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Building the modules into a low-profile steel case A high-quality stereo DAC for superb sound your DVD player, Pt.3 The final article this month shows you how to assemble the various modules for the Stereo DAC into a low-profile steel case. We also tell you how to get the remote control working and how to customise the configuration. F OR THE PURPOSES of this article, we’ll generally assume that you’re building the unit from a kit and that the case comes with all the holes pre-drilled. If not, then you will have to drill the holes yourself using the photographs and the layout shown in Fig.12 to guide you. As previously stated, if you have to buy a case separately, then we recommend the Altronics H-5035 rack case. Basically, you will have to drill/cut holes in the front panel for the mains switch, the earth point (4mm), the 66  Silicon Chip three pushbutton switches (10mm) and the two LEDs (5mm). You will also need a 5mm hole for the IR receiver plus four 3mm mounting holes for the Switch Board. Note that the Switch Board is directly attached to the front panel and not mounted on a sub-panel as in the prototype. Make sure that the cut-out for the mains switch is the correct size, so that it snaps securely into place and is retained by its plastic locking tabs. This involves drilling a series of holes inside the marked cut-out and then siliconchip.com.au By NICHOLAS VINEN from carefully (and tediously) filing it to shape. Alternatively, you can use a toggle switch that requires a round mounting hole but make sure that the switch is mains rated. On the rear panel, you will need clearance holes for the various input and output sockets, holes for the fuseholder and rear-panel earth point (4mm) and a cut-out for the IEC socket. An alternative here is to use an IEC socket with an integral fuse, in which case the external fuseholder is no longer necessary. Drilling the bottom of the case is straightforward. First, use the PC boards as templates to mark out their mounting holes. Note that the Input and DAC boards sit right at the rear of the chassis and their sockets must be correctly aligned with their rear panel holes to avoid shorts. Drill these holes to 3mm, then drill two 4mm holes for the earth points plus a mounting hole for the transformer. Having done that, fit four feet to the bottom of the case if it doesn’t already have them. These can be either a selfadhesive type or you can use bolt-on feet in which case you will have to drill the necessary holes. Mains wiring Once the case is ready, the first step is to install the transformer, power switch and the 230VAC wiring. As shown in Fig.12, all the mains wiring is located in a partitioned-off area in the lefthand side of the case. However, this steel partition will only be present if you purchase a custom case as part of a kit (ie, from Altronics). If you buy a standard rack case, then you can purchase a length of anglealuminium from a hardware store and fit it yourself by bolting it to the base (make sure it is well earthed by scraping away the powder coating on the chassis around the mounting bolts). Before fitting the mains transform­ er, scrape away the powder coating around its mounting hole on the bottom of the chassis. This is done so that the flat metal washer under the head of the bolt contacts bare metal, so that the bolt is correctly earthed. Having done this, mount the transformer in position. Note that the large flexible washer supplied with the unit must be installed between the transformer and chassis. A second flexible washer is then fitted between the top of the transformer and its dished metal clamp plate. Orient the transformer so that the wires exit at the top, with the primary wires nearest to the side of the case – see Fig.12. Do not over-tighten the mounting bolt, otherwise you could distort the chassis. The transformer’s secondary side terminations can now be fed through a grommetted hole in the partition, NOTE: THE SUPPLY LEADS TO THE FINAL VERSION OF THE INPUT BOARD ARE REVERSED AT THE TERMINAL BLOCK COMPARED TO THOSE SHOWN HERE. siliconchip.com.au November 2009  67 SAFETY FUSEHOLDER S/PDIF INPUT REAR PANEL EARTH E TOSLINK RECEIVER 1 1NI BROWN (ACTIVE) LK1 V5 BROWN (ACTIVE) BLUE (NEUTRAL) 3NI 5V V3.3 SHEATH FUSEHOLDER BODY WITH HEATSHRINK SLEEVE GRN/YELLOW (EARTH) TOSLINK RECEIVER 2 2NI A N 3.3V IEC MAINS INPUT CONNECTOR CHASSIS EARTH POINTS +5V 0V ++ SECONDARY (OUTPUT) V5+ NI REWOP –- O/I LATIGID DIGITAL I/O PRIMARY (230VAC INPUT) RUBBER GROMMET 15VAC POWER SUPPLY BOARD 0V +15V CON3 CT CON1 15VAC CON2 –15V TRANSFORMER* 0V +5V 1. ALL MAINS CONNECTIONS SHOULD BE MADE WITH FULLY INSULATED 4.8MM FEMALE SPADE CRIMP CONNECTORS. 