Work Day 14th May 2022

T86

Started the day underneath the rear of the chassis to remove loose rust and then applying corrosion treatment. One note: The level of corrosion in the back half of the chassis is significantly worse than the front half but nothing is corroded through thanks to the heavy duty steel frame and axles etc. Working sessions under the radar are limited to two hours and no photos this week to bore you!

LCP

Some of our readers may not have seen the condition of our LCP before recovery and the condition after our early work on the outside, here are a couple of reminders:

The first task in the LCP this week was to resolve the ‘Mode Change Not Allowed’ message on the displays. After some initial checks  it was found that the +5V power supply feeding the Digital Input box had a low voltage output which was soon adjusted.  This power supply was a spare and when fitted last week the output was not checked due to time pressure. A set of fault finding notes in a binder now resides in the LCP to guide everyone through the checks needed to resolve the cause of a ‘Mode Change Not Allowed’ message on the displays. A point of interest is that the sense lines are not wired in on this power supply in the RAF equipment but they are in the Swiss kit; we shall rectify this so that the supply is held more stable.

Now the simulator was running again a final check was carried out on a CHARGE controller populated with two new EPROMs and two replacement GALs instead of the original PALs, these components are specific to monitor type. Following the donation of two CHARGE Controllers, which were configured for a different monitor, we had to configure to the Bloodhound standard with new components. The controller being tested worked as expected creating the correct display and colours.

The CHARGE system was well ahead of its time for graphic display. The first photo below is the Controller Card followed by the Pixel Store Card showing the complexity of the boards with very dense component placement.

Pete H

Work Day 7th May 2022

T86

A few jobs were carried out before venturing under the chassis again including prepping the two rear jacks. The photo below shows the rear  axle and what we are faced with.

The metal surround of the cable outlet on the rear of the cabin had been fibre glassed previously, it was badly corroded and impossible to replace. As can be seen now it is smoothed with filler and is ready for sanding and painting. See accompanying photo.

Visible in the photo are the support frames for the Ward Leonards, the supports are sound unlike other T86’s in museums where they tend to be badly corroded.

LCP

Both patches on the LCP cabin have now been primed. A small strip is still required where the patches join. See accompanying photo.

The simulator was given a run but the 5V power supply for the analogue box on the I/O rack had failed and has been replaced by a spare.

The simulator initiated but also failed to run with a ‘Mode change not allowed’ message. Something we are familiar with and often down to a switch in the wrong position and at worst a fault. We have some experience of this problem which can be isolated by some observation checks, e.g. the LEDs that are on or off in the Digital Input rack, PeriBus errors etc. Time didn’t allow for fault finding so this will be re visited next week.

Away from Cosford

A lot of work has gone into checking and converting donated CHARGE chassis and cards, Controllers and Pixel Stores. CHARGE Controllers have some components specific to particular display monitors; they are two EPROMs and a PAL devices. They required replacement devices programmed to the Bloodhound standard; something which has been successfully carried out.

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