[vdr] Re: Is this DVB-C card compatibel with VDR?

["Reinhard Walter Buchner" <rw.buchner@freenet.de>]

Hi Juri,

> >> one) are _very_ sensitive! I wrecked my composite out
> >> on my DVB-C, too. I hope my J2 still works...
> > 
> > Sorry, NO luck possible. J2 CVBS is _the_SAME_  as
> > composite RCA plug. 
> 
> I thought more about the RGB signals. Any experience?

RGB works good on a non-sick card. However, if you (or
anyone ;o)) shot the composite, you will most likely also
receive a bad picture via RGB. Internally (at least as far as
I can "see" from the few specs we have of the TI chip) RGB
is generated and is then muxed to composite & Y/C (where
Y/C is also "placed" on the Composite & R lines. Each output
is clamped via two diodes. If you overvolt these, they die
and short internally, which leads to an overload condition
of the outputs. This is what you see as a washed out picture
or a picture containing too much red.

Currently I am working on a DVB extension board which will
incorperate a (replaceable) safety circuit, which will hopefully
kiss the danger of killing a DVB card goodnight. I am in heavy
email contact with Thomas Breuer on this subject. (who is BTW
also working on a VERY neat DVB extension board, quite a bit
more sophisticated than mine. Watch out for his release. It will
be worth the wait ;o))  However, I am sure he will notify the ML
once his prototype is up & running.

Turns out that the output filter & safety circuit need quite a bit
of thought before actually building it ;o)) (the problem being
not to mess with the signals coming from the DVB. However,
I think it is worth the effort and hope it  will save the lives of
some DVBs.

I will think about releasing the plans for a safety / filter circuit
on it's own (i.e. for those of you who don't need or want the
more sophisticated board like Thomas's or mine).

As for those who already have a dead DVB card, Thomas described
how to burn the dead diodes out. Please have a look at the ML
around October for the  thread 'burned DVBs-s' 

PLEASE NOTE: NO one can guarantee this will work. You may
damage your DVB even further! If you try it, remember it is
your decision, your DVB board and your money. Neither Thomas
nor I will be responsible for a loss.

Greetz,
Reinhard



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