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Satellite Workshop 16
The local chip shop owner is Italian. He called me to complain that the receiver I sold him four years ago had gone faulty "under guarantee." Now, I don't know the legal situation in Rome but in Britain the usual guarantee period is 12 months! Anyway, I agreed to call on him to investigate and promised not to charge for the call out.
"It's a verra pecooliar" he told me. "When I walk-a across-a da floor-a da satellite she changes-a channel by herrself!" Now Mario lives in an old thatched cottage and the floorboards creak as you walk. Sure enough, as I approached the JSR3300 receiver, it changed channel before my eyes!
I checked the external connections and removed the batteries from the remote control but tapping the unit still produced erratic behaviour. It had to be a workshop job.
Back on the bench I soon discovered that the connector plugs from the front panel to the main board were no longer making good contact. A squirt of switch cleaner on each plug soon cured the problem.
I earned myself a nice sack of potatoes!
I've had a GRD150 receiver in the workshop for seven weeks and it has driven me almost to tears. The symptom was simply that, after a warm up period of several hours, the decoder on-screen messages would disappear and it would no longer unscramble the pictures.
I replaced every IC on the decoder board before realising that the decoder was actually working but the ASIC was bypassing it and feeding the still-scrambled signal directly to the output sockets. It took several weeks to acquire the ASIC from Germany. I managed to remove the suspect device from beneath the board by using a paint stripper heat gun (I'm not recommending this method!) An hour later I had soldered all 128 pins of the new one but it took another twenty minutes to retouch the dry joints which initially prevented it from working.
Anticipating success, I left the receiver on test while I had a nice hot bath. Upon my return to the workshop, however, I found the darned fault still remained. Finally, I traced the culprit by using freezer spray and a hair dryer (she'll never know!)
A few more weeks passed before the new microcontroller kit arrived from Germany, minus instructions. However, a quick call to a friendly Grundig agent clarified matters and, five minutes later, the GRD150 was finally repaired.
I've repaired a number of Grundig receivers in the past. You need a good working knowledge of the signal paths. Faults do occur in the decoder ICs and, occasionally, the ASIC which handles most of the video and audio routing. In fact this circuit is very similar to the one used by Cambridge in the ARD200 (and clones made for BT, JVC et al.) I've even seen a Grundig receiver which used an ASIC with a Cambridge "ICCS" part number. Some faults are quite obscure. I had one unit which occasionally gave a blank screen only on decoded channels. The cause I traced to a faulty inductor, L11. Not something you look for first of all! My GRD/Minerva Service Manual from Grove Farm Publications (mentioned in a previous issue) has now paid for itself several times over.
A customer posted me an MSS300 which displayed some intermittent faults after about fifteen minutes warm-up time. The screen would show a row of zeros in the top left corner, although the front panel display was not affected. Sometimes a whistle could be heard from the TV loudspeaker and sometimes the audio would disappear entirely.
I've seen similar problems on the MSS500 and they have usually been caused by a bad connection in the microcontroller socket. However, this MSS300 had a masked micro which was soldered to the board.
A call to Pace elicited the suggestion that the audio processor was faulty (hence the sound problems) and was affecting the I2C bus, thereby causing the incorrect graphics display. They were correct, of course, as a new MSP3400 sound processor verified. Of course I knew the answer all the time. I was just testing them.
A small number of ARD200 receivers seems to kill the series 10 Sky card for no reason. The card might last for a week or two then show the "Card Invalid" message. On one which I had in the workshop, simply scraping the black spot off the card cured this intermittent problem (not recommended by Sky). With others, however, the card really is dead. Last week I received a call from a lady in distress. Her fifth Sky card had been invalidated and she had been advised to buy a new receiver. Could her ARD200 be repaired so it would not kill the cards?
I agreed to have a look at the receiver which gave the correct "Expired" message with an old series 07 card and an 08 card. It was with some trepidation that I tried a new series 10 card but that worked perfectly. The customer explained that a new card could last for a week then fail without warning. Now I'm not a card "hacker" and I know nothing about the inner workings of these cards but I tried an experiment. The card receives a supply voltage of 5 volts when it is inserted. There is also provision for increasing the supply to 12.5, 15 or 21 volts, under microprocessor control. However, the 15 and 21 volts lines don't seem to be needed so I inhibited them by soldering together the base and emitter of both Q45 and Q46. These are surface mount transistors which sit directly beneath the card. If the circuit was switching these higher voltages to the card intermittently, this would stop it. Only time will tell if this "cures" the problem. I suspect that "pay per view" may no longer work and advised the customer to save up for a new receiver.
