[GreenKeys] Teletype Model 15 power Q's...

[Eric & Jia Bigham]

Jim,

Thank you so much for your detailed reply :) !  Now that I have the right model number, the schematic makes a little more sense ;p heh.  My AC plug is an everyday three-prong plug… missing the fourth prong - terminal 22, but since I don’t have a table with a switch and rectifier, it looks ok.  I looked at this schematic here:

http://www.virhistory.com/navy/manuals/tty/jh/ttyman9/drawings/military/19x02.pdf

…and it seems that, according to note #3, the terminal block is already wired for bypassing a line-relay.  Can’t figure out, by looking at the schematic right now, what those few other wires taped off - next to the block is, but maybe that will come in time ;o …

…so using a transformer (PowerSpecialists CSI12001X) on the DC lines coming in and using he proper voltage/current (120vdc/60ma)… if everything else checks out, the keyboard and printer should then work with the line-test switch… am I right ;o ?  I think I’m finally catching on here ;D ~…..

…slowly but surely :) ~

^_^


> On Nov 9, 2016, at 9:17 pm, Jim Haynes <jhhaynes at earthlink.net> wrote:
> 
> What you have there is most of a Model 19.  The printer says it is a 15-Y
> because the same printer is used for Models 15 and 19.  The fact that it
> is 15-Y says it is a Bell System unit rather than one for some other
> customer.
> 
> Go to www.rtty.com and click on the Model 19 item and download the
> schematics, if you don't have them already.  There may be variations
> between those and what you have, but you can probably figure them out.
> 
> It's conventional in 15s and 19s to have a four-wire power cord: incoming
> hot, incoming neutral, safety ground to frame, and outgoing hot wire
> that has been through the power switch.  This allows the power switch to
> control a rectifier DC power supply located in the table.
> 
> The round knob above the keyboard is probably a line-test switch as I
> mentioned in a previous mail.
> 
> At the left rear of the base is a line relay mounting.  Most likely you
> don't want to use a line relay, so you can wire around it and remove it.
> 
> I see you have a holding magnet selector and the toggle switch for series
> or parallel connection of the coils for 20 or 60 ma operation.
> 
> On the left side of the base above the keyboard is the send-receive-break
> switch.  On receipt of a break signal this goes to the receive position
> and shorts the keyboard.  You have to manually flip the switch to the
> send position to resume typing on the keyboard.  If you push it to the
> break position that opens the line to send a break signal to stop the
> other end from sending.
> 
> On the right side of the base is the keyboard-keyboard/tape-tape switch.
> In keyboard position the tape punch is disabled and it works just like
> a Model 15.  In the keyboard/tape position it works like a 15 and
> also punches tape.  Depending on how the external stuff is wired this
> might let you send to the line from the keyboard while punching tape, or
> it might just let you print a copy of what you are punching.  In the
> tape position the keyboard is disconnected from the signal generator
> so you can only punch 'blind' from the keyboard, but you can punch
> really fast.  The printer might be connected to copy what you are
> sending from the tape reader.
> 
> The dial with the pointer is the character counter, so you know when
> to put in CR and LF while you are punching tape blind.  The red light
> comes on when you are near the end of a line.  I'm puzzled by the cover,
> since normally there is a glass window for viewing the character counter
> dial.  Another version of that machine puts the character counter on the
> right side of the base rather than on the left.
> 
> The solenoid next to the fuse is the motor control relay.  It looks to be
> disconnected in your machine, with the wires jumpered and taped so the
> relay is not needed to turn on the motor.
> 
> In the last picture I see a speed governed motor.  The light bulb is to
> illuminate the black and white wheel while you are looking at it through
> a tuning fork with a light shutter on the prongs.  That's how you adjust
> the speed.  A sync motor is more desirable, but requires a different set
> of gears.  As an alternative to the tuning fork you can buy from China
> on ebay a digital photo tachometer for about $10.
> 
> You need something like a 1 amp 120V DC power supply to run the punch and
> the local loop that is set up with the line-test key.  When used with the
> four-wire power cord the power switch can turn the DC supply on and off.
> Then there are an additional two terminals on the blocks where the output
> from the DC supply goes in.  In the official Model 19 setup the power
> supply is a big heavy thing that uses a constant voltage transformer or
> a magnetic amplifier voltage regulator.
> 
> So get the schematics from www.rtty.com and go to work with an ohmmeter
> and mark them up if they are different from what you find you have.  It
> should be obvious how to disconnect and remove the line relay mounting
> when you look at the schematic.
> 
>