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Just about any IR remote control that’s capable of outputting Philips codes can be used. This is the Select 1 from Jaycar. Last month, we gave the circuit details for our new 6-Channel Remote Volume Control and showed you how to build the PC board assemblies. This month, we complete the construction and give the test and setup details By JOHN CLARKE N OW THAT ALL THE PC boards have been built, it’s time to prepare the metalwork. Hopefully, this unit will be made available as a complete kit, in which case the metalwork will be supplied predrilled. Alternatively, if you’re buying the bits separately, you will have to drill the case yourself. As supplied, the case comes in pieces and it’s a good idea to drill the front and rear panels before putting it together. The front and rear panel artworks (Fig.12) and the main wiring 70  Silicon Chip diagram (Fig.10) show the positions of these holes. Starting with the front panel, you have to drill holes for mains switch S1, the 20-LED display, the three pushbutton switch­ es, the acknowledge LED and the infrared receiver. The rectangular cutouts for the mains switch and LED bargraph can be made by first drilling a series of small holes around the inside perimet­ er of the cutout, then knocking out the centre piece and filing to the correct shape. Don’t make cutout for the mains switch too big – it must be a tight fit so that it is properly secured by its retaining tabs. The pushbutton switch holes should be about 9mm to allow clearance for the 7.5mm diameter switch caps. The rear panel requires holes for the RCA sockets, the safety fuseholder, the mains lead cordgrip grommet and the earth terminal adjacent to the RCA sockets. Take care with the hole for the cordgrip grommet. This hole is not round – instead, it must be carefully profiled to match the shape of the grommet, so that the grommet can not later be pulled out when the mains cord is fitted. The holes for the RCA sockets must be large enough to prev­ent the RCA plugs from making contact with the metal chassis when they are connected. Once these holes have been drilled, assemble the case with­out the lid, using the machine screws supplied. The next bit is important: be sure to scrape away the paint at the countersunk screw points, so that each section of the case makes good metal-to-metal contact. This ensures that each section www.siliconchip.com.au This close-up view shows the mounting details for the Control & Display board. It mounts at the front of the chassis on four tapped 12mm spacers and is secured using eight M3 x 6mm screws. is properly earthed to mains earth (important for safety reasons) and also prevents hum problems. Next, mark out the mounting holes for the three PC boards on the baseplate and drill these holes to 3mm. You will also have to drill mounting holes for the earth lug, the mains terminal block screws and the transformer bolt (see Fig.10). Deburr all holes using an oversize drill. Next, scrape away the paint or anodising from the area around the two earth lug mounting holes. This is necessary to ensure that the earth lugs make good contact with the bare metal of the case and is also an important safety measure in the case of the mains earth lug. For the same reason, scrape away the paint or anodising from the bottom outside of the chassis around the mounting holes for the mains terminal block. This will ensure that the mounting screws are properly earthed. Installing the hardware The various hardware items – including the power transform­er, switch S1, the fuseholder, the mains terminal block, the earth lugs and the PC boards – can now be installed in the case. The boards are installed as follows: (1) Signal board: this mounts on two 6mm-long untapped spacers at the front and is secured using two M3 x 12mm screws and two M3 nuts and star washers. The RCA sockets are www.siliconchip.com.au The Signal Board is secured by attaching it to two 6mm-long untapped spacers along the front edge and by fastening the RCA socket assemblies to the rear panel using 6g self-tapping screws into the plastic mouldings. then secured to the rear panel using 6g self-tapping screws into the plastic mouldings. (2) Display board: this mounts on four tapped 12mm spacers and is secured using eight M3 x 6mm screws; (3) Power supply board: this mounts on four 10mm M3 tapped spacers and is secured using eight M3 x 6mm screws. The toroidal transformer is secured using the supplied bolt, rubber washers, metal mounting plate and nut. The rubber washers are placed between the transformer and chassis and bet­ween the transformer and the metal mounting plate. The assembly is then secured using the mounting bolt. Do the bolt up firmly but don’t overtighten it – you’ll distort the chassis if you do. The mains terminal block is secured to the chassis using two 12mm x M3 screws and nuts. Note that a piece of Elephantide insulation material measuring 35mm x 35mm is mounted under April 2002  71 This view shows how the completed modules are installed in a 1U rack chassis and interconnected using two 8-way cables fitted with pin headers. the terminal block as an additional safety measure. Make sure that the mains earth lug is properly secured – it must be attached using an M3 x 10mm-long screw, nut and two star washers as shown in Fig.11. A second lock nut is fitted to this assembly, so that it cannot possibly come loose later on. Now use your multimeter to confirm that there is zero ohms resistance between the earth lug and all the panels of the case. You should also get zero ohms resistance between the earth lug and the two mains terminal block mounting screws. Before installing the mains wiring, it’s necessary to check that the power switch is the right way up. To do this, switch it to the ON position and use a multimeter to check that the resistance between the two contacts is 0Ω. If the rocker needs to be in the OFF (up) position to get a 0Ω reading, the switch will have to be inverted. Mains wiring Fig.10 shows the mains wiring details. Exercise extreme cau­tion when installing this wiring and be sure to The Power Supply board mounts on four 10mm M3 tapped spacers and is secured using eight M3 x 6mm screws. 