X10 European Lamp Module (LM12 etc)

[miweaver@xxxxxxxxx]

Although I live in Australia, I will head this request as "European" since =
the X10 modules sold in Australia appear to be the same as those in Europe =
/ UK (Marmitek, etc) except with the standard Australian / NZ plug / socket=
 arrangement. So, I have had a couple of these which have died on me, and I=
 am trying very hard to repair them as I still have a very good application=
 for using them. Having dismantled the modules and checked the associated c=
ircuit board, I can see that most of the circuit appears to be similar in d=
esign to that widely published on the Internet by SM Bloom for the 110v lam=
p module with obvious changes to take account of the higher supply voltages=
 in European countries (220v through 250v). However, there is one area of t=
he circuit that leaves me perplexed. In the 110v circuit, the 120Khz 'contr=
ol' signals are fed to pin 1 of the associated 78561 microcontroller via a =
variable coil and what appears to be a couple of clamping diodes and a 33pF=
 series capacitor.=20

However, on the European models, the associated circuitry is much more comp=
lex. The 120KHz signals are again fed to pin 1 of the 78561 via a variable =
coil but then via a much more complex circuit consisting of two extra trans=
istors as well as a number of associated capacitors and diodes. I have trac=
ed the circuit and there are certainly some anomalies! The first transistor=
 used is marked C705 and a 'net search shows this as a small signal RF NPN =
transistor. However, the references to this show a nonstandard pin configur=
ation (ECB rather than EBC)) which certainly does not appear to be the case=
 on the one I have removed from a PCB. I am 99% certain that the one used h=
as a standard EBC configuration. The second transistor is marked C623 which=
 seems to be the same as others on the PCB. I have a sketch of how I believ=
e the circuit is laid out, based on the best of my ability and without dest=
ructively unsoldering too much (The tight layout makes this a difficult tas=
k, to say the least!). My question is, does anyone have ANY knowledge of wh=
at the purpose of this extra circuitry is and how it works? I am happy to s=
hare my sketch if there is anyone out there that might be able to answer me=
!

Oh, and my fault-finding so far seems to indicate that the major problem is=
 a breakdown of the initial 0.33uF 630v polyester capacitor that is used in=
 place of the "large blue" 0.68uF capacitor on the 110v modules.

Many thanks in advance for any assistance - there is precious little inform=
ation available on 'true' European voltage modules.