Customer Repairs

Marine receiver

 A customer dropped in a small receiver the other day and it went into the backlog to be dealt with when the spirit moved me or otherwise.
"Otherwise", usually means that the owner telephones me to ask on the progress, and this was the position here as the owner did indeed call after only a few days.
I scrutinized the little set during the phone call, which was really concerned with non-escalating costs. It was more of a "nice to have receiver" fitting into brackets somewhere within the cabin of the small boat.
Keeping costs within reason is is not an unusual type of request, as it's a simple matter to multiply a living wage hourly rate by a few hours and arrive at a figure well in excess, of a cheap replacement (no matter whether it's a receiver or some other piece of consumer equipment).

It's rapidly becoming obvious that the only items worth the true cost of repair, that come my way these days, are parts of complicated items such as large industrial machines, or parts of the general fabric of a building, such as a lift.

All that having been said, I like fiddling with interesting things and this little receiver promised some interest.
So it was then that, having recently finished sorting out a computer, I laid the little receiver on the bench and reached for my screwdriver.

Immediately before this I'd connected a 12-volt power supply to the set after wondering vaguely whether the blue and brown mains lead was really for mains connection or just happened to be available to the manufacturer when he'd made up a power lead. The give-away was a small label on the rear proclaiming use of a DC supply of between 12 and 30 volts or so.
I must admit that I used logic to decide on the polarity, choosing brown for plus.
The receiver front panel had come to life and the display showed a number like 268 but there was silence. Does it have a loudspeaker? I looked around for a grille before seeing a little switch labelled SPKR. Pressing the switch upwards (upwards?) resulted in a loud noise like interference from a million television sets. I found a long wire aerial and poked it into various sockets before being rewarded by a change in the background cacophony. Twiddling the tuning dial to 198 then resulted in Radio 4 muting the noise and I heard speech.

What was the compliant?
"No FM", I recall was the message I'd had.
I switched the knob to FM and a number showed in the display. "10.7", it said. Odd that sounds like the IF frequency of an FM receiver.
I switched back to medium waves and tuned in Radio 5 Live. That sounded OK apart from then fact it was a bit subdued. Short waves also produced some signals but switching back to FM did not. True that on the second attempt the display showed 95.7 rather than 10.7 but still no sound.

I twiddled some more and decided that the problem lay with the wave-change switch. It felt ever so unpositive, and electrically certainly dodgy as indicated by inconsistent readings on the display.
It was at this point I decided to fill in the next 30-minutes with a quick repair of the receiver. A squirt of switch cleaner, replace the screws and Bob's your uncle. A "Low Cost Repair", as the owner had requested.

I removed the screws, revealed the switch, and squirted switch cleaner. Not easy as the switch was a peculiar affair with enclosed wafers.

I powered it up. It was much the same. Intermittent dial readings. But wait; as I looked inside the set and waggled the wave-change switch knob I noticed the switch seemed to have a kind of inbuilt delay and a mind of its own.
It was only with the greatest reluctance that the certain sections of the switch actually responded to movements of the knob.
I donned my magnifying headset and soon found that the section of the switch nearest the knob was broken.
I've gone this far I thought, so I might as well bash on and spend another 30-minutes or so.

An hour later I'd dismantled the set. It was typically British in design. Absolutely no thought to servicing. The case was attached by various electrical fittings to the chassis and couldn't be detached. The front panel was merely a plastic cover and to go further meant that the set would have to be taken entirely to pieces.

So it was then that after another hour it was completely in pieces.
In fact it was only now I could see that to actually proceed would involve unsoldering the switch from the printed circuit.
Only 24 soldered pins to each wafer and a mere eight wafers. That's 192 solder joints. Not too long with my unsoldering tool I imagined. At least the holes weren't plated-through. Being a British-designed set it had that in its favour.

Now I don't know if you've ever tried to remove a soldered-in device. Take a three legged transistor for example. Every leg has to be entirely free of solder otherwise one cannot pull it away from the circuit board.
This device had 192 legs. It took ages with a solder wick and a strong magnifier before I'd freed all 192 legs sufficiently for me to lever the switch away from the board.
What I removed was in a very sorry state indeed.

