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Return to SatCure index page HOW DO I PLACE AN ORDER? Frequently Asked Questions Amstrad SRD400 Contents 1. Why do I get no pictures since I changed my "Blue Cap" LNB for a new one ? 2. My receiver is stuck in standby. Is this Parental Lock Mode ? 3. Some channels are sparkly. How do I tune them in? 4. I can't get 6.60 Audio channels. Is there an upgrade ? 5. Can I use the SRD400 as a stand-alone Videocrypt decoder ? 6. How can I get more channels ? 7. Is there a factory reset ? 8. Why do I get poor pictures with wavy lines ? 9. Why do I get a blank screen ? 10. How do I connect a Mac decoder ? 11. Can I use an ADX Channel Expander? 12. Can I use it in a caravan with a 12 volt supply? 13. Can I use a Universal LNB? 14. How can I watch MTV Germany? 1. Why do I get no pictures since I swapped my "Blue Cap" LNB for a new one ? Perhaps you short-circuited the coaxial cable inner wire to the outer plug. Check the connections very carefully to ensure that strands of wire are not causing a short circuit. Locate the top fuse of three inside the receiver. Replace it with a T1A fuse. Locate a brown disc capacitor labelled CP527 or C527 which usually sits near to the ribbon cable which goes into the main board from the decoder. Sometimes it is soldered across a diode labelled DP505. Sometimes it is beneath the board. Sometimes it is not fitted at all. Remove this capacitor. This is an Amstrad-approved upgrade. If there is still no LNB power supply from the LNB input socket check whether RP506 (6R8, 2W wire-wound) is open circuit. This resistor is located below a little printed circuit board which is fixed to the large, black, finned heatsink. 2. My receiver is stuck in standby. Is this Parental Lock Mode ? Probably; you can check quite easily. Press the front panel button sequence [H/V] [H/V] [Audio]. If four horizontal dashes appear in the display then your receiver is locked. The User Handbook instructs you as follows: Unplug the receiver from the mains power. Plug it back in. Leave it for more than 48 hours to "count down." Do NOT touch any buttons in the meantime or you'll have to unplug it and start again. If you can't wait 48 hours, there's a quick method: Connect a 1k resistor between pin 5 of IC104 and the tuner metal can. Press [Standby]. The display will show a figure "8". Press [H/V] [H/V] [Audio]. The display willshow ---- Press any handset number button four times. The display will show eight vertical bars. Disconnect one end of the 1k resistor. Press [audio] firmly twice. Press [Standby] to confirm the unit is reset. 3. Some channels are sparkly. How do I tune them in? There is a frequency offset adjuster which you can turn by putting a jeweller's screwdriver through a tiny hole in the plastic base of the receiver. However, to avoid damage it is best to adjust this from inside. Set this adjuster to its central position to begin with. Turning it one way will reduce black sparklies and turning it the other way will reduce white sparklies. It reacts very slowly so give it time. It should be set for the best compromise on all channels (usually middle position). If some channels are still sparkly, proceed as follows: If black sparklies are present, press [tune up] then immediately press [H/V]. If white sparklies are present, press [tune down] then immediately press [H/V]. Once you have a good picture, press [Preset] twice. If you see both black AND white sparklies then tuning will not help as: The dish is not aligned. The cable is kinked, has moisture inside or bad connections. The LNB is faulty. The receiver tuner module is faulty. 4. I can't get 6.60 Audio channels. Is there an upgrade ? Yes there is. It's a small circuit board assembly with just three wires to solder in place. You can adjust it to get either 6.50, 6.60 or 6.65 MHz audio channels. However, if you leave it adjusted to 6.60 MHz it will receive the other two with only slight distortion. You can buy it from me or from several other stockists. It comes with simple fitting instructions. The 6.60 MHz audio channel can be selected simply by pressing the [TV/SAT] button. Alternatively, if this is in use, you can connect a manual switch instead. 