A few years ago, MIRACLE SYSTEMS redesigned their parallel printer interface so that its circuitry now fits safely within the confines of what would appear — from a distance — to be a standard, metal CENTRONICS plug.
Oh, how I wish this had been the original design. I don’t know what your experience was with the older style parallel interface, but if it was similar to mine, then you probably had the misfortune of breaking the blue-plastic, CENTRONICS plug away from BOTH the black box AND the circuit board!
Okay, the misfortune means one of a few things:
1) I am clumsy; AND,
2) my printer is NOT well situated; and/or,
3) the design is unintentionally fragile.
After “breaking” my parallel interface for the umpteenth time, I finally decided that it was time to find my ohm-meter, warm up my 15 watt soldering iron, and make a short adapter cable that separated the CENTRONICS plug from the circuitry.
After opening the interface box and looking at the short jumpers I had previously employed to RE-connect the CENTRONICS plug to the circuitry, it occurred to me that I might as well make a hard wire connnection directly between the circuit board and a standard, 25-pin female D-subminiature plug — the same connector used on the ISA boards of IBM computers for parallel circuitry. Using an “IBM” connector would mean that I would be able to use any length, readily available extension between my QL and the printer.
NOTE: If you are not confident of your soldering skills in tight areas then consider making a non-invasive, adapter cable. Also, neither I nor ZQA! take responsibility for the end results of any hardware modifications that you might make.
For conceptual clarity (?) the following shows the “front” view (i.e., the working end) of the CENTRONICS plug, and the “rear” view of the 25-pin D-connector where you will make your solder connections. In other words, you will be connecting pin-1 of the CENTRONICS plug to pin-13 of the D-connector; and, so on. Note that you will only be making eleven (11) connections to the D-25 plug since there are only that many signals being used by the MIRACLE parallel interface.
CENTRONICS plug: -> 1 2 3 4 5 6 7 8 9 t 1 2 3 4 5 6 7 8
[front view]
A B C D E F G H I o J o o o o k k o
===================================================
K o o o o o o o o o o o o o o o o o o
25 female plug : -> 13 d h t 9 8 7 6 5 4 3 2 1 [rear view]
A B C D E F G H I o J o o
o o o o K o o o o o o o o
Connect ‘A’ to ‘A’, ‘B’ to ‘B’, and so on.
Note that I ran a jumper between the ‘K’ pin on the lower row of the CENTRONICS plug and the double ‘k’ pins on the upper row of the same plug.
I used a solder-type D-connector and eleven short (about 6″ long) pieces of multi-strand wire.
If you are simply making an “adapter” then you may note that using IDC (ribbon-type) plugs should be much faster — only the ground (‘K’) connection needs to be “off-set” with a jumper.
If you are hard-wiring, look at the circuit board carefully, and then decide where you want to make your connections — I chose to hard-wire directly to “pins” on the circuit board — visually tracing back from the CENTRONICS plug to the first available pin. A hard-wire implementation will minimize components.
I twisted the wire together (loosely) and then wrapped the cluster (tightly) with electrical tape.
Finally, I used my soldering iron to melt-away a small “cut-out” in the back edge of the base of the interface’s black plastic box so that my short pig-tail adapter could exit the opposite end of the repaired CENTRONICS plug. Take your time (test fit often), and don’t make the hole too large.
Since my QL’s components are nestled inside a salvaged PClone case, my old style, MIRACLE parallel interface can now rest near the back of the case (on the inside) out of harm’s way with the 25-pin connector firmly attached to the rear of the case using an available opening intended for this type of connection.
I can now employ ANY LENGTH of any “standard” IBM printer interface cable to complete the connection of my QL to my printer (long IBM-type parallel printer cables tend to be much cheaper than a CENTRONICS-to-CENTRONICS cables of equal length; and certainly, easier to find in a store).
With a little effort on your part, you can add the same flexibility and durability to your MIRACLE parallel printer interface.
HAPPY TRAILS,
AND COMPUTING, TO YOU …