Pincushion?

On 1 Aug 2005 10:29:31 -0700, "solder lung" put finger to keyboard and composed:

If this is a digital monitor, then I expect that its uP would be adjusting the pincushion via an E-W correction IC. If you are completely in the dark, then you might consider recording the part numbers of the various ICs and searching the Net for their datasheets or functional descriptions. ISTR there was a particular ST Microelectronics IC (8-pin DIP?) that caused a few E-W problems in some monitors.

- Franc Zabkar

There is on made by ST micro.. its a dual op amp LM358n.. i'll try replacing this and see how it goes. thanks

On 28 Aug 2005 11:09:04 -0700, "solder lung" put finger to keyboard and composed:

I was expecting something like a TEA2031A, but that was just a WAG. The E/W correction can be done in *many* different ways. You really need to identify the various ICs. E-W correction works by varying the current in the horizontal yoke according to the vertical beam position. The current is at maximum when the beam is at the middle of the screen, and minimum at the top and bottom of the CRT. What you should be looking for is an additional coil or transformer in the horizontal section that is driven by a parabolic signal from the vertical section. For example, a model 4CM8270 15" Philips monitor has an E-W circuit which is controlled from the "Vertical Parabola Output" pin (11) of the TDA4850 H&V deflection controller IC.

- Franc Zabkar