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Thread: ASR Model 33 Teletype top tips for new owner

  1. #1
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    Default ASR Model 33 Teletype top tips for new owner

    So I have a Teletype on the way from the US and could use some advice on checking it out and getting it going safely.

    Its been sold as 'excellent working condition' so I'm hoping that provided it survives the trip over to the UK I shouldn't have too many issues.

    On my list so far:

    1. Suitable power supply using a DC supply and pure sine wave inverter to give me 110V @ 60Hz - already have this working setup and note that another European user does something similar. I do wonder though why the frequency is important for this machine - I have read that perhaps it used to derive baud rate timing - can anyone confirm ?
    2. Check the hammer has suitable replacement protection to stop it beating the print head to death. I see that many seem to use PVC sleeving over the hammer. I did wonder whether perhaps several layers of heatshrink tube would provide a tighter fit ?
    3. Current loop to RS232 conversion - I have an old interface for this.
    4. Suitable ribbon replacement - I have ordered one of these - I hope its the right type.
    5. A supply of paper tape for the punch/reader - I'm hoping that @daver2 is going to provide me with a suitable contact.
    6. The machine should come with several original rolls of paper which should keep me going for a while.
    7. Lubrication - what are the essentials to check/apply before use and what types of lubricant should I use ?
    8. This model comes with a touch-tone CCU - I'm not actually sure what the implications of this are for interfacing through to RS232 via current loop conversion ? I have read that it may actually be a TWX CCU and might need some 'jiggery pokery' to get an interface working.

    Thoughts ?

    Thanks

  2. #2
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    Just on the way out of the door (so no time to actually check - so may be talking rubbish) but does the ASR contain an induction motor as its drive? If so, this explains the 60 Hz, otherwise everything will run ‘slow’ if fed from 50 Hz. Just a thought...

    Dave

  3. #3

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    Dave is right, all of the timing is determined by the rpm of the motor, including baud rate. It is likely that the person shipping it didn't lock down the print assembly. It will likely have dropped the H connector piece between the keyboard and the printer. It is used to reset the keyboard after you press a key.
    Looking at the front, it should be on the right side of the keyboard between the keyboard and the printer. If it is missing don't power things up until you find it. It can do a lot of damage in the wrong place.
    You can manually run the printer by turning the motors fan. You need to lock up the clutches on the shaft or it will have a lot of drag. Not having the current loop powered will cause the clutch on the input solenoid to constantly trip. You can either use a power supply and resistor or rubber band to keep it from tripping. ( never run it manually if you have AC connected, even with the power off )
    Most errors can be found by running it manually. With things flying around fast, things get bent or broken. Keep things oiled. The hammers rubber is likely bad. Use a rubber foot for a replacement.
    That is about all I have.
    Dwight

  4. #4
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    just a thought. i believe you can run it in local loop for test with any 110v transformer. the keyboard and receiver run off the same motor...
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  5. #5
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    1: As mentioned, the motor speed is critical.
    2: Most people just put a piece of tube over it. That should last a lot longer than heat shrink.
    3: That will work fine
    4: That will work fine as well
    5: I have no leads on more rolls myself but have been stuck with a reinforced tape for almost a decade. The machine punches it fine but you need scissors to cut it.
    6: I use the tractor feed paper but where on earth do people even find the rolls now?
    7: I used 3 in 1 and light sewing machine oil on the main shafts and the punch rods. An oil damp foam paintbrush helps apply a thin film of oil on many tight spaces and clean them as well.
    8: The only telephone interfaced CCU's that were not acoustic typically relied on a dataset stored in the base and had their own serial to current loop converter. TWX CCU's will plug into a model 33 but are designed for the model 32 which is a BAUDOT machine.

    Honestly there are no photographs of the guts of a modem CCU, just the front panel. Photographs would be an excellent start.
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  6. #6
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    Quote Originally Posted by NeXT View Post
    1: As mentioned, the motor speed is critical.
    2: Most people just put a piece of tube over it. That should last a lot longer than heat shrink.
    3: That will work fine
    4: That will work fine as well
    5: I have no leads on more rolls myself but have been stuck with a reinforced tape for almost a decade. The machine punches it fine but you need scissors to cut it.
    6: I use the tractor feed paper but where on earth do people even find the rolls now?
    7: I used 3 in 1 and light sewing machine oil on the main shafts and the punch rods. An oil damp foam paintbrush helps apply a thin film of oil on many tight spaces and clean them as well.
    8: The only telephone interfaced CCU's that were not acoustic typically relied on a dataset stored in the base and had their own serial to current loop converter. TWX CCU's will plug into a model 33 but are designed for the model 32 which is a BAUDOT machine.

    Honestly there are no photographs of the guts of a modem CCU, just the front panel. Photographs would be an excellent start.
    Plain FAX (non-thermal) paper is available in both the US and UK. Try Amazon or Staples or Office World. (not sure what they are all called in the UK and USA but I am sure you get the drift.
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  7. #7
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    Quote Originally Posted by g4ugm View Post
    Plain FAX (non-thermal) paper is available in both the US and UK. Try Amazon or Staples or Office World. (not sure what they are all called in the UK and USA but I am sure you get the drift.
    Ooops I forgot, probably not in Kamloops. A couple of nice brewpubs yes, but they probably expect you to fell your own trees, pulp them, and make your own paper....
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  8. #8

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    Not sure any of this is of use, but here goes...

    I have an ASR33 with a UK Kode (Datel line) CCU - but the previous user used a direct current-loop to drive it from a Commodore PET (last used over 25 years ago)
    Though this is a `normal` ASR33, it came with a manual for a Data Dynamicss 390 + what seems to be most pages of manual for the Kode unit.

    I have scanned both and they are at: http://www.cmas-net.co.uk/vintage/Teletype/

    The DD390 manual is now residing at the Centre for Computing History in Cambridge: http://www.computinghistory.org.uk/

    Chris
    Thatcham UK

  9. #9
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    Thanks all for the responses. Some useful tips.

    I have an opportunity to get a 50Hz motor for the machine.
    Is it a straight swap or would gearing need to change too ? Having looked at the technical manuals there doesn't seem to be any reference to 50Hz or 60Hz gears. I would expect that if a change was needed it would be the intermediary gear assembly.

    regards

  10. #10

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    In the docs I scanned, page 450 of the manual for the Data Dynamics 390 ( mostly a dressed up ASR33 ) :-
    shows diffent motors and gears for 50Hz vs 60Hz - no idea if there is more to it !

    http://www.cmas-net.co.uk/vintage/Te...ssue-3-All.pdf


    Chris

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