[GreenKeys] How hot is too hot? (Teletype 32)

Wed Sep 7 11:49:45 EDT 2022

Hey there Paul - for some reason my machine seems to run in Local mode with
no cables plugged into telex.  That never happened before. Nor have I
pressed any of the buttons like Start or Stop. Notes below!

> Mode 1: local mode
> - Teletype in ready to receive mode: all lamps out, motor off, a few ma of
> current
> - press local button. Teletype comes on in local mode. Can type. Not sure
> current draw. - Stays on until I press stop button
>
*no cables connected, I run in Local (typing) mode regardless. I cannot
exit by pressing STOP*

>
> Mode 2: Telex Mode
> - Teletype in ready to receive mode: all lamps out, motor off, a few ma of
> current
> - Press and hold the start button for one second. Dial Lamp comes on,
> motor still off
> - Dial a number
> - when finished dialing, I-telex turns the motor on, current goes up to
> 40ma and a call is made
>
*When I power up 32, the motor runs and the CONN lamp is illuminated.*
*Next - I switch on my iTelex.  The motor stop - all lamps are out.*

*Next I press CONN to dial - the dial lamp is illuminated*
*I then dial a number (I can see the data LEDs on the iTelex when I dial. I
am definitely connected to the internet)*
*Machine does NOT spring into life*

*OK i press STOP (lamp is off now)*
*I press i-Telex Test button*
*Machine motor comes to life - as if it is about to print*
*but... after a few seconds powers off.*

>
>
> Does local mode work for you?
>
> *Yep, but not in the usual manner. No more open 😳*
On Wed, Sep 7, 2022 at 1:06 AM Paul Heller <paul0926 at comcast.net> wrote:

