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A high-quality DAB+ tuner to build Last month, we introduced our new DAB+/FM Stereo Tuner and gave the circuit details. This month, we show you how to assemble the two PC boards and install them into a low-profile steel case. I F YOU WANT TO BUILD this project, there’s just one way to go – buy the complete kit from Jaycar Electronics (see panel). There are several reasons for this. First, the Venice 7 radio module is not readily available from other sources. Second, the main PC board supplied with the kit will have the surfacemount dsPIC microcontroller (IC1) already soldered in place (and preprogrammed). And third, the Jaycar kit will come with a pre-punched custom steel case with screened lettering to Where To Buy A Kit Of Parts A kit of parts for the DAB+/FM Tuner will be available from Jaycar Electronics – Cat. KC5491. This kit will be complete and will include the Venice 7 radio module, double-sided plated-through PC boards, a pre-punched custom steel case with screened lettering and the remote control. The main board will be supplied with the dsPIC microcontroller (IC1) soldered in place. Kits will be available by early December and can be pre-ordered at your local Jaycar store. 70  Silicon Chip give the unit a professional finish. Having the microcontroller already soldered in place is a real bonus. It will save you the hassle of having to solder this part in by hand and risk ruining the main board. The DAB+/FM Stereo Tuner will take you quite a few hours to build, so it’s best to tackle it in stages. There are two PC boards to build: (1) a main board which carries the Venice 7 module, the microcontroller, the power supply components and several input/output connectors; and (2) a front panel board which carries the LCD, switches, rotary encoder and the IR receiver. You will need only a few basic tools siliconchip.com.au CON10 CON14* Pt.2: By MAURO GRASSI CON13 CON9 4 1 3 2 CON11* L 330 510 Q4 100nF 33k R44 CON12* 1 AG + 100nF 100 2.2nF 2.2nF 100nF REG1 7805 L R CON3* 1 CON2* 1000 F 560 CON1 56k 15nF 1nF + D1 IC3 LM833N 620 100nF 100nF IC5 4066 1nF 2200 F D2 220nF 3.0k 100nF GND 9VAC 510 R 100 AG 33k 220 620 15nF 3.0k 560 1N4004 33k 56k Q3 220nF 2.2k 510 + CON15* 2200 F REG2 7905 IC4 LM833N 100nF 1k 100nF 1N4004 D3 REG4 LM3940 330 470 F + REG5 + 100nF 100nF 100 F 100nF 470 F CON5* Q5 1 100nF K A 220 LED2 33k* 10k 33k* 220 CON7* 1 F 16V* K A + 56k 4.7k CON6* 33k* 33k* (SD MEMORY CARD SOCKET) 33k* 100nF 10k CON16* 33pF IC1 CON8 1 100nF 4.7k 100nF 1 33pF 330 100nF Q2 X1 1 33k 1 + 10 F 2.2 220 100 33k 33k* 1k Q1 1k 10 10k 330 1k 510 CON4 (ON REAR OF BOARD)* IC2 74HC00 LM317T + siliconchip.com.au 470 F 33k 330 * LM3940 VENICE7 DAB+ RECEIVER MODULE 1000 F + REG3 Main board assembly We’ll begin with the main board assembly. This double-sided board is coded 01110101 and measures 114.5 x 194mm. As mentioned, it’s supplied with IC1 already soldered into place and should be carefully inspected for defects before proceeding. Refer now to Fig.3 for the main board parts layout. Begin the assembly by installing the resistors, taking care to fit the correct value at each location. Table 2 shows the resistor colour codes but we strongly advise that you check each one using a DMM before installing it. Follow these with the three 1N4004 diodes (D1-D3). These must go in with their striped ends orientated as shown. The four IC sockets (for IC2-IC5) can then go in with their notched ends matching the board layout. Follow these with the ceramic, monolithic, MKT and electrolytic capacitors, in that order. Make sure the electrolytic capacitors go in the correct way around and note that some of the 100nF capacitors are MKT types + 100nF to build the tuner – a soldering iron (preferably a temperature-controlled type) with a fine tip, a pair of needlenose pliers, a pair of side cutters and an Allen key. A DMM (digital multimeter) is also necessary. LED1 * INSTALL CON4 ON REAR OF PC BOARD WITH KEY SLOT TOWARDS IC1 * DO NOT INSTALL – MAY BE USED FOR FUTURE EXPANSION Fig.3: install the parts on the main PC board as shown here. Make sure that all polarised parts are correctly