[GreenKeys] RS232-Current loop converter troubleshooting

[drlegendre .]

"..worked fine at first.."

In other words, some part(s) broke down during operation. There aren't too
many things to break in this design, save the two optocouplers - so I'd
look at those, first.

My build broke early on as well, but in that case, it was due to nicked
(solid-core) wire that broke off of a soldered connection. I used salvaged
telco wire, and that stuff is pretty fragile when it takes a nick. For the
second-round repair, I used a hot stripper - so no damage to the wiring.

On Sun, Jan 17, 2016 at 9:34 PM, Sarah Autumn <neverether at gmail.com> wrote:

> 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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