> Andy, I’m confused.  Mine works differently.
>
> Mode 1: local mode
> - Teletype in ready to receive mode: all lamps out, motor off, a few ma of
> current
> - press local button. Teletype comes on in local mode. Can type. Not sure
> current draw. - Stays on until I press stop button
>
> Mode 2: Telex Mode
> - Teletype in ready to receive mode: all lamps out, motor off, a few ma of
> current
> - Press and hold the start button for one second. Dial Lamp comes on,
> motor still off
> - Dial a number
> - when finished dialing, I-telex turns the motor on, current goes up to
> 40ma and a call is made
>
>
> Does local mode work for you?
>
> You can see mine operating here:
>
> https://www.youtube.com/watch?v=v4risjgiX1E
>
> Hope it helps
> Paul
> W2TTY
>
> On Sep 7, 2022, at 1:36 AM, Andy KN4UCL <kn4ucl at gmail.com> wrote:
>
> 
> Good evening/morning folks!  After wasting a good amount of time on a
> blown fuse in my low-grade multimeter, I finally managed to measure the
> current between the Teletype and the i-Telex. Below are my findings
>
> Teletype + i-Telex powered on: *4 mA (*Dial lamp illuminated - motor
> starts to run but does NOT run "open")
>
> If I press STOP button on Teletype: *58mA *(Dial lamp extinguished)
>
> Similarly, if the Dial Lamp is illuminated, and if I try and dial a number
> - the motor switches off very quickly.
>
> And finally - if I press the Test button on my i-Ttelex, the motor spins
> up and shuts down after about 7 seconds (no printing.)
>
> Thank you for your guidance!
> Andy
>
>
>
> On Tue, Sep 6, 2022 at 11:03 AM Andy KN4UCL <kn4ucl at gmail.com> wrote:
>
>> Hey Paul I have the single TW39 card... ummm let me see if I can use my
>> multimeter to measure the current 😱😊
>>
>> On Tue, Sep 6, 2022 at 10:34 AM Paul Heller <paul0926 at comcast.net> wrote:
>>
>>> In my case the resistor mods were not enough. I never understood why,
>>> nor did Russ. It still drew way too much current and I blew up the TW39
>>> port. Do you have a dual TW39 card? Maybe try the other port?
>>>
>>> I had to add additional resistance in the loop to get the current down
>>> to 40ma.
>>>
>>> Be sure to measure your loop current and keep it around 40ma.
>>>
>>> Paul
>>> W2TTY
>>>
>>> On Sep 6, 2022, at 4:22 PM, Andy KN4UCL <kn4ucl at gmail.com> wrote:
>>>
>>> 
>>> Thanks guys for the helpful responses!  I am ashamed to admit that after
>>> an excellent chat session yesterday (with the cover off - keep things cool)
>>> my beloved 32 no longer properly wakes up when I receive a message or send
>>> a test message from the i-Telex!  The motor runs, but no typing.  After
>>> about 7 seconds it shuts down. I wonder if I disturbed something removing
>>> the cover, or maybe my resistor modifications finally broke something
>>> 😳😱... iTelex seems fine as I can see messages coming in overnight by
>>> looking at my TW39 serial port in tera term. cheers!  Andy
>>>
>>>
>>>
>>> On Tue, Sep 6, 2022 at 6:56 AM Joe Duszyński <joeduszynski1 at gmail.com>
>>> wrote:
>>>
>>>> For the i-Telex,
>>>> Better yet use a Diode and a momentary push button in parallel to
>>>> short out the diode to dial out.
>>>> You hold the button down while you dial the number and release the
>>>> button when the current reversal happens,
>>>> then the power consumption is Zero at idle. Fancy relays.... BAH!! LOL!
>>>>
>>>> 99% of the time the machine sits idle with i-Telex (unless you call out
>>>> a lot).
>>>> The diode will not affect the current reversal.
>>>> If you have a machine that "only" sits on a subscription service and
>>>> never dials out on I telex like I do,
>>>> you don't even need the switch just the diode because all you are
>>>> doing is waiting on a call (Current reversal).
>>>>
>>>>
>>>> I made an "el cheapo" FSG for a machine without one, using a diode,
>>>> momentary push button,
>>>> a 100ohm resistor, optocoupler, a phone dial and a countdown timer
>>>> relay set for 2 seconds.
>>>> Even put it in a fancy 3d printed potted box with wiring terminals and
>>>> everything! ;-)
>>>>
>>>> When the reversal happens the optocoupler trips and holds the timer
>>>> relay, since the relay is set for 2 seconds the pulsing on and off of
>>>> the message does not affect the relay and when the current reverses
>>>> back to hang, up the relay shuts off in 2 seconds.
>>>> When you hold the momentary push button down (only hooked across the
>>>> diode not the optocoupler) you get full loop current to the dial and
>>>> the motor stays off.
>>>> If you want the schematic to make an FSG for a machine without one, I
>>>> can send it.
>>>> The one I built has been running 24/7 since April or May of this year.
>>>>
>>>>
>>>> Some ITELEX FYI.....
>>>> The i-Telex doesn't "look" for the really low idle current like a real
>>>> telegraph exchange.
>>>> In a real telegraph exchange there needs to be a really low idle
>>>> current of around .004 ma.
>>>> The i-Telex does provide this very low current but it does not look
>>>> for it to exist. The i- Telex only cares that
>>>> the current flow is lower than its threshold to register as an off
>>>> condition. The i-Telex does not care if the current is present or if
>>>> it exists at all.
>>>>
>>>> The i-Telex actually only looks for the circuit to go open or closed
>>>> because the optocoupler can only sense "ON" and "OFF"
>>>> The high impedance "low current" state of the FSG is the same to the
>>>> i-Telex as an open circuit, it is sensed as an OFF state.
>>>> The circuit is such that the really low draw won't activate the
>>>> optocoupler.
>>>>
>>>> The i-Telex mimic's the operation of an exchange rather well but if
>>>> you have a FSG that the high impedance relay draws slightly too much
>>>> current
>>>> the optocoupler then activates and the i-Telex will think the
>>>> teleprinter has gone "off hook" and cause problems, in this case you
>>>> have to add some resistance to
>>>> the relay or if its circuit is adjustable "Adjust it" to negate the
>>>> excess current draw and that can be a balancing act with an old
>>>> finicky FSG.
>>>>
>>>> "The more you know"
>>>>
>>>> JD
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Tue, Sep 6, 2022 at 4:25 AM Paul Heller <paul0926 at comcast.net>
>>>> wrote:
>>>> >
>>>> > This is a good idea - stand the resistors off of the board as much as
>>>> possible. Why not?
>>>> >
>>>> > Paul
>>>> > W2TTY
>>>> >
>>>> > On Sep 6, 2022, at 10:14 AM, Henning Treumann via GreenKeys <
>>>> greenkeys at mailman.qth.net> wrote:
>>>> >
>>>> > 
>>>> > European (or better non Teletype) machines use a very sensitive
>>>> polarized relay to detect
>>>> > the current loop reversing of the TW39 system which switches the
>>>> motor power relay after
>>>> > an incoming call.
>>>> > Hence stand-by power usage of an European Telex control unit is
>>>> almost nothing.
>>>> >
>>>> > I would install the mentioned resistors on a small distance to the
>>>> PCBs.
>>>> >
>>>> > And yes... it should be online 24/7 - that's the fun of i-Telex. :-)
>>>> >
>>>> > 73
>>>> > Henning DF3OE
>>>> > i-Telex 925302
>>>> >
>>>> > www.i-telex.net
>>>> > www.telexforum.de
>>>> >
>>>> >
>>>> >
>>>> > Am Mo., 5. Sept. 2022 um 22:54 Uhr schrieb Paul Heller <
>>>> paul0926 at comcast.net>:
>>>> >>
>>>> >> Nice machine!
>>>> >>
>>>> >> A fan is an interesting idea. A small one that runs off 120vac
>>>> perhaps.
>>>> >>
>>>> >> I don’t have that insulator in mine and I think Wayne’s suggestion
>>>> to remove it is a good one. I often leave the lid opened to let air
>>>> circulate in there.
>>>> >>
>>>> >> It seems like a bad design. The European machines have a relay which
>>>> is much better. I don’t know how they dissipate power from the small amount
>>>> of loop current when not in a call, but I’ve not noticed heat build up in
>>>> them. Yes it gets pretty warm and I often worry about that but so far all
>>>> is doing ok on my machine. I do power it off when going away for any
>>>> extended amount of time.
>>>> >>
>>>> >> Paul
>>>> >> W2TTY
>>>> >>
>>>> >> > On Sep 5, 2022, at 4:37 PM, Andy KN4UCL <kn4ucl at gmail.com> wrote:
>>>> >> >
>>>> >> > 
>>>> >> > Hey folks, I recently got my M32 up and running on i-Telex and all
>>>> is good but things are getting a little toasty and I am not sure how much I
>>>> need to worry.  Please see attachments - the circles I drew show where it's
>>>> getting hot.  120-130F if my Harbor Freight thermometer is to be believed.
>>>> >> >
>>>> >> > As there is quite a bit of room in there, I was wondering if a
>>>> small fan would be helpful.
>>>> >> >
>>>> >> > Any thoughts appreciated!
>>>> >> >
>>>> >> > thanks
>>>> >> > Andy
>>>> >> >
>>>> >> >
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