Date   : Sun, 09 Oct 2005 00:57:54 +0100
From   : "Ian Wolstenholme" <BBCMailingList@...>
Subject: Re: Domesday Rattling

I noticed this a long time ago when using the actual Domesday
discs but I got the same thing happening (on a VP410 player) today
when playing a couple of ordinary laser discs.  On one occasion,
the picture breaks up when the rattling starts and then eventually
the picture stops and you have to search forward to get it to come back
but on other occasions, it just seems to rattle for a few minutes without
any picture or sound disturbance.  Maybe it just happens when the laser
reaches a certain point.

Best wishes,



Ian

----- Original Message -----
From: Jules Richardson
To:  bbcmicro@...
Sent: Sun, 09 Oct 2005 00:29:02 +0100
Subject: Re: [BBC-Micro] Domesday Rattling

Ian Wolstenholme wrote:
> Does anybody know what causes the occasional rattling which comes
> from inside the Domesday laser disc player?  Sometimes, but not always,
> this is accompanied by picture interference.  Is there a remedy?

Afraid I've never heard that - I'm tempted to say that it's not supposed 
to do that! Possibly some sort of recalibration due to error (similar to 
a hard drive bouncing the heads to track zero upon error)?

The annoying thing with these players is that there's no easy way to see 
what's going on with the mechanical side of it; even with the lid off 
the disk obscures everything :-(

Do you get interference on the screen in the form of static-like snow, 
or some sort of picture tearing and break-up? Reason I ask is that if 
the speed of the disk rotation goes out then it tends to result in 
tearing on the display; I wondered if the rattling is the sound of the 
hub rings slipping (can't remember, but they're probably rubber and 
maybe prone to getting dirty or even starting to break up after all 
these years). Might be worth checking that as an easy test, also 
cleaning the laser, blowing dust out of any optical sensors etc.

I've got a feeling that the laser assembly slide on these is greased 
too, but check for evidence of such - lubricating anything that looks 
like it was originally lubricated may well be a good plan as any grease 
has likely all but dried up over time.

Wish I'd taken lots of pics when I had my player in bits to fix it now, 
as I can't remember the exact construction inside!

cheers

Jules