[DarrenCarter]

Thanks torbjorn for your reply.
Because the line output transistor never blew i presumed it would not be component or capacitor failure so ordered a new flyback transformer after reading this article. http://www.repairfaq.org/REPAIR/F_monfaq8.html#MONFAQ_004 . I fitted it this Saturday morning and set the focus and screen pots to the same positions as the old one and Hey Presto, perfect picture and problem solved. It must of been flashover in the EHT tripler to the focus output which i understand is quite a common fault.
Thanks again for your reply.
Darren.

[torbjorn]

More likely, it is a flashover in the CRT from the EHT (anode) supply to the focus or screen grid, and then the flashover current takes the way through the spark gaps to ground.

Before blaming the CRT, check that the spark gaps are clean, disassemble and blow out dust with compressed air as necessary. Also, it is a good idea to check that the set operates with correct EHT voltage. If you haven't access to a high voltage probe, then you can assume that it is within spec if the picture width is correct (check by a test card) and the supply voltage to the line output stage is correct.
Too high EHT is often caused by a wrong value flyback capacitor or, in case of several parallel flyback capacitors, of one of them going open circuit. If there is only one flyback cap and this goes open circuit, the line output transistor will usually fail immediately. Of course, it can as well be bad solder joints, PCB cracks etc that cause disconnection of one of the caps.
If the set has a bleeder resistor from EHT to ground, also check that it has not gone open circuit. It can be difficult to measure it as the resistance often is hundreds of megohms, but you should at least take a look to see if the resistor casing is cracked or if there are signs of overheating.

[DarrenCarter]

Hi All,
Just joined this forum after searching the database and comming up with nothing and wonder if anyone can help.
The said set decided to go wrong last night with an intermitent tick noise followed be picture collapse and recovery. The set has perfect picture and sound between ticks. After removing the back and inspecting all the usual suspects for dry joints i noticed with the lights off an arcing in the tube base connector where the anode supply enters. The arcing was comming from the spark gap assembly in the base connector.
This leads me to belive there is intermittent HT comming up the anode from the LOPT. Could it be there is flashover in the LOPT to the anode.
Any ideas.
Thanks.
Darren