CRT Monitor Problem

[lulugrant_is_a_dog]

Hi,

About a week ago my 19" CRT started displaying an extremely distorted
picture. It intermittently goes into a state where the picture is
broken up into fuzzy lines (I can't describe it well) and the
slightest tap on the case could cause it to return to normal
(temporarily) or get worse.

I've checked for any broken video connections inside or outside, but
there are none. What's weird is that I ran the monitor with the
plastic case off and the problem disappears. But as soon as I put the
case back on the slightest movement or tap near it makes the picture
go crazy again.

Does anyone have any ideas as to what the problem could be? Could the
case be causing some sort of interference?

Thanks in advance for any comments.

 

[Arno Wagner]

Hi,

About a week ago my 19" CRT started displaying an extremely distorted
picture. It intermittently goes into a state where the picture is
broken up into fuzzy lines (I can't describe it well) and the
slightest tap on the case could cause it to return to normal
(temporarily) or get worse.

Contact problem affecting the sync-signals. May be in the external
connector or in some internal ones.

I've checked for any broken video connections inside or outside, but
there are none. What's weird is that I ran the monitor with the
plastic case off and the problem disappears. But as soon as I put the
case back on the slightest movement or tap near it makes the picture
go crazy again.

Probably removing the case puts the problematic connection
under different mechanical stress than when it is on. This
often improves contact conditions.

Does anyone have any ideas as to what the problem could be? Could the
case be causing some sort of interference?

No. This is very typical for a broken solder point or a marginal
connector. This is also very hard to find. Fix is easy once
you know here the problem is. If is a connector, you may
want to remove and reseat every connector you can get at. Be
careful that the CRT may remain charged up to some hours
after it has been disconnected from power.

Arno

 

[lulugrant_is_a_dog]

Contact problem affecting the sync-signals. May be in the external
connector or in some internal ones.


Probably removing the case puts the problematic connection
under different mechanical stress than when it is on. This
often improves contact conditions.


No. This is very typical for a broken solder point or a marginal
connector. This is also very hard to find. Fix is easy once
you know here the problem is. If is a connector, you may
want to remove and reseat every connector you can get at. Be
careful that the CRT may remain charged up to some hours
after it has been disconnected from power.

Arno

Thanks for the quick reply. I did look to see if there would be any
obvious stress from the case being on, but you're right it is probably
going to be hard to find and somewhere *not* obvious.

 

[William Sommerwerck]

No. This is very typical for a broken solder point or a marginal

Thanks for the quick reply. I did look to see if there would be any
obvious stress from the case being on, but you're right it is probably
going to be hard to find and somewhere *not* obvious.

You now have to decide whether you want to systematically resolder "all" the
joints, rather than trying to find the specific bad connection.

 

[hr(bob) hofmann]

You now have to decide whether you want to systematically resolder "all" the
joints, rather than trying to find the specific bad connection.

An other alternative is to put the case back on, but with something
inside the case that "bends" the guts slightly and see how long that
"fix" works - maybe.

 

[James Sweet]

Thanks for the quick reply. I did look to see if there would be any
obvious stress from the case being on, but you're right it is probably
going to be hard to find and somewhere *not* obvious.

These sorts of problems are actually pretty easy to track down most of the
time. Find yourself an insulated stick of some sort, my favorite is the
plastic rod from a set of window blinds but I've used wooden dowels, plastic
pen bodies, etc. Remove the cover from the monitor, power it up, and start
gently poking and tapping areas of the board until you find the ticklish
spot, and then flip the board over and inspect carefully for cracked solder
joints.

 

[Franc Zabkar]

Hi,

About a week ago my 19" CRT started displaying an extremely distorted
picture. It intermittently goes into a state where the picture is
broken up into fuzzy lines (I can't describe it well) and the
slightest tap on the case could cause it to return to normal
(temporarily) or get worse.

I've checked for any broken video connections inside or outside, but
there are none. What's weird is that I ran the monitor with the
plastic case off and the problem disappears. But as soon as I put the
case back on the slightest movement or tap near it makes the picture
go crazy again.

Does anyone have any ideas as to what the problem could be? Could the
case be causing some sort of interference?

Thanks in advance for any comments.

Tap test the open monitor with an insulated rod. That may narrow down
the location of a dry soldered joint.

- Franc Zabkar

 

[JANA]

If you are tapping on the monitor case to have a temporary repair, this
means that there is a cold solder connection somewhere in the monitor. More
than likely it could be on the main circuit board, one of the daughter
boards, or a connector.

The monitor would have to be un-assembled, and jigged up so that it can be
worked on. The process of slightly flexing boards and connections can be
done to try to zero in on where the fault is. Once found, then the
connection can be re-soldered. This can be very time consuming work.

Working on a monitor requires good electronics experience, a sound knowledge
of monitors, and troubleshooting skills. There are many safety issues
involved. I would suggest you take the monitor to a service centre and have
an estimate done in order for you to make a logical decision if it is worth
to service or not.

--

JANA
_____


Hi,

About a week ago my 19" CRT started displaying an extremely distorted
picture. It intermittently goes into a state where the picture is
broken up into fuzzy lines (I can't describe it well) and the
slightest tap on the case could cause it to return to normal
(temporarily) or get worse.

I've checked for any broken video connections inside or outside, but
there are none. What's weird is that I ran the monitor with the
plastic case off and the problem disappears. But as soon as I put the
case back on the slightest movement or tap near it makes the picture
go crazy again.

Does anyone have any ideas as to what the problem could be? Could the
case be causing some sort of interference?

Thanks in advance for any comments.