Philips 55PP8620/79 rear projection picture ok but not centred

You need to replace the convergence ics. Repair is usually pretty reasonable. Hope this helps.

A common problem is dull or washed out video.

Your set may have one or more of the following symptoms....

*Dull looking picture
*White looking picture
*Halos around objects
*Red/Orange looking picture

You can see some more examples and find a fix using this link on Fixya http://www.fixya.com/support/r2861467-solution_video_looking_whiteish_dull

The convergence ICs need replaced and likely several resistors in that circuit.

Sounds like your regulator ic is about to go, not an expensive repair but you have a good thought about buying a new set. If your fluid has never been changed I bet it's due also. Give the choice serious thought.

Replace your STKs 392-110s upgrade to the 180s.

Yes the box marked sanyo is the focus and screen control box. All stk Convergence ICs for rear projection TVs are made by Sanyo, which was the origional producer of the STK series Convergence IC. You need the convergence repair kit for the DPTV series rear projection which consist of two STK392-120 ICs and 11 6.8 ohm 1watt metal film resistors. You can get the repair kit for your model at the following link , they do ship to Austrailia however they do have an international shipping charge which must be purchased for orders outside the north American continent,. They also probide free installations instructions with pictures and free tech support. Heres the link.
http://servicemanuals.vstore.ca/

You can get the entire coolant replacement kit at the following link. which contains 48 ounces of coolant and an instructional CD that explains the process step by step with pictures. Its listed under their repair kit catagory.
Here is the link.
http://servicemanuals.vstore.ca/

coolant fluid on picture tube may be contaminated replace it an setbe ok (this is a technician job)

do you get a blinking read light?

you need a new flyback.
that is the problem.