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An error analyser for CD players, Pt.3 This month, we conclude our series of articles on the CD error analyser by giving the constructional details. We also show you how it is connected to typical CD players. By STEPHEN McBRIDE If you haven't already realised it, this is definitely not a project for one who is just starting out in electronics. While the construction of the CD error analyser itself is relatively straightforward and no more complicated than, say, a digital frequency meter, you also have to make connections 72 SrucoN CHIP inside your CD player. And that means you have to know what you are doing. But before we go into how the connections are made, let us discuss the construction of the CD error analyser. As shown in the photos in this and the two previous articles, the CDEA is built onto two PC boards housed in an attractive low profile case which is readily available (Jaycar Cat. HB5915). A third PC board is housed inside the CD player, to make the buffered connections to it. Most of the connections between the two PC boards are made by simply butting them together at rightangles and soldering the adjacent pads. Before you start assembling the boards, it's worth spending a few minutes ,with a continuity tester to check there are no shorts between adjacent tracks, especially on the display board where many of the tracks are closely spaced. Once that is done, install the 14 wire links on the main board using tinned copper wire- see Fig.3. Stretch the wire slightly before cutting it into lengths so that the links are straight. GROMMET I Fig.3: the main wiring diagram for the error analyser. Be sure to use insulated mains-rated hookup wire for the bypass link at the bottom left of the board & take care with component polarity. An on-board power supply is shown here but you can also wire the board to accommodate external supplies. The link for the overflow indicator can be installed in one of three positions , depending on how many digits for the interpolation readout are desired. The holes are marked on the PC board as '4', '5' & '6' while the common is marked 'OF'. Just link the 'OF' pad to the appropriate hole. Next mount the resistors and diodes, paying particular attention to the orientation of the diodes. The 74C926's aren't cheap so it is worthwhile fitting IC sockets. Take care not to form a solder bridge between adjacent pads. Don't use a socket for the MOC3041 optocoupler; it is soldered straight in later (if used). The 7-segment displays are mounted in sockets. These can be proper IC sockets or a row of Molex pins. As noted previously, the display PC board mounts at right angles to the main PC board. Rather than just form a solder bridge across the adjacent solder pads, I fitted right-angle wire links for added stability. These links were pulled out of 0.1-inch right-angled PC board pin launchers. Once the two boards are butted together, tack solder the two outermost end pads, then check that the boards fit into the case correctly. If they don't, re-melt the solder and adjust the assembly until a proper fit is obtained. Once you are satisfied that all is well, finish soldering all the others. Again, be careful of solder bridges forming between adjacent tracks. Now install the capacitors and transistors, paying attention to the polarities. Note that Q4 is a PNP type BC328 while all the others are NPN types (BC338). If the Farnell transformer is used, it can now be fitted, making sure it is pushed down snugly against the board. Likewise the heatsink can now be fitted and it too should be pushed in tight. Use a large tip on your soldering iron to solder the heatsink lugs to the board; remember that it is a heatsink and so it will naturally draw a lot of heat away from the pins. Give it ample time to cool as it will be very hot after soldering. Now bend the leads of the 7805 regulator slightly so it sits flat on the heatsink. Remove the 7805 . wipe a smear ofheatsink compound over the back surface of the regulator and refit it. Fix it to the heatsink using a screw & nut, then solder in the leads to the board using a fine-tipped iron. There's no need for a mica insulator pad. Now the two ribbon cables can be fitted if the 5 or 6-digit option is used. Note that the two cables cross over each other. Follow the wiring diagram (Fig.3) for the connection details. Four PC stakes are also fitted where indicated. Two are used as a manual counter reset by shorting them together, out only when the automatic reset facility isn't implemented. The other pair, when shorted together, inhibit the MUTE control line from disabling the counters, so both counters will register counting when a search function is implemented (ie, track jumping), thus verifying that the counters are operating correctly. This NOVEMBER 1991 73 Fig.4: this is the wiring for the satellite PC board. It is connected to the main board in the error analyser via a 6-way shielded cable while the remaining external wiring points go to the CD player (see text). MUTE 2 MOTE1 6-CORE _ SHIELDED CABLE Ii D pair