the one that downloads the programs and flips the switch to "RUN"?

Good job keepping the hard copy, local copy and PLC up to date. There were some problems with this. You could upload the program and sometimes you didn't have the original program....working with downloaded program (without comments, titles and I/O functional names was fun. Even more so, if you had most of the program ans then decided to download something from PLC, it would wipe out the commets from similar named nets. We used download only for backups, programs were always uploaded. Live (hot fixes) were rare and generally frowned upon. Good times, but such times that will not be missed.

[awemawson]

Well the spare interface card including it's daughter card with (I think) 16 kb x 16 byte battery backed ram card arrived the other day from my son in Houston.

Now it was this little RAM card that had failed when I had the lightning, and although I had a spare with which the machine worked, it didn't translate error numbers into error text after it was fitted. As the file of error texts is stored in the RAM I wanted to try a second spare, hence getting this one.

Well, ominously, the lithium battery on this recent card was absolutely flat - not even millivolts - I've seen several of these cards but the batteries have always had something in them - reputedly they are good for ten years but there is no date on the battery.

As the battery had to be unsoldered anyway I thought that I might as well fit my 'remote battery' lead to it as that's the eventual configuration the I want to end up with.

OK battery transplant done, machine reloaded, but various error messages. Three more total wipes and reloads (which is quite a complicated process!) performed but with the same results.

Accepts facts Andrew, the card is dead 

So first replacement RAM card re-installed - a further total wipe and re-load performed and we are back running but of course still without error texts.

So I now have two (or is it three  ) faulty RAM cards so I want to reverse engineer them for testing and repair.

They look fairly conventional with four 32k x 8 bit static Ram chips and minimal logic gluing them together and a bit for isolation of the main 5 volt rail when on battery back up.

Mind you it's all a bit small for my old eyes and will involve magnifiers !

[Sea.dog]

That should be a doddle for you to troubleshoot, Andrew 

There are some cheap, UK stocked ones on eBay - https://www.ebay.co.uk/itm/224365359347

Obviously the first thing that you'll check are the "easy" surface mount components. I would not expect there to be any problem with the resistor packs, but you never know.

[awemawson]

I've started 'knife and forking' my way about the board - even made up some extra sharp probes - then realised jottings in my note book weren't going to cut the mustard. So I dug out an old copy of Protel DXP to start drawing the circuit, but failed at the first hurdle as I can't find a component library for Protel that has the NEC uPD43256v 32k x 8 RAM chip, and although I could draw one up myself it gets extremely long winded.

My copy is dated 2002 so I would have expected it to be in the 'known chips' provided by Altium, but it isn't

. . . my head hurts . . 

[AdeV]

The uPD43256v seems to be an ultra-elusive chip; I can only find 2 references on the googlemachine... neither of which are useful.

Maybe it'd be worth contacting NEC directly for a pinout, and you'll definitely have to draw your own symbol!

Is it definitely the "V" variant (16 pin single-in-line)? The DIP version ("C" variant) returns waaay more results.

[AdeV]

If the "V" was actually a fat-fingered "C"  then this page might help: https://componentsearchengine.com/part-view/UPD43256BCZ-85L/NEC

As I'm registered, I downloaded the file & it has an Altium footprint in it... I can forward it to you if you like.

[awemawson]

Ade,

Thanks but I have the pin out and a copy of the data sheet. I started defining the chip as a component in Protel just before supper, but then realised that I'd made the outline far too big. I'll re-do it in the morning. It's just to be able to draw a readable circuit diagram that I can easily modify, I don't intend to incorporate the twinkly bits for Spice modelling etc as I don't need them.

Last time I did this I was resurrecting the Numericon 850 control on a Chipturn CNC lathe back in 2012 so my memory of the 'how to's ' is rather hazy - after all it was four CNC lathe rebuilds ago !

[Sea.dog]

I'm looking forwards to this thread hitting fifty pages 

[awemawson]

I'm looking forwards to this thread hitting fifty pages 

Just a short one then you think Graham 

[awemawson]

Well I've not been idle today, apart from taking grandson round Bodium Castle I've made progress on the circuit for the RAM card.

I've created a 'pin out' model for the actual RAM chips and the resistor arrays as they didn't exist in Protel, and I've started drawing an embryo circuit diagram with all the components, so that as I identify inter-connections I can edit the drawing accordingly. There is a 'dual analog precision comparator chip which did exist in Protel, and several SMD three legged (transistor / dual diode / MOSFET) SO-23 devices that are proving elusive to positively i/d. One is definitely a PNP transistor but hopefully the other three will become obvious as I map the circuit.

Rather fuzzy photos of them from several angles haven't really helped much - they are only 2.9 mm x 1.45 mm ! They have a very faint possibly 'A J' printed on them

I am expecting that the 'dual precision comparator' chip will be being used to monitor the back up battery level, as an alarm should be generated if it falls too low.

The unidentified three legged devices I'm pretty certain are in the change over circuit  from normal to battery power - I'm attaching a circuit of a  typical change over circuit that amusingly is servicing a similar static ram chip and this circuit will probably closely follow it.

Tomorrow if I get a chance I will model the 48 pin card connector and start doing the virtual wiring up - hopefully things then will become a bit clearer.

[awemawson]

A bit of a hectic day today (grandson back to Hampshire, and two sets of cottage guests departing and arriving) but I did manage to draw up a skeleton pinout for the DIN41612 48 pin plug so I have places to anchor connections on the circuit diagram that I'm generating.

To that end I removed the mating socket from the original Interface Card that had been dissolved when the first RAM card spewed it's lithium juices before I got the machine. I reasoned that although interesting, I was never actually going to re-use it, so the manner of removing the 48 pin socket didn't have to be delicate.

. . . blowlamp to the rescue . . and off it came in excellent condition, which is more than can be said for the PCB it came off !

I can now start mapping the outside world contacts to the various address and data lines onboard the card.

Duty calls so more later.

[awemawson]

Today I managed to trace out the address bus with it's associated pull up resistor packs, and the data bus, and get them on the circuit. The 15 address lines of the four RAM chips are commoned, the the data bits of two are commoned to form the least significant byte, and the other two are commoned to form the most significant byte of the 16 bit data word.

Although I've traced the logic for the chip select signals back to the card connector I've not yet sussed the switching between the two pairs of ram chips, this switching must form the 16th address bit to map all the memory.

Yet to do is trace out the Vcc  (+5v)  logic supply switching and the battery (3.7  volt) stand by switching that involves the various SMD chips and the analog comparator  chip that I thinks is for low battery alarm.

It looks like some of the SMD chips may be power supervisory circuits:

"The PT7M7xxx family microprocessor (μP) supervisory
circuits are targeted to improve reliability and accuracy
of power-supply circuitry in μP systems. These devices
reduce the complexity and number of components
required to monitor power-supply and battery functions"

But that is more joy for tomorrow, I need to uncross my eyes !