2. INSULATE ALL EXPOSED MAINS CONNECTIONS USING HEATSHRINK SLEEVES. 3. USE NYLON CABLE TIES TO SECURE ACTIVE & NEUTRAL WIRES. SHEATH MAINS SWITCH BODY WITH HEATSHRINK SLEEVE SPST 250VAC ROCKER SWITCH 68  Silicon Chip STEEL PARTITION IMPORTANT: NOTE: TRANSFORMER LEAD COLOURS ARE FOR THE * ALTRONICS M-4915A. REFER TO TABLE IN ARTICLE FOR LEAD COLOURS FOR THE JAYCAR MT-2086. FRONT PANEL EARTH siliconchip.com.au LEFT CHANNEL AUDIO OUTPUT L RIGHT CHANNEL AUDIO OUTPUT TU O R 2.2nF 19090110 INPUT BOARD DAC BOARD LENAP TNORF O 1 29090110 + DIGITAL I/O – O/I LATI GID + +15V 0V -15V - TUP NI V 5 1-/ + 16-WAY IDC CABLE 14-WAY IDC CABLE K K A A K IR RECEIVER BUTTON/LED FRONT PANEL BOARD 01109093 siliconchip.com.au A Fig.12: follow this wiring layout to assemble the unit. Note in particular that all 230VAC mains terminations must be fully insulated and no low-voltage wiring is to be routed on the mains (left) side of the metal partition. The Input & DAC boards are mounted on M3 x 10mm tapped spacers while the Power Supply and Front Panel Boards are mounted on untapped 6mm Nylon spacers. November 2009  69 The connections to the mains switch are made using fully-insulated spade connectors. Sheath the entire switch body with heatshrink sleeving after making the connections and fit a cable tie to the wires immediately after the spade connectors so that they can not possibly come loose. Note the earthing arrangement for the front panel. ready for connection to the power supply board. Position all the wires so that there will be plenty of clearance to the lid when it is installed later. The Altronics and Jaycar transformers use different colours for their leads. A Jaycar transformer was used in the prototype whereas the wiring diagram shows the lead colours for the Altronics M-4915A transformer. In particular, note that the Altronics transformer uses brown & blue leads for its primary winding. By contrast, the Jaycar MT-2086 transformer uses orange leads for its primary, while its secondary leads are yellow, white, red and purple. In this case, the white and red leads go to the centre tap (CT) on the Power Supply Board, while the yellow and purple leads go to the outer 15VAC terminals. Table 5 shows the wiring colour codes for the two transformers. Just use the corresponding colours shown in the righthand column if using the Jaycar transformer. Table 5: Transformer Lead Colours Altronics M-4915A Primary Colours Brown & Blue Red White Secondary Colours Black Orange Jaycar M-4915A Orange Yellow White Red Purple Next, push the mains rocker switch and IEC socket into their respective cutouts, noting that the earth pin of the socket goes towards the top. That done, install the fuseholder. Note that you must use a safety fuseholder as specified in the parts list in Pt.1. You can now run and terminate the mains wiring. Use only 7.5A or 10A/250VAC mains-approved cable for all connections. Do not solder the wires directly to the switch or socket pins! These devices are not designed to withstand high temperatures during soldering Player Faults & Detecting CDs With Pre-Emphasis During testing, we came across at least one DVD player which incorrectly set the deemphasis bit on its digital output when playing a CD. If your player has a similar fault, the result would be that high frequencies are attenuated during playback. As a result, the software in the Stereo DAC has been configured so that both the yellow and green LEDs are lit during playback when the de-emphasis is active. This can help you determine if your player has this same fault (unlikely), while for players that operate correctly, it will indicate if any of your CDs were recorded with pre-emphasis. Pre-emphasis was mainly used on some older CDs and very few modern CDs use it. This means that if the yellow and green LEDs are always lit during playback, it indicates a fault with the player. 