Phillips 28PW6006/5, brightness flash and soft picture.

[matchfacts]

Hi all,

For a while my Philips 28PW6006 has been intermittently flashing the brightness.  The whole screen would show a high change in brightness level before returning to the preset levels.

Now after this has occurred, sometimes the screen will show a blurriness at the edges of the screen and what looks like a ghosting of image - but only at the edges.  It's not like a registration error as a white line looks like it's repeated not like it's dividing in R G B.  Also, flyback lines can be seen in the blacks at this point.

Any ideas if this is a simple fault or an accumulative effect of a number of errors?

[brainstorm]

Hi, It sounds like you have a CRT(tube) fault, but you could try adjusting the Grid 2 supply in case this control is "noisey" or out of adjustment. The Grid 2(sometimes called A1) adjustment is usually found on the Line output transformer(bottom control)- try tweaking it a little one way another,dont adjust it too much or you may trigger the protection circuits! But you won't do any harm. Also just be careful where you put your fingers coz there is approx 28KV coming out of the transformer!

[lubos55]

Hi,
you have probably problem in system of CRT.Try regenerate CRT or remove short in system CRT.

[greywolf]

Yes, probably problem with CRT - different RGB cutoff voltages. There is also too little RGB amp. supply voltage (180V instead 200V = bad design) in this model. From this two causes results bad function of cutoff control loop (flickering, fly back lines, in extremal case protect turn off with login 5, 11).

The cure consists in check / increase of heating voltage (5480), check / increasing +180V filter capacitor (C 2495 up to 47uF) and readjustment of Vg2. In extremal case you will need increase supply Vrgb by 20V (aditive winding, 3 winds aright phased in serial with D 6495).