[GreenKeys] Current loop not providing (enough) current

Fri Sep 27 12:22:42 EDT 2019

Zach,

I believe you have it backwards. The relay should be energized and the during the stop bit and should open on the start bit.  From the way I read your email, you are looking at it the other way around. Maybe I misread your email.

Once you start changing the distance of the relays you can get into a real problem that is very hard to fix. I’d avoid that at all costs.

It sounds like there is not enough energy in the coils to close the relay. Are you still in a low current situation or have you resolved that problem? Depending on how the magnets are wired (parallel or serial) you need to be at 60ma or 30ma. Maybe try wiring for 30ma?

Paul
W2TTY

ITTY:			HTTP://INTERNET-TTY.NET:8000/ITTY
AUTOSTART: HTTP://INTERNET-TTY.NET:8030/AUTOSTART
EUROPE:		HTTP://INTERNET-TTY.NET:8040/EUROPE

> On Sep 27, 2019, at 4:24 PM, Zach Zarzycki <shardsofaperture at gmail.com> wrote:
> 
> 
> Yeah, not sure why if it autocorrected DMR but that was me! 
> 
> 
> I'm wondering if it's mechanical and the armature needs to be closer to the magnet to sense the start bit?   
> 
> 
> 
> From: steve.n4tty at gmail.com
> Sent: 27 September 2019 10:06
> To: shardsofaperture at gmail.com; greenkeys at mailman.qth.net
> Subject: RE: [GreenKeys] Current loop not providing (enough) current
> 
> 
> Zach,
> 
> From watching your video it looks to me as if the following is happening:
> 1. You manually move the magnet armature against the magnet and the magnet
> has enough current to hold the armature in the mark condition.
> 2. You then press any key and the "start bit" opens the circuit so the
> machine starts running open until you manually move the armature again.  In
> other words the magnets are not pulling the armature back to the mark
> condition.
> 3. At one point you adjusted a screw that stopped the running open and even
> pressing a key would not start it running open again, even though you could
> see the magnet release the armature when a key was depressed.  Not sure what
> that screw is since I have never seen the model TTY you are working with.  I
> would say return that screw to it's original adjustment, as I don't think it
> is a part of your issue at all.  It just appears to me to be keeping the
> machine from sensing even the "start bit."
> 
> I haven't been following all of this thread, but did I see you, or was it
> someone else, mention DMT?  If it was you, were you wanting to use DMR to
> talk directly to someone?
> 
> Keep plugging away, you'll get it working eventually!
> 
> Steve G./N4TTY
> 
> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net <greenkeys-bounces at mailman.qth.net>
> On Behalf Of Zach Zarzycki
> Sent: Friday, September 27, 2019 9:42 AM
> To: GreenKeys <greenkeys at mailman.qth.net>
> Subject: Re: [GreenKeys] Current loop not providing (enough) current
> 
> Removed resistor no change. The magnet is sort of working. If I push it
> toward the coil, it closes and doesn't open until I press a key or hit
> break. I think thats reverse. It's sort of like the magnet is always
> energized and only a keypress breaks the loop, instead of the keypress
> energizing the magnet. I've tried flipping polarity, I have it hooked up
> just like I showed here minus the resistor https://i.imgur.com/KYAiy42.jpg
> and key presses register on the computer still, but typing on the computer
> and typing on the teletype doesn't cause the key to press. Best way I can
> describe what is happening is everything feels backward.
> 
> Here is a video that might better show what I'm seeing is here - maybe
> someone else can see something I'm not. https://youtu.be/CbZMtXkXz4w
> 
> On Fri, Sep 27, 2019 at 8:52 AM Zach Zarzycki <shardsofaperture at gmail.com>
> wrote:
>> 
>> Well, I think as it was suggested, a resistor may be the culprit.
>> There is a resistor that one the one schematic is labeled as "Station
>> Line Resistor" with a note "when required". This is on the line relay
>> - switch control two wire line or line to grnd diagram. This is NOT
>> how I am wiring this thing up as I don't believe it is necessary for a
>> single unit, and involves equipment I don't have.  I've highlighted
>> the resistor in this photo - https://i.imgur.com/QOAsNqX.jpg and the
>> position of the resistor matches up on my unit here >
>> https://i.imgur.com/Kk8LU8i.jpg . The parts diagram shows it as a 5k
>> or 1050 ohm resistor  https://i.imgur.com/TXwsVbi.jpg (highlighted
>> yellow).
>> 
>> I believe I need to remove the resistor and hook everything up like
>> this > https://i.imgur.com/KYAiy42.jpg where the loop is in red, the
>> resistor in question needs removed from the spot in the drawing from
>> contact 26 to the sending contacts (yellow), this diagram is the
>> "Local Attended TWX Service, no line relay switchboard" diagram.
>> 
>> I'm not sure what a station line resistor is, can anyone confirm this
>> is safe to remove? Worth a shot?
>> 
>> 
>> On Fri, Sep 27, 2019 at 7:21 AM Zach Zarzycki
>> <shardsofaperture at gmail.com> wrote:
>>> 
>>> So there was a little operator error here, therefore, Jordan, I really
> don't think the board is bad. I didn't swap my lead on the meter from v to
> ma (amperage , ma are separate ports, then volts, ohms, temp, diodes and
> caps on another port).
>>> 
>>> I have 60mA at the supply, between the 2 points it hooks to the PC
> interface and therefore at the terminal hookups on the teletype. between two
> windings down the loop on unit itself it reads 53mA, and at 2 other windings
> 0.
>>> 
>>> The break key and any strike does break the loop. Now it's a matter of
> figuring out why the machine itself / magnet won't energize.
>>> 
>>> 
>>> I'm going though the schematic again to see if coils are supposed to be
> in parallel or series with the way I have the loop hooked in - thinking
> about what Ralph had said with regard to reversed coils.
>>> 
>>> Ralph,  Ohio, and yeah, 40 is 2 far and my hf setup right now is awful,
> antenna down and what not!
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