70  Silicon Chip and may be damaged. Instead, terminate each wire end in a fully insulated 4.8mm female spade crimp terminal. Note that a ratchet-driven crimping tool is required for this job. Low-cost automotive type crimpers are not suitable and their use may result in unsafe connections. If you don’t have fully-insulated spade connectors, be sure fit heatshrink insulation over any exposed metal. It’s also a good idea to place a rubber boot over the IEC connector and to use 16mm-diameter heatshrink tubing to sheath the entire fuseholder (run the leads through the heatshrink first). Similarly, use 20mm-diameter heatshrink to sheath the power switch after attaching the leads. The connections to the chassis earth points are made by terminating the green/yellow earth leads in 5.3mm ID insulated crimp eyelets. After crimping the wires, it’s a good idea to also the solder wire ends adjacent to the eyelet holes, as a “belts’n’braces” measure. These eyelets are then bolted to the chassis earth points using M4 x 10mm machine screws, nuts and shakeproof washers. An additional nut is then fitted to serve as a locknut, so that the assembly cannot possibly come loose – see Fig.13. Important: be sure to scrape away the paint from around the holes before fitting the earth screws (ie, you must have good metal-to-metal contact be­ tween the chassis and the earth eyelets). This step is vital to ensure safety. Depending on the colour of the chassis, you might want to use black screws for the front and rear panel earth points. We used a black countersink hex head M4 x 12mm screw on the front panel to ensure good appearance. Use small cable ties where applicable to keep everything neat and tidy. Refer to Fig.12 and the photos for all the details. In particular, fit cable ties close to the switch and to the IEC input socket, to make it impossible for any leads to accidentally come adrift. Once the mains wiring is complete, go back over it and make sure that everything is correct. Check also that each connection is secure and well insulated. If necessary, use heatshrink tubing to completely cover any exposed terminations. That done, use your multimeter to check for continuity between the earth pin of the IEC socket and any convenient point on the chassis that is devoid of paint, siliconchip.com.au Where To Buy Kits For The Stereo DAC Both Jaycar and Altronics will be supplying kits for this project and both companies will be supplying the Input and DAC Boards with the surface-mount ICs (IC3 & IC6) already soldered in place. The Jaycar kit will be in short form only and will consist of the Input, DAC and Front Panel Boards plus all on-board parts. A kit for the Power Supply Board is available separately (Cat. KC-5418). The Altronics kit will be complete and will include all the modules, the power supply components (including the transformer) and a laser-cut custom steel case with screened lettering. The modules will not be available separately except for the Power Supply Board (Cat. K-5501) and the remote control is not included. If your infrared receiver module has a metal shield like this one, then be sure to insulate it from the front panel as described in the text. MAINS EARTH LEAD such as the countersunk screws in the side panels. This test must be repeated later when the top panel of the case is fitted. At that time, use your meter to check that the top and both side panels are earthed. If not, carefully remove the paint from beneath the heads of the retaining screws to ensure a reliable connection – see panel titled “Making Sure The Case Is Securely Earthed”. Mounting the modules The four PC board modules can now be installed in the case – see Fig.12. Both the Input and DAC Boards are mounted on M3 x 10mm tapped spacers and secured using M3 x 6mm machine screws from either side. By contrast, the Power Supply Board is mounted atop 6mm untapped Nylon spacers and secured using M3 x 15mm screws, shakeproof washers and nuts. Similarly, the Switch Board is secured to the rear of the front panel using 6mm untapped Nylon spacers and M3 x 15mm screws, shakeproof washers and nuts. Make sure that the switches and LEDs just protrude through the front panel holes and that the switches operate correctly, without jamming. The IR receiver LED must also be correctly aligned with its front-panel hole. Important: if the infrared receiver includes an external metal shield (see photo), then steps must be taken to ensure that it is insulated from the chassis. We suggest a short strip of ordinary insulation tape on the inside of the front panel, with a hole cut out to match the hole in the panel. Do not rely on the paintwork or powder coating to provide insulation! Note that in the prototype (Jaycar rack case), the Front Panel Switch Board was fitted with spacers at the back and mounted on the sub-panel siliconchip.com.au – see photos. However, for the Altronics case, the spacers must be fitted on the front of the board and directly attached to the front panel. INSULATED CRIMP EYLET LOCKING NUT STAR LOCKWASHER Low-voltage