repairing h-scan on a Commodore 1701

From: bill claussen <elecdata_at_kcinter.net>
Date: Tue Jul 10 19:11:49 2001

Chuckling, My post should have read horizontal! I'd be happy to get the scans for you
and send to you. Check for cracks around the flyback transformer as well. Now all I
have to do is find the manual. It's here but just where is the question.

I agree with Tony, you won't need a scope.

Bill

Tony Duell wrote:

> > > Check for cracks near the deflection cable for the vertical, and check to see if
> > > the high voltage cap this is in the vertical circuit is okay, it maybe defective.
> > > I have the schematics at the shop somewhere I'll look if you want and scan as
> > > necessary.
> >
> > Hi Bill, thanks for you help! Let me ask you, did you really mean "vertical
> > circuit"? My problem seems to be with horizontal deflection since all I see
>
> I would agree. This is a horizontal deflection problem.
>
> > is one vertical line with colors matching the image. Where is that
> > circuit physically located in the box? My box seems to have received a smack
> > on the right side (looking from the rear). There seems to be some separate
>
> Interestingly, the horizontal output circuit in just about every monitor
> is on the RHS as seen from the rear. There are a few exceptions to this,
> though. The easiest way to find the horizontal output circuit is to find
> the flyback transformer (trace the HV cable from the side of the CRT
> flare, although if I have to tell you to do that, you probably should be
> reading a book on TV operation and repair before you get to work on this
> monitor).
>
> > aggregate on that side. But I can't see anything obviously damaged here. I'd
> > need to focus in more to be able to find something. Eventually I need to
> > measure I guess. Is there anything I could debug without a scope?
>
> If the monitor has received a heavy knock, then it's possible that some
> large/heavy componnts have either broken their soldered connections to
> the PCB, or have pulled the pads away from the PCB and broken the tracks.
> Look for that sort of damage.
>
> Alternatively, the widings on coils, etc may have been broken away from
> their solder tags. This sort of damage is easy to repair, normally.
>
> >
> > (I'm now hunting for a scope on ebay, but those go away like crazy and I'm not
> > even going to be sure whether the unit I will receive will work ... I don't
> > want to end up having to repair the scope in order to repair the monitor :-)
>
> I don't think you'll need a 'scope for this one...
>
> -tony
Received on Tue Jul 10 2001 - 19:11:49 BST