Work Day 6th May 2017

Saturday was all about painting and Dave had the best job, though he may not have thought so, painting the front wall of the cabin. The LCP is starting to look like an LCP again as seen here.
LCP Cabin End Repaint 2 wm.jpg
Any patches noticeable on the LCP cabin photo is where the paint is still wet. I busied myself giving the awning frames a second coat, a laborious and time consuming task. Painting is also taking place away from Cosford on the LCP cabin fittings and more information will be provided in the next couple of weeks on the refurbished cable duct covers etc. The LCP is being painted in matt NATO Green, not the IRR version of NATO Green which fades dramatically in a matter of a couple of years. NATO Green was the final in service colour of the LCP and T86.

LCP Cabin End Repaint 1 wm.jpg

Technical Bit
One of the first tasks in restoring the Bloodhound simulator was to refurbish ALL the Farnell G Series power supplies in the MK2A LCP, a total of fifteen. All the RIFA  (metallized paper X2) capacitors used as filters/interference suppressors have to be replaced.

RIFA Capacitor 1 wm.jpgThe original RIFA capacitors, being at least thirty years old, have split plastic encasing and a deterioration of the dielectric Applying power to a power supply with the original RIFA capacitors fitted will cause the capacitors to ‘boil’ and create a large amount of smoke.  All RIFA capacitors need replacing before power can be applied to a Farnell G Series power supply. The restoration of the simulator is complete but now and then a Farnell power supply from our spares stock is refurbished as one was last week. See the accompanying photo which illustrates the problem with the original RIFA metallized paper capacitors.

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2 thoughts on “Work Day 6th May 2017”

  1. Just out of interest, what are you replacing them with? Kemet? Farnell have some PME271Y522MR30 rated to 100C which is slightly better than these at 85C. They don’t look like X2 – that one in your photo is Y – did you mean Y in your update? I’m looking dodgily at those tanty beads too.. in fact they all probably get replaced at some point, do they?

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    1. Hi Dave,
      Where possible we replace with like-for-like to keep things as close to original as is practical. Indeed the Rifa in the photograph is a Y type; we get both and mixed up the text and photograph. We have replaced a lot of tantalum bead caps but not found them to be especially unreliable. If we have to dive in to get one we tend to change them all but we have to be cost conscious as all costs come from personal pockets only.

      One oddity that we have not worked out a reason is that whilst we have had very few active components fail but looking at TTL failures there is a marked number of 74LS04 faults compared to anything else. With that being about the most basic device for this technology it is a puzzle.

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