Work Day 7th October 2017

The focus has been on getting the LCP fully serviceable again so no other topics to report on until now.  I am delighted to be able to say that serviceability has indeed been achieved; the investigation has revealed that we had, at least, two faults:

Fault 1
The ‘Mode Change Not Allowed’ fault was due to a faulty GX processor for whatever reason it was not reading PeriBus replies from just the Digital Input box. We shall have to research this to help identify what could be wrong with the GX.

Fault 2
The ME186 PeriBus converter was preventing the initialising of the software which was  preventing the Bloodhound banner from displaying. This fault occurred last Saturday and was additional to Fault 1.

Resolution of the problems has been delayed, in part, due to the unknown condition of spares, especially GX processors. Serviceable GX and ME186 are now installed with known good spare GX in the LCP. Back in the workshop we tested it by installing and running the simulator.

We established early on that no inputs were being read from the Digital Input box and Stuart’s software analysis showed us what should happen and the messages that should be displayed depending on the Mode and Roll switches on the console, but whatever we did it was always the same message that was stopping the simulator booting – ‘Missiles not at Reload’ indicating the A and B Reload/Available switches where in the wrong ‘Available’ position which they were not. All other aspects and indications of the boot sequence were correct, displays, flashing lamps etc. but nothing happened when pressing the Simulator button.

Initial indications pointed to a problem with the Digital Input box or a switch, an obvious place to start. Could it be a faulty input card ‘locking’ data bits, could it be a faulty Serial to Parallel converter? Fortunately we have a spare Digital input box so I built a test rig consisting of my PeriBus simulator, a Digital Input box and switchable inputs to Slot 14, all cards were rotated through Slot 14 for testing. Slot 14 was used as it was the only card position that used a single input socket (OA8) and the slot also used the lower voltage (3V) bias. I had an original OA8 wired socket, carefully salvaged by Mike with all other wiring and connectors from a derelict LCP at Luffenham. It was simply a case of adapting it to connect to a +5V supply to simulate switched inputs. With this rig I could test all input cards, Termination Buffers and Serial to Parallel Converters. Several faults were found including a Serial to Parallel converter with a U/S 74S04 [amazing how many of this gate device has been a problem! – Ed] setting two data bits permanently, an input card with a U/S LM337 giving a bias of 11 v instead of 6v and an open circuit leg on a plug in DIL component (Ferranti PAL) due to oxidisation. All good stuff and an expectation that the fault would be cleared, but it wasn’t.

It was appreciated from the beginning that there could be a PeriBus problem and other fault finding measures including swapping out the ME186 PeriBus converter on the A700, as well as all other cards except the GX. The reason being that the spare GX in the LCP was definitely U/S. I originally considered the GX to be the likely problem as it was handling all other routines for starting the simulator software. Surely if there was a problem with the PeriBus it would affect everything that is connected to it. The Serial PeriBus cable and termination were also replaced.

On Saturday Sept 30th, Pete M and I tested the Digital input box in-situ with the PeriBus test set and all looked to be OK and working normally. Attention then reverted back to the A700 and the GX as it was the only item not swapped out. Removing and reinserting the GX caused another problem (fault), the boot message on the FT81 only displayed the three initial lines then everything stopped, the boot sequence was not completing to the stage it was with the ‘Missiles not at Reload’ message. Priority was now to get a serviceable (spare) GX.  I am able to test GX processors to a point where the software can be booted but it does not proceed past the first line of the boot message, normal for a standalone A700 which is what I have at back in the workshop [used to be called home for Pete H! – Ed]. On Saturday I arrived at the LCP with two spare GX’s. Both GX’s then gave the same fault of the first three lines of the boot message on the FT81 – both GX’s could not have the same fault. Swapping cards revealed it was the ME186, PeriBus Converter, causing the three line boot fault. We now had two faults, the ME186 obviously going U/S on Sept 30th.

Once the ME186 was exchanged and a working ‘spare’ GX was fitted in the A700 the simulator booted correctly and ran as expected, fault fixed. I then spent an hour breaking the rule of, ‘if it’s working don’t touch it’, swapping back in the original faulty GX and ME186 to prove the fault conditions which confirmed the original GX was the cause of the permanent ‘Missiles not at Reload’ status message and the ME186 was the cause of the halted boot after three lines, this elimination task was needed to prove that we had two separate faults and this it wasn’t the ME186 causing both all along.

Moral of this saga, always ensure we maintain a set of known good spares in the LCP. What follows on from this fault is our ability to repair faulty cards. I have started on the Digital Input box and look to extend this testing capability to all I/O boxes and their cards. The challenge is to test and repair A700 cards, i.e. no extender cards exist for a start; then there is the fact that we do not have any test specifications.

As Dave has already suggested, a fault log is required and steps are in hand to set one up to be kept in the LCP.

