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Satellite Workshop 19
Sometimes I see attempts to repair which are quite beyond belief. A good example arrived in a Range Rover and was carried gently into my workshop by a portly gentleman in tweeds with a big dog. He told me that his MSS1000 had "died" and the local repair shop had failed to fix it after six weeks. He had finally managed to snatch it back after a long argument which ended when his German Shepherd lost her patience because she was hungry.
I didn't ask for the gory details but remained behind the counter, keeping good English oak between me and the bitch. I promised to do my best and the animal towed her rotund master back to his vehicle.
Inside, the MSS1000 was a mess. The power supply had been "repaired" but not with the proper kit. The electrolytics looked under rated to me but I left them alone because they were sticking proud like mushrooms and I didn't want to risk more damage to the tracks.
The display panel was amazing. It had been snapped into two and then somebody had soldered about forty wires across in a futile attempt to repair it. I replaced it with a new panel which I had in stock. (Yes, honestly. I keep one for each model, mainly for testing purposes, because the display panel holds a second microprocessor which must "talk" to the main board processor for the unit to work). The panel is flimsy and tricky to fit but Pace, with excellent foresight, have devoted a page of the service manual to sketches and explanation of the procedure. It's quite easy when you read this.
The receiver sprang to life when mains was applied and functioned perfectly, although the pictures were a little streaky. I decided to leave it at that because the panel alone costs over forty pounds. I offered to upgrade the electrolytics if the owner would pay extra but he declined on the grounds that he'd already paid the last "engineer" for an "estimate" and was short of funds.
No sooner had the new stock replacement display panel arrived than a shop sent me an MSS500 for repair. The fault report said (helpfully) "dead." Inside, someone had fitted a power supply repair kit quite neatly and the dc voltages were all correct. However, the receiver did not function. Closer inspection revealed that the display panel had melted copper tracks! Clearly, the original power supply fault had resulted in more widespread damage. However, the replacement display panel provided a complete cure and the receiver worked perfectly. This was a rather expensive "power supply" repair but I've seen a few of these receivers which had also destroyed the tuner, microprocessor, audio processor and decoder chips to boot, so this owner was lucky. The very same day, another MSS500 arrived. I was praying that it didn't need a display panel! Luckily, the fault was a whistling power supply and a lack of decoder messages. The whistling was cured by resoldering the large 1k ceramic resistor R7 which had dry joints and by replacing every electrolytic capacitor in the power supply area. This also cured severe streaking on the pictures but there were still no decoder messages. On checking the Installation Menu, I discovered that the contrast was set at its maximum value of "8". Reducing it to the correct value of "4" produced very dull pictures indeed. At this stage I decided to switch on my "scope" and to trace the video path with the aid of the Pace service manual. It took about ten minutes to discover that surface mount transistor Q58 was faulty. A new BC856B effected an immediate cure of the contrast problem and the decoder messages also reappeared. Note that other transistors in this area cause problems. I had a report from Holland that Q62 (BC846B) can fail.
Some Satellite "Installers" seem to be lacking any sort of formal training. In fact some appear incapable even of reading the User Instructions. An amusing example was one chappie who sent me an SR-800 "under warranty." He thought that I'd repaired it for him about 9 months previously. I hadn't, but that's another story. His complaint was "No channel display on front panel." For those of you not familiar with this model, I should explain that it does not have a number display!
I returned the unit with a curt note and an invoice for carriage. Blow me if it didn't come bouncing back the following week with a label that read "U/G. Picture still too bright." I adjusted the video deviation in the menu from 16 to 21 MHz which is best for Astra. This made the picture look less bright. Now I'm awaiting payment of my proforma invoice before I ship the receiver back again. I may have to charge for storage, too!
A local installer pleaded with me for help with a Pace Apollo. His customer was complaining of interference on both terrestrial and satellite channels and he had "tried everything." The unit produced excellent pictures in the workshop so I agreed to go with him to the customer's house but only after he accepted my normal rate of 1 per minute.
"That doesn't worry me. You'll have it sorted in five minutes!" he assured me. My charge includes driving time but I decided not to mention that until we'd completed the forty mile round trip.