wiring Now for the low-voltage wiring. First, trim the secondary leads of the transformer to the right length, then scrape the insulating enamel off the wire ends and tin them with solder. You should have about 5mm of tinned wire protruding from the insulation. That done, solder the correct two leads together to form the centre tap. This will either be the white and black leads for the Altronics transformer or the white and red leads for the Jaycar transformer. The secondary leads can then all be connected the power supply module’s AC input (CON1). Before connecting anything to the output of the supply, apply power (don’t forget the mains fuse) and measure the three rails at the supply outputs (CON2 & CON3). Assuming all is well, the +15V, -15V and +5V rails should all be within ±5% of the nominal values. Now switch the power off and physically disconnect the 230VAC mains lead to prevent accidents while working under the hood! The +5V and 0V supply leads for the Input Board can now be run. Heavyduty hook-up wire should be used for this job and you should begin by stripping about 8mm of insulation from the ends of each wire. That done, tin the bare ends with solder and trim them to about 5mm before connecting them to the terminal blocks on the Input & Power Supply Boards. It’s a good idea to twist the two supply leads together to reduce noise and improve appearance but be careful not to get them mixed up. Screw the terminals down tightly to ensure reliable connections. M4 x 10mm SCREW & NUT BASE PLATE OF CASE NB: CLEAN PAINT AWAY FROM MOUNTING HOLE Fig.13: the earth terminals are all secured to the case as shown here. The top nut serves as a locknut, so that the assembly cannot possibly come loose. Make sure that the crimp eyelet makes a good electrical contact with the base. Important: note that the supply leads to Input Board used in the proto­ type are reversed at the terminal block compared to those for the final version of this board. The wiring diagram (Fig.12) is correct (ie, the positive lead goes to the left). Note also that the ±15V supply leads to the DAC Board are not installed at this stage. That’s done later, after you’ve tested the Input Board. Secure the +5V & 0V supply leads with cable ties as shown in Fig.12, so that they can not come adrift and contact other parts of the circuit. Testing the Input Board You are now ready to do some initial tests, starting with the Input Board. Begin by plugging in the 14-way IDC cable between this board and the Front Panel Switch Board, then connect a multimeter in series with the +5V supply. You will have to temporarily disconnect the +5V supply lead at one end (eg, at the Power Supply Module) to do this. Set the multimeter to the amps range, then apply power and check the current reading. It should be around 0.1A and certainly not more than 0.2A. November 2009  71 The prototype was built into a Jaycar 1U rack case but we recommend the Altronics rack case if you’re not building from a kit. If you do use the Jaycar case, fit covers over the ventilation slots above and below the mains wiring. What To Do IF There’s No Audio Output From The Stereo DAC In order for the Stereo DAC to work correctly, it must be fed with LPCM (linear pulse code modulation) data from the DVD player (ie, uncompressed audio). If there’s no audio output and the green and yellow LEDs on the Stereo DAC front panel are flickering rapidly, this indicates that the output from the DVD player is set to AC3/Dolby Digital. In that case, you will have to step through the menus of the DVD player and set the audio output to stereo LPCM. Note that on one recent Pioneer DVD player we tested, it was impossible to change the audio output format with an HDMI cable hooked up. The trick was to disconnect the HDMI output and use either component video or a composite video connection instead. This then allowed the AC3/Dolby Digital output to be changed to stereo LPCM, after which the HDMI connection could be re-instated. Other DVD players may require a similar procedure. 