Phil Allison wrote:
Jeroni Paul wrote:
Here is its schematic:
http://www.rom.by/files/q9t4-fp91g-power_bd_1.pdf
** If the mosfet blew, R615 must have too.
Did you maybe replace it with a wirewound type ?
That would explain most of you symptoms, running OK at low loads but failing if the current in the switch is higher - also made worse if the AC supply voltage is lower as it will be with a lamp in series.
R615 ( 0.22 ohms 2 watts ) must be a metal film or composition type.
IOW *low* inductance is crucial.
..... Phil
Thank you Phil.
The resistor you mention was good and is the original. Finally I got it working by wiring 4 100W bulbs in parallel, so I removed the bulbs and all is fine.