is marked 'TEST' on the PC board. Diodes Dl-D7 and DlO are for protection purposes. D13 is used to match the brightness of displays 9 & 10 to displays 1-8. Without it, non-standard value resistors would be needed. The front panel is a piece of neutral gray filter acrylic cut to size by deeply scoring a line, then breaking it away from a 220 x 130mm sheet. Be careful not to scratch it during handling. The lettering was put on using standard white Letraset®, which is available from drawing office suppliers. Satellite PC board Fig.4 shows the assembly details for the satellite PC board. This is connected to the main PC board by a 6- core shielded cable. If you wish, you can hard wire the two together, but I chose to fit a 7-pin DIN socket to the rear panel of my CD player, and have a flying cord from the CDEA fitted with a matching 7-pin DIN plug, so that the two units can be separated. Drill two holes in the back panel of the instrument case to suit the power and data cables, and install rubber grommets. Feed the cable through the grommeted holes and solder them to the appropriate holes on the PC board. For the 240VAC cable, the Brown wire is Active, Blue is Neutral and Green/ Yellow is Earth. For the data cable, the colour combination is not critical; just be sure that you're consistent. Important: don't connect any of the data wires, especially the shield, to the metal shroud of the plug/socket as you would normally do; to do so would mean connecting the OV rail of the CD player to its chassis and this could cause damage. To help prevent accidental contact with the 240VAC mains tracks on the PC board, place a strip of insulation tape on the inside of the case over the ventilation holes directly under the transformer primary terminals and mains input terminations. Now screw the main PC board into the bottom half of the instrument case and attach the cable restraints to the two cables. Don't fit the LED displays or ICs into their sockets yet. The satellite PC board can now be constructed by following the component overlay diagram. The lOkQ linking resistors at the inputs to the comparators must be fitted to suit the polarity of the tapping points in your CD player. The requirements for the inputs to the main PC board are: UNEC and HFD inputs are normally low and go high when an error occurs; MUTE is normally low and goes high during searching and/or track jumping, pause etc; FCO is normally high and goes low to initiate a counter reset on startup. Connecting the CD player The main & display PC boards are soldered together at right angles & are mounted behind a neutral gray acrylic filter inside a plastic instrument case. Take care when installing the mains wiring. 74 SILICON CHIP The fun part is finding the correct places to tap into the CD player's circuits to pick off the required signals, assuming that the machine you have has the necessary tapping points. A service manual, or in some cases just the circuit diagram, should have sufficient information for you to locate the appropriate tapping points. Remember, each manufacturer has their own terminology and abbreviations or jargon, and they also have different ways of performing the decoding process. The names, titles and abbreviations used in most of this text are all based arounp. the Philips chipsets, and are intended to be used as generic rather than specific terms. Philips themselves use SMSE, MUSB and MUTE to mean 'MUTE', depending on which generation of chipsets is being referred to. As another example, the line marked 'DEFECT' on the Sony CXA1081S (pin 21) appears to be the same as HFD. Most manuals provide a cross- Table 1 · DEVICE PACKAGE DEVICE DESCRIPTION SIGNAL NAME DIRECTION PIN No. TDA5708 28-pin OIL 28-pin OIL 28-pin OIL HFD HFD HFD HFD PLLH HFD Output HI TDA8808 SAA7010 Photodiode Sig. Proc. Photodiode Sig. Proc. Demodulator, Decoder 19 10 6 SAA7210 SAA7310 SAA7310 SAA7000 SAA7020 40-pin 40-pin 44-pin 18-pin 40-pin OIL OIL QFD OIL OIL 40-pin 40-pin 44-pin 24-pin 28-pin OIL OIL QFP OIL OIL HFD HFD HFD UNEC UNEC UNEC UNEC UNEC UNEC FCO HFD HFD SAA7210 SAA7310 SAA7310 Deco.der, ERCO, CIM Decoder, ERCO, CIM Decoder, ERCO, CIM lnterpolator, Muting CIRC Error Corrector Decoder, ERCO, CIM Decoder, ERCO, CIM Decoder, ERCO, CIM Digital Filter, CIM Input HI Input HI Input HI Input LO Output LO Output LO Output LO Output LO Input LO 28-pin 16-pin 16-pin 40-pin OIL OIL OIL OIL SAA7220 TDA5708 TDA8808 HEF4094 HEF4094 SAA7020 Photodiode Sig. Proc. Photodiode Sig. Proc. Expander for MAB8440 Expander for MAB8440 CIRC Error Corrector HFD UNEC UNEC EFAB EFAB EFAB EFAB FCO FCO RD SIRD FCO SAA7310 SAA7320 40-pin DIL 44-pin QFP 44-pin OFP Decoder, ERCO, CIM Digital Filter, CIM Digital Filter, CIM Decoder, ERCO, CIM Decoder, ERCO, CIM 256x0/S,Bit Strm.DAC MUTE MUTE MUTE MUTE MUTE MUTE MUTE MUTE SMSE SMSE MUTE ATSB MUSB MUTE MUTE MUTE SAA7320 44-pin QFP 256x0/S,Bit Strm.DAC MUTE ATT SAA7210 SAA7220 SAA7220 SAA7310 40-pin OIL 24-pin OIL 24-pin OIL Output HI Input HI Output LO Output LO Output HI Output HI Input HI Input Input Input Input Input Input HI HI HI HI HI HI Input HI 26 26 34 5 36 36 36 4 21 6 14 4 39 11 22 23 11 18 35 36 Note: if the SAA7220 is fitted, the MUTE line on the SAA7210 and SAA7310 is usually not used. Therefore, it is preferable to use both the ATSB and MUSB lines on the SAA7220 if they are connected. All the above points normally run as +5V logic but check just in case your machine doesn't. reference of abbreviations and special circuit symbols. If in doubt, use a logic probe to help you make a decision. If your machine has a Philips chipset fitted, Table 1 gives the relevant connection points. 