12 June 2011

Cracked walls, shrinking ground and 5x TCs

Just when I thought life was settling down to a mundane background hum, nature in all her bountiful splendour pulls a fast-one on me. Then to make me doubt my abilities with a soldering iron and design minded ideas, a TC from 51 weeks ago turns up with a dead PSU!! Aargh! no no no... this cannot be. I give a 1 year warranty on the PSU repairs with the expectation that it will NEVER be called on. It is there to show I have confidence in what I do, not as a by-line to hook-in the unwary.

The gentleman in question was existent on my repairs database (such as it is) emails and log-book. It transpires he did not have a Fix and Modify (F&M on my shorthand) but a CHECK and Modify. This seemed like a good idea at the time, I would load check the PSU and dab my new whizzy ESR meter onto some of the vital capacitors, to take their pulses, so to speak. In reality I discovered my well-meaning intensions were actually taking MORE time than doing a repair, since one capacitor would need to be removed to be checked with the ESR meter and if found to be OK, put back! What I did was to put in a new capacitor and not charge for it, taking the cover off to get at the back of the printed circuit board (PCB) took just as long as doing a repair but needed to be a lot neater since this was only a check and I did not want to disturb things. Nett result was I took longer and gave away a component to only ensure the PSU was working under load without a problem. The ESR meter will work with some capacitors in circuit but the readings are compound not individual.

I had only done one such CHECK and Modify as it undervalued my time to an unacceptable degree, like £8 per hour. This was the one. The kind gentleman paid for my time to do a complete replacement of components and tested repair, on his PSU. He gets a full one year warranty from this weekend. I had no need to have panic in my heart - it was not a full blown repair from a year ago - so my fix rate remains at 100%.

It gives me limited but useful information, however. Even a working PSU that is tested under a full load, will have undergone heat related stress such that the components are walking wounded. Even with cooling, their lives have been shortened and they will ultimately fall over. The components I use in the repairs are far superior to the standard items and with cooling will go on for years.

It has been very dry here. Almost no rain at all in April, very little in May (2 days I think) and June has had very few rainy days. The 5-sided field walked every day has cracks in the ground wide enough to break and ankle and deep enough to make my walking staff drop about 300 mm down into the ground. Sadly and unfortunately The Homestead is built on this same clay base and as it has been so dry the ground has shrunk away and the house has cracked in half! The new triple glazed windows, so beautifully fitted in January and that run along one half of the North end of the bungalow (nearly 8 m of window frame in one piece) has one window that now will not open. An internal door in the hallway will not close and a large 2 mm wide crack has appeared in the East wall, the central support wall and possibly the west wall - examination will tell. This is a simple result of the ground drying out.

Judicious use of the hosepipe (no ban here yet) running near to the east wall and tucked down a dry-crack in the ground, after several hours is still seeming to feed a bottomless pit. The ground greedily sucks all the water away. It may take days to rehydrate, expand and allow me to open windows and close doors. 1950 foundations were never expected to survive ground shrinkage like we are seeing... this fun storyline will continue to excite no doubt.

Apart from the re-visit of the TC from the past, there were 4x more to be worked on and I spent my whole weekend at the workbench and in the garage, doing all the modifications. One such TC, arrived in the most vandalised state I have seen in a while. (Yes, if you’re reading this, you know who you are!).

The rubber base mat was about 50% removed, sufficient to get to the 10x small screws - 2x of which were missing. The PSU screening foil was on the OUTSIDE of the case along with the grey legend strip from the base mat. The PSU had only half a plastic case and might as well have had teeth marks in it! This was a sorry state. I have no spares for most of these missing pieces, simply what I have accumulated over the year from odd scrapped TCs I have bought via eBay.

THINKS... I must get some small screws and find a kind friend with links to the ‘Mother Ship’ that could possibly get some new grey rubber mats?

I informed the customer, who had paid up front for a full F&M, that it was almost beyond repair, since I could not put it (the PSU) back into the case without insulation. While I waited for his reply and being creative with next to no spare parts, I fixed the PSU, which was easy enough as I have all those parts, the tools and the test gear - it worked a treat. Scrabbling around in the back of the garage I found an old unused (cracked) thin plastic box for the freezer that was also dishwasher proof and made from some horrorshow plastic (Thank you Clockwork Orange for that phrase from the book and film!) meaning it was as tough as hell, seemingly immune to the blast from the heat gun and a good electrical insulator. Vast expensive tin-shears in hand and with tongue tip between the front teeth, I set about creating in best ‘Blue Peter’ style (BBC tv children’s program that made ‘things’ from washing up bottles and sticky-backed plastic - “Here’s one I made earlier...”).

Three hours later, and with lots of Kapton tape holding it together, I had a really good looking complete and working case for the fixed PSU. It fitted inside the TC, it could withstand the temperature from an uncooled PSU on full load and I had even managed to put the original Flextronic sticky labels onto the cover. Kind customer paid me for my time, what he considered it was worth to him, since I had proceeded without his say so. To say I am pleased with this whole TC repair is understatement... I am delighted!

If pressed I may even offer this as repair option. With some practice and skill I could make a new case in less time. It makes for a very complete and elegant solution. I even managed to rescue the Apple symbol from the central part of the savaged rubber mat and stuck it on the base in a small circle of the remaining grey rubber.

I may add to this blog, some intensely personal writings I did many years ago, after the untimely and early death of Carol, my first wife. I discovered these while searching for some material with which to make the new PSU case. I read them and they rocked me to my core - as they probably would. I was grieving for a number of years and did not realise that I needed to kick myself out of the loop I was stuck in. They may help others in a similar situation. I will think on it... If anyone every reads this (I suspect I have a worldwide audience of possibly 2 or 3 people) and sends me a note (email) I will tell the tale. It is a quite remarkable story I think and ends on a happy high note. We shall see...