----- Original Message -----
Sent: Monday, November 19, 2001 3:42 AM
Subject: [M]: Re: SV: Re: Dead RS232 port


> Joe,
>
> Thanks for your reply. Do you know of, or have any instructions for
> "swapping out" the chip? Which chip is the bad one and what is the
> replacement? Keep in mind I have not had my scope apart to view the
> motherboard so I will need to take a peek at Doc G's site for some idea
of
> what the innards look like before I try anything myself.
The chip most likely to be concerned, is U9, which is a pretty 'standard'
MAX232 transciever (probably one of the commonest RS232 transciever chips
now in use. Remember the following things:
1) Work carefully. If you are not sure about doing something, stop...
2) Arrange anti-static precautions before doing this work.
3) It is safer to say that the chip is so cheap, that you will sacrifice
it straight away. Cut the legs off the old chip, and remove them one by
one. You are far less likely to harm the board working like this, than if
you try to 'desolder' the whole chip.
4) If you are not 'into' this type of soldering work, ask someone like a
local TV repair man to do it.
It is a relatively easy repair, and the chip is very cheap - in the UK
they are about £1, in 'one off' quantities.
You might want to consider inserting a good quality IC socket instead of
resoldering the new chip. That is down to how likely you feel a second
failure is...

Best Wishes

> > Agree, that a "break-box" with leds is a good help.
> > And the RS232 buffers are usually almost free of charge ttl chips to
just
> > cut out, desolder, suck out the leg-remains and re-install a fresh
one.
> > Joe
> >
> >
> >
> >
> > Dave,
> >
> > First, I wouldn't assume the worst - ACP is a bit quirky sometimes
(IMHO)
> > and it simply needs to be re-initialized in order to set it straight.
> >
> >
> > For a physical indication to see if things are 'flowing', Radio Shack
and
> > others make a serial port data indicator that has LED's on the face
and
> > plugs in line with a serial cable, the LEDs light up/blink when data
is
> > passed back and forth. This would be a great indicator to tell you
> whether
> > or not signals were actually going to the panel of the LX.
> >
> > Good skies,
> > sg
> >
> >
> >
> > ----------------------------/\------------------------
> > Pyramid Engineering / \\ www.pyreng.net
> > Colorado Springs, CO /_____\\ 719.570.9106
> > ------------------------------------------------------
> >
> >
> >
> >
>
>

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