Discussion in 'Diesel & Electric Traction' started by majorsmallpiece, Jun 12, 2016.
An update on the retoration of the Class 89 at http://www.aclocogroup.co.uk/news.php
I'd love to see this banking on the Lickey, but the speed limit over the summit would probably be exceeded.
Is the Lickey going to be electrified?
Since electrification is being extended to Bromsgrove I should imagine so !
Would it even notice the Lickey?
The article on the micro processor troubles is a worrying glance into the future for the preservation of more modern locos/units which are far more electrically orientated than the kit we tend to play with at the moment. Let's hope the skills to deal with that sort of stuff aren't lost..
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I would rather hope that micro processor skills would be part of the future mind you in the time since that loco was built, technology has moved on so quickly that most of the processing functions could probably be done on a modern laptop?
Whilst the "skills" might still be present I wouldn't be so sure that software compatability can be guaranteed. I currently have a link to a company which I have added as "Favourite" on both MAC and Microsoft XP Platforms but only the Microsoft link (unusually) works without problem ! If the systems can't / won't talk to each other today -- Heaven help those future generations when society becomes increasingly machine-dependent.
There has been a similar, successful project at Crich Tramway. Blackpool 762 has a thyristor controller, which thanks to a volunteer who's job is in electronics, is now running pretty reliably. I don't know the full details, but I know a lot of work went into rewiring and improving it.
Much will depend on what design documentation is available. If that is absent or incomplete it may be easier (or less difficult) to design and build a complete new controller than to repair the old one.
We are continuing to work away at the 89. Understanding the foibles of the electronics is moving on at a reasonable rate. However, sometimes you need help from a friend with a crane...especially when the electronics needing repair are the size of a large fridge! http://www.aclocogroup.co.uk/news.php
Not content with taking the roof off and lifting major components out of the 89 we've moved on to lifting the loco body off of the bogies...http://www.aclocogroup.co.uk/news.php
In Derbyshire something stirs...
I do find it mildly curious that she uses the same microprocessor as the Sega Mega Drive.
Plenty of spares then?
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I remember 68000s running in a lot of broadcast hardware in the 80s; I think the Aston 4 character generator was one. Plus, didn't some older Macs use 68000s?
Either way, it can't be that hard to find them. What will be a LOT harder is finding suitable EPROMs and hopefully, somebody is stockpiling some and making backup copies of the code in the control system.
I am making *huge* assumptions here but a lot of the interface I expect to be a mixture of on/off type interfaces (e.g. pan up/pan down) and A-D/D-A functions (speed, braking, current consumption, wheelslip). All tied together with redundant processors, I'd hope!
I also wonder how much use was made of tantalum bead caps in the control boards, given their propensity to fail short-circuit - but I'd hope in safety-critical systems such as this, they're nowhere to be seen
The 68000 hasn't in itself been a problem and following the repair of another card that has a watchdog function the micro now works. In general much of the electronics is, though obsolete in it's design, functional and pretty well understood. However, the A-D card designs are unique to Brush and in some case unique to the 89 so the spares pool is not many to zero but generally haven't been a problem- the 6 Field Convertors (each comprising a rack 1500 tall x 600 deep x 200 wide and full of finest "unobtainium" such as Power Transistors) are far more of a problem. Our electronics expert isn't at all phased by anything that he's seen in the several months of intensive testing and digging into the loco that we've now undertaken.
Running up the one TM blower is of course a bit of a side show, though obviously it is the ultimate output of a circuit/system proving.
Much of our work is focusing on finding methods of testing/examining equipment that would probably only ever have been checked out on commissioning or post repair test runs, hopefully we'll get chance to film some of these static tests as it will be interesting to be able to see how the loco responds.
The repair/overhaul of the heavier items of equipment (motors, rheo stacks) is again something that you get to know by doing it; the motors we've done previously, the rheo stacks are a new challenge albeit that the concept is familiar from classes 85-87 but of course being the 89 they're different and have suffered an 'interesting' life. Mercifully the 89 was at least designed using ISO (i.e. metric) units so many mechanical items are readily available.
What was the watchdog meant to be kept in check by, or did its timing components fail?
When you mention "Field Converters", is this loco one that turns single-phase AC into variable-frequency three-phase AC? (Forgive me, although I rode behind 89 001 in service a few times I never really considered what was going on). Large power transistors can be fun to locate/buy (even things like MJ2955s for example!) but there are component brokers out there. Of course, that doesn't stop them being bespoke devices!
A-D devices are the sort of thing that can be 're-imagined' with modern devices if needed, but I'm sure your electronics expert will tell you that!
I'm impressed that it uses a 16-bit processor when you'd have thought 8 would do!!
A few updates on the 89.
Armature Converter testing this weekend http://www.aclocogroup.co.uk/news.php
A video of some more extensive Traction Motor Blower testing
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