Just made up a mains cable from the Plessey 3 pin MKIV plug Woodchips kindly sent me. Unplugged secondary transformer from main PCB, turned on, getting 16 0 16 V off the secondary.. All working great!! So the initial problem was a dud tantalum.
Very happy. Now onto solving getting the reader doing something...
Update. I've got the reader reading. Reading didn't work connecting rts/cts so I tried using this pinout:
Seems to work. Or the step button now steps through a piece of tape 1 character at a time and RDR on streams the tape through at a nice speed. I managed to get Realterm to print out the numbers 1 to 5 which I punched on a length of tape. This was using 300 baud 6N1. No letters though. Just odd symbol characters. Do I need to set the terminal to a particular type of display? I dunno. Also, as the machine has a couple of EPROMS, I wonder whats on them?
I'm going to try a few more settings and see if I can get proper codes punched and read. At least now I can reassemble the beast back into one piece.
OK, All back together. I've just tried a punch/read test using Realterm. The settings are in the 1st image.Looks like its punching in some kind of order but not the correct characters.. I sent the characters a-z with a space inbetween to the punch. The reading is shown. So it looks like its offset. I've also included a picture of what the punched tape looks like..The picture has gone on sideways. Starting from the bottom, thats a, the top is z I've compared against a baudot chart and it doesn't correlate..:dontgeti:
Anyone have any ideas what I'm doing wrong? Or what type of code it might be punching out?
That's 5 level tape, so if you send it ASCII it will print 5 out of 7 bits. It looks like its printing the least significant bit in left most track. Will it punch 8-track tape? Do you have any 8-Track tape?
Hi Dave. A few updates since the last post. Firstly, I got it printing baudot code by switching from 5 to 7 data bits and it's now punching and reading back. I've checked the punchout with a baudot chart and it all correlates. It will also print out the Letter or number shifts when I send numbers or punctuation which is great. I would be nice to use the nice roll of pink 8 bit tape I've got however, in order for the GNT36 punch to deal with wider paper there are some spring guides that need to be changed (its in the GNT36 manual which I found on Google.) Also, the reader which is a Ghielmetti FER203 (not much info on that one) has a small switch on the front for selecting 5, 6 or 8 bit reading. The switch isn't electrical but mechanical, a small thumb switch (the kind thats small, black, square and plastic with ridges) and its part of a wheel with indentations in. Depending upon whether you select 5,6 or 8 the wheel moves around and pushes pins on springs into holes in the reader mechanism..its a bit broken as 2 of the pins fell out but I could change it to do 8 bits... fiddly but possible. Then I'm guessing one of the dip switches on the main PCB would have to be changed for 8 bit communication...
Oh, also, John, the guy I got them from has given me another 2 of the beasts and a few more rolls of paper!! :D One of which is in pristine condition and the other very dirty looking with sticky buttons.. I think before I plug any of them in I'll get the lids off just in case another tantalum explodes.. Also, I've looked EVERYWHERE for a Serial terminal for windows that has a baudot setting. I've only found 1 so far. Its called RTTYart and was written for making artworks out of teletype (I think).. It works but it will only read letters seperately (or with the step button.) If I switch to continuos reader mode it prints out garbage..
Haha. Thanks again Dave. Heavy Metal punches very nicely! I found this out by clicking on the "info" help button and the machine started punching out the help file!! :D
I've found a program that reads nicely with the machine in continuous read mode: TTYTerm.
Thats very kind to offer to send a reel of tape. I'll pm you.