[zxspectrum] Re: QL con problema
- From: Rich Mellor <rich@xxxxxxxxxxxxxxxxxx>
- To: zxspectrum@xxxxxxxxxxxxx
- Date: Mon, 02 Jun 2014 15:23:16 +0100
On 02/06/2014 15:13, Massimo Raffaele wrote:
Hi Rich,
I can see from the photos that this QL is suffering from 'screen
flare'. This is normally down to the MC1377P chip, but can also
be the 8301 and/or 8302 ULA causing interference.
It can also be a problem with the TV modulator itself.
Hmmm, a premise: I fear I would get the same problem if connecting the
QL via composite signal... because the VCR I have (with the same
defect) is connected via composite and not RF.
That said, you could be right.
Apart from the composite signal on the RGB Out socket is cleaner than
that going into the TV modulator on the QL.
I would recommend that in the first instance, you remove the 8301
chips from their sockets and push them back in (as it can be
carbon build up on the pins).
Damn, so I'll have to open it, risking my poor old membrane...
Ok, if necessary I'll do it.
Yes - go on, chance it!
I have in the past tried to do a composite video modification to
the TV modulator on the QL, but this does not work due to
interference. There is a much simpler solution however, which is
to make up a composite video lead which takes the video signal
from the RGB connector to give a stable supply (use PIN 1
Composite PAL and PIN 2 GND on the RGB socket) -
http://www.fruitcake.plus.com/Sinclair/Spectrum128/SCARTCable/Spectrum128SCARTCableQL.htm
Wow, thanks for the new fruitcake website link! I had the old one and
it's not complete anymore.
Yes, one of the ideas which came to my mind was to try buying a RGB
cable from eBay (I know a pair of guys are selling true RGB cables for
the QL, for 13..15 euros).
I could indeed build myself a composite SCART cable, as you suggest, but:
1) I would prefer a RGB signal, which is cleaner
2) if the problem is due to some bad component influencing both the
composite and the RF signals, but _not_ the RGB output, I could bypass
the issue using a RGB cable.
I basically just took an old QL monochrome monitor cable and moved one
pin from the composite mono signal to the composite PAL signal - worked
a treat :) No need to use a SCART then as you plug it directly into the
TV's composite video in.
You can use the QL RGB to SCART and a lot of people have used this - one
advantage is that you can use an upscaler box to view the full QL screen
(512x256 pixels) on a TV (rather than being restricted to 448 x 240 pixels).
What do you think?
Max
--
Rich Mellor
RWAP Services
Specialist Enuuk Auction Programming Services
www.rwapservices.co.uk
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