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Satellite Workshop 17
The local butcher brought me his brand new MSS100 which looked
horribly bent and twisted. This is the model which, everyone says,
looks like a pair of bathroom scales. Apparently he had bought it to
replace his aging SRX200 but he could get no TV pictures after
connecting it. (This turned out to be because the RF connector centre
pin had been pushed right in by the plug). Anyway, he'd decided to
bring it to me but had stopped at the bathroom to answer the call of
nature. His wife had just joined the local weight watchers and chose
that moment to enter the bathroom to weigh herself and....
some things are inevitable, really! Needless to say, I couldn't do much with the receiver after it had been subjected to twenty stone of butcher's wife.
Have you noticed that it's always the very last component you replace which cures a fault! So it was with my wife's sister's daughter's receiver. What made it worse was that, to someone who has replaced the little tuner capacitor in thousands of Hitachi tuners in Pace receivers, it should have been blindingly obvious! The symptom was horizontal lines on the screen which gradually resolved into a very poor quality picture as the unit warmed up. It was only after replacing every electrolytic on the main board that I thought about the tuner. I replaced the 10 F and the 3 3F but it was the 100 F, of course. Next time, I shall replace the last one first!
The Oritron D2Mac Eurocrypt decoder has been sold under other names such as "Dixi", "Aegir" and "Lenco". A characteristic of this model is that it has a heatsink at the right hand side which becomes incredibly hot. The unit is not easy to work on, which is why I think of it, always, as the "Horrortron."
The one which arrived by post from the Midlands was no exception. The symptom was that it did not respond to the remote control. (All Oritrons suffer from this to some extent. Usually, you have to stand at least two metres away to get reliable operation of the handset. However, this one would not respond at all). It remain ON but stubbornly refused to give anything other than a blank raster. A phone call to my friend at Satfix revealed the possibility that the DMA2286 might be at fault. This chip, of course, was soldered directly to the board. It is square with at least 64 "J" shaped legs. These curl beneath the IC and there is almost NO possibility of removing it with a soldering iron (although one enterprising dealer told me he uses a pin to lift each leg in turn!)
I decided there was nothing to lose and placed a sheet of aluminium foil over the board. Pressing down firmly, I cut a square hole to expose the suspect chip and applied heat from my trusty paint-stripper. A quick flick with my penknife had the chip off that board in three seconds. It also had me hopping round the workshop, sucking my burned fingers!
Luckily, the board had survived my treatment and the copper tracks were intact. I positioned the new (expensive!) I.C. and soldered each leg in turn with 0.4mm solder and my finest Weller tip. Amazingly, the decoder worked! However, I definitely don't recommend that you try this yourself. I have practised on dozens of scrap boards and my success rate is still depressingly low. There is also the safety aspect to consider.
When I used to repair CB radios I was never surprised to find them full of straw because the farmers used them in their tractors. However, the mind boggles when confronted by a satellite receiver which is full of straw! Lying in the hay and watching the Sky takes on a whole new meaning.
Needless to say, the internal insulation had done this particular receiver no good at all. The red and green LEDs flashed simultaneously from the moment I applied mains power. Usually, this is a symptom of low LNB voltage so I removed the detection diode, D4, but the fault persisted. The voltage on the detection pin 8 of the microprocessor was 5 volts. If the LEDs flash even with pin 8 high, this usually indicates a faulty processor. Replacing it had no effect. I suspected a data line fault and disconnected the SDA pin of the tuner. This stopped the lights from flashing but replacing the tuner had no effect! After some head scratching and peering at the circuit diagram, I traced the fault to an open circuit 47k resistor which connects the SDA line to the EEprom.
The puzzle of the straw was solved when the owner of the receiver came to collect it. He'd sent it to a repair shop which had been unable to fix it but had returned it packed in straw. Well, this is farming country.
People still write the most curt messages to me! Here's a typical one. This is the complete message, as it arrived, apart from his name:
"PRD900. Problem is as follows. Sound okay but after 10 minutes Picture flashes on and off intermmitently (sic) leaving black raster. Thanks in anticipation."
"What's wrong with that?" I hear you say. What's wrong is this: imagine you are writing to your bank manager for an interest-free loan. Do you think you would get one with a letter like this? There's no "Dear Sir"; no introduction, no mention of this guy's technical ability, soldering skills, available equipment. How do I know what he wants? He doesn't mention the serial number of the receiver, age of the equipment, history of the fault, method of connection to the TV/VCR, tests he's carried out. Worst of all, he doesn't mention "Television" magazine so there's no way he's getting free advice from me! (The fault cause is probably Q105 but don't tell him!) In fact I was unable to reply because he gave no return address!
So when you send e-mail to me, tell me who you are, what your abilities are, where you found my address and give a complete description of the equipment, symptoms, fault history. It's also fun to learn about your interests, hobbies and have a general chit-chat! Maybe it's because I'm a Yorkshireman but I simply don't enjoy replying to a message which looks like a telegram. Finally, do type your return address. I reply to all messages. If you get no reply it's always because you gave an incorrect return address or none at all.
It occurs to me that I have never mentioned satellite signal meters. Since these meters cost more than the average satellite receiver, you can charge a goodly sum for the repair! So, here's what I know!
The Altai SM-01 is made with various brand names, including Manhattan. It suffers from a number of faults but the most common are:
1. Signal meter reads backwards when the unit is switched on. Simply replace the 1k trimmer potentiometer "SFR1" and adjust it for zero meter reading. The trimmer fitted as standard seems to be under rated and melts!
2. No LNB power output. Check inductor "L5". This is 4 7H and tends to go open circuit.
The "Satfinder" low-cost meters seem to suffer from some kind of burn-out if they are left switched on until the batteries are almost discharged. I've never bothered to look inside to find the source of the smoke since Satfinder UK offer such a quick, low-cost repair service. Ring them on 01491 573390 for information.
The now obsolete Maspro LC2E meter has always been the favourite meter of time-served installers. Its main problem is that copper wire strands are to be found in the nut at the rear of the threaded input connector. The result is an intermittent short circuit which makes the front panel LED go out. Simply unscrew the connector behind the panel and blow out the offending strands. If you have any other problems, I've found that Ali and Ishar at Satellite Services provide a good repair service. Telephone 0181 961 4662.
For Promax meter repairs, contact Promax on 01727 832266.
The clips which secure Pace front panels take the form of plastic tabs which, unsurprisingly, can become brittle when exposed to heat for a number of years. I've seen all sorts of bodged repairs when they snap off, ranging from watchmaker's screws holding a bridging piece, to a strip cut from a leather belt superglued in place!
For some time I've replaced broken plastic tags simply by using a soldering iron to melt a paper clip into the remaining plastic. Tape the base and front panel securely together and fit the paper clip into place with a screw. Press the tip of your soldering iron firmly down on the paper clip where it rests on the remaining section of the plastic tag. I've never had one break after this repair.