Wiedemann@RADC-MULTICS.ARPA (03/19/85)
Here's some information I found on the CompuServe IBM SIG this weekend.
It could prove useful for those setting up remote bulletin boards using
the Anchor Automation Signalman Mark XII modem.
The following modification to the Anchor Signalman MK XII modem was
taken from a FIDO newsletter. It describes a hardware change which is
supposed to add DTR support to the modem, to allow its use with Fido
BBSs. I don't have the Anchor Signalman modem, so I cannot say for sure
that it works for this purpose, and I certainly can't say whether it
works for other BBS software, but I am uploading it at the request of
another SIG member, who is trying to use the Anchor modem. If you try
this modification and you find it works, or even if you find it does not
work, please let us know on the SIG, so others will know whether or not
to try it.
Anchor Signalman Mk XII DTR fix
-------------------------------
The Anchor SignaMK XII does not support the RS-232
DTR (data terminal ready) signal. Too bad, since at $250
(discounted) this is probably the cheapest stand-alone 1200
bps modem available, and seems to work just fine otherwise.
Unfortunately, quite a bit of software (BBSs especially)
depend on DTR to hang up the phone.
This file describes a hardware fix which will add DTR to
the MK XII. Obviously, this voids your 2-year warranty.
However, the same thing COULD be done with an external box.
----------------------
You will need:
1 - 2N4401 transistor
1 - 10K ohm 1/4 watt resistor
a short piece of thin wire (#30 wirewrap wire
suggested)
shrink-wrap & tape (to do it right)
an exacto knife
solder, soldering iron, and the ability to use it
-----------------------
1) Using a flat-blade screwdriver, open the Signalman
case Try not to mangle it too badly.
2) Remove the circuit board and turn it so that the
solder side is facing up, and the serial cable is at
the bottom.
3) It should say "Anchor Automation Inc 00472 Rev A" in
the upper right-hand corner. If it doesn't, this
may not work, or may not make sense.
4) In the lower right-hand corner of the board, just to
the left and above the right-hand phone connector,
you will notice two vertical groups of three pads.
The left group has no traces coming from it. The
right group has traces coming from the bottom and
top pads.
5) Cut the trace coming from the bottom right-hand pad.
Try to do this near to the pad.
6) Position the 2N4401 transistor with the flat side
toward the board, and the wires toward the top of
the board.
7) Solder the RIGHT-hand wire of the transistor to the
lower right-hand pad of the group of six that you
located above. (The one that you cut the trace to.)
8) Solder the MIDDLE wire of the transistor to the cut
trace, on the other side of the cut.
9) Solder one end of the 10K resistor to the remaining
wire of the transistor.
10) Solder a 3" piece of wire to the other end of the
10K resistor.
11) Slip a piece of heat-shrink over the resistor, and
shrink.
12) Now, find the group of pads coming from the RS-232
cable. Find the 4th pad from the left, and 2'nd
from the bottom. There should be traces coming from
the pads just above and below it.
13) Solder the other end of the wire to this pad.
14) Put a piece of tape over the whole shebang, just to
keep it from moving.
15) That's it! The modem should now observe DTR. If
the DTR signal is 0 or negative voltage, the
telephone line (through the on-board relay) will be
disconnected from the modem. If the DTR signal is
above a couple of volts then everything works
normally.
16) Make sure that you connect DTR to your computer and
that your computer asserts DTR! The modem will NOT
operate without DTR asserted!
17) If DTR is dropped, the line to the modem will be
dropped. The modem should notice it and drop
carrier detect to your computer, as well as decide
to hang up on it's very own. At this point, you can
bring DTR back up, and the caller (or callee) should
be gone. I have no idea what the timing should be -
whatever it takes the relay to operate. 1/10 second
should be more than ample. This works with FIDO - I
can't tell you what other BBS software will do.
[ Ed. Note: Fido drops DTR, waits 2 seconds, then raises it
again. ]
18) You will soon discover why people with Hayes modems
are constantly pulling the front off to operate the
DIP switches. PC-Talk (and maybe other programs)
insists on dropping DTR when you exit or change
communication parameters. Oh well, you can't have
everything!
19) Oh yeah - quit gawking and put the thing back
together.
20) Pray.
By the way, I have this modem on my Z-120 and I have a minor complaint.
Seems that the commands to the modem do not echo and, therefore, the
"AT?" doesn't give me my menu either. The commands DO function
otherwise and all modem operation is normal in every other respect. Is
there an RS-232 signal at the connector I can use to "fool" the modem
somehow into letting me see the commande, and the mmenu?
Wolf Wiedemann RADC-MULTICS