Half-duplex VT420?

From: Carlos Murillo <cmurillo_at_emtelsa.multi.net.co>
Date: Wed Oct 10 06:44:35 2001

One odd failure that I had in a pc-compatible mainboard
originally manifested itself as a non-functioning mouse.
The mouse worked elsewhere. I said "toasted serial driver
or receiver" and then I swapped the serial card (no Tony,
no individual 1488's or 1489's to replace here; it was one of
those integrated functions card).

Still not working. Eventually I traced the fault to
a broken -12V trace feeding all of the slots; the NiCd
battery had begun spilling (though that was hard to see
until I desoldered the battery) and that trace was the first
to go... a little precision soldering and v`oila, problem fixed.

By the way, I normally use vinegar and a toothbrush for
cleaning NiCd messes, followed by rinsing with lots of water
(water is not too hard here), some gentle shaking to shed
off excess water and finally placing the board on top
of one of the older monitors (gentle heat). When I suspect
that there are crevices where a lot of water is hiding I use some
isopropyl alcohol before drying.

The vinegar seems to do a good job of eating the NiCd spill
and corrosion. What do other people on the list use?



At 06:31 PM 10/9/01 +0100, you wrote:
>Hmmm.. It is likely that the CTS signal uses another section of the same
>line receive chip that is used for RxD. I wonder if that chip is zapped....
>
>> But if I have a toasted line driver, wouldn't that strike both inbound and
>> outbound data?
>
>Not normally. There are combined driver and receiver chips (driver ==
>output from terminal, receiver == input to terminal), some of which even
>include voltage multiplication circuity to produce the +/-12V (or so)
>voltages needed for an RS232 interface from the +5V line. But a lot of
>devices, particularly mains-powered ones, use separater drivers (like the
>1488) and receivers (like the 1489).
>
>
>-tony
>
>
--------------------------------------------------------------
Carlos E. Murillo-Sanchez carlos_murillo_at_nospammers.ieee.org
Received on Wed Oct 10 2001 - 06:44:35 BST