Upon arrival, I could see the interference immediately. It was a ghost of a picture in the background of the terrestrial picture. I advised my friend to replace the standard 10GHz LNB with an "Enhanced" one which has a local oscillator of 9.75GHz. That would shift the satellite channels another 250MHz higher, out of range of the terrestrial signals. I suggested that he might also move the aerial cable away from the LNB cable since the two runs were actually touching.
The interference on the satellite channels disappeared when I removed the aerial plug from the receiver. Fitting it back with a 6dB attenuator got rid of most of the patterning on the picture. Moving the two cables apart would surely clean up the rest.
A week later the installer confirmed that my diagnosis had been correct as he begrudgingly paid me. I still don't understand why he needed me to tell him how to do his job. This was simple stuff. How on earth does he cope with multi-point distribution systems?
I thought the pretty girl was bringing me her bathroom scales to repair but, actually, it was a Pace MSS100 which would not light up. The power supply was "tripping". It didn't take long to trace the cause to D11 - a UF5402 diode in the power supply secondary circuit. The unit appeared to have been "investigated" by Wossname up Church Street because the cover had been removed by prising with a large screwdriver and the aerial connection had disappeared inside. I pushed the tiny contact tube out and ran solder down the outside to prevent its being pushed back in. Once the damaged cover was repaired and the missing screws replaced, the receiver was as good as new. That reminds me; most of the receivers brought for repair have at least one screw missing. Will the person who is collecting screws, please send me some?
Alex Hoyle of Trackdown Consultants has asked me to mention that he has finally obtained a number of SR5500 remote control handsets. A number of people had contacted him previously but he had no stock at that time. Phone him on 01608 678057 for this and other handsets.
This receiver seems to have been manufactured by the same far eastern company which made the later receivers for Amstrad. Certainly, the "repairman" who brought me this one thought so. Unfortunately, he'd fitted an Amstrad "kit" which was not quite right. In addition, the "2R2" resistor which he'd used was actually 0R22 so the current sense circuit was a little unhappy. Once I'd fitted the correct kit the receiver appeared to work but switched to standby each time a vertically polarised channel was selected. I confirmed the fault by watching the menu of a horizontally polarised channel and altering the setting to vertical. Into standby it went. For some reason it was giving zero LNB volts instead of 13. However, it worked fine while my oscilloscope probe was on one connection of the power supply output socket! After messing about for what seemed like hours I finally "threw in the towel" and "bodged" it by fitting a 56k resistor between the power supply H/V select input and ground. I still don't know what had caused the problem but my little "fix" did the trick.
A foreign looking gentleman came all the way from Leeds to complain that his Pace D2Mac decoder reported "No Access" when he tried to view the "CTV" package transmitted by Intelsat at one degree west. Why he came to me I'll never know! I'm really not interested in these exotic programmes. I can happily sit in front of "Classic Coronation Street" all night long. Anyway, Pace were very helpful and sent a new Eprom, part number 807-2301009, which (according to the customer who phoned me later) solved the problem. Apparently, some D2Mac channels use "Symulcrypt" which is a combination of DMAC and D2MAC. Standard Pace D100 and D150 decoders don't understand "Symulcrypt" transmissions (nor do I so don't ask!)
There are several new "Sky" channels broadcasting from Astra satellite 1D but you won't receive them unless your system can "see" these lower frequencies. To a large extent, Sky solved this problem by providing subscribers with an "ADX-plus Channel Expander" made by Global Communications. I make a few pennies by modifying customer's SRD510 and SS9000 receivers to control these "Expanders" automatically with a menu option. Unfortunately, one customer reported that, although her son had fitted the "Expander" very carefully and had adjusted the menu settings accordingly, her SRD510 steadfastly refused to show anything apart from the most dreadful snow showers on the Astra 1D channels. The installer who called round to see me told me how he had made two calls so far and had not been able to remedy the situation. I couldn't suggest anything other than to check the cable and replace the LNB. The following day, however, he phoned me to say, rather sheepishly, that he'd discovered an Astra 1D notch filter fitted next to the LNB!