A shop some twenty miles away occasionally sends me receivers to
repair. They use a local chap to collect and deliver so I try to
carry out the repair while he waits. In return, he goes in the
kitchen and makes me a cup of tea.
The label on an MSS1000 that he brought me annonunced "PSU
ticks."
I'm very wary about ticking power supplies. That's usually a sign
that it's going to make a very loud noise the next time someone
connects the mains power. I like to make sure that I am not that
someone, so my first move is to replace all the electrolytic
capacitors in the power supply primary section.
Once this was done, the receiver worked perfectly but, for good
measure, I replaced the secondary electrolytics as well. Some of
these are the Ultra-low ESR type so I opened a "Relkit 10" for safety
sake. We finished our cups of tea while watching "Sky News" (it's a
sad life) then Dave went on his way.
A week later he was back. "Still ticking", he announced.
"But it was working - you saw it yourself!"
"Yep, but the customer didn't. He collected it from the shop and an
hour later he brought it back and it's still ticking."
I removed the cover. There was no sign of a problem so I plugged it
in. The power supply could be heard ticking, slowly. Damn!
I dismantled the whole unit and inspected it. No obvious short
circuits but the secondary F2A fuse that protects the 5 volt supply
had melted. I was doubtful about fitting another fuse without knowing
the cause but, eventually, I decided to take the risk. The receiver
worked perfectly. I was puzzled but I replaced the Dolby Audio board
to see if the additional load would make the fuse melt. It didn't, so
I reassembled everything and reconnected the mains. There was a faint
ticking sound from within....
I suspected the Dolby board. Call it intuition if you like but I'd
never seen this symptom previously. Usually that fuse melts only when
there's a serious fault that causes the power supply voltages to go
extremely high. I tried a spare Dolby board and the receiver was
fine. I replaced the original Dolby board and it was fine. But the
instant I screwed it to the rear panel, the fuse melted. Here was the
clue!
I removed the black plastic insulating cover from the rear of the
Dolby board and looked at it closely. There was a factory-fitted
ceramic disc capacitor soldered to the back of the Dolby board. The
insulating sleeve on one of its wires was a fraction too short. It
appeared that, each time I tightened the screws in the rear panel,
that capacitor wire touched the leg of a surface mount transistor.
That's another hour's work that I won't get paid for.
Sky Digibox
So far I've had very little to do with these digital satellite
receivers. Oh, I went on the Sky training course and took the test
but, as I do very little installation work, it was of very little to
interest me. Pace very kindly gave me a repair course but, as most
Sky digital receivers are still in warranty, I have not had any for
repair. Yesterday that all changed.
A local installer brought me one to inspect. I hasten to add that it
was not made by Pace. He had installed it for a customer who had used
it for a month then reported an intermittent fault. The box had duly
been returned to the manufacturer whose service department returned
it untouched, with a scribbled note that there was "water damage" and
it would cost 380 to repair!
There was certainly corrosion inside the receiver. The amount was
tiny and could have been introduced from a polish spray or a single
raindrop. The puzzling thing was that the receiver had been taken
straight from its box and installed inside a cabinet, so how had
moisture got inside? It was near the centre of the board and had
definitely not come down any cable. I began to think that it could
easily have been caused by careless use of a cleaning spray or a
worker's sneeze in the factory. The modem board, power supply board
and other parts such as tuner module were undamaged. All it needed
was a mother board which probably costs less than 200 to manufacture.
I can't understand where 380 price came from. Apart from that, it
seems to me that a company ought to give a customer the benefit of
the doubt in a case like this and either repair the unit at no cost
or at least keep the cost to a minimum.
Anyway, it's interesting to know the cost of repair for a "free"
Digibox. I think I'll "prepare the ground" and put in a weekly
newspaper advert announcing "digital repairs from 295."