First a note of warning! Although this project is cheap to build (only 4 small parts in all) it is definitely not for you if you've never held a soldering iron in your hands before. You also need to know the basics on working with electrostatic sensitive devices. Such as grounding yourself and your solder station. You will also need to do some pretty fine soldering work on a specific IC as well as make an 1/8th of a inch cut (with a sharp blade) to metal traces joining some of its pins. Now if this all sounds too critical of a job for you, my advice is, don't sweat it and let someone who's use to doing this kind of work, do the work for you. If this no problem to you, you should then soon enjoy the addition of your new coaxial output.
O.K. I'll assume that if you are reading this, you're probably experienced enough to handle the job and complete it without a hitch (still you should follow the instructions exactly as they are laid out to you). I've manage to complete the project in about two hours , including mounting the hardware (PHONO digital output jack ) on the back of the units.
NOTE: If you are planning to be doing both the coaxial input and output installations you should try working on both project simultaneously step by step, so that you don�t repeat some of the same procedures twice. E.g.: Removing the main board, putting it back etc.
If you are only performing this coaxial out installation then simply follow each steps bellow. TIP: You may find that printing yourself a copy of this entire project (including all images) first, might be easier to work from then off of your monitor screen.
Circuit of your new coaxial output (Figure 2) will connect to Hex/Buffer IC 314 (SN74HCU04AN) of your MDS-JE510 (see Fig B and C )and use available I/O pin 1, 2, 3, 4, 5, 6, 8 and 9 of that IC. Although pin 2, 4, 6, and 8 are initially not connected to any other part of the circuit, pin 1, 3, 5 however are joined together (by metal traces) and are all common with circuit�s ground. Pin 9 comes joined (by a metal trace) to pin 14 VDD of the IC. All of those metal traces have to be physically (cleanly and carefully) cut first in order for the new circuit to work .
Once completed, your new circuit will provide simultaneous digital signals to both the new coax output (phono) jack and optical TOSlink module of the MDS-JE510 unit.
Obviously you could buy or build an external digital signal converter to do the same job really but doing it this way quite simply solves the problem right at the source and saves you money to boot!
-TIPS ON MAKING CLEAN CUTS ON COPPER TRACES-
In order to make a clean cut to any of those small copper traces involved in this project, I find that using a magnifying glass really comes in handy as well as cleaning up the area right after I've made a cut. For that I use a cotton swab moisten with isopropyl alcohol. Also to make sure that the trace I'm cutting won't be a problem, I make two small cuts side by side instead of one big one, spacing them approx. 1/16 of a inch apart and digging or scrapping out the unwanted portion of copper with the end of my blade. To check your cut against continuity, an ohmmeter or multimeter will do the job fine here, though you will need to locate the other end of the trace PRIOR to making your cut as you'll want to check for contiguity (or lack there of) from one solder joint to another (the actual trace being covered with lacquer). Trying to follow a trace that is no wider then 1/64th of an inch across, zigzagging all over the board is not exactly entertaining that's why one of my preferred method is to hold the board against a strong light source (back lighting it) and checking out the cut that way. Still works for me every time!
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1- UNPLUG YOUR UNIT and remove top cover and back panel. Disconnect 110 cord inside connector (push/clip-on type) CN301 in Figure A.
Pull out the three flat type cables that connects to the main board (pull straight out, not at an angle)
NOTE: In all units I've worked on, these flat cables were white.
Unscrew board and unclip PCB holder at front left corner of main board (see Fig A).
Remove main board and flip over (Foil side up) Oh yeah, clean up your bench first : )
Locate IC-314 (Figure A and C) and carefully cut each copper traces that joins pins 1, 3 and 5 (make sure not to cut off any of the other fine copper traces nearby and MAKE SURE THAT YOU ARE WORKING ON THE RIGHT PINS BEFORE CUTTING!!! (Check pin number by turning board over if you have to) Use a continuity checker to make sure that your cut is clean and that connection is really broken off between ground and pins 1, 3 and 5 (check out "TIPS ON CUTTING TRACES" up above for help!).
Again from IC-314, (Figure C) locate pin 9 and carefully cut the trace that is leaving in the direction of the TOSlink module. If you follow this trace you will see that it connects to pin 2 of the optical out TOSlink module (IC-312) which then joins pin 14 VDD of IC-314. You need not be concern with the other trace leaving pin 9 as it simply leads to a dead end.
Cut one insulated wire approx. 6" long, strip ends and solder one end to the ground location indicated in Figure C (Heat up solder while inserting wire from top)
Clip two legs off of any 1/4 watt resistors and bend the wire into M shape figure. See the exact dimension on the right. Clip off any excess. Set one wire aside and from the bottom (foil side) of the board, solder the other one so that it joins pin no 2- 4 and 6 of IC-314 together. (see Figure B and C )
Use a piece of the excess wire or cut yourself a new piece just long enough to join pin 9 of IC-314 to pin 1 of optical out TOSlink module. Figure C. You are now done as far as the underside of your board goes.
Screw main board back into place (Don't forget to push down on the board so as to "snap it" into place onto the plastic board holder) and reconnect the 3 flat type cables.
NOW, FROM THE TOP OF THE IC, solder the other "M" shape wire to pin no 1- 3- 5 of IC-314 (see Figure B).
Cut yourself another piece of wire approx. an inch long (preferably insulated ) and solder one end to pin 8 of IC-314. Solder the other end to any spot of the M shape wire that you've just soldered to pin 1- 3 and 5.
At this point you should cut-out the hole in the rear panel for your Phono (coaxial out) jack . Bring panel well away from PC board before drilling your hole!! Although you can position your jack wherever you prefer, installing it above the Toslink digital output jack as in the coaxial input installation makes the most sense to me.
Install the PHONO jack on your rear panel and solder the 100 ohm � Watt resistor between PHONO jack's center lug and its metal shell casing or ground washer. Mount rear panel into place and (now) solder that ground wire coming from ground location in to the PHONO jack's ground washer. Make sure that ground wire is not caught between the main board and the panel (don't forget any screws!).
Solder a 3" wire to the PHONO jack center lug and solder the 330 Ohm � Watt resistor at the other end.
Solder one leg of the 0.1 �F cap to that resistor, and solder a 3" wire the other leg of the cap. Insert heat shrink tubing over (optional) and finally solder that wire to pin no 6 of IC-314 (Always double check pin location before soldering).
Tie-wrap or tape any loose wires inside the unit and try it out by sending a signal to a sound card, MD or other devices that has coaxial input. If everything works out fine, tighten everything up and put your cover back on.
FOOT NOTE: Once completed, this circuit will supply a digital signal simultaneously to both the coax output (phono) jack and the TOSlink module of the MDS-JE510 unit.
You can BTW buy a proper video cable (75 ohm impedance) specifically design to handle such digital signal, although I have yet had any problems whatsoever using a regular RCA type audio cable. Eventually I might break down and buy that expensive fancy one at the video shop : ) I just can't put a date on it!
I apologies in advance for not having supplied any scanned picture of the MDS-JE510 unit in this project, however if you have any to share, please contact me and let me know. Also if you have spotted any mistake, omissions, typo errors or simply have come up with other ways in which to improve on this project, please feel free to contact me as well.
You can e-mail me at: [email protected]
Thanks,
A.J. Aylestock
[email protected]
