Re: X10 European Lamp Module (LM12 etc)

[andrew@xxxxxxxxxxxxxxxxxxxx (Andrew Gabriel)]

In article <da4b9883-8af5-4fe6-80a7-665d91e9fcfb@xxxxxxxxxxxxxxxx>,
	miweaver@xxxxxxxxx writes:
> 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.

If that capacitor short circuited, I suspect it will have blown
all the low voltage circuitry, unless a zener diode held on for
long enough to blow the resistor in series with the capacitor
(which you can test with a test meter, although it's often
obvious when they blow).

If it just went open circuit, then you should be able to simply
replace it. Use a Class X1 or X2 capacitor to reduce chance of
it shorting (these are designed specifically to have mains
voltage across them and remain safe).

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

--
Andrew Gabriel
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