The old paxolin Yaxley switch used to work for 60 years and no doubt longer when they get the chance. Sometimes one will break but that's often due to rough handling not the basic design.
This modern equivalent of Yaxley's design was absolutely awful. Each wafer relied on a flimsy plastic disk to pass turning movement to the contacts. Worse. The end operated by the knob relied on only half the thickness of the section, not only to rotate the contacts, but also to pass turning movement to the whole switch.

With years of use and stiffening action, the end plastic disk had more or less disintegrated. At least the bit that relied on passing energy from the knob to the remaining sections. All the others, under less stress, were cracked in varying degrees indicating to me that the design was flawed.
My supplier's catalogue was strangely mute on any rotary switches let alone this complicated beast.
I looked at it wondering how I could cut my losses.

If this was an essential part of a lift, I would dutifully search the Internet for a manufacturers' catalogue and a stockist, but that would take time and lead to an expensive conclusion.

As all eight sections of the switch were identical maybe I could move them around. Put a good one at the end and the others further along the shaft?
I set to and after 20-minutes had the switch in pieces in front of me. At least most of it, as at one point there was a sort of flicking noise and bits flew in all directions.
I looked half-heartedly on the floor amongst the debris of earlier jobs and retrieved a tiny ball-bearing.

I t was at this point I'd realised why the set reacted strangely when the wave-change knob was rotated. Some of the wafers seemed to have a mind of their own, sometimes rotating with the rest, sometimes not and sometimes grudgingly moving only halfway. Because the plastic had broken on most of the wafer assemblies, the two metal wipers were not always pressed against the corresponding metal inserts for the switch positions.

I worked out a solution so that at least the set could be used. If I added a shim between each wafer assembly the parts would be forced together. Depending on the damage to the assembly I would either add a wide shim or a narrower shim. I went off in search of something suitable.

I came up with some of those square nuts used for coach bolts. I found seven that were just the right thickness for the narrower shim and by adding an extra washer a thicker shim could be fashioned.

I carefully reassembled the switch.
That is until the final section when I refitted a tiny spring and a ball bearing. It was at this point I realised that two ball bearings were required, one either side of the spring, which fitted inside a hole in a plastic plate. The bearings located in indents so that precise switch positions were made.

There had been a sort of subdued rattle from somewhere on the floor. Underneath the bench was an old computer chassis so I lifted this and shook it. A few odd screws fell out. I moved the chassis and detached my specially strong horseshoe magnet from the side of the electric fire where I won't forget it.

After brushing the magnet around the floor for a few moments it had attracted numerous computer screws, bits of wire and lots of iron filings but no ball bearing.
I wondered what to do next as the future of the whole project seemed now to rest on a ball bearing about a millimetre in diameter.

I have a plastic bag containing an assortment of these kinds of things but Goodness knows where I put it. I also have a collection of old Yaxley switches with the odd ball bearing but I couldn't remember where I put them either.

I went outside and looked in our old garden shed, after finding the key and getting wet feet as I approached it via the long grass. Lots of bicycles, a lawnmower, a shredder and a mountain of perilously stacked boxes bulging with useful stuff.
I pulled out a steel toolbox with the vain hope of finding a stray ball bearing in its recesses. All I discovered was a lot of rusty tools and a red tubular thing labelled "parachute distress flare". I vaguely wondered if these were allowed on 5th November? Maybe not near the South coast I thought, but what about somewhere inland… like Birmingham? There can't be too many coastguards on the lookout in Birmingham? I put it back and dropped the old toolbox back on the floor, locked up the shed and went back to the workshop.

Another, wider scan with the magnet revealed nothing except some more computer screws so I thought very hard. Where might I find a small ball bearing?
How about a little ball of solder? I'd tried that once but it was too soft.
What about the front fork of a bicycle? I had memories of spilling dozens of ball bearings the first time I slackened the large nut under the handlebars of my old bike, maybe 55 years ago.

