When a repair shop some distance away phoned me for advice on an
NEC receiver with "no audio" I told them, sadly, that I could not
help.
"I may be old, but I'm not THAT old." I pointed out. "It was obsolete
seven years ago and NEC pulled out of the satellite business so spare
parts and service information are probably unavailable."
"So what do I tell my customer?"
(It amazes me how often I get asked this question! Why are these
people in business if they can't speak intelligently to the general
public?) I gave my usual, joking, reply:
"Tell him to chuck it in the bin."
"He'll kill me! He says he paid five hundred pounds for it, new."
"Did he buy it from you?"
"No."
"Fine, so tell him you'll get it fixed for 499 and bring it to
me."
The phone line went very dead. Some people can't take a joke. I would
have done it for a bit less than that. Anyway, I carried on working
for half an hour then the phone rang again. I noticed that the area
code was the same.
"I've got an NEC 4012 with no audio and I wonder if you can help
me?"
Oh, boy! He'd given the customer my number. I tried to explain the
merits of the new Sky digital system but he wasn't interested.
Eventually, against my better judgement, I agreed to have a look at
the receiver. It was an hour's drive so he agreed to bring it to me
and leave it for however long it needed.
On the bench the receiver worked perfectly so I left it on "soak"
while I went out to deliver a tired SRD510 back to a shop. On my
return I found that the 4012 was hissing to itself and no amount of
button pressing would bring back the sound. However, when I gave what
I guessed was the audio circuit a good dose of freezer spray then
switched the receiver off and on, the sound came back. With the help
of the famous hairdryer (she bought a new one) I traced the cause to
a Sony CX-7925B. Unable to find this listed in any catalogue, I
fitted a miniature cooling fan above it and phoned the customer with
the news. He was delighted to get the receiver back "for the match"
but still wanted it fixed "properly". I promised to locate a CX-7925B
and he collected the receiver to put back on top of his VCR in its
nice warm cabinet (I warned him but he wouldn't listen).
To cut an already long story shorter, I discovered that our very own
Grandata stock this I.C. and it arrived next day. The customer's
invoice should be slightly less than 499, (but not much less).
Now that Sky Digital satellite transmissions are with us, I'm getting
a lot of people asking me why their picture and sound disappear in
heavy rain while the analogue picture simply used to go a little
"sparkly". The simple answer is that digital tends to be an "all or
nothing" system. If the installation is not perfect then poor signal
and/or cross-polar interference can cause drop-out. The solution is
to make sure that the highest quality cable has been used and that
the dish is accurately aligned and not distorted. In addition, the
LNB "skew" or rotational angle is very critical and ought to be
checked with a spectrum analyser, although a rough check can be made
with a signal strength meter equipped with a 22kHz oscillator that
will switch the Universal LNB to "high band" (10.60 GHz local
oscillator frequency).
Recently, a local installer asked me if I could add a 22kHz
oscillator to his Manhattan signal meter. This wasn't difficult and I
achieved it simply by fitting a 22kHz tone board from SatCure* inside
the meter, with a switch to bypass it. It's important to insert the
tone board in series with the dc voltage feed and NOT in line with
the coaxial signal feed. A normal satellite signal strength meter
designed for analogue signals will read 3 to 4 dB low on digital
signals because it sees peak signal level. Since digital
transmissions have a more even energy spread across the band, the
peak reading is lower. This doesn't matter but you should be aware of
it. The Sky Digibox gives bar graph indications of signal strength
and of error rate in the Installation Menu. There's also a "Lock"
indication which should state "OK". If it doesn't then the error rate
is too high and the installation needs to be checked thoroughly.
*Box insert if you wish: 22kHz tone board from SatCure can be fitted
inside most satellite receivers and signal meters. State make/model.
Price 9.95 plus 2.50 P&P. SatCure, PO Box 12, Sandbach, CW11
1XA.
When Wossname from up Church Street waddled into the workshop and
presented me with a 90 channel Pace SS9200 I feared the worst. Ever
since he bought a copy of the first "Satellite Repair Manual" he's
considered himself a first class repairman. That wouldn't be so bad
except that he brings me the ones he's messed up and expects me to
fix them while he points out what I'm doing wrong!
"Blank screen" he said. "Replaced tuner as per page 77 but no better.
Must be the decoder chip as per page 83 but I don't have one. Bung
one in for me, there's a good chap. I'll just hold this solder for
you."
I pushed his helpful hand away and checked the video output from each
socket. There was the normal flickering picture from the decoder
scart socket but the TV and VCR scart sockets produced no output at
all on any channel. I checked for sync signals going from the
TEA2029C sync separator I.C. to the decoder board connector and found
none. Replacing U6 cured the fault.
"Oh, that's not in the book!" remarked Wossname. I grinned and handed
him the receiver together with his change.
"A quid!" he exclaimed. "Is that all the change I get?"