This receiver came in with the usual symptoms associated with old
electrolytics. I replaced all of those which come in "RELKIT 2" and
the receiver worked OK.
However, when it had cooled down and I tested it again (as you all
do, I'm sure) before returning it to the customer, the darned picture
was just a mess of coloured lines. It was a strange effect that
looked like a decoder fault - except it did it without the decoder
fitted! It was as if each line had been chopped into two or three
sections then shifted left or right (not rotated). Hard to describe a
mess of coloured lines in words.
This effect would clear after a minute or so and the picture would
jump now and again or show horizontal "pulling" or "cogging" like
one-directional "pin cushion" distortion. All signs of sync problems
of course.
It took a lot of freezer and patience to trace the cause to C184,
100uF/16v next to the TEA2029C sync separator I.C.
"Have a look at this?"
Huh? The gent must have been seven feet tall and I found myself
looking at his navel; but that wasn't what he was indicating. In his
banana-like fingers he held what might have been an Amstrad satellite
receiver. I say "might have been" because the cover showed signs of
distortion. In fact "melted" might be an accurate description.
"What was it, erm I mean what model is it?"
"Chernobyl" he replied. "A Fidelity SRD750, Chernobyl class."
"Hmm, I see what you mean. Nice warm Hi-Fi cabinet?"
"Yep."
"On top of a video."
"Yep."
"It's pizzafied."
"Yep, thought so, thanks" and he turned towards the door..
"Ah, just a moment! Can I interest you in a nice reliable refurbished
Pace PRD800?"
"Nah. I can get Sky to install a complete new system for fifty
quid."
"New, eh. What model?"
"Not sure SVS-something or other, maybe?"
"Ah. See you in thirteen months. Bye."
He grinned, stooped in the doorway, and walked out.
I confess that this environmentally-conscious society worries me. On
the one hand we sort meticulously through bottles, cans and
newspapers for recycling in the Saturday supermarket bottle-bank
ritual while, on the other hand, happily disposing of electronic
equipment every year or two to replace it with newer units which,
generally, are even less reliable than the previous ones.
With the advent of digital MPEG systems I can see this going even
further so that, if it's not a simple power supply fault, we shall be
forced to discard the "mother board" and replace it with another. The
possibility of repairing will not even exist except for those
well-funded workshops that can afford the equipment. Having said
that, it might actually be good for the repair industry. The proposed
digital satellite receiver for the UK is likely to have a build cost
of around 300. It might be subsidised to an artificial 199 but the
actual replacement cost could be a lot higher. It will be interesting
to see if Sky can provide a replacement for "fifty quid". Maybe the
public perception of the value of equipment could change? (Maybe it
will snow blue snow).
(picture supplied on floppy disc)
I don't see many of these but two arrived in the same week. One
displayed a permanent "No signal" message on every channel and the
other was dead. The "No Signal" fault was caused by the tuner module
- it's easy when you have two identical receivers to compare! So now
I was left with a dead receiver requiring a replacement tuner to
replace the one that I'd "borrowed". I fixed the dead power supply
using SATKIT 25, ordered from SatCure's Internet web site at
www.netcentral.co.uk/satcure/ but I still need a tuner. The importers
want a silly price so I'm looking for an alternative. The Sharp tuner
from an early Pace PRD800 is almost identical but has three pins less
and doesn't work in the ST-8. My next step is to send the faulty
tuner to MCES in Manchester for repair.
This is the twin-input version of the GRD150 and also has a vacuum
fluorescent display. The customer reported that the receiver was
"dead" but, as is often the case, it was the customer's brain which
was dead. The receiver worked perfectly but the display didn't light
up. Thanks to a tip-off from Nigel Goodwin (WWW.LPILSLEY.DEMON.CO.UK)
I was able to fix the problem in just ten minutes by replacing the
10uF electrolytics on the display panel.
I could smell the "hops" aftershave even before the door opened.
"Morning, Alfie! How's the head?"
Our friendly postman simply grunted and banged the parcel down on the
floor. Clearly, he'd been propping up the bar last night, as usual.
He trudged off without a word, leaving behind a sweet-sour aroma that
spoke of heavy exertion, curry and too many liquid lunches. I left
the door open.
Inside the box was another box, carefully packed like a glass
ornament. Inside that was more packing and nestling in the middle was
an SRD510. I was pleased that this particular customer had taken note
of my suggestions for packaging. All too often I receive parcels
which rattle and have to be "returned to sender" unopened.
A label on the receiver stated the owner's name, address and
telephone numbers. Another label gave the fault report which,
although brief, was adequate for diagnosis:
"After one to two hours from cold start, a squealing noise comes from
the left side, red and green LEDs flash together, picture changes to
a blank screen then everything goes off. Sometimes comes back on by
itself."
I recognised these symptoms as being caused by a poor connection
between power supply and main board. The connector is not very well
designed and oxidation occurs. The result is usually a high
resistance connection which can often be cured simply by soldering in
a wire to bypass the zero volt connection and cleaning the connector.
I use WD-40 but any proprietory switch cleaner will do. This problem
can also prevent the receiver from responding to the remote control -
a disaster for a receiver with no front panel controls!
This model has been around for several years and the electrolytics
become "tired" so, as a precaution, I installed all the parts from
the Reliability kit (Relkit 3). In addition, I replaced R9 - a 470R
resistor just in front of the decoder video connector - since it was
hidden by glue that had turned black. My experience is that this type
of petroleum-based glue becomes both conductive and corrosive causing
open-circuit resistors and current leakage paths elsewhere. The
C-Band switch also goes open-circuit so I replaced that with a single
wire link.
My mail box is always full of enquiries from readers with picture
faults and many of these problems arise from the use of incorrect
Scart leads. A Scart lead used with an external D2Mac decoder needs
to be as short as possible. Sometimes it's a good idea to pay the
extra and buy the best lead you can find from a Hi-Fi shop. The video
wires should be screened individually.
A Scart lead used to connect a receiver to a television should have
the minimum number of wires possible. A nine-wire lead is usually
adequate but even then you should disconnect the wire at pin 19 (TV
end only) otherwise ghosting or patterning can occur if the TV is
sending a signal out on that wire.
The on-screen channel names and clear (not blue screen) menus were
drifting from right to left on this receiver. I replaced the most
obvious cause - the PTV110 - and this fixed it but now I got a "Card
Invalid" message on inserting the Sky card. I checked and there were
no clock pulses reaching the card so the card supply voltage,Vcc,
wouldn't stay high. Since the clock pulses are supposed to come from
the PTV110 I replaced it again. This time the card worked and I got
pictures but there were large black "sparklies" on all card channels
but not Sky News or German channels or QVC. The "sparklies" danced
around on the left 3/4 of the picture. Right 1/4 of picture was free
from dots. Yes, it was the PTV110 again! Since this I.C. is
officially not available as a spare part I was taking used ones out
of other "unrepairable" receivers. Finally, I found a good one which
resolved all the problems.
If you are Greek or if you are interested in digital satellite
systems, take a look at a new web site at
http://www.netcentral.co.uk/satscene/
This is run by Mike Hancox who has proved helpful in the past when
I've had installation problems. Mike offers an email "helpline" for
installation as I do for repair problems.