[GreenKeys] RS232-Current loop converter troubleshooting

[Sarah Autumn]

I tried 2 different supplies. One was an acoustical coupler modem, which
does have its own resistor, and I also tried a Teletype REC-50 which I
believe does not have its own. Not sure though. Could open it up and check.
On Mon, Jan 18, 2016 at 4:01 PM <hwhall at compuserve.com> wrote:

> That sounds suspiciously like a problem I've seen one or two times. A
> wire or contact is broken or in poor contact, a high resistance contact, so
> that it can carry a very small current (milli or micro amps) and show near
> normal voltage but when more current is demanded, the voltage drop becomes
> large and the load isn't satisfied. Worst case was broken wire inside an
> otherwise OK-looking length of zipcord. Took a while to actually believe
> what the meter was telling me because I "couldn't see anything wrong."
>
> Check all the wires, connectors and related solder joints closely for
> minute breaks, cold joint, etc.
>
> Wayne
> WB4OGM
>
> -----Original Message-----
> From: Sarah Autumn <neverether at gmail.com>
> To: Greenkeys <greenkeys at mailman.qth.net>
> Sent: Sun, Jan 17, 2016 10:17 pm
> Subject: [GreenKeys] RS232-Current loop converter troubleshooting
>
> Hi all,
>
> I finally got around to building the loop to serial converter that
> everyone knows and loves (http://www.aetherltd.com/connecting.html). It
> worked fine at first, but now I'm getting this weird behavior.
>
> When there is no teletype connected, on the pins for the selector magnet
> (J1 5&6) have voltage. When I connect the teletype to the pins, the voltage
> drops to almost nothing, and the magnet doesn't operate. If I remove the
> teletype from pins 5&6, the voltage jumps back up to 100V. When I hook the
> teletype directly to my loop supply, it runs fine.
>
> I have also tried 2 different power supplies: One is an acoustic coupler
> modem used for the deaf, and another is a REC-50.
>
> I have checked the values of all my resistors and capacitors. What simple,
> easy thing am I doing wrong?
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