Monitor destroyed by install

[Mike McCarty]

Les wrote:
> On Mon, 2006-12-11 at 11:20 -0800, ols6000 at sbcglobal.net wrote:
> 
>>At 10:59 AM 12/11/2006, you wrote:
>>
>>>There isn't even a software capability to make that occur.
>>
>>There is a warning in the monitor docs not to set the frequency and 
>>resolution out of range, as it can cause physical damage to the monitor.
>>
>>The monitor was definitely working before the FC6 install, and 
>>definitely not afterward. During the install, the screen went blank 
>>and stopped responding to any signal (not just Linux).
>>
>>
>>> What is the bug#
>>
>>I did report this as a bug, #218416. 
>>
> 
> I have destroyed several monitors this way (I have been programming a
> long time, and hacked a lot in my early years), but I never saw the
> interface itself go bad.  What happened was that the flyback (the

That's right. The flyback ends up working at a non-resonant
frequency, and it ends up burning itself out. That's how the
early malware worked.

[snip]

> use a separate source for the horizontal sync signal, and while it might
> be possible to cause the deflection coils to do something similar, it is
> not likely).  But the interface itself is independent of the HV supply

Those coils are very robust, anyway. If that were a problem, then
loss of horizontal synch (back when we had "horizontal hold" and
"vertical hold" controls) would have burnt them out. Doesn't happen,
AFAIK.

> and would not suffer from a frequency problem.  However, a hot plug
> situation could cause a spike in the input that could fry the buffers
> and the input circuit would be dead.  In the old days, the buffer was

Well, hot plugging anything not specifically designed for that is
bad news. But what we're talking about here is the monitor having
a warning on it that it can't take frequencies other than those
it was specifically designed for. These days that is, IMO, a design
defect.

> separate, something like an opamp chip and you could replace a single 16
> or 20 pin device and be back on the road.  However today things are
> typically more integrated and you may have an expensive repair (several
> tens of dollars for the component and typically 60 an hour for a capable
> tech for the high density multilayer boards.

Yep.

Mike
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