GR Electronics Pocket Terminal Type 8

[SkeneAli]

I am hoping to restore this terminal, which currently has jammed keys.
Assuming these can be freed, I would be grateful for any advice on the setting of the DIP switches: which switch does what?

Thank you

[Phil__G]

Fascinating. And reminiscent of Ian's recent 'Telekit' journey
I see the seller says its proven working, presumably you've asked him?
In the absence of any documentation, I'd hook txd up to one of those cheap Saleae-clone logic analysers, you'll soon find the dipswitch settings for serial comms
Phil

Edit: theres a later model on YT: https://www.youtube.com/watch?v=sQciIBW_J4Y
I expect the D25 pinout will be the same as Rtech Labs unit...

[TonyDuell]

Do you even know that it's an RS232 interface? Some of these small terminals used 20mA current loop. If you spot optoisolators on the board then it's likely to be that.

Any recognsable ICs inside? Can you post a photo of the PCB etc?

Pity you're so far from me, I have serial comms analysers and the like.

[Phil__G]

Originally Posted by TonyDuell

Do you even know that it's an RS232 interface? Some of these small terminals used 20mA current loop

Yeah but conversion is so trivial we're happy with either

I found Cheryl Webb on FB and have asked on SkeneAli's behalf (Oyster Terminals UK company secretary)

[TonyDuell]

Yes, it's not hard to convert between RS232 and 20mA loop. But you do need to know what the interface on the terminal is to be able to connect it up and test it.

[Cobaltblue]

We used GR terminals in the distant past initially they were standard product but we were purchasing a few hundred so they were modified mostly around the front panel. Initially they used a bubble LED display but by the early 90's they were LCD. Ours were RS232 set to 1200 7bit 1 stop bit even parity which is our industry's standard default since 1980. We still use terminal most recent by TechTerm.

The 25way D connector connections we used were in the snip (still the same even on out current products however not all the cores went to the handset the handshaking was linked across on the back of the 25way D.

The important connections were 2, 3 and 7 and power.

Cheers

Mike T

[SkeneAli]

Many thanks for these helpful responses - what a brilliant forum this is!

I did contact the seller, but he evidently knows nothing about the terminal, and hadn't actually tested it..... I also messaged Guy, who previously posted a related thread (t=168040). He was a least able to advise me that S6 is used to connect or isolate GND

Thanks to Mike for the connections screenshot.

It is kind of Phil to contact Cheryl Webb - I look forward to hearing any reply.

Tony makes a good point about the possibility of 20mA loop. See photo. I presume that the vacant 6 pin areas 'a' and 'b' would have been for opto-isolators. Therefore, I am guessing this is an RS232 model.

With best wishes

Alastair

[Cobaltblue]

I still have not located my LED version but I did come across the slightly later LCD version. This one went out of service around 25 years ago.

This one has the usual issue with the cable breaking where it joins the body, considering these things go into the tool box and out up to 20 times a day and used in all weathers they are remarkably resilient.

The earlier ones like your type 8 had the DIP switches behind the little door (removed in the 3rd picture) the

Cheers

Mike T

[TonyDuell]

The +12V and -12V marked on the OP's crcuit board suggest RS232. And maybe I'm seeing what I expect to see but I think I can make out 1488 and 1489 on the 2 chips just above the microcontroller. Those are common RS232 drivers and receivers.

I agree that the empty 6 pin spaces are likely to be for the optoisolators for a 20mA loop interface.

So having seen the board I think it is RS232.

[SkeneAli]

Thank you for this confirmation that the terminal is likely RS232.
I can't work on this project just now, but in due course will proceed on the assumption of RS232