beware there are two different
versions of this board, when
replacing zener diode Z D 1 0 0 2 on th e
secondary check w hich part you take
out, the k it comes with a 1 2 volt
zener B Z X 5 5 - C 1 2 but some versions
are fitted with a I N 4 7 4 6 which is a 1 8
volt zener, if you fit a 12 volt zener
place of the 18 volt the set will work
normally for awhile then the diode
will go short circuit.