oriented and note that CON4 is installed on the rear of the board with its keyway towards IC1. (around the regulators and op amps) while the others are monolithic types (around IC1 and IC2). Note also that some 100nF mono- lithic capacitors have a lead spacing of 0.1-inch (2.54mm) whereas others have a 0.2-inch (5.08mm) spacing. The PC board uses 0.1-inch spacing so if the November 2010  71 The completed main board assembly is installed at the righthand end of the chassis. Leave the Venice 7 module and ICs2-5 out until after the initial power supply checks have been completed (see text). Table 1: Capacitor Codes Value 100nF 15nF 2.2nF 1nF 33pF µF Value IEC Code EIA Code 0.1µF 100n 104 .015µF 15n 153 .0022µF 2n2 222 .001µF 1n 102   NA 33p 33 capacitors supplied are 0.2-inch types, you will have to bend their leads with needle nose pliers to make them fit. Next, install the 2-way screw terminal block for CON1. CON 2 & CON11 are 3-way screw terminal blocks but it’s not necessary to install these (or any other parts marked with a red asterisk) and they are not included in the kit. If fitted, they give on-board access to the two stereo audio outputs, which may be useful for a future modification. The BC337 NPN transistor (Q1) can be installed next, followed by the 72  Silicon Chip three BC327 PNP transistors (Q2-Q4). These transistors must go in the right way around. Push them down onto the board as far as they will comfortably go (but don’t over-stress the leads) before soldering them into place. Follow these parts with the 2N7000 FET (Q5), the 7.3728MHz crystal (X1) and the two 3mm LEDs (LED1 & LED2). The latter must be correctly orientated (see Fig.3) and are installed so that they sit flush with the surface of the PC board. Installing the regulators The five 3-terminal regulators (REG1-REG5) are next on the list. As shown in Fig.3, these are all installed with their metal tabs flat against the PC board. This is done by first bending their leads down through 90° about 5mm from their bodies and then securing them to the PC board using M3 x 6mm machine screws, flat washers and nuts. Note that REG1 & REG2 must be fitted with mini heatsinks under their tabs but these are not necessary for REG3-REG5. Tighten the mounting screws down firmly before soldering the regulator leads to the board. Don’t solder the leads first, otherwise the solder joints and PC board tracks may fracture when the screws are tightened. Sockets & connectors Two 7-pin female header strips can now be installed to make up the 14-pin (ie, 2 x 7-way) socket for the Venice 7 module. Once these are in, use 2 x 7-pin and 2 x 8-pin strips to make up the 30-way socket for the other side of the module. These 14-way and 30-way sockets allow the Venice 7 module to be easily removed later on, if required. The connectors can now be installed along the rear edge. This involves fitting the stereo RCA connector (CON9), the TOSLINK transmitter (CON10) and the DB9 serial port (CON13). Once these are in, install the 40-way siliconchip.com.au vertical IDC header CON4 on the rear of the board. It’s important that CON4 be orientated correctly. It must be installed with its key slot towards IC1, so that its pin 1 (indicated by a small triangle on the black plastic housing) goes to the square pad. The memory card socket (CON8) is next on the list. This is a surface-mount socket and is mounted on the top of the board. Begin by positioning the memory Table 2: Resistor Colour Codes o o o o o o o o o o o o o o o o siliconchip.com.au No.   3   6   3   2   2   1   6   2   2   4   6   4   4   1   1 Value 56kΩ 33kΩ 10kΩ 4.7kΩ 3kΩ 2.2kΩ 1kΩ 620Ω 560Ω 510Ω 330Ω 220Ω 100Ω 10Ω 2.2Ω 4-Band Code (1%) green blue orange brown orange orange orange brown brown black orange brown yellow violet red brown orange black red brown red red red brown brown black red brown blue red brown brown green blue brown brown green brown brown brown orange orange brown brown red red brown brown brown black brown brown brown black black brown red red gold brown 5-Band Code (1%) green blue black red brown orange orange black red brown brown black black red brown yellow violet black brown brown orange