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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
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4th Oct 2014, 8:28 pm | #1 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Hazeltine 1500 faulty keyboard
Hey folks, new guy to the forum here.
So I recently aqquired an old Hazeltine 1500 serial console from around 1977. Most of it works okay (screen is a little glitchy). It's main problem is that only a small number of keys on the keyboard work (1,3,5,7,^,TAB,reset). I have tried re-soldering all of the keys and stilll made do difference and the main board has also been cleaned. It is set to half duplex mode so that it can display keyboard characters on the screen. As of the moment I do not have an RS232 cable available but I am pretty sure the connection is fine. But like I said, main problem is the keyboard. If anyone has any suggestions on how to fix or how I could get a refurbished board, please let me know. Thanks in advance. I hope I enjoy my time here in the future! |
4th Oct 2014, 9:21 pm | #2 |
Octode
Join Date: Jan 2005
Location: Hyde, Greater Manchester, UK.
Posts: 1,074
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Re: Hazeltine 1500 faulty keyboard
You may have to resort to removing each switch dismantling cleaning and re-assembling. There is an excellent video on You-tube by RetroGamerVX where he strips cleans and reassembles the keyboard from a late 70's terminal. Do you have a multimeter? try a continuity check on the pins on the back of each switch just to determine it is the switches at fault.
Jay
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4th Oct 2014, 9:48 pm | #3 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Hazeltine 1500 faulty keyboard
Thanks, Jay.
I'll post some pics of the keyboard but under the keys I can see that it makes contact okay, I will try checking the connection with the multimeter whenever I can. |
4th Oct 2014, 11:20 pm | #4 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,643
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Re: Hazeltine 1500 faulty keyboard
It probably works on a matrix principle, it may just be one of the lines not working.
As well as a photo of the layout, a complete list of either the working or non-working ones, whichever is easiest, may help. |
5th Oct 2014, 3:44 am | #5 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
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Re: Hazeltine 1500 faulty keyboard
These keyboards almost invariably operate on a matrix principle. One "row" at a time is energised and the columns read. The switches often have two pins connected to each contact, to use as pass-throughs to simplify matrix design. Look out for dry joints and cracked print between key switches.
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5th Oct 2014, 4:12 pm | #6 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Hazeltine 1500 faulty keyboard
Thanks. I have checked the joints on the bottom of the keyboard and they all seem to be fine. I'll check the switches too when I can.
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5th Oct 2014, 7:26 pm | #7 |
Heptode
Join Date: Aug 2009
Location: Worthing, Sussex, UK.
Posts: 662
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Re: Hazeltine 1500 faulty keyboard
Yes it is a matrix drive and all of 1,3,5,7,^,TAB are on the X1 line. The keyboard encoder activates each of the 9 X lines in turn and reads on the 10 Y lines. This is driven from an AY-5-3600 keyboard encoder (U60). (Page 145 and Page 146 B-24, B-25) of the service manual.
It will be worth checking that the pins on the keyboard encoder (pins 32..40 are X8..X0, pins 17..29 are Y0..Y9). Pin 16 should pulse when a valid key is pressed. (It is possible you also have some shorted lines which are stopping the keyboard working. With the power off check remove the AY-5-3600 (Assuming it is socketed). Check for each X pin check that it is not connected to any Y pin or ground. Also check for shorts between X and GND and also between Y and GND. Hope that helps. |
9th Oct 2014, 8:45 pm | #8 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Hazeltine 1500 faulty keyboard
I just connected this to my PC via a straight through RS232 (db25 to db9) but I cannot get anything to appear on the terminal. I can set the baudrate and stop bits but that's about it. Anyone know how I could overcome this?
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11th Oct 2014, 8:48 am | #9 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,010
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Re: Hazeltine 1500 faulty keyboard
You will need a crossover-cable.
In the traditional days on 25-pin V.24 connectors we wired 1 to 1 [chassis earth] 2 to 3 [transmit to receive] 3 to 2 [receive to transmit] 7 to 7 [data earth] Then we strapped 4 and 5 together at each end, [CTS/RTS] and 6-8-20 together at each end [DSR/DCD/DTR]. |
11th Oct 2014, 10:37 am | #10 |
Rest in Peace
Join Date: Apr 2012
Location: West London, UK.