5. Can I use the SRD400 as a stand-alone Videocrypt decoder ? Yes, you should be able to inject 1 volt video (doesn't need to be clamped, but should be low-pass filtered to remove subcarriers, etc.) at CA02 on the decoder PCB. Disconnect CA02 negative leg from the board and apply video at this point. Alternatively you could go in unfiltered and unclamped (but de-emphasized) at the interface connector CNM2 (pins 1 & 2), but you would need 2V video with 2V DC bias for TA06 in the decoder. The decoder video output goes out from the Scart on pin 19. Credit to: Giacomo Bozzoni, Milan, ITALY e-mail: bozzoni@mbox.vol.it 6. How can I get more channels ? Introduction ============ As standard, the Amstrad SRD400 satellite receiver appears to be capable of storing only 48 channels. For Astra satellite television viewing only, this is fine. However, for those wanting extra presets to store radio stations and/or to store the different frequencies on the Eutelsat and Intelsat satellites, then this limited selection of presets is somewhat frustrating. Various commercial '99 channel' upgrades have been available for these receivers for some time - however their relatively high price has made it difficult for most Amstrad owners to justify this expense! This article describes how to access an extra 80 presets and the good news is that this will not cost you a penny or involve any modifications whatsover. Accessing the Free Presets ========================== Selecting the extra 80 presets is simplicity itself. Go over to your SRD400 and press PRESET then press either one of TV/SAT or RECALL. If you pressed TV/SAT your display will now show channel 0 (Zero)! If you pressed RECALL your display will show a frequency, then the audio mode then 0 (Zero)! I would recommend that you use the second method (PRESET then RECALL) to access these extra presets, just in case you have an ADX unit connected or intend to fit one at a later date. The only drawback to these extra presets is that you can only access them sequentially, by pressing the CHANNEL DOWN key to scroll through them (you can press TUNING UP or TUNING DOWN though). Whilst in this mode, which we will call Extended Mode, you can return to Standard (48 channel) mode by pressing CHANNEL UP key, or by directly accessing one of the normal, standard, 48 channels. Do not store anything on these Extended Presets at this time - read this article in full first! If you press CHANNEL DOWN you will notice the display changes to channel 95. Pressing it again will show channel 94 and so on in steps of -1 (minus one). The first 80 of these presets, in extended mode, are extra presets. The next 48 are repeats of your Standard (48 channel) mode - so changing any of these (in extended mode) will also change them in Standard mode. The next 80 presets after this are repeats of the first extra 80 presets in Extended mode, so I suggest that you do not store anything whilst displaying these, or be aware that any changes you make will also change the first 80 presets! After you have scrolled through these you will return to Standard (48 channel) mode. There does appear to be an exception to this rule though. If you press CHANNEL DOWN until you come to channel 31, in extended mode, you should see either a sparkly Teleclub or an Astra 1D TestCard (at the time of writing) - these are two channels on Astra 1D but the Amstrad SRD400 is picking them up (without an ADX!!). Pressing RECALL shows the frequency to be around 6297 (or 16.297 GHz) which is incorrect. Channels 31 through to 20 step -1 show these funny frequencies together with Astra 1D channels 55 (Teleclub) or 56 (Astra 1D TestCard). If possible, do not store anything on these channel presets in case someone can shed some more light on these. If you keep pressing CHANNEL DOWN until channel 63 is displayed then theory dictates that channels 63 to 52 step -1 should be repeats of the first set of Extended presets 31 to 20 step -1, but this time no TV transmissions are received and pressing RECALL displays a frequency of around 2106 (12.106 GHz). Whilst exploring these extra presets you will notice some funny channel numbers being displayed. The following table, summarising the sequence of channels, should be of use to you when using these extra (Extended) presets: Column Column Column Column (1) (2) (3) (4) Number Remarks Number Remarks Displayed Displayed --------- ---------------------- --------- -------------------- 0 ||8 Repeat of channel opposite 95 