Since the original Cambridge satellite company no longer exists, there is no technical helpline for this product. The SVS200 is a British Telecom "clone" of the ARD200 and I believe that BT spares and technical information are held by Tele Aerial Satellite which is now part of the SKY group. Unfortunately, it does not seem possible to obtain any information about decoder faults so we are left guessing.
Another receiver sold under the BT badge is the SVS300. I suspect this is manufactured in China and is based on a design which has been sold in Europe as the "Houston 1002". It is remarkably similar to some Amstrad models. Recently, a power supply from one arrived in the mail. Another dealer had attempted to fix this unit but without success. Several repair kits had been tried but all resulted in loud bangs. The cause was not hard to find. Someone had removed the switching transistor complete with heatsink and copper land. On replacing it they had failed to notice that the heatsink land is required for continuity between two halves of the circuit.
I repaired the broken track and fitted another complete kit, in case any of the components had been degraded by previous bangs. The supply now tried to work but "ticked." It took ages to trace the fault to a combination of faulty transformer and a shorted 2SB1143 inside the little metal can.
When Astra 1D began transmissions it was possible to make a little profit by selling Global "ADX" frequency convertors. All that changed when SKY offered these units to subscribers for just 9.99. However, we independents are left to sort out the ensuing problems since the information leaflet supplied is not very comprehensive.
Last night I was having a quiet pint when my neighbour approached me with an ADX in his hand.
"Do us a favour, Jack? Can't get this sod to work. Come across and fix it fer us termorra?" With that, he plonked the unit into my hand and left. I was so bemused that I accidentally paid for the round!
This morning I got my own back by waking my neighbour at 8 am. His receiver is a Pace SS9210. This is a two-input receiver and the tuner uses IEC connectors instead of "F" connectors. I made a short adaptor lead with CT100 coaxial cable, making sure that the IEC plug was soldered. With a TV aerial you can get away with simply poking the inner wire into the plug but an LNB requires current so the connection must be good.
Once I'd demonstrated the working of the unit and explained that "Sky Movies Gold" had to be tuned 500MHz higher than its listed frequency, my neighbour was a happy man; so happy, in fact, that he gave me 50p.
Thank you, SKY. Without you I'd be out of business!
The following might be useful as a filler
A lot of my email comes from people asking about upgrades. Here is a brief look at what is possible and what is not:
500 channels in an MSS500 or MSS1000 (as in the latest versions with internal positioner). Upgrading is possible but a kit is NOT available and is unlikely to be made available because of the large number of variants. However, Pace might be able to upgrade your receiver at their factory if it is a very recent model. Be sure to tell them the complete serial number and model number if you enquire.
Internal positioner in an MSS500 or MS1000 . This is not available as a kit but you can send your receiver to Pace for upgrade. (Not any longer. Pace stopped doing this).
Internal polariser board in MSS models . Not available.
Internal 22kHz tone generator . Available from SatCure.
Videocrypt AND Eurocrypt/D2Mac decoders inside one receiver . Not available.
199 channels and a favourite channel menu. A kit is available from SatCure to upgrade your PRD800. Not approved by Pace.
J17 deemphasis with wide band audio . A kit from SatCure improves distorted audio on foreign channels. Not approved by Pace. Comes with comprehensive instructions but the J17 kit in particular is not easy to fit, due to the number of fiddly surface mount components required.
Enhanced menu options . This kit IS approved includes a new microcontroller to give you a choice of LNB local oscillator frequencies. Most tuners will cope but you might also need to buy a 2GHz tuner if you want the maximum tuning range.
External switch controlled by satellite number . A unit is available from SFM Engineering (01407 742436) and apparently works with any Pace model from the SS9000 onwards. You select a satellite position number in each channel menu and the switch selects one of five outputs. Some or all outputs can be used to control an LNB switch, 22kHz tone generator, Christmas Tree lights or whatever!
Computer interface to control Pace receivers . Not possible, however an interface with Windows software is available from Kesh Electrics (013656-31449). This interface allows you to download the channel information to your PC, rearrange it as you wish, then upload it back to the receiver. It could be useful to a dealer who wants customised programming for a batch of receivers but, at £199, it's a little expensive for the home user.