🚀 go-pugleaf

Burton L. Palmer <blloydp@halcyon.com> wrote:

>Re: V34 Internal Modem Reports "NO Dial Tone"...

>I have an external v.32 supra fax modem that suddenly no longer sinks
>enough current from the tel-co line to make the tel-co see that I am
>off-hook.

A quick test here shows that for my local exchange the dial tone sense
limit is about 12 milliamps. The line voltage is about 48V under these
conditions. However a modem would normally pull more current than this
so the dissipation in the line hold device would be much less than the
600 mW maximum. Your allnight session could have triggered thermal
runaway if the hold current started off on the low side. It does not
sound a difficult repair once you locate the damaged part, probably a
transistor or resistor.

Interesting note about Tandy cables. I was given a Tandy pushbutton
phone some years ago because it was incompatible with the owner's
installation - it rendered all the other phones in his house dead! It
turned out to be a design fault, the A and B wires were swopped over
on the schematic. And this phone had a green type-approval sticker on
it. Makes you wonder.
Regards, Jeff Howell
Email - howell@anglianet.co.uk