To help understand which processor handles which task our software guru has been studying the Argus 700 source code [Coral 66 – Ed] which is from another military customer’s archives but close enough to the RAF’s and came up with this list of definitions in the BHMACRO file which shows which processors in which tasks are run. SYSSUP, which does all the MODE and ROLE button input reading, would seem to be running in GL2:

+ Task numbers for BH2 programs. Bracket comments
+ show the processors that run each of the programs.
‘C’ Task number £42 is spare ;
‘C’ Task numbers £60 to £63 are spare ;

This indicates that not all tasks are fixed to a processor but this begs the question, how are non-fixed tasks managed;  assigned dynamically or shared perhaps?
We initially assumed (mistakenly) that the GX was OK because the system correctly read the console keyboards. The keyboards are read by the BHTEST.BH2 task, which it seems is not fixed to a processor. Note also that CHARGE displays were not affected because FDCP is fixed to GL2.
If the above makes sense to you it might mean you are an expert with Coral66; please make yourself known if you are.

Big hooray; we ran the simulator again today for a visitor and it remains ‘S’

UK P Display Tgt Data - Num Errors.JPG


Work Day 16th September 2017

Hi folks, this posting is a bit of a catch up on a couple of previous weeks as well as this one.

Mode Change Not Allowed…. the fault still exists after another fruitless day trying to fault find in the LCP. The decision was made on last Saturday to remove the Digital Input box from the I/O rack and check it out in the workshop. It is now obvious that trying to fix this fault without known good spares is almost mission impossible. We have spare cards for the Digital Input box but as-recovered not as-issued from the manufacturer or third line – those were the days.

The plan is to test all the input cards in the workshop and several faults have already been found including a Serial to Parallel Converter that permanently activated data bits 2 and 3 irrespective of the Digital Input box addressing and irrespective of data being read from the corresponding inputs. Still no joy though when that fault was repaired (a faulty 74S04 TTL device – what is it with these most basic of TTL ICs as we have had LS04 failures too?).

All sorts of issues were experienced on Saturday such as the +5v increased to +6v on the Digital Input box when cards were removed. Luckily no obvious consequential damage but it did create havoc with the timing on the cards in the Digital Input box.

Working on the Digital Input box ‘standalone’ in the workshop using our PeriBus test set allows the addressing of individual input cards and the reading inputs from them. We can then sign-off good cards and not be misled by additional faulty cards being used in the Digital Input box which we assume to be ‘S’ spares when in fact they are U/S.

Testing Inputs - LCP wm.jpg

The photo above shows the test set up in the LCP. Waveforms and voltages are displayed on a laptop using a PicoScope (USB oscilloscope), great bit of kit. I’ll never use a standalone oscilloscope again. The two LED’s extinguished on the extended input card are LED’s 22 and 23 indicating (correctly) that the A and B Reload/Available switches are in the correct Reload position for running the simulator. The evidence in the LCP for “Mode Change Not Allowed” fault is that all relevant switches are operated and indicated by their LED’s on the Digital Input cards but the Argus is not seeing any inputs from the Digital Input box on the Serial PeriBus, disconnect the Serial PeriBus from the Digital Input box and the fault stays the same.

A further problem last week was that a 15V 16A power supply blew one of its paper filter capacitors, lots of smoke and a horrible smell. Replaced the power supply with a spare. We thought all the power supplies installed in the LCP had their paper filter capacitors replaced as a matter of course, obviously not!

T86 Radar
Neil succeeded in lowering the Aerial pedestal a few inches after a few weeks of trying ways to get the retraction chain moving on the cogs that wind down the pedestal; he was ably assisted by Dave S, or is it the other way around? Anyway, we can now hand crank the pedestal up and down manually with the retraction gearbox which required some major refurbishment. We needed to be able to retracts the  pedestal for corrosion treatment and to check the seal between the pedestal drain trough and the cabin roof. Lowering the pedestal with the aerials on their back allows for better access to the aerials for refurbishment.The photos below give two views of the pedestal lowered, the top one is from the cabin roof, the bottom one is from inside the rear of the T86 cabin looking up at the roof aperture.

T86 Pedestal 1 wm.jpg

T86 Pedestal 2 wm.jpg

Work Day 26th August 2017

The main task today was to give the rear of the LCP cabin its first top coat of paint. As usual, what you think will be a quick job took most of the day but the accompanying photo shows the result. The paint is still wet hence the reflections. The photo also shows the axles used to move the LCP short distances when needed. A local mod that saves having to hire a crane every time the LCP needs to be moved!

LCP Cabin Rear Wall Painted wm.jpg

Last week we left the simulator with two faults, intermittent booting and a permanent ‘Mode Change Not Allowed’ message that prevents the simulator completing its switch on. The intermittent booting fault has been resolved by replacing the SCSI ribbon cable. The second fault is not so straight forward and fault finding continues. Today was all about painting so the Mode Change fault will be pursued next week. It’s hard not having test procedures!!

Work Days 12th & 19th August 2017

We are on catch up in this blog with activities from two work days.

T86 Radar
Refurbishment of the pedestal retraction gearbox is complete; from an originally seized gearbox you can now turn the gears with your fingertips! See three stages of re-assembly.