black black brown brown red red black brown brown brown black black brown brown blue red black black brown green blue black black brown green brown black black brown orange orange black black brown red red black black brown brown black black black brown brown black black gold brown red red black silver brown November 2010  73 330 100 LED3 S7 LCD MODULE + 330 IRD1 10 F* D4 4148 D5 4148 D6 4148 D7 4148 100 F* + 100nF* S8 CON17* 1k 1k 1 100nF* SG16080E ROTARY ENCODER + 1000 F* Fig.4: follow this diagram to install the parts on the front panel PC board. Note that the IDC header (CON17) and all five capacitors are mounted on the rear of the PC board (see photo below). This is the fully-completed front panel board, with the switch caps installed and the L-brackets mounted in position. Be sure to align IRD1’s lens vertically with LED3 and with its domed top 11mm above the board, as described in the text. This rear view of the display board shows how the IDC header and capacitors are installed. Be sure to install the IDC header with its key-slot towards the bottom edge of the board. card socket so that its two plastic locating pins fit into two matching holes in the PC board. That done, use some sticky tape to hold it in place while you solder the two metal tabs on the sides of the connector. The tape can then be removed and the remaining 13 terminals carefully soldered to 74  Silicon Chip their respective pads. Take care with these and avoid touching the plastic connector with the soldering tip. Venice 7 module The Venice 7 module connects to the main board via 30-way and 14-way pin headers. It’s supplied with the 30-pin (2 x 15-way) header already in place but you will have fit the 14-pin (2 x 7-way) pin header yourself. To do this, first cut a 2 x 7-way header from the supplied 2 x 20-way header using side cutters. The 2 x 7way header can then be carefully soldered to the Venice 7 module (see photo). siliconchip.com.au S1 S4 S2 S5 S3 S6 * MOUNT CON17 & ALL CAPACITORS ON REAR OF BOARD The Venice 7 module comes with a 30-pin header already in place but you have to also solder in a 14-pin header (near the opposite edge) yourself. Additional 14-pin header As usual, begin by carefully inspecting the PC board for hairline cracks or unintended shorts between nearby tracks (use a magnifying glass if necessary). Manufacturing defects are rare but possible and it is much easier to spot any problems before the parts have been installed. Fig.4 shows the parts layout. Start the assembly by installing the resistors, then install the four 1N4148 signal diodes (D4-D7). Make sure that the latter are orientated correctly, ie, with their cathodes to the left. The capacitors can be installed next. These must all be installed on the rear of the PC board – see photo. Make sure that the three electrolytic capacitors go in with the correct orientation. The eight pushbutton switches and the rotary encoder are next on the list. These parts will only fit the right way around. Be sure to push the plastic locating pins on the pushbuttons into their corresponding holes so that the switches sit flush against the board and are straight. The blue LED (LED3) can now be fitted. It must be correctly orientated and installed so that the top of its lens sits 14mm above the board. This can be done by inserting a 9mm cardboard spacer between its leads and pushing the LED all the way down onto this before soldering. Follow with the infrared receiver (IRD1). This goes in with its leads bent down by 90° and its domed lens facing upwards (so that it will later face the front panel). Adjust IRD1 so that the top of the lens is 11mm above the board surface and is vertically aligned with LED3 before soldering its leads. All that remains now is to install the 40-pin IDC header and mount the LCD module. This header goes on the rear of the board (see photo) and must be orientated so that its keyed slot is towards the bottom edge of the board – see Fig.4. Mounting the LCD That completes the assembly of the main board apart from installing the Venice 7 module itself and fitting ICs2-5. Leave these parts out for the time being. Front panel board assembly Like