[Boatanchors] Re: ft 757 problem

Mon, 29 Jul 2002 08:51:50 -0400

Ray, 	

There are some older units that do not recharge the Lithium battery. They do
expire and must be replaced. It is primarily used to store data in memory. It is
doubtful this is the problem here. 	

----------
From: Ray Friess <[email protected]>
To: [email protected]
Cc: [email protected]; [email protected];
[email protected]
Subject: [Boatanchors] Re: ft 757 problem
Date: Monday, July 29, 2002 2:24 AM

The ft 757gx has a lithium battery in it.  would this battery be used in the
tuning/frequency control/memory functions?   If so, would it cause the problem
by going weak???

W1EOF wrote:

> Ray,
>
> You have an intermittent connection. Could be an IC socket, a connector, or
> a broken trace on the PC board. This is what I would do:
>
> 1. Remove the cover and power the unit. Attempt to duplicate the problem by
> gently tapping in different areas. I don't know the layout of this rig. It
> might mean tapping on the circuit bd on bottom, then on top, etc. Try to
> isolate the problem to one major area of the radio.
>
> 2. Look carefully at IC sockets and connectors. You can very often narrow
> down a problem by simply looking, or I should say studying the radio. Look
> for tarnished pins, connectors, etc. Also look for an area of the PC board
> which has an accumulation of rusty-looking gunk. Sometimes stuff gets
> spilled down into a radio and it takes awhile for the stuff to rot through a
> PC board land. In your case I would start in the area around the digital
> freq controls, the microprocessor, etc. Very often these chips are not
> soldered in, but are plugged into sockets. Great if you need to replace the
> chip, terrible in long-term use due to tarnish on the IC pins and/or
> sockets.
>
> 3. If the visible portions of the IC legs look tarnished, they must be
> cleaned. Carefully remove them. Find something that you can lay the pins on
> to support them, but NOT bend them. This could be a thin tabletop or
> something like that. Use a pencil eraser to clean off the pins by brushing
> away from the IC body. Same thing with connector pins.
>
> 4. Another common source of intermittents is a broken land on the PC board.
> This can be found by gently tapping, or gently applying pressure to slightly
> bend the PC board. If you find a land that is broken, you can easily fix it.
> Use an exacto-knife to scrape the conformal coating off the copper material
> about a .25" to .5" in both directions. This must be done carefully so that
> you don't strip the copper of the board, or cause more problems. Use a small
> soldering iron and tin a very small gauge wire. Wire-wrap wire is ideal for
> doing this kind of repair. Bend the wire so you have a long piece to hold on
> to, and a short/tinned piece that will be long enough to cover the section
> of copper you stripped. Once you have the wire tinned, use the iron and hold
> it against the copper. Remove the iron and you should now have a "bridge"
> that goes across the break in the copper foil. Ue small cutters to clip the
> wire that did not get soldered. Two points I cannot stress enough here:
>         You have to solder the wire down quickly. Too much heat will pull the
> copper off the board.
>         Make sure you do not short this run to an adjacent one.
>
> After you care done, carefully inspect your work to ensure a good connection
> with no shorts.
>
> Power on the radio and try tapping around in the same area. Hopefully you
> are done and can button-up the radio and get back on the air! Hope this
> helps, let us know how what you found.
>
> 73,
>
> Mark W1EOF
>
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]]On Behalf Of Ray Friess
> > Sent: Monday, July 29, 2002 12:09 AM
> > To: [email protected]; [email protected];
> > [email protected]; [email protected]
> > Subject: ft 757 problem
> >
> >
> > I have a problem with a yaesu ft757gx I'm hoping someone can help me
> > with.
> > The frequency display keeps going in and out....  when it goes out I can
> > no longer
> > change frequency with the vfo dial or with the frequency step switch.
> > It's an intermitten problem that happens at times when the case is
> > tapped on...
> > Any suggestions?
> > Ray  WA7ITZ
> >
> >

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