72  Silicon Chip If you see a reading of 0.2A or higher, switch off immediately, disconnect the power cord and check the Input Board for short circuits and incorrect parts placement. If that doesn’t solve the problem, disconnect the 14-way IDC cable and quickly re-apply power in order to rule out a fault with the cable or Front Panel Switch Board. If the current is in the acceptable range, check that the blue LED on the front panel nearest the IR receiver is lit. No other LEDs should be lit initially but after about 10 seconds, the unit should enter scanning mode whereby each LED briefly lights in sequence. If that checks out, switch off, remove the siliconchip.com.au Make Sure The Case Is Securely Earthed Unfortunately, many rack mount cases have no electrical connection between the six or more panels that make up the external surfaces of the case. That’s because they are either painted or powder-coated and the paint/powder coating acts as an insulator. For safety reasons, you must make sure that all panels (including the lid) are securely earthed when the case goes together. For our case, this involved running separate earth leads from the front and rear panels to an earth point adjacent to the mains earth on the base. We also had to dismantle the case and scrape away the paint from the panel mating surfaces and under the screw heads, to ensure good metal-to-metal contact when it all goes together. It’s important also to scrape away the paint from around the mounting holes for the earth screws, the transformer bolt and for the screws used to secure the rubber mounting feet. After you install the mains wiring, use your multimeter to check that the various panels are correctly earthed. You can do that by checking for continuity between the earth pin of the IEC socket and bare metal points on the chassis panels. If you use the Jaycar case, then you must also make sure that the internal rails are earthed. We also suggest that you cover the ventilation slots immediately above and below the IEC socket and any mains wiring (this can be done using black plastic or metal panels). NOTE: THE SUPPLY LEADS TO THE FINAL VERSION OF THE INPUT BOARD ARE REVERSED AT THE TERMINAL BLOCK COMPARED TO THOSE SHOWN HERE. multimeter and reconnect the +5V lead to the terminal block. The next step is to feed a signal into one of the inputs (ideally you should test all three inputs). If your DVD player (or CD player) has a TOSLINK output, connect it to the TOSLINK1 input on the Stereo DAC using an optical cable. The player needs to be switched on for this initial test but not playing anything. Now power the unit back up. The TOSLINK1 blue LED should be lit along with the S/PDIF yellow LED. If the either LED fails to light, switch off immediately and check for faults on the Input and Front Panel Switch Boards. One of the most common siliconchip.com.au causes of LEDs not lighting up is cable crimping problems, so check this out carefully. Other possible faults include shorts between adjacent pads, missing links, missed solder joints and incorrect parts placement or orientation. Assuming all is well, you can now test the other two inputs. Press each button in turn and make sure that its corresponding blue LED lights. The yellow LED will go out if there’s no signal input for that channel. If that checks out, connect the DVD player to the TOSLINK 2 and COAXIAL inputs in turn and check that the yellow S/PDIF LED lights when the corresponding input is selected. Note that these tests (and the fol- lowing tests with the remote control) are all done without the ±15V supply wiring in place. Testing the remote control This unit can be controlled using a Philips RC5-compatible remote control. That includes just about any universal remote. You will need to program the remote to control a Philips TV. For example, if you have a Jaycar AR-1726 remote, you need to set its code to 103 with the TV control mode selected. Similarly, if you have an Altronics Aifa A-1009, set its code to 026. Having done that, point the remote at the Stereo DAC’s front panel and press some buttons. The yellow LED should flash each time a button is pressed. If so, you should then be able to select each input in turn using the 1, 2 & 3 buttons on the remote or by pressing the CH+ and CH- buttons. If you don’t wish to use the Philips TV code (eg, if you have a Philips TV), you can set the unit up to recognise a different RC5 code (see Programming The Remote Control Codes). Final testing You are now ready to test the complete unit. To do this, first switch off, disconnect the DVD player and November 2009  73 Programming The Remote Control Codes & Customising The Configuration It isn’t necessary to configure the Stereo Digital-To-Analog Converter before use. Most constructors will be happy to settle for the default settings in the firmware but some people may wish to customise it to suit their individual needs. Basically, you can change the remote control codes, the scanning behaviour and the initial input selection (TOSLINK1 is the default) when the Stereo DAC is switched