T86 Pedestal Gearbox Re Assembly wm.jpg

This is showing the gearbox after refurbishment.

T86 Pedestal Gear Box Refurbished wm.jpg

Here is the gearbox refitted at the top of the picture.

T86 Pedestal Gear Box Refitted wm.jpg

We now have the ability to raise and lower the pedestal manually. The drive motor for the pedestal gearbox is three phase A.C. driven and we don’t have a three phase supply. The motor is in poor condition and is awaiting refurbishment which is not a priority as we now have manual control of the raising and lowering of the pedestal. On the next working day we will re-tension the pedestal drive chain ready to lower the pedestal a few inches to check its seal. The gearbox refurbishment was carried out off site, as a policy we do not waste time on-site by working on items that can be refurbished elsewhere.

Preparation of the T86 cabin for repainting continues and it is starting to look the part.

T86 Prep for Painting wm.jpg

Launch Control Post
Work has started on painting the rear wall of the LCP cabin which will receive its first top coat on the next workday. Here we see Neil in full flow with his mastery of the 4” roller to apply the etch primer.

LCP Priming Cabin Rea wm.jpg

More time was spent on the simulator fault – the simulator boots but fails to initiate the simulator. The software checks the state of several switches i.e., Missiles set to Off,  Firing Circuits  are Open and Missiles are at Reload. Switches not being in the correct position causes the ‘Mode Change not Allowed’ message on the console display screens. The fault condition is; the switches are in the correct position but the Argus 700 is not seeing that they are, or at least one of them, so gives the Mode Change message.

Mode Change Message wm.jpg

LED’s on the Digital Input cards associated with the switches indicate correctly. One possibility is that there is a problem with the Parallel/Serial PeriBus which for whatever reason is dropping a bit. Unfortunately with this type of fault there is no one item in the system that is obviously unserviceable. The software does report faults on the CHARGE display system and the GL coprocessors in the Argus but not the integrity of the complete I/O system at boot, e.g. it does not tell us which switch is in the wrong position as far as the Argus is concerned so investigation continues.


Work Day 5th August 2017

Six of the team were present for Saturday’s working session so a lot was achieved but not until grabbing the chance for a group photo!  [Your blogger was unfortunately not there due to family commitments].

Group Photo wm.jpg

Work continues on completing the painting of the LCP cabin’s rear wall. Holes were reamed and re tapped for the roof catches and primer applied to the places were using the paint roller is not practical.

The majority of work is now focused on the T86 with several tasks being undertaken.

De rusting and priming the wheel arches inside the T86 cabin. The original flooring was removed some time ago as it was completely rotten due to water ingress and fortunately the steel sections of flooring had not corroded through, namely the wheel arches. Here you can see the stripped floor and the primed wheel arches.

T86 Wheel Arches Primed wm.jpg

And here the floor is being refurbished.

T86 Floor Refurbishment wm.jpg

Removing as many of the external fittings to the cabin as possible, as there is usually corrosion underneath them, specifically the reflectors (seen below). Not an easy task so an impact driver was required to remove the corroded in self tappers.

T86 Impact Driver Removing Reflectors wm.jpg

Rubbing down the end wall of the cabin. Unlike the LCP the T86 cabin is in much better condition paint wise so no going back to bare metal much to everyone’s relief – especially those working on it (live action below!).

Working on the T86 wm.jpg


The simulator was run up for its usual weekly check for us to discover it has a fault. It boots to the initial Bloodhound display screens the console lights flash (usual start up sequencing) but not all together as they should and the simulator then freezes. No time on Saturday to pursue the fault but the suspicion is a missing input to the Digital Input box so the Argus hangs waiting for it ……… we think!

Off Site – Pedestal Gear Box Refurbishment
Refurbishing the Pedestal Gear box so the pedestal can be lowered. The gearbox has been dismantled and bearings removed, the majority of which are U/S due to corrosion again caused by  water ingress. Here are the bearings being removed using a puller.

Pedestal Gearbox pulling bearings.jpg

And here are the culprits:

Pedestal Gearbox  bearings.jpg

The bearings are imperial sizes but fortunately still available so a new set has been ordered.

Off Site – Test Rig Development for I/O Cards
The test rig for checking Digital Output cards is progressing well using an Arduino to set the required addressing and data required to test the card. The digital outputs are now controllable so the next stage is to attach LED’s to the switched outputs that correspond to the LED indications on the front of the card. The test rig which is the basis for eventually testing all I/O cards for the LCP MK2 consists of:

  • Laptop for programming the Arduino and displaying waveforms/logic levels from a PicoScope (an excellent bit of kit).
  • An Arduino
  • A locally designed Serial PeriBus generator which has six lines that connect to the I/O box with a 20 way ribbon cable
  • A salvaged Digital Output box to replicate the Digital I/O box in use in the LCP. The Digital I/O box containing a serial to parallel PeriBus converter card , a parallel PeriBus Termination card and the Digital I/O card under test.

Here is the rig in its development stage of build driving a Digital I/O card.

Simulator Driving Digital I-O Card.jpg