We promised a unique video about the Bloodhound missile. Here it is hot off
the press from our specialist: “An introduction to the Countermeasures that a
Cold War enemy might have employed against the Bloodhound Missile System and
how the system dealt with them.” There will be further videos about specific
countermeasure methods in due course.
Wishing all our readers a very happy and peaceful Easter time.
Two jobs carried out yesterday:
Neil cleaned the LCP roof of any dust residue from the rubbing down and primed the roof ready for a top coat.
I (Peter H.) gave most of the LCP cabin awning frames their first top coat.
Neil also stuck together three dust sheets to provide a dust cover for the LCP to protect it as painting the roof has now started and there’s a lot of dust in the hangar!
Off-site the cable duct covers have now received their second top coat and preparation is under way to renew their rubber seals and replace the chrome lock covers.
Here is a photograph of the LCP as recovered from a a field is included with this blog to illustrate its condition in its original ‘abandoned’ state. Watch this space for a comparison with the completed article. The eagle-eyed will spot the T86 behind the LCP in both this picture and the one at the top; that has changed beyond recognition too but not so advanced.
Engagement Controller’s Monitor
Following the changing of the Technical Supervisor’s monitor the previous Saturday the EC’s monitor went a bit ‘funny’, the colour wasn’t right. After a short investigation of the obvious – and after the Red channel of the RGB video input disappeared – it was found that the Red channel termination switch, it switches in or out 75 Ohms, on the rear of the monitor had been switched over or stuck in the middle. Obviously accidently touched the pervious Saturday. With the switch now in correct position the monitor display is back to normal. We like these sorts of ‘faults’; keeps us on our toes!
After successfully formatting the SCSISD, see previous blog, and loading it with the Bloodhound software (SCSISD is a SCSI-2 hard disk emulator, it replaces a SCSI disk with a micro SD card!) in the workshop it was time to see if would run the LCP – answer; it does. The SCSISD is not as fast to boot the LCP as the original SCSICF product (CF card) we used for SCSI-2 disk emulation but it works! Slower it may be but still a lot faster than the original CDC Winchester disk. The SCSISD emulator is about a sixth of the cost of the SCSICF emulator but there is a very good reason for this. SCSISD is an open source item aimed initially at the Amiga computer (yes the original Amiga) whereas the SCSICF product is aimed at mission critical applications in industry. For our use the SCSISD is fine as the days of the LCP being ‘mission critical’ have long gone. Performance of the SCSISD is less than the SCSICF at boot but the LCP appears to perform normally when using the SCSISD, see the accompanying photos of the displays running with SCSISD and the SCSISD card under test in the Argus 700 disk/tape shelf. One issue with SCSISD is that on switching on the Argus the Argus has to receive a reset before it boots from the SCSISD. This issue will be looked at but if it turns out to be a ‘feature’ of the SCSISD it is not a problem, particularly where costs are involved.
Painting and Scraping
Work has started on the preparation needed to repaint the LCP roof. When the many coats of paint were being removed, with a heat gun and scraping, a significant number of rivet heads came off. The reason being that the hole in the centre of the pop rivets had not been sealed and over the years water ingress into the centre of the rivet had caused the aluminium shaft of the rivet to corrode through. All the pop rivets that had lost their tops through corrosion had previously been replaced but the task on Saturday was to seal the tops of the replacement and original pop rivets to prevent any future water ingress. Isopon car body filler was used for this purpose. Next Neil used ‘wet and dry’ paper to rub down the roof, with plenty of wet, and is now ready to receive its coat of primer next Saturday. Neil also worked on creating a cover for the LCP roof to protect it from dust once repainting starts in earnest.
The underside of the steel section around the base of the LCP cabin was given a good going over with a ‘stripping disk’ (far superior to a wire brush for flat surfaces) and once cleaned of any corrosion and loose paint received corrosion treatment before primer will be applied next Saturday. Generally, the underside of the LCP is in a good condition considering its age and the years it spent dumped on the bare earth, subject to whatever the weather could throw at it. Two accompanying photos show the two worst cases of corrosion found, both at the ends of the LCP, these areas will be treated and repaired. The underside of the LCP is constructed from a perforated steel sheet on which five steel skids are fixed. The perforated steel sheet is covered in what looks like a resin coating, this can be seen in one of the attached photos where the steel sheet has been punctured at some time in the past.
It was also decided that items that can be refurbished away from Cosford, e.g. cable duct covers, will be done so. All work at Cosford is then concentrated on the LCP cabin and the T86 cabin in its turn.
One of our longer term challenges is establishing an alternative method of loading programs, currently on vulnerable QIC tapes, to the Argus hard drive. However, an alternative would be to have all the tapes pre-loaded on a ‘hard’ device.