Can press CHANNEL UP for 0 ||7 Repeat of channel opposite 94 ||6 Repeat of channel opposite 93 ||5 Repeat of channel opposite 92 ||4 Repeat of channel opposite 91 ||3 Repeat of channel opposite 90 ||2 Repeat of channel opposite 89 ||1 Repeat of channel opposite 88 ||0 Repeat of channel opposite 87 | 9 Repeat of channel opposite 86 | 8 Repeat of channel opposite 85 | 7 Repeat of channel opposite 84 | 6 Repeat of channel opposite 83 | 5 Repeat of channel opposite 82 | 4 Repeat of channel opposite 81 | 3 Repeat of channel opposite 80 | 2 Repeat of channel opposite 79 | 1 Repeat of channel opposite 78 | 0 Repeat of channel opposite 77 A9 Repeat of channel opposite 76 A8 Repeat of channel opposite 75 A7 Repeat of channel opposite 74 A6 Repeat of channel opposite 73 A5 Repeat of channel opposite 72 A4 Repeat of channel opposite 71 A3 Repeat of channel opposite 70 A2 Repeat of channel opposite 69 A1 Repeat of channel opposite 68 A0 Repeat of channel opposite 67 99 Repeat of channel opposite 66 98 Repeat of channel opposite 65 97 Repeat of channel opposite 64 96 Repeat of channel opposite 63 95 Repeat of channel opposite 62 94 Repeat of channel opposite 61 93 Repeat of channel opposite 60 92 Repeat of channel opposite 59 91 Repeat of channel opposite 58 90 Repeat of channel opposite 57 89 Repeat of channel opposite 56 88 Repeat of channel opposite 55 87 Repeat of channel opposite 54 86 Repeat of channel opposite 53 85 Repeat of channel opposite 52 84 Repeat of channel opposite 51 83 Repeat of channel opposite 50 82 Repeat of channel opposite 49 81 Repeat of channel opposite 48 80 Repeat of channel opposite 47 79 Repeat of channel opposite 46 78 Repeat of channel opposite 45 77 Repeat of channel opposite 44 76 Repeat of channel opposite 43 75 Repeat of channel opposite 42 74 Repeat of channel opposite 41 73 Repeat of channel opposite 40 72 Repeat of channel opposite 39 71 Repeat of channel opposite 38 70 Repeat of channel opposite 37 69 Repeat of channel opposite 36 68 Repeat of channel opposite 35 67 Repeat of channel opposite 34 66 Repeat of channel opposite 33 65 Repeat of channel opposite 32 64 Repeat of channel opposite 31 ( Displays frequencies 63 ( Displays frequencies 30 ( in the range 6297 MHz 62 ( in the range 2106 MHz 29 ( (channel 31) to 6128 61 ( (channel 63) to 1953 28 ( MHz (channel 20). 60 ( MHz (channel 52). 27 ( Actual frequency must 59 ( Actual frequency could 26 ( be between 0818 and 58 ( not be determined as 25 ( 0803 as these would 57 ( no transmissions have 24 ( be the frequencies of 56 ( been received on these 23 ( transponders 56 and 55 ( presets!!! They are not 22 ( 55 on Astra 1D, which 54 ( repeats of channels 31 21 ( it displays!!! 53 ( to 20 step -1 in column 20 ( 52 ( (1) opposite !!! 19 51 Repeat of channel opposite 18 50 Repeat of channel opposite 17 49 Repeat of channel opposite 16 As Standard Mode channel 48 15 As Standard Mode Channel 47 And then back into Standard 14 As Standard Mode Channel 46 48 channel mode. Press PRESET 13 As Standard Mode Channel 45 and RECALL to re-enter extended 12 As Standard Mode Channel 44 mode at channel 0 in column (1). 11 As Standard Mode Channel 43 10 As Standard Mode Channel 42 09 As Standard Mode Channel 41 08 As Standard Mode Channel 40 07 As Standard Mode Channel 39 06 As Standard Mode Channel 38 05 As Standard Mode Channel 37 04 As Standard Mode Channel 36 03 As Standard Mode Channel 35 02 As Standard Mode Channel 34 01 As Standard Mode Channel 33 00 As Standard Mode Channel 32 9 As Standard Mode Channel 31 8 As Standard Mode Channel 30 7 As Standard Mode Channel 29 6 As Standard Mode Channel 28 5 As Standard Mode Channel 27 4 As Standard Mode Channel 26 3 As Standard Mode Channel 25 2 As Standard Mode Channel 24 1 As Standard Mode Channel 23 0 As Standard Mode Channel 22 -9 As Standard Mode Channel 21 -8 As Standard Mode Channel 20 -7 As Standard Mode Channel 19 -6 As Standard Mode Channel 18 -5 As Standard Mode Channel 17 -4 As Standard Mode Channel 16 -3 As Standard Mode Channel 15 -2 As Standard Mode Channel 14 -1 As Standard Mode Channel 13 -0 As Standard Mode Channel 12 U9 As Standard Mode Channel 11 U8 As Standard Mode Channel 10 U7 As Standard Mode Channel 9 U6 As Standard Mode Channel 8 U5 As Standard Mode Channel 7 U4 As Standard Mode Channel 6 U3 As Standard Mode Channel 5 U2 As Standard Mode Channel 4 U1 As Standard Mode Channel 3 U0 As Standard Mode Channel 2 ||9 As Standard Mode Channel 1 And then to channel ||8 at the top of column (3). Credit to: mike ginger <mike.ginger@metricom.seuk.com> 7. Is there a factory reset ? No, there's no secret button sequence but you can solder in a new SDA2516 EEprom. This will automatically be reprogrammed to factory defaults on power-up. 8. Why do I get poor pictures with wavy lines ? This is usually caused by electrolytic capacitors overheating. Try replacing all the 100uF and 470uF capacitors around the tuner module. Replace them one by one, testing each time, and be sure to fit them the correct way round. 