Broadcast receiver quirk

[Geoff S]

We have a fancy DB radio in the kitchen, which is controlled (like many things) with a remote control.  Earlier this week it began switching itself off randomly several times an hour. Switching it back on with the remote worked OK but it quickly got old.  As a teenager back in the 1950s I used to repair radios for a living but they were valve radios (transistors were very much in their infancy and the only semiconductors were diodes) so I was frustrated that I hadn't a clue how to even attempt a repair.

 

The only recent thing we'd done was that my wife had replaced the batteries in the remote. I'd bought a load of AAA batteries from a formerly reliable supplier a couple of years ago and many of them were DOA but I'd saved the ones that apparently checked OK on my volt meter.  My wife had used a couple of them.  In desperation she swapped the batteries again for some new Duracells.  The problem has vanished.

 

I can only assume the remote was randomly sending a switch-off signal while, at the same time, apparently working correctly in every other respect. Why, I have no idea.  There's a lot to be said for a simple on/off toggle switch and an analogue tuning dial with pointer/tuning capacitor drive cord and all 🙂 At least I knew how to fix them!

[J D 8]

Well you did fix it, found the problem and sorted with new batts, or at least your wife did.👏

Many modern vehicles are the same, year before my cars alternator quit but car did not tell me of the problem until voltage was so low systems started shutting down, power steering first to go. then into limp mode. Nearly made it home before it shut down.

   My old Land Rover has a ignition charge warning light that comes on straight away if battery is not being charge and being a mechanical diesel engine would keep going even with a nearly dead battery.

[Cuban8]

This illustrates how things have changed with regard to electrical/electronic equipment and repairs. Firstly, the vast majority of modern products are incredibly reliable and manufactured to standards that could only be dreamed of a few decades ago (I'd hazard a guess that your modern TV hasn't missed a beat since you bought it). Volume manufacture means machine assembly, cutting out the human error factor and that coupled with surface mount tech means tiny devices that can be manufactured at speed with repeatable high quality.

A double edged sword..........cheap and reliable consumer products but with little scope for economical repair. Far fewer costly technicians needed with the knowledge to make repairs to component level - so we get the board changers who might return stuff to a central hub for the more complex repairs, but only on very high end stuff where the cost might be worthwhile. Cheap mass produced TVs, radios and similar items are usually simply not worth the cost of professional repair except where a fix can be made quickly and without the need for very specialist knowledge.

I used to work for a firm that provided monitoring equipment to the power industry and I repaired very expensive and specialist kit to component level. I might take a day or two to track down a fault after a lengthy time dismantling the kit and putting it back together, quite apart from  repairing the fault in the first place.  That's fine on a bit of equipment worth tens of thousands of pounds and I believe repairs were usually billed at around £500 to as much as several grand depending on what was done - mid 1990's prices. Goodness knows what the cost would be now.

[Peter Christy]

I've just had a similar problem that I eventually traced to the battery!

 

I've been upgrading the RF module in my single-stick Ace MicroPro from a FrSky XJT to the newer XHT. The transmitter had been exhibiting slight "jitter" for a while, noticeable as the servos constantly "ticking". I had been blaming the module, as the pulse train looked fine on a 'scope until the module was connected.

 

Changing the module didn't help! There seemed to be a lot of stray RF coming back down the signal leads, so I tried extra decoupling capacitors and ferrite clamps, but nothing worked.

 

Eventually, in desperation, I changed the battery. Instant cure!

 

Both packs were 3-cell LiFe, both showed the same voltage. The only difference was the age. I can only assume that the internal resistance of the older pack had increased over time. However, I find it hard to believe that it would have increased beyond the expected level of the NiXX cells for which it was originally designed!

 

Another of life's great mysteries!

 

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Pete