Posts: 665
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Re: Hazeltine 1500 faulty keyboard
Hi G6Tanuki, at one end (I would think the pc) he has a 9 pin socket.
I think your connections may need modifying to take this into account, unless Mean is already using a 25 to 9 pin adapter. ==== Hi Mean, you should be able to also set up:- Data bits (6 or 8) Parity (yes, no, odd, even) Under dos the MODE command was used for this. Are there any options to change settings (such as terminal emulation) on the Hazeltine? Regards - Mike |
11th Oct 2014, 1:30 pm | #11 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Hazeltine 1500 faulty keyboard
Im guessing I will need a db25 to db9 modem cable then. I have one but it has female on both ends.
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11th Oct 2014, 4:10 pm | #12 |
Pentode
Join Date: Oct 2010
Location: Melton Mowbray, Leicestershire, UK.
Posts: 156
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Re: Hazeltine 1500 faulty keyboard
Hi,
It does sound llike a keyboard problem primarily but if you want to test comms here is what I'd try. If you know the terminal is set to no handshaking or software handshaking, just set it to full duplex and connect pins 2 and 3 together on the terminal end and try pressing a few keys. You don;t need the PC. You should see what you typed appear on the screen as you've connected RX and TX together. If there is hardware handshaking, connect 2 to 3, 4 to 5 and 6 to 8 to 20. This should fool the terminal that it's good to go. again you don't need the PC. These two routes will check the terminal as far as the socket on the back. It's a handy test as you don't introduce too many unknowns such as the PC cables, comms software etc. Cheers, Andy. |
11th Oct 2014, 5:03 pm | #13 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Hazeltine 1500 faulty keyboard
Thanks, Andy.
I am pretty sure the comms are okay since the photo's of the terminal in the auction showed a CP/M computer loaded up on the screen. I just need the keyboard and caps sorted first |
12th Oct 2014, 12:30 pm | #14 |
Rest in Peace
Join Date: Apr 2012
Location: West London, UK.
Posts: 665
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Re: Hazeltine 1500 faulty keyboard
Hi Mean,
when RS232 appeared, there was no definite standard covering the connections, especially as at first upto 25 (+ possibly the screen) were available. (The 9 pin version became common later when it was realised 25 were often far more than required.) More so, when handshaking etc. was used e.g. DSR/DCD etc. Thus you cannot assume a modem cable will have those you require. I found it best to check which connections a cable has, by opening its plugs. If this is not possible, metering out may not be easy if any are cross wired. To connect a dumb terminal, probably no more than 3 - 6 end to end connections are required. I think G6Tanuki is incorrect advising connecting 1 to 1. We were told to connect the cable screen to pin 1 at one end only. As this is for safety, you can see why. Should one chassis become live, you do not want the other one to do so. Regards - Mike |
12th Oct 2014, 4:26 pm | #15 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Hazeltine 1500 faulty keyboard
I think what I will do is get a db25 / db25 modem cable with a 25pin to 9pin adapter on the PC's end. Is this a good plan of action.
The cable schematic in the manual matches that of a db25 modem cable if that is of any help. |
12th Oct 2014, 6:11 pm | #16 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,130
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Re: Hazeltine 1500 faulty keyboard
Just be careful to heed the advice given above about making sure that the needed signals are available on the appropriate pins, otherwise you may need to make up your own cable with the specific requirements of your setup.
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13th Oct 2014, 8:08 pm | #17 | |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,010
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Re: Hazeltine 1500 faulty keyboard
Quote:
When you're controlling gear that can spot-weld the entire side of a Transit-van to its chassis in a second you need to be sure of your different grounds. The coming of EIA-485 balanced circuits made life a lot easier when provisioning large production-lines. |
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14th Oct 2014, 6:48 pm | #18 | |
Hexode
Join Date: Apr 2003
Location: Cotswolds, UK.
Posts: 465
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Re: Hazeltine 1500 faulty keyboard
Quote:
Robin |
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