the main board, the front panel board is doublesided with plated through holes. It is coded 01110102 and measures 277 x 57mm. siliconchip.com.au Now for the LCD. This must first be fitted with a 20-pin header strip, obtained by cutting eight pins off the supplied 28-pin strip. This can easily be done using side cutters. Solder the 20-pin strip into place, then mount the LCD module on the PC board as shown in Fig.5. Note that two M2 nuts are fitted between the LCD module and the board at each corner location, to provide a 3mm spacing between the two. Note also that you will have to file away a small section of the head of one of the four mounting screws so that it clears the LED backlight assembly installed inside the LCD module. This is the screw that fits in the top right corner when viewing the LCD module in the normal orientation. In addition, it may be necessary to file a small notch in bottom-left corner of the IDC socket (as viewed from the back of the board) to clear the adjacent mounting nut. Tighten the assembly down firmly, then solder the 20 header pins from the LCD module to the display board. Work quickly November 2010  75 tors at the rear are correctly centred in their rear panel cut-outs before tightening the screws down. Front panel board mounting Above: this view shows how the 20-pin SIL header strip is fitted to the LCD module. M2 NUT 2 x M2 NUTS FRONT PANEL PC BOARD M2 NUT LCD MODULE (FRONT) M2 x 15mm SCREW M2 x 15mm SCREW 2 x M2 NUTS Fig.5: the LCD module is attached to the front panel board using M2 x 15mm machine screws and nuts, with additional M2 nuts (ie, two at each corner) used as spacers. during this procedure and do not apply heat to any pin for more than five seconds. The front panel board assembly is now complete except for the switch caps. These are best left off until the board is mounted in the case, so that they don’t get lost. Mounting the main board The two PC board assemblies can now be installed in the metal case. As mentioned earlier, the Jaycar kit will come with a pre-punched case with screened lettering on the front and rear panels. This makes the final assembly easy, since you don’t have to drill any holes. Figs.6 & 10 shows the mounting details for the main board. It sits on stacked M3 x 10mm metal spacers in the righthand section of the case. The first step is to secure the stacked spacers to the bottom of the case using M3 x 16mm countersink head (CSK) screws – see Fig.6. That done, fold the 40-way IDC cable at right angles exactly as shown in Fig.7 (note the position of the lead with the red stripe). Check the cable carefully against Fig.7, then plug the righthand header into CON4 on the underside of the main board. The lead with the red stripe should go to pin 1 of the board header – see Fig.3. You should find that the IDC cable emerges from the lefthand side of the main board under transistor Q2 and the vacant holes for CON16. Important: if the headers on the supplied IDC cable do not have a key (to match the key slot in the board header), then make sure that the side with the red stripe goes to pin 1 of the board header. This pin is indicated on the parts layout diagram (Fig.3) and is also adjacent to a small triangle on the plastic body of the header. The main board can now be mounted on top of the stacked spacers and secured using four M3 x 5mm machine screws (black). Check that the connec- MAIN PC BOARD This board is attached to the top and bottom rails on the back of the front panel using six L-shaped metal brackets. Before fitting the board though, you will need to remove the front panel from the case by undoing the screws at either end and along the bottom edge. Each L-bracket has one M3 tapped hole and one untapped hole. Fig.8 shows how they are attached to the display board using M3 x 10mm countersink (CSK) head machine screws and nuts into the untapped holes. Note that a flat Nylon washer is fitted between each L-bracket and the PC board. Be sure to adjust each bracket so that it sits square with the PC board before tightening its mounting screw (see photo). This is necessary so that they later line up with the mounting holes in the front-panel