Today started with something I haven’t done in a long time…putting a hairdryer into a video recorder! Why, you might ask…well I was called to install this machine not knowing that it had just been brought in from a cold car. Videos suffer badly from condensation and being brought into a warm room had caused a lot of it to form on the rotating heads. In this condition putting a cassette in results in the tape sticking to…and wrapping itself around the heads. Lucky I checked then, and two minutes with the hairdryer had it in a safe and usable state. A good start to the day then!
The next call, out in Washford, was to an old LG TV, it was an LCD but it was almost as old as the Video I had just been to. It was stuck in standby after being unplugged for a while. It was quite a job to get apart and I found that the standby 5 volts was down to 4.3 volts, the suspect was the decoupling capacitor and so I boxed it up and returned it to my workshop.
Next was a Panasonic 37″ with a pixelating picture, it was proven to not be the aerial because the customer had recorded the very program that was breaking up and it played back perfectly…so they did my job for me, the TV was definitely at fault. Panasonic have a history of dodgy tuner units and it seems this is the problem, so it will be booked into the workshop for attention in a few days.
Back in the workshop I was able to get started on the LG, I replaced the decoupling capacitor, which did indeed read faulty, but it made no difference, next I checked the associated rectifier, this read leaky and was replaced but it still didn’t work. Definitely a capacitor, so I methodically checked the secondary decoupling caps…all checked ok, so onto the primary circuit where several caps were off value and high ESR, but one in particular had an ESR so high it wouldn’t even register on my meter…even though it’s value of 22uf was spot on. So the LG lived again!
None of the faulty capacitors showed any outward sign of failure by the way, so when the ‘YouTube heroes’ say you should look for faulty capacitors bear in mind that very rarely do they actually look faulty.
Next on the bench was a 26″ sony I had collected a few days ago, it was completely dead, not even a standby light. A quick check showed there was no standby voltage leaving the power supply. I had no circuit diagram and so removed the power supply to trace the missing voltage from the connector back to it’s associated circuit. Everything checked out ok and on refitting the panel the standby voltage appeared and the set sprung in to life, a bit worrying as I hadn’t done anything, so I took the panel back out and resoldered any suspect joints I could find, there were a few and on refitting the set worked perfectly, it will now be on test for several days.
The afternoon was just as varied, starting off with a samsung TV stuck on More 4, the banner at the top of the screen would not go and it would not change channels. Luckily I’ve had this a few times and a reset via the service menu sorted it out. My customer was very happy as he’d been told it would not be fixable.
Next job was to put a small TV on a bedroom wall, no dramas here although I think I should have charged more, considering Currys charge £150 plus the bracket!
Then back to Minehead to reset and retune another Panasonic recorder falling foul of the BBC’s red button software, it really is messing them up and at the moment there doesn’t seem to be a complete fix!