Changing the Amstrad SRD510 satellite receiver tuning range

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Changing the Amstrad SRD510/520 tuning range

The Amstrad SRD510 has 99 channel capability with full audio tuning range but the actual channel frequency range is limited to 950 - 1700 MHz. By changing the microprocessor and EEprom to those used in the SRD540 you can store 199 channels and get an increased tuning range in the on-screen menu. Unfortunately, the tuner module itself will go no higher than 1900 MHz so, with an "Enhanced" (9.75 GHz) LNB, you still can't watch "Sky Sports 3."

The solution to this problem came to me via e-mail from a clever young engineer in Poland. Tomasz runs his own repair business in Warsaw and he discovered that you can simply remove and resolder one surface mount capacitor inside the tuner. This has the effect of shifting the tuning range upwards so you might lose the German "ARD" channel, at the bottom of the range, but you will gain "Sky Sports 3."

This job is not for the faint of heart and it helps if you are short-sighted!

The picture shows "before" and "after" pictures of the modification. You must dismantle the receiver and carefully desolder the tuner module from the PCB. Lift off the side cover and look inside the tuner. Locate the varactor diode which is marked "T3." Next to "T3" is a capacitor which sits between two ICs. Very carefully touch both ends of the capacitor with a fine, hot soldering iron tip and flick it off its copper pads. Put the capacitor somewhere safe. Its value is 1nF. Its physical size is critical.

Now use a sharp blade to scrape away the square solder pad which is connected to "T3."

Solder the capacitor back in place at an angle of 45 degrees by soldering one end to "T3." Use the bare minimum of solder and remove any excess with Multicore desolder wick®. The idea is to reduce the effective circuit reactance by a fraction. If you lose or damage the capacitor and replace it with another, the replacement must be identical in size. A larger device simply will not work.

Replace the tuner and reassemble the receiver. Test it to ensure that it still works as before. Now dismantle it and replace the microcontroller I.C. (the largest chip) with an AM242306 micro. A 40 pin socket would be a good idea! Remove the EEprom which is a 24C08 or a 2856 and replace it with a 24C16 instead. Reassemble the receiver and switch it on. The red and green lights will come on for a few seconds while the micro reprogrammes the EEprom. Occasionally I have had to perform a factory reset by pressing the appropriate sequence on the handset. The receiver should now have 199 channels and should work perfectly with an "Enhanced" LNB.

The new microcontroller does not give a "dish-A/dish-B" option so you can no longer control an ADX automatically (see SRD510 FAQ). With an "Enhanced" LNB you won't need an ADX anyway but, if you use a "Universal" LNB, you will need an external 22kHz tone inserter. In this case you should use an AM242284 microcontroller. It gives an "external audio" option which, in the SRD510/520, will control the voltage on pin 14 of the Decoder Scart. You can use this function to control an external unit on a per-channel basis.

Before you carry out such a major modification on a relatively old receiver, you would be wise to replace the parts which tend to give long term problems. An SRD510 reliability kit containing capacitors, resistors and instructions is available - RELKIT 3.

Download this picture and print it out:

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Copyright ©1997 SatCure
Version 1.1 updated on 3/5/99
This file may be downloaded for private and personal use but NO part of it may be published in any form without the prior permission of the author.
Send this page address - CLICK HERE - to a friend !


Sky Digibox	Sky Analogue	Computer	Car Caravan	Audio Visual	Books
If you find this information useful and want to thank me, why not buy one of my low-cost "virtual books" that you can download direct to your computer? My books can be read on-screen or printed out on paper. They are full of colour photos and illustrations. Click on "Books", above, for more information. Send this page address - CLICK HERE - to a friend !
Return to SatCure index page Changing the Amstrad SRD510/520 tuning range The Amstrad SRD510 has 99 channel capability with full audio tuning range but the actual channel frequency range is limited to 950 - 1700 MHz. By changing the microprocessor and EEprom to those used in the SRD540 you can store 199 channels and get an increased tuning range in the on-screen menu. Unfortunately, the tuner module itself will go no higher than 1900 MHz so, with an "Enhanced" (9.75 GHz) LNB, you still can't watch "Sky Sports 3." The solution to this problem came to me via e-mail from a clever young engineer in Poland. Tomasz runs his own repair business in Warsaw and he discovered that you can simply remove and resolder one surface mount capacitor inside the tuner. This has the effect of shifting the tuning range upwards so you might lose the German "ARD" channel, at the bottom of the range, but you will gain "Sky Sports 3." This job is not for the faint of heart and it helps if you are short-sighted! The picture shows "before" and "after" pictures of the modification. You must dismantle the receiver and carefully desolder the tuner module from the PCB. Lift off the side cover and look inside the tuner. Locate the varactor diode which is marked "T3." Next to "T3" is a capacitor which sits between two ICs. Very carefully touch both ends of the capacitor with a fine, hot soldering iron tip and flick it off its copper pads. Put the capacitor somewhere safe. Its value is 1nF. Its physical size is critical. Now use a sharp blade to scrape away the square solder pad which is connected to "T3." Solder the capacitor back in place at an angle of 45 degrees by soldering one end to "T3." Use the bare minimum of solder and remove any excess with Multicore desolder wick®. The idea is to reduce the effective circuit reactance by a fraction. If you lose or damage the capacitor and replace it with another, the replacement must be identical in size. A larger device simply will not work. Replace the tuner and reassemble the receiver. Test it to ensure that it still works as before. Now dismantle it and replace the microcontroller I.C. (the largest chip) with an AM242306 micro. A 40 pin socket would be a good idea! Remove the EEprom which is a 24C08 or a 2856 and replace it with a 24C16 instead. Reassemble the receiver and switch it on. The red and green lights will come on for a few seconds while the micro reprogrammes the EEprom. Occasionally I have had to perform a factory reset by pressing the appropriate sequence on the handset. The receiver should now have 199 channels and should work perfectly with an "Enhanced" LNB. The new microcontroller does not give a "dish-A/dish-B" option so you can no longer control an ADX automatically (see SRD510 FAQ). With an "Enhanced" LNB you won't need an ADX anyway but, if you use a "Universal" LNB, you will need an external 22kHz tone inserter. In this case you should use an AM242284 microcontroller. It gives an "external audio" option which, in the SRD510/520, will control the voltage on pin 14 of the Decoder Scart. You can use this function to control an external unit on a per-channel basis. Before you carry out such a major modification on a relatively old receiver, you would be wise to replace the parts which tend to give long term problems. An SRD510 reliability kit containing capacitors, resistors and instructions is available - RELKIT 3. Download this picture and print it out: Return to SatCure index page Copyright ©1997 SatCure Version 1.1 updated on 3/5/99 This file may be downloaded for private and personal use but NO part of it may be published in any form without the prior permission of the author. Send this page address - CLICK HERE - to a friend !