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Re: Problem Using a Commodore 1084s Monitor on a IIgs
Polymorph wrote:
On Feb 20, 4:01 am, ferd...@gmx.de wrote:
If the things you tried didn't help at all, then it doesn't seem to be
bad luck...
You could try replacing C222 or just bridging with your 150�F/400V
cap. At least in theory there cold be a fault elsewhere but this would
be VERY difficult to find, even with an oscilloscope. Using could
spray to cool the parts related to the horizontal output stage one at
a time can help to locate the fault.
I'll give your suggestions a try. I've used up all of my cooling
spray, so I'll need to get some more prior to trying this.
BTW does the problem disappear if the power is turned off for a short
time (i.e. 1 minute or so)?
I believe it does go away when turned off for a minute or two, but
returns quicker than if the unit was cold. It does appear to be heat
related.
(Sorry for not chiming in earlier--I was travelling. ;-)
I think cooling spray is the correct route to locating the problem.
(Do avoid spraying it near the HV components, though. Components
outside the "cage" are fine.)
The "singing" component is almost certainly just a symptom of
the problem, not its cause, which, as Ferdinand has pointed out,
is instability in the horizontal output stage.
Almost any component can be temperature sensitive, but capacitors
and resistors are high on the list.
From your description of the problem, it sounds like it will be
easy to locate with a 10-20 degree temperature drop.
Well I'd be interested in fixing these monitors because they have
interesting defects, but this is not an option.
I'm interested in fixing *this* monitor as I bought it for my
daughter, but in future I would prefer to have a working monitor
straight away. With 2 young kids and 200+ driving per day, I don't
have much spare time up my sleeve to be worrying about these things.
Mind you, it has been educational and I am sure I have benefited from
the experience imparted from you (Ferdinand) and MJM.
Most people don't relish repair work, but it is inevitably educational,
and adds to your confidence that you can fix other things. ;-)
-michael
NadaPong: Network game demo for Apple II computers!
Home page: http://members.aol.com/MJMahon/
"The wastebasket is our most important design
tool--and it's seriously underused."