'Signal' is the CDEA data line name. 'Name' is the data line name most likely to appear on a circuit diagram of the device in question. 'Direction' indicates if the signal is an input or an output, and if the line is normally high ('HI') or normally low ('LO'). This applies while in the play mode with no errors for HFD and UNEC; in the play mode for MUTE (ie; not in stop, search, pause, etc); and in the stop mode for FCO (prior to the reset command being given). Be careful: not all manufacturers utilise the ICs to the fullest exte.n t so the fact that say, the SAA7210, has a input doesn't mean it is used, even though the machine may be fitted with a TDA5708 which has an HFD output signal intended for the SAA7210. Sure it sounds strange but these setups do exist so check that the inputs to each device actually do come from somewhere, and not just a termination resistor, by tracing the tracks. The servo microprocessor is normally one of the MAB84x0 or 68xx series, depending on which model player you have. The following information is only intended as a guide; your machine may be different. There are several combinations of ICs possible, depending on the model and manufacturer of the player, so determine which devices are in your machine. To configure the satellite PC board HFD to suit the polarity of the data lines from the CD player, the lOkQ linking resistors must be installed correctly. Refer to the PC board component overlay to find hole locations and designations and to Table 2 to determine the link positions. The label 'lOkQ link A-B' means install a lOkQ resistor across the holes/pads marked A and B on the overlay diagram. Leave any holes or pads not mentioned vacant. For machines using chipsets from other vendors, the relevant lines will need to be identified, then the link setup for the satellite PC board set to suit that machine's circuitry. Remember, some machines don't provide external access to the necessary information and control lines so unfortunately, there's nothing you can do. Here's an example: for a Philips NOVEMBER 1991 75 Table 2 · SIGNAL POLARITY DURING INSTALL 1OkO COMMENTS HFD HFD UNEC UNEC FC0 FC0 Norm. Norm. Norm. Norm. Norm. Norm. Play mode Play mode Play mode Play mode Stop mode Stop mode M-L and K-J M-K and L-J A-C and B-D A-Band C-D F-H and E-G F-E and H-G Pulses high on dropout Pulses low on dropout Pulses high on dropout Pulses low on dropout Goes high on start-up Goes low on start-up low high low high low high For MUTE, there are several possible combinations: (1 ). One Mute line; ie, MUTE, SMSE, etc. Wire link T-U; connect to MUTE1 input.; if Norm. low, 10kO link S-R and Q-N; if Norm. high, 10kO link S-Q and R-N. (2). Two Mute lines, same polarity; ie, ATSB and MUSB, etc. Wire link V-W, connect one line to MUTE1 and the other to MUTE2 input. If Norm. low, 10kQ link S-R and Q-N; Rx3 = 47kO; install 2 diodes, 1N914 anode to Yand cathode to X, 1N914 anode to U and cathode to T. If Norm. high, 10kn link S-Q and R-N ; Rx4 = 47kO; install 2 diodes, 1N914 anode to X and cathode to Y, 1N914 anode to T and cathode to U. (3). Two Mute lines, opposite polarity; ie, one Norm. low and one Norm. high. RX3 = RX4 = 47kO; 22kQ link T-U and X-Y; 10kO link P-R and S-Q; connect Norm. low line to MUTE2 and Norm. high line to MUTE1. Notes: Norm. low= normally low during play, goes high on Pause, Search, etc; Norm. high= normally high during play, goes low on Pause, Search, etc. CD960, the machine has a TDA5708, a SAA7210 and a SAA7220. So first find HFD. Pin 19 of TDA5708 is HFD output and pin 26 of SAA7210 is HFD input. Tracing the tracks shows that the two are connected, therefore we can tap into any convenient point between the two devices or onto the IC pins directly. This HFD is Norm. high so we fit 10k0 resistors across M-K and L-J. Now we want UNEC. Pin 36 of the <at> SAA7210 is the EFAB output and pin 4 of the SAA7220 is an EFAB input and tracing reveals they are linked. EFAB is Norm. low so UNEC Norm. low requires 10k0 linking resistors across A-C and B-D. What about FCO? The TDA5 708 has an RD output on pin 21, so we can use this. Since it is an output (ie, it generates a signal), it really doesn't matter where it goes to. So we just follow the track to a convenient point. From the chart, we need to 10k0 link F-H and E-G. That leaves MUTE. The SAA7220 has ATSB (pin 22) and MUSB (pin 23) which both trace back to the control microprocessor, therefore we use these in preference to the MUTE on the SAA7210, which in this case isn't connected anyway. ATSB and MUSB are