9. Why do I get a blank screen ? Someone may have fitted an incorrect fuse which has melted. The top fuse should be a T1A and the other two should be T2A fuses. Also, make sure that the decoder board connectors are secure in their sockets. (The brown one at the right doesn't matter; it is used only for card authorisation.) Make sure you have 5 volts on the 5v pin on the decoder board. Another symptom: "As soon as the unit is switched from standby, a blank screen is presented, with a faint high pitch whine from the receiver. After about 3 seconds the screen then displays peak white "pulses" that scroll along the lines in a random manner. They appear up and down the screen, at about 10 line intervals. The rest of the raster stays at black level. The high pitch whine can be heard from the TV as well as the receiver if the test bars are ON. At this point, if the LNB connection is made and broken repeatedly a number of times, the picture might appear correctly. Oscillation subsides if LNB is disconnected, leaving a blank screen with minimum noise content." Reason: You are trying to use the SRD400 with a later type of LNB for which it was not designed. A small modification is required inside. Remove the four recessed cover screws underneath. Slide off the top cover. Remove two screws which secure the decoder board, unhook the wires, disconnect the right hand small brown plug and lift the decoder out of the way. Somewhere close the the multi-wire decoder connector on the MAIN board you will find a small brown disc capacitor. This is labelled C527 or CP527 or it is soldered across a diode DP505. Cut out this capacitor and discard it. Reassemble your receiver which will now work perfectly. You may find that the top fuse, a 630mA, tends to melt from time to time. You may uprate this to a T1A fuse, as recommended by Amstrad for later LNBs. Be careful not to short out the LNB cable! The fuse will melt and also the 6R8/2W resistor. 10. How do I connect a Mac decoder ? Easy! Connect the decoder to the SRD400 using a modified Scart lead: Mark one Scart cover "Receiver". Remove the Scart cover. Cut the wire which goes to pin 19 and solder a 200mm wire to it to extend it back out of the Scart cover. Replace the Scart cover. Solder a Phono plug to the wire. Plug the Phono into "baseband out" at the back of the SRD400. Plug the "Receiver" Scart plug into the Scart socket on the back of the SRD400. Plug the other Scart plug into your D2Mac decoder. Set the decoder menu options as appropriate (D2Mac). You'll need a smart card. 11. Can I use an ADX Channel Expander? Yes. Simply connect it in line with the LNB cable. You can also make a little board with four wires to solder inside your receiver. This will switch the Channel Expander ON automatically when you select channels 40 to 48. So you can tune these nine channels to Astra 1D programmes! Amstrad SRD400 Channel Expander Control The only switching function which can readily be used on the SRD400 is the TV/SAT button. However, this selection can not be stored on a per-channel basis. The ideal solution would be to allocate a specific number of channels for Astra 1D programmes and to have the ADX switch on automatically when each of these channels is selected. My initial thought was that it would be a simple matter to select a number-display segment which lit up only for a specific range of channels. The top left segment of display three was chosen as being ideal in that it lights only for channels 40 through 48. The initial enthusiasm was dampened when a glance at the circuit showed that the LED segments are multiplexed. They are actually pulsed by the display driver IC which, in turn, receives serial data, from the