on. The yellow LED should flash whenever a button on the remote is pressed. If you can get it to flash but not all the functions work or if you don’t want to use the Philips TV codes (eg, if you have a Philips TV), then you can reprogram the unit to accept different codes. To do this, hold down all three buttons on the front panel at once, then release them. Be sure not to release any until all three have been pressed or you may get into the wrong mode (if you do, just turn the unit off and then on again). When the buttons are released, the lefthand blue LED will be flashing. Point your remote control at the IR receiver and press the button that you want to assign to select TOSLINK1. Hold it down for a few seconds until you see both the yellow and green LEDs flash. The first blue LED should then stop flashing and the second should start, at which point you should release the button on the remote. If the yellow and green LEDs don’t flash, make sure that the remote control is transmitting an RC5 code. Provided that you choose a Philips code, you will be OK but that might not apply to the codes for other manufacturers. Check also that the remote’s batteries are OK. If the first blue LED is still flashing, stop for a few seconds and try again. The Stereo DAC waits until it receives 10 identical codes in a row before programming that code. This is done to avoid the possibility of a transmission error programming in the wrong code. If you don’t want to assign that function to a button on your remote control, press any of the front panel buttons on the Stereo DAC to skip it. You now repeat the above procedure for the following functions in this order: Select TOSLINK2, Select COAXIAL, Select Next Input, Select Previous Input, Mute Output, Volume Up and Volume Down. Each time you program a code, the flashing blue LED should cycle to the next button, wrapping around from the third to the first. Once all the codes have been pro- cable. Note: do not apply power to the DAC board unless it is connected to the Input Board via the 16-way cable. Once everything is in place, apply power and check the ±15V supply rails at the input to the DAC board. If these are OK, check the +5V rail at the output of REG5 on the DAC Board. Switch off immediately and check for errors if any of these voltages are incorrect. If all is well, the front panel LEDs should light as before. It’s now just a matter of checking that the unit works. Connect your DVD player to the TOSLINK1 input (or to the COAXIAL input if there’s no TOSLINK output) and check that the yellow S/PDIF LED lights when that input is selected. In fact, the unit should automatically select that input if it was scanning. Now start playing a CD or DVD – the S/PDIF LED should immediately turn off and the green DATA LED should come on. If that doesn’t happen, there may be a problem with the DAC (IC6), the 16way cable or one of the parts associated If you are using a universal remote, the simplest solution is to set it to control a Philips TV. This will allow the CH+ and CH- buttons to select the inputs. And if your remote has numeric buttons, you can also use buttons 1, 2 and 3 to select a particular input. In addition, the Mute button should toggle mute on and off. While muted, all three blue LEDs should flash in unison to indicate this condition. Finally, the VOL+ and VOL- buttons should control the Stereo DAC’s volume. Check that these functions all work. Remote control reprogramming Virtually any universal IR remote control can be used, including the Digitech unit from Jaycar (Cat. AR1726) and the Aifa RA7 unit from Altronics (Cat. A-1009). Set the Digitech unit to code 103 and the Aifa unit to code 026. disconnect the mains lead. Now install the +15V, 0V and -15V leads between the Power Supply Board and the DAC Board. As before, use heavy-duty hook-up wire and twist the wires together to minimise noise pick-up. Secure the leads using cable ties as shown and tighten the terminal block screws down firmly to ensure good connections. Finally, check that these supply leads are correctly wired at both ends. The next step is to fit the 16-way IDC 74  Silicon Chip siliconchip.com.au Table 6: Selecting The Programming Function Function Auto-Scan Delay, No Signal Present Auto-Scan Delay, No Audio Present Auto-Scan Delay, No Signal Present After Manual Input Change Auto-Scan Delay, No Audio Present After Manual Input Change Default Input At Switch-On Input Scanning At Switch-On Table 7: Setting The Multiplier Value 10ms Seconds Minutes Button 1 2 3 grammed, the