I had found several bikes in the shed but those were in quite good condition so those I ruled out. I trudged outside again in the steady drizzle and lo and behold behind the dustbin in the veritable mountain of rusty bits of old Landrover chassis I found the frame of a bike.
I pulled it out. The front forks were present. A 6-inch section of the frame had been neatly removed. At first I couldn't remember why. Then I remembered I'd used it to repair my Rover 820. It was now somewhere in the cooling system.
I looked at the top nut. It was very rusty but after thumping it with a hammer and heaving on it with a large pair of pliers it moved. Twenty minutes later I'd retrieved a couple of ball bearings. Unfortunately they were far too big.

Somewhere in the dim recesses of my mind I recalled I'd had this trouble before. What had I done then? After bashing a pedal off the bike and giving up on the centre bracket I remembered where I'd found a miniature ball bearing once before.
I looked around the workshop and picked up an ancient hard drive.

The thing was extremely tightly held together with torx screws, but luck was with me for once, and I actually found my box of miniature torx screwdrivers and set to work dismantling the thing.
There were dozens of screws, followed by a lot of shiny disks, a set of heads and finally a cylindrical lump containing an armature.
I looked at the aluminium cylinder. No obvious means of taking it apart so I bashed it with a hammer and after raining a multitude of blows extracted not one but two miniature bearing races.

I prised away the seals and underneath I could just see some miniature ball bearings.
Next I had to get the inner and outer rings apart.
They looked pretty solid.
I decided to use a proper engineer's bench vise and a press made from an old screwdriver.
My vise is unfortunately at the back of my son's shed, in which rests, and entirely occupies, an old car in the process of being taken apart for spares. I found the shed key and squeezed past the remains of the old Sunbeam Rapier to the bench vise.
I fiddled around and got precisely nowhere using a delicate approach so I just squashed it until it broke.

Unfortunately it broke with a sudden bang into several pieces and all the ball bearings flew into the air and landed in the innards of the partly dismantled Sunbeam. Lost forever.

I looked at the second, identical race. I couldn't afford the time to find a third so this one had to yield the necessary parts.
I squashed it… but this time I placed my fingers either side to lessen the explosive impact as the cast steel shattered. It worked and, when I cupped my hand under the remnants, a few small steel balls dropped in.

Clutching the things firmly I squeezed past the car back to the drizzle and locked up the shed.

The ball bearings from the hard drive were exactly the right size.
I dropped one into the switch on top of the tiny indent spring and very very carefully pressed the parts together until there was a click and a few moments later after inserting the shims, pressing the sections onto the shaft and finally tightening up the longitudinal securing screws the switch looked OK but was a trifle stiff to operate. Slightly slackening the screws reduced the pressure and it worked normally.

I looked at the set of solder tags. I now had to thread 192 pins back through the holes in the printed circuit board.
I didn't feel like tackling this, and anyway as it was then 6pm, I placed it on the bench, turned off the lights and went in. I refuse to work after 6pm unless it's a really interesting job. This wasn't.

Next morning, after toast and coffee, I threaded the 192 pins and soldered them in place. It took ages. It's bad enough inserting the 14 pins of an integrated circuit back through holes only just large enough and half packed with old solder.

Now that the switch was back in place I reassembled the radio. That is, I went as far as screwing all the parts together before I found that the last two assemblies wouldn't fit together.
It's a British-designed radio and the mechanical design is absolutely awful. It's one of those cases where all the bits have to be presented together at about the same time and jiggled. Eventually, after unscrewing the parts for a second time, then reassembling it in an illogical manner, it was back in one piece.

Finally I slid the outer case over the chassis. As I did this I heard a little rattle and what did I find rolling around inside the case? A tiny ball bearing.
I sighed, put it in a plastic bag with the rest of my new collection, and carefully placed the bag in a little drawer marked "24-volt Relays". If I knew where I'd put my labels I would have made a new one but they went missing a few days ago.

Did the radio work?
Yes, it did, but goodness knows for how long before the plastic bits in the switch finally disintegrate totally.

The price was £25 which works out at around £3 per hour.

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