Building the XXP1541 Serial+Parallel Y Cable
Parts needed:
- (1) 6-pin DIN male plug with cover (1541 serial port)
- (1) DB15 male plug + hood
- (1) DB25 male plug + hood
- (1) 6' or 1.8 meters (max) 4 conductor shielded cable (for serial connection)
- (1) 6' or 1.8 meters (max) 8 conductor unshielded cable (for parallel connection. These two cables should be the same length, but only for cosmetic reasons.
Visit the ports, parts & pinouts page for a descriptions of all the above parts.
Tools needed:
- Multi-meter with DIODE checker
- Soldering iron
- Solder
- Wire cutters
- Wire strippers
- Various screw drivers
- Small vice
- A lighted magnifier is very handy
This is called an "X serial-parallel" cable because it combines the X1541 and the XP parallel cables. See the X1541 cable page for the summary of the X1541 cable limitations. The XXP1541 allows for high speed transfers but you must have the C= parallel option installed in your disk drive in order to take advantage of the parallel portion of the cable. Like the X1541, it is a simple cable to make as it requires no extra components like diodes or transistors, and is restricted to working under DOS. It is not recommended to build this cable due to its limited usefulness and its requirement for older parallel ports. Instead, look at the XM1541, XMP1541, XA1541 or XAP1541 for better options. This cable works with Star Commander, but not MNIB/NIBTOOLS as the X1541 portion is not supported.
If you're not sure this is the right cable for you, see my cable picking guide to check.
X1541 cable copyright Leopoldo Ghielmetti, 1992
XP cable copyright Joe Forster/STA, 1997
Step 1: Prep the DIN6 plug and attach the wires
- Pre-solder pins 2 to 6 on the DIN6 so that the wires will solder better
- Strip off one end of the 4 conductor cable about 1/2" (1.2 cm) back.
- Strip the individual wires back about 1/8" (3 mm) to expose bare wire.
- Twist and tin the wires and ground shield wire
- Solder these 5 conductors into the cups on pins 2 to 6 of the 6-pin round DIN plug, making sure the outer ground shield goes to pin 2 (GND). Mark down the wire colors going to each DIN post for later. Pin 1 on the DIN6 is not used.
- Fit the completed DIN end into its shield, crimp the cable into the tail clamp, and put the outer sheath over the shield, completing the DIN end.
Step 2: Prep the DB25 connector and attach the DIN6 wires
- Strip the other end of the 4 conductor cable back about 3/4" (2 cm)
- Strip each wire back about 1/4" (5 mm) to expose bare wires
- Twist and tin the wires and ground shield wire
- Solder bridge pins 18 to 25 on the DB25 connector to make the ground strip. It may help to cut and bend a wire so it fits from pin 18 to 25 and solder it to the cups.
- Pre-solder DB25 cups 1, 14, 16 & 17 so that DIN6 wire insertion will be easier.
- Attach the wires from the 4 conductor cable to the DB25 pins, using the previous color code as a guide.
- DIN6 to DB25 pins...
- 2 to 18
- 3 to 1
- 4 to 14
- 5 to 17
- 6 to 16
Step 3: Prep the DB15 connector and attach the wires
- Strip one end of the 8 conductor cable back about 3/4" (2 cm) to expose the wires.
- Strip each wire back about 1/4" (5 mm).
- Twist and tin each wire.
- Pre-solder each DB15 cup from pin 1 to 8, so that wire insertion will be easier.
- Attach the 8 wires to pins 1 to 8 on the DB15. Mark down what wire color goes to what pin, for later use.
Note that there is no ground line on this half of the cable. This portion of the cable relies on the ground from the serial cable portion.. Inclusion of a ground line here could cause a ground loop condition, something which must be avoided. Also, the parallel port add-on on the C= disk drive doesn't contain a ground line for this very reason.
Step 4: Prep the other end of the 8 conductor wire and attach to the DB25
- Strip the other end of the 8 conductor cable back about 3/4" (2 cm) to expose the wires.
- Strip each wire back about 1/4" (5 mm).
- Twist and tin each wire.
- Pre-solder the DB25 cups from pins 2 to 9.
- Attach each wire to the DB25, using the color code from the previous step on the DB15.
- DB15 to DB25 pins...
- 1 to 2
- 2 to 3
- 3 to 4
- 4 to 5
- 5 to 6
- 6 to 7
- 7 to 8
- 8 to 9
Step 5: Check the cable
- Using a multi-meter on DIODE (continuity) check, measure between the pins on the following chart.
There should be a short between each of the pins from one connector to the other
- DIN6 to DB25 wires
- DB15 to DB25 wires.
- Verify that pins 18 through 25 on the DB25 are shorted together.
Cable pinout chart
DIN6 (male) |
DB15 (male) |
DB25 (male) |
|---|---|---|
2 (GND)
|
18-25 (GND)
|
|
3 (ATN)
|
1 (STROBE)
|
|
4 (CLK)
|
14 (AUTO FEED)
|
|
5 (DATA)
|
17 (SELECT IN)
|
|
6 (RESET)
|
16 (INIT)
|
|
1 (PB0) |
2 (DATA0) |
|
2 (PB1) |
3 (DATA1) |
|
3 (PB2) |
4 (DATA2) |
|
4 (PB3) |
5 (DATA3) |
|
5 (PB4) |
6 (DATA4) |
|
6 (PB5) |
7 (DATA5)
|
|
7 (PB6) |
8 (DATA6)
|
|
8 (PB7) |
9 (DATA7)
|
|
18 to 25 shorted |
Step 6: Finish the cable. Mount the DB ends in their hoods
- Mount both the DB15 and the DB25 connectors in their respective hoods. If the wires need to be squished a bit to fit, it should be OK to do so.
- Test the cable to make sure it works.
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Schematics drawn using ExpressPCB, a free and excellent solution which also supports PC board layout editing.
Email the author: Peter Schepers | Last updated: Mar 17, 2009