DIYbanter - Sony GDM-F500

On Wed, 22 Feb 2006 00:43:40 -0500, "Jimmy Martin"
wrote:

"Wayne" wrote in message
.. .
On Tue, 21 Feb 2006 04:50:38 -0500, "Jimmy Martin"
wrote:

The problem is a constant pincushion effect that is concave at left and
right sides of the screen. I have the schematics for this model. Any ideas
on what might be causing this? A bad cap? I'll try some freeze spray on a
few areas.

jimbo

IC007 CXA2043Q is a common failure - results in all sorts of
deflection-related faults.

Wayne

This is a 48 pin surface mount chip. What level of difficulty is it to
desolder and resolder? Can I use a 30 watt fine tip iron and solder wick for
this job? I found the chip for $32.99 at WWW.Bluestar-online.com

I think I will order it and give it a try.

Jimbo

I have done a few of these - just finished one this week. The method I
use to remove the IC is on page 9 of the REV 1.3 pdf at
http://www.geocities.com/vk3em/smtguide/smtguide.htm
(the procedure for Small Outline IC's)
I find that enameled wire that is .010 dia works best.

I've done these with a simple 25 watt weller iron with a very fine
tip, that I filed myself, as my cheapie iron does not have a fine
enough tip commercially available for it. Before I did my first one,
four years ago, I practised removing sm ic's from old motherboards.
Replacing the CXA2043Q requires above average soldering skills, and
you don't want to damage any of the very fine tracks that the ic is
soldered to, so if this is your first attempt, better practise ahead
of time and perfect your tecnique.

In the ones I've done, a number of the electrolytics near the IC have
to be removed to give enough room to do the job successfully. On all
the Sony pcb's that I've done, the pcb's are through-plated, and you
have to really careful removing the electros so as to not damage the
pcb. This also requires a good tecnique. What has worked for me is
this, for each electro.

1 - add a small amount of flux to the electros two solder pads on the
bottom of the pcb
2 - use solder wick to removes most of the obvious solder. You want to
end up at this point with a partially open (from the bottom of the
pcb) through-plated hole. The electro will still be firmly soldered to
the board, however.
3 - while applying heat to the lead of the electro, again from the
bottom of the pcb, use a very small jeweller's screwdriver to bend
the leads of the electro up and away from solder connection to the
bottom of the pcb
4 - use needle nose pliers to gently grab the leads of the electro and
bend the leads close to straight up and down, i.e., perpendicular to
the pcb.

In all cases in the process, you have to be careful to not use
excessive mechanical force or apply too much heat. Some of the plated
through holes are very small diameter and some of the tracks are very
thin. Easily damaged!

5 - now lightly resolder the two electro leads to the pcb, from the
bottom. the idea here is to add enough solder so the next step works
well.
6 - what you now need to do is to use a finger from one hand to
(gently) rock the electro alternately from one side to the other while
applying heat to the appropriate lead with your iron, from the bottom
of the pcb. each gentle push in one direction on the top of the
electro on the top side of the pcb while heating/melting the solder on
the appropriate lead from the bottom of the pcb will result in fairly
quickly levering/extricating the electro out of the pcb, with the pcb
unharmed.
7 - once the electro is out, then use your solder wick to remove the
remaining solder in the through-plated hole. usually this can be done
from just the bottom, but sometimes going to the top side of the pcb
is also required. Also you may have to add a bit of solder or flux to
facilitate removing enough solder from the hole to be able to insert
the electro (new or reused) for reinstallation after the CXA2043Q has
finished installation.

The biggest thing I learned while practising both of the tecniques (IC
removal/installation and electro removal) was to be gentle and not
overdo the heat with my soldering iron. The job can be done with
simple tools, but if you're not experienced, be sure you practice
ahead of time. Tracks are easily damaged!

Wayne