Tandy Model 100/102 modem pickup line

[CedsRepairs]

Hello everyone,

I might be entering a sub-sub-n iche here, but i'm trying to make the internal modem of my Model 102 work again.
I've connected it to a small home phone exchange (pabx) so that I have real proper vintage phone lines ( did I mention this would be of interest to a sub niche ?)

Problem is ; my model 102 does not pickup the line. A phone does, a good old USR 56K does, but it does not.
I have the proper grey/beige(rather pink now) cable

It's inserted in the right way. My init string (STAT) is starting with M, for internal modem

If I put a phone on the gray line, and "pink" in the PABX ; i can hear my dial tone, until I make the M102 dial, in which case the phone goes silent (which is normal).
But the PABX doesnt show the line as beeing picked up, I can hear the M102 pulse dialing in the void, but to no end...

It seems either the voltages are not right, or something is not working like it should.
I tried BASIC with "CALL 21200" (which pickups the lines) you can hear the relay click, but again, the PABX does not see that as someone picking up a phone.

I have an European M102 (could that be an issue ?) My "phone line" (vintage PABX) is a european (belgian) one.
However the M102 has been "upgraded" by a REX rom , that may be an issue (this upgrade was not my doing. I can barely use REX.)

It's unclear if, eventually, the modem section could need a repair (recap or smth)


Any help appreciated

 

[jwse30]

Is the switch on the side of your 102 set to originate? Does your phone system accept pulse dialing? My MagicJack doesn't, so I have to dial on a phone and then connect the modem once I hear the other modem pick up.

It's been a while since I used the modem; I bought a wifi modem for it a while ago, and just use that (with a cellphone battery pack to power it, so my M100 is still "cordless".

Hope this helps, or at least gives you something to build on.

J White

 

[CedsRepairs]

Yes it's set to ORIG,

The PABX's doc says it supports pulse dialing, but to be fair I wouldn't blame them to not support a pulse dialer from 1982
But really the problem is before the dialing,

The doc of the 102 says to pickup the phone (connected on the gray line) then hit CALL
This does take over the line from the phone but it basically hangs up the line, as far as the PABX is concerned

Also I tried the other way around, the modem does not pickup calls in ANSWER mode either.

Everything seems tidy on the motherboard, this unit is as close to pristine as can be, i'd be surprised there is an hardware problem with it (but you never know)

I still believe this has something to do with the "improved" ROM ( REX# v2.00 ) or the ROM itself

 

[mykrowyre]

I believe the original had two cables coming from the din connector. One goes to the phone line and the other to the phone itself. When going off hook, the phone line side goes off hook and the phone side disconnects (so you cant pick up the phone while connected and disrupt the connection).

It's possible you are connecting them backwards or the cable is not wired correctly. The phone handset side originally had a plug on adapter to convert it from male to female.

So the grey line would go to the pbx and white (now pink) to the handset, which is the reverse of what you described. Hope this helps!

 

[danielbooneamerica]

Wont software need be running and respond to ring with DTR signal?

Most modems are setup to not answer unless signaled by app.

It is possible to have modems that answer no matter what (programmed in strapping of modem).

I know nothing about this computer but I have lot of modem experience. Just throwing this idea out there.

 

[mykrowyre]

hel

Wont software need be running and respond to ring with DTR signal?

Most modems are setup to not answer unless signaled by app.

It is possible to have modems that answer no matter what (programmed in strapping of modem).

I know nothing about this computer but I have lot of modem experience. Just throwing this idea out there.

Hes trying to dial in this case. This old modem has answer and originate controlled by a switch and is pulse dial only. I think its just a wiring error, there are two plugs provided and only one works for dialing.

 

[danielbooneamerica]

I see now. Title was modem would not pick up so I was a little confused (as always).

Before you go too far, try on a different phone line.

You mentioned you have a home PBX, I have modems not recognize off dial tone before on PBX and PBX not recognize modem.

BATT provided by PBX would be too low or other reasons. Before I went to far on this I would take somewhere else and try on POTS line.

PBX knows you went off hook by resistance/ current flowing on TIP RING of line.

Your modem may have a signal problem. Try measuring resistance across your line connector and tell modem to dial, there should be a sudden drop in resistance when you hear relay click.

 

[mykrowyre]

If I put a phone on the gray line, and "pink" in the PABX ; i can hear my dial tone, until I make the M102 dial, in which case the phone goes silent (which is normal).

I'm pretty sure the cables are reversed. I actually used this old pulse modem a bunch in the early 90s!

Also, I just happen to have a nice M102 arriving today. I'm sitting here waiting for the fedex truck!