LEDs will stop flashing and the Stereo DAC will revert to its normal mode. You can then check that the remote control codes have been properly assigned. If not, start again. Scanning delays/default input The scanning delays and the initial default input can also be reprogrammed. This is done by holding down one button on the front panel, then pressing a second button and releasing both together. The buttons pressed and their order determines which function you are configuring, as set out in Table 6. After pressing one of these combinations, the lefthand blue LED will flash. Each additional button press after that will cause the flashing LED to cycle to the next step until the configuration is complete. To set any of the auto-scan delays after selecting the configuration mode, you first press one of the buttons to get a multiplier value – Table 7. It’s then simply a matter of making two further button presses to set the delay value as shown in Table 8. with the DAC chip. You should also check the two BC327 PNP transistors on the Input Board and their associated resistors. Assuming that it all works so far, switch off and connect the Stereo DAC’s outputs to an amplifier, turn the volume down and reapply power. Now play some content and slowly turn the volume on the amplifier up. You should hear clean, undistorted sound. Once you have verified that this works, test the other two inputs. Check siliconchip.com.au First Button 1 1 2 2 3 3 Second Button 2 3 1 3 1 2 Table 8: Setting The Delay Value Value 1 2 3 5 10 20 30 40 50 First Button 1 1 1 2 2 2 3 3 3 Second Button 1 2 3 1 2 3 1 2 3 As an example, if you wanted to set the delay to five minutes, you’d press and release button 3 (Table 7), then button 2 and finally button 1 (Table 8). The default auto-scan delay values are (in the order shown in Table 6) 10 seconds, one minute, five minutes and never. By the way, the sequence 1, 1, 1 is a special sequence which is interpreted as “never” and thus disables that scanning mode. Default input There are two choices when it comes to programming the default input: (1) you can either have the unit remember the last channel it was set to and restore that channel at switch on or (2) you can program also that you can adjust the volume from the Stereo DAC up and down using the VOL+ and VOL- buttons on the remote control. However, as explained in Pt.1, it’s best to set the volume from the Stereo DAC to maximum if you want the best performance and use the volume control on the amplifier instead. Enjoy the sound That’s it – your new Stereo DigitalTo-Analog Converter is now ready for the unit to always select one of the inputs. If you want it to remember the last channel, select the “Default Input At Switch-On” function by pressing the buttons shown in Table 6, then press button 1. Alternatively, to always select a certain input, select the function, then press button 2 and then the button for the input that you want selected. The default state is for TOSLINK1 (Input 1) to be selected at switch on and most readers will probably leave it at that. However, you might want to change it to Input 3 (COAXIAL) if you are only using the COAXIAL input. Scanning behaviour There are three options for input scanning behaviour on start up: (1) to configure the unit to immediately begin auto-scanning, select the “Input Scanning At Switch-On” function from Table 6 and press button 1 (left); (2) to configure it to begin scanning after the usual auto-scanning delay (the default behaviour), press button 2 (centre); and (3) to make it act as if the default channel has been manually selected at switch on, press button 3 (right). Wait – there’s more! There’s one other feature we haven’t mentioned. Even if you have auto-scanning enabled, there may be times when you don’t want it to happen. In that case, all you need to do is switch to the input that you want to lock and then press the selector button a second time, holding it in for about a second. The LED will come on but blink off occasionally to indicate this “input lock” mode has been enabled. In this mode, auto-scanning is disabled. However, the next time you manually change the input, or when you turn the Stereo DAC off, it will reset to the default mode. use. Hook it up permanently to your system and you can now enjoy highquality, hum-free stereo sound from SC your DVD player. Balanced Outputs In response to a number of requests for balanced outputs, we have produced a balanced output board with XLR connectors. This will be presented in the December issue. November 2009  75