RE: Re: OT: VCR picture flashing

["Keith Doxey" <ukha@xxxxxxx>]

OK.... unlikely to be MacroVision then :-(
so a different train of thought....

Maybe the inputs to the amp are AC coupled instead of DC coupled.

For most equipment this doesnt matter but there are some pieces of kit that
refuse to work properly with AC coupled inputs. I have had a few cases
where
similar problems have happened with KAT5 and a slight mod has cured the
problem. The equipment that was affected was made by Sony and Panasonic.
These required a DC coupling to hold the output stable.

A Video signal must have a 75 ohm termination to work at the correct level
and AC and DC coupling are described below.

AC Coupling

Cap
INPUT-----------Circuitry Signal

75R

Ground------------ Circuitry Ground


DC Coupling

Cap
INPUT-----------Circuitry Signal

75R

Ground------------ Circuitry Ground

Obviously you cant start hacking your Denon Amp about but one thing you
could try is adding a resistor across the input to clamp the signal to a
ground reference. 75ohm would result in double termination and a signal
level half what it should be. At best it would be a dark picture, at worst,
unstable or non existant. Start by using a 1k resistor and drop the value
until you get a picture that is stable and watchable. Failing that, you may
need to add a video amp to the input.

Hope that makes sense, if not, contact me off list and I will talk you
through it.

Keith

www.diyha.co.uk
www.kat5.tv


> -----Original Message-----
> From: yhkeppy [mailto:keith@xxxxxxx]
> Sent: 27 April 2003 21:09
> To: ukha_d@xxxxxxx
> Subject: [ukha_d] Re: OT: VCR picture flashing
>
>
> Keith (you're right, it is strange!)
>
> By recorded, i mean ones i have recorded to watch no pre-rec as I
> have virtually none of these after moving to the little silver disks!
>
> It does manifest itself a bit like macrovision (have seen this in
> action out of interest), but the next problem is that the screen i
> mentioned is a plasma. So I could probably rig the VCR up to go
> straight to the plasma, (and will try when i find/make the
> appropriate cabling) but i guess i'm interested if anyone else has
> seen this.
>
> Interestingly, this is the second VCR that did this (last one was
> stolen) and this Denon amp is not the common factor as the previous
> amp was a Sony (also stolen!), so therefore the only common
> components are the NTL digibox (not stolen) and the plasma (also
> stolen), but in both cases i was using composite (i know, will be
> cabling up properly when i decorate) therefore the screen(s) is(are)
> probably discounted.
>
> Cheers,
>
> Keith
>