72  Silicon Chip follow Fig.10 exactly – your safety depends on it. First, strip back about 350mm from the outer sheath of the mains cord, so that the Active (brown) lead has sufficient length to reach both the fuseholder and the power switch (S1). This done, clamp the mains cord into position using the cordgrip grommet. Check that the grommet properly clamps the cord to the chassis; you must NOT be able to pull the cord back out. Next, trim the Active (brown) lead so that it is about 70mm long. The Active lead then goes to the centre terminal of the fuseholder, while the leftover brown lead is run between the outside terminal and the mains terminal block. Slip a 40mm length of 10mm-diameter heatshrink tubing over the two leads before soldering them to the fuseholder. Once the connections have been made, push the tubing over the body of the fuseholder (so that the terminals are covered) and shrink it down using a hot-air gun. The Neutral (blue) lead from the mains cord goes directly to the mains terminal block, while the Earth (green/ yellow) lead is connected directly to the main earth lug. The Earth lead should be left long enough so that it will be the last connection to break if the mains cord is “reefed” out. Now set your multimeter to low ohms range and check the resistance www.siliconchip.com.au www.siliconchip.com.au April 2002  73 Fig.10: here’s how to install the modules in the chassis and complete the wiring. Take great care with the mains wiring and be sure to insulate the exposed terminals on the fuseholder with heatshrink tubing as described in the text. The mains wiring should also be secured using cable ties as shown, so that the leads cannot possibly come adrift. Another view inside the completed unit. Use cable ties to secure the mains wiring, so that the leads cannot possibly come adrift (see also Fig.10). between the earth pin on the mains plug and the vari­ous chassis panels. In each case, you should get a reading of close to zero ohms. Next, the .001µF capacitor can be installed and the trans­ former and mains switch wiring completed at the terminal block. In each case, make sure that the wire insulation goes into the mouth of the terminal block and is pushed all the way up to the brass Fig.11: this diagram shows the mounting details for the two earth lugs. The second nut locks the first nut, so that there is no possibility of the earth lug later working its way loose. Don’t forget to scrape away the paint or anodising from the area around the two earth lug mounting holes, to ensure proper contact with the chassis. 74  Silicon Chip connector before doing up the screw. Leads that share a common connection should be twisted together and lightly tinned with solder before inserting them into the terminal block. Don’t use a terminal block that’s too small to accept the insulation from two leads – you must be able to push the insulation of both leads fully into the terminal block and all the way up to the brass connector. The connections to the mains switch are made using fully-insulated female spade terminals. Make sure that the spade termi­nals are securely crimped to their leads before fitting them to the switch – a ratchet-driven crimping tool should be used for this job. Finally, connect the transformer secondary leads to the Power Supply PC board as shown in Fig.10. Use cable ties to lace the mains wiring to­ gether. In particular, you should install one tie close to the mains switch, another close to the fuseholder and several more close to the mains terminal block. This will prevent the leads from coming adrift and if one does come loose, it will be held in place so that the exposed end cannot move and make contact with the case. Any remaining cable ties can be used to secure the transformer’s secondary leads. Completing the wiring You now need to make up two 8-way leads with pin header sockets at each end to interconnect the three PC boards. Begin by cutting a 110mm length of 8-way rainbow cable from the 270mm length supplied. That done, strip the wire ends, crimp them into the header pins and insert the pins into the header sockets (note: the header sockets must be oriented as shown in Fig.10). Now repeat this procedure for the remaining 160mm length of 8-way cable. Connect the finished cables to the Signal and Display Boards but leave the Power Supply Board disconnected at this stage. You have to make sure that the supply board is delivering the correct voltages before making this connection. Switching on Before switching on, check the mains wiring carefully to make sure there are no mistakes. Check also that the wiring to the power supply board is correct. Once you’re sure that everything is correct, install a 0.5A fuse in the fusewww.siliconchip.com.au Remote control Assuming everything checks out so far, you can now test the unit with the IR remote control. First, you have to set the remote control so that it trans­mits codes that are suitable for Philips devices. Initially, it is best to set the IR remote to the TV1 code, since this is the default setting for the 6-Channel Remote Volume Control. If you are using the Big Shot 3 IR remote from Jaycar or the Altronics AV8E (Cat. A1007), for example, you need to set it to code 191. This is done by pressing the SET and TV buttons together and then releasing them. The transmit LED will light and you then enter the number 191 using the number buttons. Another suitable IR remote control is the Select 1 from Jaycar. This has to be set to code 11414. To do this, you first press both the CODE and