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Hi all,

I chanced upon a reasonably priced Hasler (GB) Telex 3600-3 on eBay and, not having seen any similar PC telex interfaces for sale recently, I decided to shoot first and ask questions later. I understand this is a PC telex adapter, apparently similar to Deutsche Bundespost's TTX 11. It came without any documentation or software, and I've had limited success (to say the least) in making progress with this device. I'm hoping to tap into the collective knowledge here.

The device was originally designed for connection to BT's network. Labels on the inside indicate quality testing was completed in 1986, and the software EPROMS carry version information labels showing the same year. This date is consistent with the BABT green circular approval label. A search for the approval number turned up empty. The only identifier on the back plane, other than the serial number, is the type 3600-3.

The line interface is not mounted on the main board. It is mounted in the top cover and connected to the main board by a ribbon cable. In addition to avoiding too large a footprint for the unit by using a stacked design, this design would also allow for different line interfaces to be easily integrated to address different markets and network types, in much the same way as many modems of the 1980s and 1990s contained interchangeable line modules to facilitate the adaptation to local type approval and network design requirements.

The line cable terminates in a BS 6312 431A plug as used from the beginning of device approval deregulation in 1982 - the cable and the plug are not visible in my photos.

I have not been able to get any reaction out of the device just yet. Even if I can figure out the V.24 interface parameters, I doubt I will be able to accomplish much without the PC client software and/or without understanding the network interface parameters. I'm afraid my knowledge of the BT telex network specifications is quite limited. I have some - probably long since outdated - information I found in Fernschreib-Vermittlungstechnik by Ehrhard Roßberg and Helmut Korta, 1960, section 2.23, but this is only a very generic description of the GPO telex network as of 1960.

Google and other searches for anything related to this device turned up empty. My question is - does anyone have any further information, perhaps even a link to a manual or the client software for this device? I'm still conducting research into the estate of Hasler (GB), but haven't been too successful on that front either, and even if I could find a contact person, I don't believe it would be too likely that they could still have information on a device almost 40 years old.

Thank you so much for any information you may be able to give.

Sorry, I can't help much. But is there a reason why the CPU 8085 is not inserted completely?

A small hint: As there are chips MC1488 and MC1489 located close to the SUB-D 25 this is obviously a RS232 interface. First step would be to check if the device needs a crossed or a straight cable to be connected to a standard RS232 port at the PC.

Further ideas: Which voltage is supplied by the main transformer to the line interface?

Is the "transformer" on the line interface a galvanic isolation between the line and the internal electronics or is it just a choking coil?

Does the line interface provides any output voltage on any pin-combination (check DC and tone frequencies).

S.C.V.F. = Single channel voice frequency (British Telex V.21)

wyssby hat geschrieben: ↑So 6. Feb 2022, 10:26 Sorry, I can't help much. But is there a reason why the CPU 8085 is not inserted completely?

Thanks for your hint - this seems to be an effect of the lighting on the photo - actually, the CPU is inserted firmly in the socket.

Hi,

SVCF in the UK on the BT431 connector normally used pins 1 and 6 of the connector for connection - these are usually orange and white in colour in all the telex connections I have found.

There should be no other need for any connections.

There is almost no information in the UK for Electronic Telex - it is rarely offered for sale, and when BT sold off the Telex equipment for scrap, it was all at clearance auctions nearly 25 years ago.

I can ask some contacts over here, but would not expect any luck.