[GreenKeys] Current loop not providing (enough) current

Fri Sep 27 21:57:28 EDT 2019

No to get off topic, but at least you didn't hook your meter up on the wrong lead ports haha.

I'm going to work with an analog meter tomorrow to do more tests, including looking at that pulse. 

	  Original Message  

From: paul0926 at comcast.net
Sent: 27 September 2019 21:32
To: wa5cab at cs.com; greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] Current loop not providing (enough) current

Yeah I must have had a stupid moment. Relay. What was I thinking! Duh. Selector is the right word.

I’ll go crawl under my rock now. 

Paul

On Sep 27, 2019, at 6:18 PM, Robert Downs <wa5cab at cs.com> wrote:

I agree, except that the selector assembly is not a relay.  The selector coils do not operate electrical contacts, they do something mechanical.

Unless you know what you are doing, don’t mess with the mechanical adjustments of the selector armature.

The Model 14/15/19 series have two kinds of Selectors, pulling and holding.  They are easy to identify.  The most common by far is the pulling.  Its magnets are large and round.  The magnets in the holding magnet type are small and square.  The holding magnet type also has a DPDT toggle switch that connects the magnets in either Series for 20 mA or parallel for 60 mA (I have never known why the proper current for the lower choice is 20 and not 30, but it is not). 

Also, you cannot run the pulling magnet selector on 20 mA because the coils are already connected in series for 60 mA.  If you connect them in parallel, you would have to run a loop current of 120 mA for it to work, not 20 mA.

Robert Downs

From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Paul Heller
Sent: Friday, September 27, 2019 11:23
To: Zach Zarzycki
Cc: GreenKeys
Subject: Re: [GreenKeys] Current loop not providing (enough) current

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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