Satellite Workshop 03
I was at the top of a ladder adjusting the alignment of an 80cm dish
when I noticed two men performing a similar feat across the two
gardens. The odd thing was that, whereas I was working on a south
facing wall, they had fixed their dish to a north facing one!
"Can we borrow your meter, mate?" shouted the smaller of the two. He
was steadying the ladder for the burly bloke at the top.
"Not much point, really," I replied and carried on tightening my
bolts.
"Why's that then?" enquired the larger man. "We've been at this for
two hours but I can't get a picture. I measured the LNB with my
multimeter and it's got two volts so it must be all right. Just let
me borrow your meter a minute to finish off."
I was not about to indulge in a hollering match so I descended the
ladder and walked towards the fence. The smaller guy let go of the
ladder and ran towards me. This was a mistake because his chubby chum
had both hands on the dish at the time. The ladder tilted sideways
and the occupant was left hanging from the wall bracket! I decided to
make my exit and headed for the house to finish tuning the receiver.
There are times when it's prudent to follow a course of
non-involvement and this was one of them.
Inside the house I showed the owner how to tune in the new Astra 1D
channels. He had just moved here and had brought his PRD900 with him.
Luckily, it had a 2GHz tuner and was able to cope with the signals
from an Enhanced LNB. The problem was to make the owner understand
that all of the channel frequencies on screen would be 250 higher
than those listed.
To further complicate matters, I had used his old Standard LNB on the
same dish to receive Eutelsat at 13 east. For these channels I had to
select the second input and the frequencies were correct. He really
didn't understand and wanted me to tune every single channel for him,
including around 30 radio channels. Frankly, I was impressed by his
knowledge. Not many people know that BBC Radio 1 to 5 are broadcast
by Astra, let alone the BBC World service.
"It's going to cost you another thirty five pounds if I have to squat
here for the next hour to tune in all the channels," I pointed out.
"It would be better if you'd let me take it back to the workshop to
upgrade the software."
He was clearly distracted, at this point, and was staring at the
blank screen which said "Radio."
"What's that?" he asked.
"That's a blank screen which says 'Radio,'" I replied, helpfully.
"Yes but there's a line moving across it!"
I stared at the screen and, sure enough, there was a vertical band
sweeping periodically from right to left. The customer grabbed the
remote control and began to flick through the channels, staring
intently at the screen.
"There it is again!" he shouted, pausing at the 'Bravo' Test
picture.
He was right, I had to admit, but tried to pacify him, saying that it
was very slight interference which wouldn't show up when he was
watching a film.
"It's not right," he observed, "and it didn't do that at the old
house. It must be the new dish."
I was convinced that it was a receiver fault and suggested that I
should take it back to the workshop, fix this fault and fit the
latest microprocessor which would be compatible with his Enhanced
LNB. Finally, he agreed when his wife strolled in and asked,
innocently, "have you asked the technician about that picture
interference?"
Back at the workshop I had the cover off his receiver and it was
clear that it had suffered overheating at some time during its life.
The interference line turned out to be a leaky C96 which, according
to a Pace bulletin, should be replaced with a 1 F multilayer ceramic.
Not the sort of thing you have lying about so I fitted a
non-polarised electrolytic as a temporary cure and made a note to
order the correct part from Davenham Satellites.
There was also a faint but audible whine on every channel. This, I
found, was C278 according to my "Satellite Secrets" book. This 2200 F
sits close to a 12 volt regulator with a heatsink and simmers gently.
For good measure, I replaced C5, C7 and C8 in the power supply since
Pace recommend upgrading them to 105 C rated devices.
Finally, I fitted the latest microprocessor kit from Davenham
Satellites. The pin-out is slightly different from the early version
and I followed the instructions to cut a track and add a link wire.
There was also a tiny surface mount resistor to change but, luckily,
the receiver already had the later value fitted so I didn't have to
hunt for my tweezers and magnifying glass!
The serial number label said that this was a 2GHz version and the
part code stamped on top of the tuner included 'G77' which confirmed
it. I did a quick check to make sure that everything worked, and that
the menu now included the 9.75GHz LNB option, before screwing it all
back together. The plastic rivets were rock solid--a sure sign that
the receiver had become too hot. I would have to make sure that the
customer did not put it back inside his so-called Hi-Fi cabinet.