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As digital satellite TV takes off in the UK, sales of used
analogue receivers has increased quite noticeably. This is partly
because Sky Digital fails to provide the Eurosport channel, CNN, The
Cartoon Channel and those naughty German channels full of ladies with
"well stocked balconies" (as they say in Austria) and partly because
a lot of fairly modern, used, analogue receivers have appeared at
rock bottom prices.
I took advantage of an offer and bought several Amstrad SRD510 "ex-rental" receivers. A couple of them had been "butchered" but most of them were repairable.
One exhibited a blank screen with good audio and I traced this fault to R5, a 12k resistor in a divider chain which creates a 2.0 volt reference for IC1 in the energy dispersal clamp circuit. As usual, the resistor was covered with black, corrosive glue and had gone open-circuit. This type of fault is very common so, before I even switch on my multimeter, I look for resistors covered with glue.
The same symptom can be caused by dead electrolytics or a faulty C-Band switch. This switch is designed to invert the video signal but sits unused for the life of the receiver. Result: one cheap switch with oxidised contacts.
This one worried me because a hair dryer didn't bring back even a flicker of "Please insert card..." message. I spent nearly an hour fitting RELKIT 17 but it failed to produce messages. However, when I replaced the glue-encrusted 28MHz crystal, it was cured!
Unfortunately, after scraping away all traces of glue from the main board and screwing everything back together I noticed that the front panel didn't light up, although the LED on the decoder board did. On a hunch, I replaced the 4MHz crystal which brought the box back to life. The following day, however, back came the long-suffering owner.
"It's dead now!". Sure enough, the front panel display didn't light up. I checked the new crystal and it wasn't oscillating. Then I noticed still more glue between the pins of the microcontroller chip. A quick scrape with a pin had the receiver up and running again. The owner trudged away, muttering to himself. My hearing is getting worse but I'm sure he got my name wrong because I heard him call me "Hugh Anchor" and he didn't seem at all grateful.
I never forget a pretty face. Last time this girl brought me her MSS100, 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. This time, however there were no decoder messages and no "transparent" menus (the ones without a blue background. Suspecting a sync problem, I replaced the PTV111. This was a lucky guess and it cured the problem. Curiously, I've never had this particular chip fail in a BT-SVS250 type receiver, despite the fact that a heatsink radiates heat down onto the chip!
(I think a dud 503kHz resonator will produce identical symptoms)
(and also MSS200, MSS300)
Credit where credit is due! David Snell from Sky-View in Hereford sent me the following information about a faulty Pace Apollo.
Symptoms : Small portions of the picture 'tearing' sideways. Also, contrast fairly poor unless set to 7 or 8 in installation menu.
Remedy : Replace C216 (100uF) next to the graphics chip.
David says that the fault was minimal to begin with, reducing further as the machine warmed up. This capacitor (and many others) is included in the Reliability kit from SatCure firstname.lastname@example.org
I've mentioned our local "Mad Cow" previously. The last occasion when this angry farmer's wife visited me, her SS9200 had died for the seventh time in as many weeks and we traced the problem to surges caused by the milking machine that was used only on a Saturday. This time her complaint was that it was "dead again" but, of course, it wasn't. However, I could see no picture when I connected the receiver on the bench.
I 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 U6, the TEA2029C sync separator I.C., to the decoder board connector and found none. Replacing U6 cured the fault. This is quite unusual. According to "The Satellite Repair Manual edition 5" the usual cause is Q24 or Q29 (BC547).