re: Megahertz PCMCIA Ethernet dongle

Technical note: PCMCIA Ethernet and dongle, and dongle pinouts Product: Megahertz CC10BT (or CC10B2) Issue: missing dongle Resources: ability to disassemble a delicate connector using cutoff wheel and X-Acto knife. Ability to solder.

Attached below is the only discussion I found about actual dongle pinouts. I make reference to the way in which the original author (Magdy / Girgis) numbers the 15 pin edge connector to the PCMCIA ethernet card.

If your laptop has an available USB connector, read no further. MicroCenter has a USB to Ethernet device for $13 by Hawking (HUF11). So, skip the idea of using a PCMCIA ethernet card.

You can also opt for the Hawking parallel port to Ethernet (HPS1P) but prices range from $40-$60.

However, if you:

  1. have a Megahertz PCMCIA card (non 3COM) 2. and a laptop without USB 3. or, just want to make your Megahertz card work

this note is for you.

History: 3COM acquired Megahertz. They, for whatever reason, did NOT maintain the same dongle connection to the PCMCIA card.

QVS does make a universal "PCMCIA LAN Replacement Cable" labeled "3COM 10BaseT Network Cards" model CPN-3C10T, and this sells for $11.95 (their SKU 753699)

QVS replacement RJ45 dongle for 10BaseT network card. It is compatible with the following 3COM PCMCIA NIC models: 3C562, 3C562B, 3C562C, 3C562D, 3C552D, 3C563, 3C563B, 3C563C, 3C563D, 3C589C, (RJ45 cable only, not coaxial), 3C589D, CCE589ET, 3CCE589EC, 3CXE589ET. (Connectors: PCMCIA to RJ45 Female; Length: 6")

However. While one might have hoped that the original Megahertz card set the standard for later 3COM PCMCIA cards, this is not true, probably because the original card supported 10Base2.

My best knowledge is that the 10Base2 transceiver was embedded in the original dongle.

Nonetheless, this card CAN be made to work in 10BaseT (aka CAT5 / RJ45) with the QVS CPN-3C10T dongle.


When dealing with 3 connectors: The PCMCIA 68 pin connector to the laptop, the 15 pin edge connector to the Ethernet card, and the 8 pin RJ-45 connector for networking, it is easy to get confused.

As I have already studied the 68 pin connector, you may ignore that. What I needed to know was the orientation of the connector to determine where ground and +5 VDC were applied. (Answer: all four pins at the outer sides of this connector are ground. And, holding the PCMCIA card, staring into the female connectors with the card's label on top, pin 1 is in the upper right hand corner. So pins run 1-34, right to left, then 35-68 on the second row, left to right. Power (from the laptop) enters via pins

17 and 15 (which are opposite each other in the dual inline connector).

The kind respondent (below) "M." provides the correct pinout for this 3COM dongle, except, neglected to mention power. Power ground is applied to pin 7 (edge connector) to wire green/black. +5 is applied to pin 13 to wire green.

This is not correct for the Megahertz card. +5 VDC is on pin 11.


It is only necessary to open the 15 pin edge connector to adapt this dongle to the Megahertz PCMCIA card.

Picture these pieces:

  1. edge connector with 15 solder pins 2. lower metal shield 3. upper metal shield 4. 2 tiny spring metal latches to hold on to the PCMCIA card (that are part of the lower shield) 5. Hard plastic cover over the connector, but, with 2 squeezable side rails, so that the metal latches can be released by squeezing 6. A crimped clip (with copper shielding) that holds the dongle cable to the shields 7. A rubber boot that slips over the 2 shields and provides strain relief for the 6" cable

In hindsight, it may be possible to remove the rubber boot, by slipping a jewelers' screwdriver under the front lip. There are 2 tongues that latch from the rubber boot to the plastic cover.

Alternatively, take a dremel cutoff wheel, at 7,500 RPM and slice into the strain relief -- on each side -- where you see the "plastic weld" and continue that cut up to the widened area of the shields. As the cord was heat welded to this cover, it is necessary to work the screwdriver around until the boot comes lose. Then, slipping the boot away, we see the two metal shields, and a cable crimp. We use the screwdriver to pry open the cable crimp. Once that is done, the "lid" shield is popped off by noting the 4 indents holding the lid to the base shield. (Be careful NOT to stretch or bend the 2 spring metal fingers at the front).