Operate (red) buttons for two seconds and then release them. You then enter the numbers 11414. Note that the Select 1 remote control will only operate the 6-Channel www.siliconchip.com.au Remote Volume Control when it is set for the TV1 code. The Dick Smith Cat. G-1223 remote control works in similar fashion. Having set the transmit code, check that it can operate the 6-Channel Remote Volume Control using the Volume Up/Down, Mute and Channel Up/Down buttons. If you have a different type of remote control, start by selecting a programming number that’s for Philips TV sets. It’s then simply a matter of trying each number in turn until you find one that works. Now test the remote control on your TV set. If it oper­ates the TV set, then you will need to use another code. The choices are SAT1 and SAT2 but note that these options are avail­able only on the multi-function remote controls such as the Altronics AV8E and the Jaycar Big Shot3 (not on the Select 1 or DSE Cat. G-1223). The SAT1 code is 424, while the SAT2 code is 425. The se­lected code (424 or 425) is entered into the IR remote control after first pressing the SET and SAT switches. The 6-Channel Remote Volume Control also needs to be changed to accept the new SAT1 or SAT2 code. The SAT1 address is selected by pressing the Up pushbutton on the 6-Channel Remote Volume Control at power up. Similarly, SAT2 is selected by press­ing the Down pushbutton at power up, while TV1 can be re-selected by pressing Mute at power up. The selection is stored in memory and will not alter unless one of the switches is again pressed during power up. Check that the 6-Channel Remote Volume Control can now be operated using the new code. If you have a different remote control unit to those mentioned above, select a code that oper­ ates a Philips satellite receiver and test it. If it doesn’t work, try other satellite codes until you find one that does. Finally, you can test the 6-Channel Remote Volume Control by hooking it up to the outputs of your DVD player and to your audio amplifiers. Check that the volume changes smoothly for all channels and that the sound is distortion-free and clear of any noise or hum. Hum problems? In most cases, you shouldn’t encounter any problems with hum and Fig.12: these two artworks for the front and rear panels are reproduced here 60% of actual size and may be enlarged to full-size for use as drilling templates on a photocopier (1.67x). If you buy a kit, then the front & rear panels will be supplied pre-punched and with screened lettering. holder, then apply power and check the output voltages from the Power Supply Board. All voltage checks should be made with respect to the 0V (GND) terminal. Check that the ±12V, ±6V and +17V (nominal) rails are all present. If these are all correct, switch off and wait for about one minute to ensure that all rails have dropped to 0V. Now plug the header into the Power Supply Board, switch on and check that one of the display LEDs is lit. You should be able to move the LEDs that are lit up and down the bargraph using the Up and Down buttons. Pressing the Mute switch should immediately cause the LED (or LEDs) to flash. Pressing Mute again (or the Up button) should stop the flashing. It’s now a good idea to check the supply rails to each IC just to make sure everything is OK. To do this, connect your multime­ter’s common lead to the metal tab of REG1 and check that the following voltages are present: +5V on pin 14 of IC1; +11V on pin 8 of IC2, IC3, IC5 & IC6; -11V on pin 4 of IC2, IC3, IC5 & IC6; +6V on pins 13, 14 & 15 of IC4 & IC7; and -6V on pins 7 & 19 of IC4 & IC7. The voltages should all be within about 0.5V of the above values. April 2002  75 Fig.13: here are the full-size etching pattern for the three PC boards. Check your boards carefully before installing any of the parts. noise but if you do, here’s a few troubleshooting tips. First, many power amplifiers don’t have the signal earth connected back to mains earth and this can make the audio signal susceptible to mains switching noise (eg, as appliances are switched on and off). Earthing the signal at one point should reduce this effect and you can do that by connecting the earth track on the Signal Board to the signal earth terminal adjacent to the RCA connectors (see Fig.10). Alternatively, if two or more of your amplifiers connect the signal earth to mains earth, you may get what’s called a “hum loop”. This will cause an audible (and annoying) hum in the audio signal. There are several ways to get round this. First, try con­necting all stereo amplifiers, the DVD player and the 6-Channel Remote Volume Control to the same power point via a multi-way power board. If that doesn’t help, try disconnecting the signal earth (NOT the mains earth) from chassis in each amplifier and then use the optional signal earth connection in the 6-Channel Remote Volume Control unit as the single earthing point. Note: for safety reasons, you must NOT disconnect the mains earth connection (if it exists) inside an amplifier chassis (or any other chassis). As a last resort, the earth tracks on the Signal Board can be broken. This involves cutting the tracks at the 76  Silicon Chip thinned sec­tions labelled “Earth Loop Break” and will separate the earthing into three sections. Use channels 1 & 2 for the first stereo amplifier, channels 3 & 4 for the second stereo amplifier, and channels 5 & 6 for the third stereo amplifier. In addition, the earth connections in the leads from the DVD player to the RCA inputs of the 6-Channel Remote Volume Control will have to be disconnected. You can do that by cutting away the outside earth lugs on the RCA plugs at one end of each lead, where they connect to the 6-Channel Remote Volume Control. Alternatively, the leads can be rewired to new RCA plugs at one end, leaving the earth braid of the cable disconnected. SC www.siliconchip.com.au