microcontroller, that would be difficult to interpret. In addition, the common cathode of each seven-segment display unit is strobed. There is no steady DC voltage or even usable pulses with respect to the zero volt reference. Luckily the old brain, being entirely uncumbered by folicular growths, remains fairly cool and immediately (well, seven months after the original idea to be truthful) came up with a solution. An optocoupler hooked across the relevant LED segment would give a pulse output which could be "smoothed" and used to control the ADX. Thus was the present design conceived. The optocoupler LED is connected between pin 16 of the LED driver, IC151 on the front panel, and the centre leg (collector) of the PNP strobe transistor, Q152. With the optocoupler transistor emitter grounded and a 1k resistor between collector and 12 volt supply, the goal is achieved. The pulses from the optocoupler are fed via a 10k resistor to a PNP BC557B (anything will do) and smoothed by a 100uF electrolytic. The BC557B is connected via a 270 to the ADX The few components required cost very little and can easily be assembled onto a piece of "Veroboard" or similar. The complete assemby should be kept small. After attaching wires, insulate it and tuck it away beneath the decoder board. The sketch of the SRD400 front panel board shows where to solder the three wires. Zero volts is point "1", Q152 collector is point "2" and IC151 pin 16 is point "3". The 12 volts is derived from point "4" on the small regulator board which is bolted to the heatsink in the SRD400. A minor drawback of the system is that the chosen segment will light while you are tuning the receiver. To overcome this nuisance, disconnect the wire and switch the ADX ON while tuning. Once the channels are tuned and stored, switch the ADX OFF, reconnect the control wire, and it will then be switched on automatically for channels 40 to 48 only. This system will also work for the Amstrad SRX200, the later version of which has 48 channels. You will have to hunt for the 12 volt supply (it's on one of the ICs near the rear of the receiver) but the front panel connections are very similar.

12. Can I use it in a caravan with a 12 volt supply? According to Nigel of "510s R Us" you can. Throw away the mains transformer. Look at the front left corner. There are three large black capacitors. Link all the positive ends to a red wire. Link all the negative ends to a black wire. Connect these wires to a car battery (through a 3 Amp fuse for safety). The receiver should now operate on vertical channels only. It will not tune to the highest channels (use an ADX Plus). To get horizontal channels, step out of the caravan and turn the LNB through 90 degrees! (If this works, please tell me. If it doesn't , well don't blame me!

13. Can I use a Universal LNB? The following information was supplied by Herve Benoit Adaptation of the 22 KHz to the AMSTRAD SRD400 The goal is to modulate the LNB supply voltage by a value of around 650 mV pp to select the "high" band of an universal LNB (9.75/10.6 GHz), in order to obtain an almost complete coverage of the ASTRA analog band (10.700 to 12.300 GHz, except a "hole" from 11.450 to 11.550 MHz). Another use could be the control of an antenna switch (Note 1). Principle of operation: On the SRD400, the LNB supply voltage is generated by means of a fixed 12V voltage regulator (7812). To obtain the required 13V (vertical) or 17V (horizontal), two diodes (DP502 and 503) and a 3.9 V zener (DP504) are inserted in series in the ground connection of the 7812 (Note 2). A NPN transistor (TP506, controlled by the H/V select) is connected in parallel with DP504 and shorts it when Vertical polarization is selected, thus giving approximately a LNB supply voltage of 13.4V (12V + 2 x 0.7V). When the Horizontal polarization is selected, TP506 is blocked and the supply voltage is approximately 17.3V (12V + 2 x 0.7V + 3.9V). The same principle will be used to modulate the 22KHz tone, by shorting DP503 with a NPN transistor controlled by a 22KHz signal generator. This will give a modulation of 600 to 650 mV pp approximately, which is well within the limits of the specs of the universal LNB and switches. (see also Note 3). SRD400 LNB voltage regulator, H/V control, 22KHz modulation :   _______ +28V | | 13V / 17V o--------| 7812 |-------------o |_______| _|_ DP502 \ / =|= |<--------|c 27K _|_ BC548 \|____-----___ 22KHz signal DP503 \ / added /|b ----- (12 Vpp) =|= |e added |_________| _|_ |c RP511 DP504 / \|____-----___ H/V control (3.9) / \ TP506 /|b ----- =|= |e _|_ _|_ GND GND Realisation : The generator (see diagram below) uses one cheap IC (HEF4011) and 2 NPN transistors (BC548 or equivalent) ; the 22KHz is switched on by means of a logic level at "1" applied at its input. In the case of the SRD400, the best way to control this input is to use the signal normally intended to switch the audio subcarriers Xtals. This signal is available on the jumper (link) J24 and is at "1" (+5V) for the subcarriers at 7.38 and 7.56 MHz (AU2, AU5 and AU6) and at "0" (GND) for the subcarriers at 7.02 and 7.20 MHz (AU1, AU3, AU4 and AU7). Jumper J24 has to be cut in its middle : the part nearest to the front panel carries the switching signal and should be connected to the input of the generator (220K resistor), the other part has to be connected to ground (J56 for instance) to select permanently the Xtal for 7.02 / 7.20 (or to a switch between 0 and +5V to keep a manual control). In this way, the 22KHz is "off" when AU1, AU3, AU4 or AU7 are selected, it is "on" when AU2, AU5 or AU6 are selected. The only drawback of this method is that the 7.38 and 7.56 MHz subcarriers cannot be selected by the remote anymore, but they are mainly used for radio programmes. Diagram of the generator : -------------------------- (from J99) + 12V o--------o--------o-------------------------------o +12V | | | o---------o----------o | === | | | | |100p | 100n === 47K| | 10K| | | |150K | |180K === | _|_ | | | | | | __ | | __ === _|14 GND | | |_1| \ |_13| \ |__8| \ |___ |_______| O--|___| O--|___| O---o 22KHz/12 Vpp 220K |c | |c 2|__/ 3 12|__/ 11 9|__/ 10 IN ___----__b|/ |_b|/ |7 (J24) ---- |\ |\ HEF4011 |6 |e |e |5 | | | GND o--------o--------o-------------------------------o BC548 BC548 GND Note 1 : For this purpose, the frequency of the tone can be modified to 60 Hz or 400 Hz by changing only the 100pF capacitor value (33nf for 60 Hz, 4.7 nF for 400 Hz).   Note 2 : The same circuit is applicable to other receivers, the differences being in the way to control its input and the way to interface it to the voltage regulator, depending on its type. A very popular voltage regulator in satellite receivers is the L200 (SGS). In this case, the 27K resistor and the switching transistor are replaced by a capacitor (e.g. 100 nF) in series with a resistor connected to the feed-back input of the L200. The value of the resistor (in the order of 100K or more) has to be selected to obtain 650 mV pp superimposed onto the LNB supply.   Note 3 : The average value of the LNB supply is decreased by 0.35V when the 22KHz is on, and by up to 0.7V when it is off, so it is possible to compensate this voltage drop by adding a diode in series with D502 if it causes a malfunction of the H/V selection (very seldomly necessary in cases where the cable length results in an important voltage drop). ____________________________________________________________________

14. How can I watch MTV Germany? Solder a 100nF capacitor to IW01 pin 39. Solder a wire to the other leg of the 100nF. Solder a wire to IW01 pin 1. Solder a switch to the two wires. Note: Keep the wires as short as possible. Do not twist the wires together. Closing the switch will make MTV appear! For a complete fault-finding guide, read "The Satellite Repair Manual V". DISCLAIMER This information is given in good faith, based on several years of workshop experience involving thousands of repairs. No responsibility will be accepted for any death, damage or injury caused either directly or indirectly by the use of this information. The reader should check the facts himself. It is assumed and stressed that the reader will be familiar with good, safe, electronic workshop practice and will be familiar with all tools, components and terms used. If there is any doubt about the reader's ability to carry out such work competently and safely, the work should be referred to a specialist engineer. THIS FAQ IS NOT APPROVED BY SKY OR BY AMSTRAD End of FAQ HOW DO I PLACE AN ORDER? Copyright ©1997 SatCure Version 1.7 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. Return to SatCure index page Send this page address - CLICK HERE - to a friend !