13 Aug
2014
13 Aug
'14
4:13 p.m.
Yup, I went ahead and re-flowed all of the pins that mount the flyback,
plus any large / heavy parts, power resistors, all of the connectors -
basically anything doing double-duty providing both mechanical and
electrical security.
But how could that bad joint blow the horizontal output? I don't know squat
about video circuitry, just never got into it.
On Wed, Aug 13, 2014 at 4:13 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Anyway, it turns out that this is one of those sets that draws its heater
supply from a second winding on the HV flyback transformer. After some
That was my first thought when I read the intial fault description : 'Does
the heater get powered from the flyback, if so, a problem with the
horizotnal output stage (or driver stage) would cause just this effect.'
inspection of the board, I found that one of the
flyback's soldered
mounting pins had cracked at the joint, causing an intermittent
connection.
You were very lucky. Often dry joints around this area will end up
blowign the horizotnal output transsitor. If you have not already done
so, I would resolder _everything_ in this area.
-tony