16 Sep
2014
16 Sep
'14
10:30 a.m.
On Mon, Sep 15, 2014 at 11:38 PM, Alex van Denzel
<alex.van.denzel at gmail.com> wrote:
Thanks Alex, I wasn't aware of that link. I probably should have said
that I have that manual in hardcopy, and am looking for a more
detailed schematic. I've taken a closer look, and drawn the primary
side of the power supply. It looks a lot like this one:
http://www.repairfaq.org/sam/mon1ps.gif, except that it uses a 555 to
provide a 100KHz clock, and a few minor details. The basics are the
same.
What I find is that the UC3842 isn't getting the juice it needs.
Monitoring pin 7 (Vcc) shows that when I switch the supply on, Vcc
ramps up to 14V, then drops down to 0.8V and stays there. When I
switch the power supply off again, after a while Vcc ramps up to 14V
again, then slowly ramps down to 0V. Any ideas as to what would cause
this are welcome.
Camiel.