With the rubber boot removed, and the 2 shields removed, we have the 15 pin edge connector fully exposed. (Note: in sliding the hard plastic cover off, one must get 4 front edges to clear the shields. You may be able to do this by prying lightly and inserting shirt pins to hold the plastic above the shield lips. If you break the extremely fragile plastic edges, you can always wrap the area with a thin guage steel wire and apply some black hot melt glue to hold the wire in place. (This, of course, is more aesthetic, than critical.)

To remedy the power supply descrepancy, unsolder the green wire at pin 13 and move it to pin 11.

Now, we need only deal with the 4 wires for Ethernet.

As "M." shows, the yellow wires are at pins 1 & 2, and the red wires are at pins 3 & 4.

This is incorrect in two ways. First, pins 3 & 4 appear to relate to 10Base2, so we (checking with an ohmmeter), find that pins 5 & 6 are also live. However, just moving the two red wires to pins 5 & 6 has transmit and receive reversed, i.e., it works, but via a crossover cable. So, one moves the two yellow wires to 5 & 6, and move the 2 red wires to 1 & 2. We leave 3 & 4 open. Keep the wires with black stripes on the same side of the 15 pin connector. (might it work fine if flipped? probably).

In determining this configuration I relied on the green hub indicator light, and, when I got the pairs correct, I also saw a green light from the side of the PCMCIA card.

So, with these changes:

  1. power 2. yellow pair 3. red pair

I had full Internet connectivity.


Be careful your resoldered leads are not too high. The external shields have insulation on the interior -- but -- a sharp edge could pierce that. I put a Dremel cutoff wheel on low speed (7500 RPM) and with magnifying goggles, I leveled each resoldered pin's top. Understand, the lead may touch the insulated shields, but, "thou shalt not pierce."

To finish the look. I take black hotmelt glue and a soldering pen. I put the boot back. I then had two seams to fix. I clamped the boot in a vise, and then ran the pen and glue into the seams. Note: for adhesion, with the hotmelt glue in the seams, run the hot pen against the original rubber. This creates a very good bond. (if you only squirt glue in, the seam will most likely pull apart)

As for 10Base2 (BNC), I suspect that the edge connector, pins

3 & 4 originally drove a transceiver that was contained inside the Megahertz dongle. Today, hubs are so cheap, if you need 10Base2, just connect this to any hub (with BNC) and connect to the BNC side of the hub. (As hubs with BNC are disappearing, try eBay.)


Curtiss Priest

********************* Original postings:

PCMCIA Ethernet and modem dongle pinout here it is

1/8/05 7:13 PM 1/8/05 7:13 PM 1/8/05 7:14 PM Magdy Girgis May 10 2002, 2:57 pm

In searching the groups, many ask the same question I was searching for an answer to, but no answers at all . so here is my answer.

Having bought a cheap pcmcia ethernet card (without dongle) to experiment with.

Because I am fed up with the stupid dongle, and my laptop has a "hidden" pcmcia slot that could have modem/ethernet card.

Next to it is a group of small sockets which are wired to both RJ45 and RJ11 in the back.

The challenge was to identify which pins of the pcmcia to connect. (groups search zilch).

So some testing and thinking.....................and later...on at last....


Now the difficult one is the ethernet card.

Mine is a SOCKET AE credit card. but having seen the xircom and others they seem to be the same (but this is at your own risk not mine if you decide to try)

By the way this only applies to those cards with straight dongles to an RJ45, not to those with pods and BNC connectors.

Now the connector is 15 pins (the card has 15 small sockets)

if holding the card again the right way up and number the sockets from RIGHT to LEFT as below

CARD 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 RJ45 6 3 2 1 As you know there are only 2 twisted pairs in use, although the RJ45 is 8 pins.

the first pair is connected to the RJ45 plug to pins 1 and 2

pin 1 should go to pin 7 of the card and pin 2 should go to pin 8

the second pair is connected to the RJ45 plug to pins 3 and 6 (yes six not


pin 3 should go to pin 9 of the card and pin 6 to pin 10 of the card

and that is it

I hope this will be of help to some of the poor souls who are kept being told to go and buy a new dongle rather than make their own cable (dongles are unreasonably expensive)

Magdy Girgis

May 11 2002, 2:46 am

Just to add the pinouts for EtherLink III (3Com)

This card has a different type connector , but still 15 pins the pinout is also diffirent and is as follows, but as usual mess about at your own risk.

again counting from RIGHT to LEFT with the dongle end facing you and label facing up

pin 1 of RJ45 goes to pin 4 of card pin 2 of RJ45 goes to pin 3 of card pin 3 of RJ45 goes to pin 2 of card pin 6 of RJ45 goes to pin 1 of card


Reply to
W. Curtiss Priest
Loading thread data ... Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.