rails. A couple of test fittings may be necessary before you get them exactly right. Before finally mounting the front panel board, it’s a good idea to fit the power switch. This should be orientated so that it is ON when the rocker is down and this can be determined by checking it with a multimeter (set to Ohms). In practice, this means that it goes in with the contact that’s closest to the edge towards the top (ours is in the wrong way around). Once the switch is in place, slip the front panel board assembly into position and secure it to the front panel using six M3 x 10mm countersink (CSK) head screws. These go through the top and bottom rails and into the tapped holes of the L-brackets. The completed assembly can then be re-fitted to the case and the knob attached to the shaft of the rotary encoder. You will need an Allen key to tighten the small grub screw inside the M3 x 5MM MACHINE SCREWS 2 x 10mm LONG TAPPED SPACERS RIGHT SIDE LIP BOTTOM OF THE CASE Fig.6: the main PC board is mounted on stacked M3 x 10mm spacers and secured using M3 x 16mm CSK machine screws from underneath and M3 x 5mm screws through the top. M3 x 16mm MACHINE SCREWS WITH COUNTERSINK HEADS 76  Silicon Chip siliconchip.com.au 40-WAY IDC LINE SOCKET (TO UNDERSIDE OF MAIN BOARD) (330mm LENGTH OF 40-WAY IDC RIBBON CABLE) CABLE EDGE STRIPE 40-WAY IDC LINE SOCKET (TO REAR OF FRONT PANEL BOARD) knob (align it so that the grub screw tightens against the flat section of the “D” shaped shaft). Now check that there is sufficient clearance between the knob and the front panel when the rotary encoder is pressed. Provided you’ve mounted the front panel board correctly, it should be OK with the knob pushed all the way onto the rotary encoder’s shaft. Power supply wiring The next step is to install the power socket on the rear panel and run the supply wiring – see Fig.10. As shown, the sleeve terminal of the power socket (which connects internally to chassis) goes directly to the GND terminal of CON1. This lead can be run using a 340mm length of black medium-duty hook-up wire. Note how the wire is threaded through a spare hole near the edge of the main PC board, to help anchor it. The centre terminal of the power connector is connected to the power switch using a 210mm length of yellow hook-up wire. A third yellow lead (360mm-long) is then run from the remaining switch terminal and is looped through another anchor hole before finally connecting to the 9VAC input of CON1. Eight small cable ties should now be fitted to secure the supply wiring in place. These not only keep the siliconchip.com.au Fig.7: the supplied IDC cable should be trimmed at one end and folded exactly as shown here. M3 x 10mm CSK HEAD SCREWS wiring tidy but also prevent the leads from moving and coming adrift at the terminals. Preliminary checks With construction virtually complete, you now have to make a few preliminary checks on the power supply before installing the Venice 7 module and ICs2-5. These checks should also be made before plugging the IDC header into the front panel board. The step-by-step procedure is as follows: Step 1: check that the Venice 7 module and ICs2-5 are all out of circuit. Check also that the IDC header to the front panel board is unplugged. Step 2: with the lid of the case off, connect a 9V 500mA AC plugpack and apply power while observing LEDs 1 & 2 on the main board. LED1 should light and stay on, while LED2 should light only briefly. If they don’t, switch off immediately and check the supply wiring and the regulator circuitry on the main board. Step 3: if Step 2 checks out, check the output voltage of the LM317T regulator (REG5) with respect to GND. It should measure close to 1.2V. Similarly, check the output voltages from the two LM3940 regulators (REG3 & REG4) – they should both measure close to +3.3V. * METAL BRACKET M3 NUT NYLON FLAT WASHER FRONT PANEL FRONT PANEL PC BOARD * NOTE: VERTICAL SCREWS MATE WITH M3 TAPPED HOLES IN BRACKETS METAL BRACKET * Fig.8: here’s how to attach the Lbrackets to the front panel board and secure the assembly to the top and bottom rails that run along the back of the front panel. If any of these voltages