I have this problem with this monitor: there is no high voltage, the HOT is
OK, and I think that the flyback is also OK. The green led is on, and when I
turn the monitor on, i think i can hear the high voltage coming up, but then
immediatly go away...

Does anyone know a possible solution for this problem, or perhaps someone
who has had the same problem with the same monitor...
Also I don't have the schematic of this monitor, so in case if anyone should
have this, it's always welcome... :-)


All help is welcome !



greetings,
Bart

I have this problem with this monitor: there is no high voltage, the HOT is
OK, and I think that the flyback is also OK. The green led is on, and when I
turn the monitor on, i think i can hear the high voltage coming up, but then
immediatly go away...

Its possible that the xray protect circuit is being activated either by
over-voltage to the HOT or by leaky caps from power sources generated by the
flyback.

My monitor experience is based from commercial video game monitors and I would
estimate that 95% of my monitor problems start with leaky capacitors usually in
power supply bypass circuits. The #1 culprit is decoupling capacitor on the
output of the B+ regulator, typically a 47-100mf @ 160V.
When that starts to go, oscillation in the B+ will eventually kill the
HOT/Flyback. There is usually a filter arrangement between the flyback and the
the xray input. A bad cap there would trigger the xray circuit prematurely.

Jim

Hey;
thanks for your response!

But I'm wondering about what you mean by X-ray protection, is that a device
that is measuring the radiation or something,...

And A secund thing that i don't know is how to find "leaky" capacitors, do
they short when measured with an ohm meter? or...



thanks,
Bart



"Jamespoore1" schreef in bericht
...



I have this problem with this monitor: there is no high voltage, the HOT
is
OK, and I think that the flyback is also OK. The green led is on, and when
I
turn the monitor on, i think i can hear the high voltage coming up, but
then
immediatly go away...

Its possible that the xray protect circuit is being activated either by
over-voltage to the HOT or by leaky caps from power sources generated by
the
flyback.

My monitor experience is based from commercial video game monitors and I
would
estimate that 95% of my monitor problems start with leaky capacitors
usually in
power supply bypass circuits. The #1 culprit is decoupling capacitor on
the
output of the B+ regulator, typically a 47-100mf @ 160V.
When that starts to go, oscillation in the B+ will eventually kill the
HOT/Flyback. There is usually a filter arrangement between the flyback
and the
the xray input. A bad cap there would trigger the xray circuit
prematurely.

Jim

"Moernoo" wrote in message (snip) i don't know is how to find "leaky" capacitors, do
they short when measured with an ohm meter? or...

If you don't know how to do that, then it is time to get the unit to a
qualified tech. You could not only cause injury to yourself, but also
turn a minor repair into an expensive extravaganza if you attempt such
action without the necessary knowledge or instruments.
Ben.

"Moernoo" bravely wrote to "All" (04 Jun 04 10:17:03)
--- on the heady topic of " Philips 107s 17c2321n problem"

Mo From: "Moernoo"

Mo Hey;
Mo thanks for your response!

Mo But I'm wondering about what you mean by X-ray protection, is that a
Mo device that is measuring the radiation or something,...

It is often a little glass diode sensor placed in the vicinity where
the crt's X-rays are expected. It is followed by a dc amplifier or
switch. When the diode's junction is struck by X-rays it generates an
emf the value of which depends on the radiation source intensity.


Mo And A secund thing that i don't know is how to find "leaky"
Mo capacitors, do they short when measured with an ohm meter? or...

Leaky caps will drag down the voltage in a resistive divider so this
is the most obvious way to tell in-circuit. Testing for capacitor
leaks is usually done off-circuit by the simple trick of unsoldering
just 1 lead free from the circuit.

Using an ohmmeter a normal capacitor will usually show infinite
resistance after a few moments of charging by the meter's internal
current. A leaky capacitor will typically stop charging part way.
Remember to use the right polarity with electrolytic caps as these
will show a lot of leakage if it is inverted by mistake.

Another way to test for leakage is to apply the capacitor's rated or
expected voltage and then measure the leakage current directly or by
waiting a number of seconds and measuring the voltage change in time.
Capacitor analyzers will do this automatically.

A*s*i*m*o*v

.... :) What does that wire do? =8Q (oh!)

I have measured the Uce of the HOT, and it seems to ben more then the normal
100V (+-210V)

Its possible that the xray protect circuit is being activated either by
over-voltage to the HOT ...


Do you have any idea of possibilities of these higher voltage?


thx,
Bart
"Jamespoore1" schreef in bericht
...



I have this problem with this monitor: there is no high voltage, the HOT
is
OK, and I think that the flyback is also OK. The green led is on, and when
I
turn the monitor on, i think i can hear the high voltage coming up, but
then
immediatly go away...

Its possible that the xray protect circuit is being activated either by
over-voltage to the HOT or by leaky caps from power sources generated by
the
flyback.

My monitor experience is based from commercial video game monitors and I
would
estimate that 95% of my monitor problems start with leaky capacitors
usually in
power supply bypass circuits. The #1 culprit is decoupling capacitor on
the
output of the B+ regulator, typically a 47-100mf @ 160V.
When that starts to go, oscillation in the B+ will eventually kill the
HOT/Flyback. There is usually a filter arrangement between the flyback
and the
the xray input. A bad cap there would trigger the xray circuit
prematurely.

Jim