both Norm. high so we configure the PC board for two MUTE lines, same polarity, Norm. high. This involves 10uF © C) + OPTION 1 OPTION 2 Fig.5: here's how to wire the main PC board for use with an external power supply. Option 1 is for power transformers (or plugpacks) with a single 7.5VAC winding, while option 2 is for transformers with a 12V centre-tapped winding. Make Rx2 = on if the CD player's control voltage is 5V, 390Q if the control voltage is SV, and 680Q if the control voltage is 12V. 76 SILICON CHIP 10kQ linking S-Q and R-N, fitting a 47kQ resistor for Rx4, and fitting a wire link across V0 W. Finally, we install the two 1N914 diodes; the first with anode to X and cathode to Y, and the other with anode to T and cathode to U. ATSB connects to either MUTEl or MUTE2 and MUSB connects to the other. That's all there is to it! How about a Philips CD104? This machine uses the SAA70x0 series devices, so: for HFD, we link J-L and K-M and tap onto SAA7010 pin 6; for FC0, link E-F and G-H and tap onto pin 14 of the HEF4094 adjacent to the MAB8440 microprocessor; for UNEC, link A-C and B-D and connect to SAA7000 pin 5 or SAA7020 pin 36; and for MUTE, link R-N and Q-S, wire link T-U and connect pin 39 of the SAA7020 or pin 14 of the HEF4094 (adjacent to MAB8440) to the MUTEl input. Just take your time to avoid careless mistakes. Once you have installed the required components, connect small wires from the input holes/pads and cut to length to suit the location of the tapping points. Also connect up the 6-core data cable, then mount the satellite PC board in a suitable place inside the CD player. I used self-tappers to mount the PC board on 3mm spacers attached to a nylon support bracket. Double check that the wiring of the data cable leaving the CD player is in the same order as the cable coming from the CDEA. Remember that the polarity/direction of the pins of a plug or socket change when you view it from the other side. Don't forget also to connect the satellite board to a 0V rail and to a +V supply, usually +5VDC. Now connect the satellite board to the CD player's circuitry, being very careful not to overheat the tracks or components, especially surface mount components. Once you are convinced that all is well, power up the CD player and check that it is functioning normally. If it isn't, switch off immediately and locate the cause before powering up again. Checking the analyser On the main PC board, there are two spare pads next to the transformer. These are for a link to be fitted which bridges out the optocoupler so you can power the unit up before connecting it to the CD player to verify opera- This close-up view shows the satellite board mounted inside a Philips CD104 CD player. The power supply & signal input terminals are connected to the various points inside the CD player by flying leads. tion. Make sure you use insulated wire for this link, as it is at 240VAC. Apply power, then assuming there is no smoke, check the IC sockets for correct supply voltages on the appropriate pins. If the +5V and 0V lines are OK, turn off the power, wait for the filter capacitor to discharge and then install the lCs. You can also install the LED displays and the two LEDs. There are three pairs of holes provided for the interpolation overflow LED. Use the one closest to the most significant digit. Both LEDs should stand proud of the display board such that the tip is flush with the front of the ?-segment displays. The leads on the dropout overflow LED need to be bent in a zigzag fashion to move its position in closer to the displays. Cut a piece of thick black paper to form a mask around the outside of the displays and a small hole for the LEDs to poke through. This will enhance the unit's appearance by blacking out the area around the displays. Now reapply power and the displays should all light up as zeros. If not, or if either of the overflow LEDs is flashing, shorting the two PC stakes next to the heatsink should reset the condition. Now for the moment of reckoning. If you're satisfied that everything is OK, switch the power off, remove the 240VAC link and install the MOC3041, ensuring it goes in the correct way around. Now connect the CDEA data cable to the CD player, then turn the CD player on and check that everything is functioning as normal. If so, turn the CD player off and apply power to the CDEA. Nothing should happen. If so, turn on the CD player. The CDEA's displays should light up immediately. If you have done everything properly, there should be no dramas at all. Start a disc playing, then short out the two PC stakes next to ICl (4093B). Now put the player in a search mode. If all is working properly, both displays will begin counting. Congratulations, you made it. You can now check out the truth behind those green CD pens for yourself! If there are no sparks but the CDEA doesn't seem to working, it's most likely that the links on the satellite board are not in the correct positions, or the 6-core cable has wires crossed. Either way, go back and check your work. It's all too easy to make a mistake. SC NOVEMBER 1991 77