Half hour into a presentation , a varying small section of the picture
would break . Perhaps due to PbF problem , but did not seem to be
vibration sensitive. If anything , it varied with picture content.
About 90 percent of the image was sync'd properly, and the interference
moved about , so the information was there.
It seemed to start when there was large areas of black in the images or
perhaps just coincidence, once started , it remained much the same ,
just the vertical position randomly moved about.
The interference was , with a vertical line, the line would break
horizontally , leaving a curved line , partial loss of line sync.
At the moment I'm running with another pc input feed, before getting
inside, and no breakup emerged over an hour, but that would be typical
PbF of course. I'd like to eliminate a problem of syncing between pc and
projector firstly. Owner of the pc , when this problem emerged had never
had this problem with any other projector and this projector had never
had that fault before, even short term intermittant.
When the projector was switched off for a 10 minute break, the same
problem was there , with the same pc feed.
No name Chinese LCD type projector.
Any advice if I need to get inside ? no manual and nothing obvious on
any of the OSD menu screens for adjustment.

"N_Cook" wrote in message
...
Half hour into a presentation , a varying small section of the picture
would break . Perhaps due to PbF problem , but did not seem to be
vibration sensitive. If anything , it varied with picture content.
About 90 percent of the image was sync'd properly, and the interference
moved about , so the information was there.

RoHS solder is a likely suspect - while you go over the soldering, watch out
for nasty smells when you heat electrolytic capacitor leads.

Its often the smaller electrolytics that can cause this sort of thing, and
the end seal often leaks around one of the leads - sometimes that lead
corrodes right through.

The best I can describe the smell; a sort of cross between burning rubber
and cat pee.

N_Cook wrote:
I'd like to eliminate a problem of syncing between pc and projector
firstly.

What was the connection to the PC - VGA, HDMI, other? VGA has separate
sync signals, and an intermittent cable or connector might cause
something like this. People often bend the last few inches of a VGA
cable quite a lot, if (for example) the connector is on the right side
of their laptop but the cable needs to run off to the left. Sometimes
they will set their laptop on top of the cable, which might cause
intermittents to show up if they use the keyboard or trackpad during
the presentation.

If the projector was on the ceiling, with a cable routed through the
ceiling and wall to a socket on the wall, maybe that cable is going
intermittent.

Matt Roberds

On 23/11/2015 21:10, wrote:
N_Cook wrote:
I'd like to eliminate a problem of syncing between pc and projector
firstly.

What was the connection to the PC - VGA, HDMI, other? VGA has separate
sync signals, and an intermittent cable or connector might cause
something like this. People often bend the last few inches of a VGA
cable quite a lot, if (for example) the connector is on the right side
of their laptop but the cable needs to run off to the left. Sometimes
they will set their laptop on top of the cable, which might cause
intermittents to show up if they use the keyboard or trackpad during
the presentation.

If the projector was on the ceiling, with a cable routed through the
ceiling and wall to a socket on the wall, maybe that cable is going
intermittent.

Matt Roberds


That was quite possible. In a public meeting , so was not able to fully
explore at the time, VGA connection. The information was there in the
image, just parts of it were breaking. The VGA socket of the speaker's
laptop looked as though it had the remnants of a sandwitch or something
on the VGA socket, which I wiped away before connecting. In the break I
powered down and reseated the connectors but , as male to male lead, I
did not think of reversing the lead, continuing problem to the end of
the talk.
The problem never returned with trying with 3 other laptops