are incorrect, switch off immediately and locate the cause of the problem. Step 4: check the outputs of the 7805 and 7905 regulators – they should measure close to +5V and -5V respectively. If they do, all is well and you can proceed. If not, switch off and clear the fault before proceeding. Note: when making these voltage checks, check the pin-out diagrams for the regulators as shown in the cirNovember 2010  77 COAXIAL CABLE FROM ANTENNA SOLDER SHIELD BRAID HERE SOLDER CENTRE CONDUCTOR HERE 14-WAY DIL PIN HEADER (UNDER) When power is first applied, the tuner should display the SILICON CHIP logo for about three seconds before warning that no stations have been programmed. VENICE7 DAB+ RECEIVER MODULE 30-WAY DIL PIN HEADER (UNDER) Fig.9: the centre conductor of the coax cable from the antenna socket must be soldered to the Venice 7 module in the exact location shown here. cuit diagram (Fig.1) in Pt.1. The pinouts differ from regulator to regulator, so don’t get caught out here. Final assembly With the power supply checks complete, it’s time for the final assembly. This must be done with the power off, so disconnect the plugpack supply for the time being. The antenna socket can now be fitted to the rear panel. Secure it by tightening down the nut firmly, then connect a 100mm length of 75Ω RG59 cable to it – see Fig.10. As shown, the shield wire must be twisted into a lead and soldered to the earth lug. Keep the stripped leads of the coaxial cable as short as possible, to avoid degrading the sensitivity. Once that’s done, solder the other end of the 75Ω coax cable to the Venice 7 module’s antenna terminals as shown on Fig.9. Note that there are two separate antenna inputs on the module – one for Band 3 (VHF) and the other for L-band. Band 3 is the most commonly used and is correct for Australia. It’s simply a matter of soldering the inner conductor of the antenna cable to the pad in the exact position indicated on Fig.9, while the shield is soldered to one of two nearby gold-plated earth pads. The Venice 7 module can then be plugged into the main PC board. Finally, plug in ICs2-5, connect the IDC header to the front panel board and fit the black plastic caps to the eight pushbutton switches. Be sure to orientate the ICs correctly and don’t get the two 14-pin types mixed up. In addition, make sure that the red-striped lead on the IDC cable goes to pin 1 of the header, as shown on Fig.10. These switch caps are simply push­ ed into place. If you like, you can apply a small amount of glue inside the caps before fitting them although this shouldn’t really be necessary. Final testing Now for the final test. Apply power This view shows the rear-panel layout of the DAB+/FM Stereo Tuner and also shows how the display board is mounted on the back of the front panel. 78  Silicon Chip siliconchip.com.au siliconchip.com.au NOTE: SHOWN HERE 50% OF ACTUAL SIZE WIRE 360mm LONG FRONT PANEL BOARD MOUNTING BRACKETS MAIN PC BOARD SCREW TERMINAL BLOCK CON1 CABLE TIES CON1 + + 1 9 4 5 CK ra cyaJ 0 4 3 8 CE FRONT PANEL 1 + 01110101 Main MG 0 2 / 5 G M ni a M 1 0 1 0 1 1 1 0 0 15/2010 0 1 0 2 / 5 G M ni a M 1 0 1 0 1 1 1 0 + + POWER ON/OFF SWITCH FRONT PANEL PC BOARD CABLE TIES That completes the assembly of the unit. Next month, we’ll explain the initial set-up and give detailed instrucSC tions on how to operate it. WIRE 340mm LONG Next month ANTENNA SOCKET + + + November 2010  79 GND 9VAC Fig.10: here’s how everything goes together inside the chassis. Note how the supply wiring is looped through a couple of spare holes in the main board and is secured using eight small cable ties. Don’t get the connections to CON1 mixed up. WIRE 210mm LONG GND 2.1mm CONCENTRIC POWER CONNECTOR, PANEL MOUNTING + to the tuner and check that the LCD lights up. It should display the SILICON CHIP logo for about three seconds (see photo) and then give a warning stating that no digital or FM stations have been programmed in. It should then default to 104.1MHz in FM mode. Assuming this is correct, switch off and attach the lid to the case, securing it using the seven supplied M4 x 6mm screws (three along the top and two at either end). (REAR OF BOX) +