We already have a solution developed and fully working for the unsustainable and highly unreliable Winchester disc using Compact Flash cards. This system is quite expensive as are the professional grade CF cards. So the next step was to see if a different SCSI2 HD replacement card will work with the Argus. An ‘open source’ product we had our eyes on only has asynchronous support and was originally designed for use with the Amiga computer; see here. A new version going to be released soon is here; this supports synchronous transfers and will give better perfomance. If the earlier version works then so should the latter. These units use SD cards and are much cheaper that the unit we have installed which uses CF cards. Watch this space.
This is our workshop test rig with the Argus 700 on the left, disc system tray in the centre and FT81 terminal emulation on a laptop.
This is the disc system tray in close-up with the interface card to the Argus 700 on the left, tape drive and tape at the front and the new card on test back right.
This is the SCSI SD card under trial.
The SCSISD gives the initial boot message, ignore the FAIL and ERROR messages as I have no ME153’s plugged in but it works!
Getting the SCSISD to work wasn’t ‘plug and play’ and I’ll write up how to configure one of these units, I couldn’t load software from tape initially! The proof of the pudding will be running SCSISD in the Launch Conttrol Post (LCP) and see how it performs which we’ll do on Saturday (today).
If it runs in the LCP OK (performance wise) it will represent a big financial saving over the SCSICF product, about a sixth of the price, but then SCSISD is not aimed at high reliability applications in industrial control. We don’t need that. If all works out well I will get several SCSICF units and a load of SD cards with UK and Swiss software loaded so we reduce the need for tapes. That said the tapes look to be loading trouble free at the moment.
Yes indeed the good news is that the monitor suspected of having a power supply fault is working but with a ‘no fault found’ solution.
Four of these large CRT monitors are used in the LCP; they are Mitsubishi Electric model C3920 for display of 682 x 512 pixels.
Here are the four displays with the simulator running.
They require an RGB input with composite syncs superimposed on the green video channel. This shows the details of the non-standard video.
Pete H was doing the work in his home workshop where it took a while to set up a test rig with CHARGE cards etc to be able to drive the monitor with the non-standard RGB video used in the LCP system.
This set-up provides a test card from firmware in the CHARGE system to supply suitable signals for fault finding.
CHARGE (that is Compact High-resolution Advanced Raster Graphics Equipment) was devised and developed by Ferranti design engineer Peter Don-Duncan specifically for the Argus 700. There were few applications of the product and Bloodhound is believed to be the sole remaining user.
Inspection had already shown that there was no visible indication of a heat-damaged component and when first switched on there was nothing on the screen as per the symptom in the LCP. After checking the 6.3V supply voltage for the tube heater voltage Pete noticed the EHT was OK …. no not because he got a belt from the supply of25kV DC but because he felt the static charge on the CRT face!
There was still nothing on the screen though so Pete proceeded to check some details when around he glanced at the screen and noticed that the test signal was displayed. So what was the fault … poor continuity on connector or an obscure dry joint!
The monitor white balance needs setting up and I’ll do this during the week.
So, what about the smell of burning experienced in the LCP ? Thankfully it wasn’t the Flyback transformer in the monitor which is a great relief, so a suspect is the usual problem that initiates a nasty smell namely a RIFA filter capacitor going in a Farnell power supply. I’m sure we have replaced all the filter capacitors in the computer rack PS’s but when we have time those in the display console and in the rack (is it S rack?)
could do with a check. A filter capacitor going U/S does not stop a PS from working.
This is a great relief as every time a monitor fails it starts me thinking about how we can replace the Mitsubishi monitors!!!!
Saturday was a painting and refurb day for Dave and I as someone (me – Pete H) forgot the LCP frame repair kit – a collection of tools and pop rivets that I’d taken home the week before.
Dave cleaned and prime the LCP roof joining sections in readiness for repainting. He then spent a happy few hours completing the de rusting, cleaning and priming all the plates used to secure the canvas cover for the two LCP’s roof joins, there are only fifty eight of them! Unfortunately the original canvas roof join covers were completely rotten but have been
salvaged to use as templates for new covers.
The refurb of the LCP door vents is almost complete, they were in desperate need of a refurbishment.
A replacement louvre for one of the vents was cleaned and primed. The replacement louvre recovered from a derelict LCP cabin as the operating arm on the original louvre was broken.
Here is work in progress and the refurbished item:
The fly mesh is beyond a refurb as seen above! In cleaning the door vent louvre we uncovered the makers name ‘Greenwood’ and a quick web search found that the company still exists (I assume it’s the same company) see product as this has a louvre very similar to the LCP door vent.
The twelve awning support frames for the LCP cabin roof are now primed and ready for a top coat.
These are just the frames on the top of the cabin roof, the eight side frames have already been refurbished and primed.
The Mitsubishi video monitor that failed is still in repair. Luckily we do have the circuit diagram but no spare parts. The fault is probably in the power supply but a Line Output Transformer (LOPT) would have been ideal to swap out but not yet found!