Re: Panasonic tv vertical sweep

From: Charlie Bress (Here-I-am_at_the-last-moment.com)
Date: 09/23/04 

Date: Thu, 23 Sep 2004 14:56:49 -0400

"Jacques Carrier" <jcarrier@collegeem.qc.ca> wrote in message
news:e8015e99.0409230449.2b050f40@posting.google.com...
> Hi Charlie,
>
> You could send me the list of all multi pins IC"s mounted on a
> heat sink.I will tell you which one is the culprit.
>
> After all pins have been well resoldered , use a DMM to be sure there
> is no short circuit between any pins. (buzzer test)
>
> Let us */suppose/ *that your vertical IC is numbered IC301.Then you
> should also replace all
>
> electrolytic capacitors whose first *number* begin with a 3
> (C301,C302,C303,etc.).Your vertical IC should have
>
> at least 12-15 pins (LA7636 or LA7637 or LA7638 or .............)
>
> Let me know about the results.
>
> Jacques

There was only one multipin IC mounted on a heat sink. There was only one
pin that did not have a good looking shiny solder fillet. I cold not see a
crack with my little magnifier, but this solder joint was malformed and
grainy- an obvious suspect joint.
Reflowing the solder with a touch of a bit more produced a better looking
joint. This joint showed solid continuity with an ohmmeter.
I did not go through the exercise of checking all the associated components
as the symptom that a little percussive maintenance was effective did not
lead me to change caps etc. and all other solder joints in the area looked
good.

The hardest parts of this repair were getting the cabinet back together and
getting the wiring hooked up in an entertainment center that is too heavy to
move. Whatever would we do without wire coat hangers?

The first couple of power-ons gave a nice stable picture.
So thanks again to all for their help.

Charlie

Relevant Pages

  • Re: Isolated donut pad??
    ... just to mechanically mount the relay, ... > Fantastic diagnosis for I am able to locate a cold solder joint on one ... The relay has three soldered on pins on a one sided PCB. ... > pin had the conductor trace on the hidden side. ...
    (sci.electronics.repair)
  • Isolated donut pad??
    ... Fantastic diagnosis for I am able to locate a cold solder joint on one ... The relay has three soldered on pins on a one sided PCB. ... the relay pins go to the other components. ... pin had the conductor trace on the hidden side. ...
    (sci.electronics.repair)
  • Re: LED Conversion
    ... Bruce's pins at Allentown I thought I'd give ... DRAMATIC difference in heat. ... measures power usage on my MM before and after conversion. ... I changed out ALL of the bulbs on my pins. ...
    (rec.games.pinball)
  • Re: Which pins to dissipate heat for SO-8 regulator?
    ... pins on a SO-8 regulator are the most significant for heatsinking? ... which don't conduct heat very well. ... power pad on the pcb below the chip and epoxy it to that. ...
    (sci.electronics.design)
  • Re: Apple ][+ gravely ill - seeking assistance :(
    ... solder joint can cause major problems, even if the chips are all good. ... Also, if the pins inside any sockets are spread, or pushed down, then ...
    (comp.sys.apple2)