🚀 go-pugleaf

In this case, get datasheet for 3842 (from Motorola -- UC3842).
Make sure that its VCC is 12V. Pin7 from memory.
Also check/replace capacitors in primary.

If you find that VCC to 3842 pulses, I would suspect fault outside of PS
primary.

Rudolf

"Alan Liefting" <aliefting@ihug.co.nz> wrote in message
news:3C96692D.587C9095@ihug.co.nz...
> I am almost 100% sure that it is a PSU fault.  The monitor will work
> occasionally.  The EHT is coming up.  The PSU control ic is not shutting
> down due to overcurrent.  There is an additional bit of circuitry that
> controls the 3842 chip.  I think it is for power save.  I am sure that
> this is the area where the fault is.
>
> Alan Liefting
>
> Rudolf Ladyzhenskii wrote:
> >
> > Check horizontal circuitry.
> >
> > Rudolf
> >
> > "Alan Liefting" <aliefting@ihug.co.nz> wrote in message
> > news:3C965925.4A3EA9E4@ihug.co.nz...
> > > Hello All,
> > >
> > > I have the above monitor which is pulsing.  The power supply is coming
> > > up and shutting down a couple of times per second.  It is definitely a
> > > power supply fault.  Voltage control is done on primary.  Disconnected
> > > optocoupler which is for power supply standby.  Still no difference.
> > > Replaced control capacitor.  No difference.  Replaced opto and UC3842
> > > control ic.  Still no difference.  Replaced a capacitor in an obscure
> > > bit of circuitry and came right.  Monitor then failed on test!
> > >
> > > FCC ID DK4M1566
> > >
> > > HELP??!!
> > >
> > > Alan Liefting