sync on green to horizontal and vertical wiring seperator.

From: jpero_at_sympatico.ca <(jpero_at_sympatico.ca)>
Date: Mon Jun 11 13:03:04 2001

> From: ard_at_p850ug1.demon.co.uk (Tony Duell)
> Subject: Re: sync on green to horizontal and vertical wiring seperator.
> To: classiccmp_at_classiccmp.org
> Date: Mon, 11 Jun 2001 18:27:07 +0100 (BST)
> Reply-to: classiccmp_at_classiccmp.org


> Before you give up, 2 checks..
>
> 1) Is the EHT voltage correct _and stable when you increase the
> brightness_. You didn't mention the picture also got larger as the
> brightness was turned up (a common symptom of EHT problems), but it's
> still worth checking.

No expanding when I change brightness, very stable. But items would
grow colorful trails to the right if I broost too much gain or screen
on each gun, it has set of 2 pots for each R, G, B guns. But this is
not the problem apprently.
 
> 2) Try boosting the heater a bit. If there's a resistor in series with
> the CRT heater, reduce it or short it out. If the heater supply comes
> from its own regulator, try tweaking it up a bit. If you can do neither
> of those, disconnect the existing heater supply and try running the
> heater from 3 (or so) turns of wire wound round the flyback core. Every
> 6.3V CRT heater I've tried will stand 8V at least. This may not help, but
> it might get you a couple more months out of an old CRT

I'll try that. I already have traced the wiring for that heater, it
leads directly from fly to the heater. I think there is a disc cap
and a resistor. Have to open it up and look again. It's very
service-friendly monitor, RF shield snaps off to expose the CRT
board, main board swings out on pair of plastic hinges. Well built
monitor, heavily shielded. Only difference on this monitor both
screen and focus is on seperate circuit board not on fly itself.

Doesn't the heater demands lot of current flow?

Doesn't this monitor can be affected by too low voltages for B+
power?

>
> > But I might have one or two monitors I might able to extract certain
> > IC to split the sync out to drive a peecee monitors which are in
> > plenty around here.
> >
> > Otherwise if there a way to build that thing from scratch is nice.
>
> Get the data sheet on the National Semiconductor LM1881 (or the Elantec
> version that's a bit better). It's an 8 pin chip that's a video sync
> separator. That should be able to pull the sync off the sync-on-green signal
> (which after all is electically the same as a composite mono signal).
>
> -tony

Cheers,

Wizard
Received on Mon Jun 11 2001 - 13:03:04 BST