Hi Noel
In directly you can you can sometimes check the ohms rating of the fly back transformer but in most cases this wont tell you if the LOPTX is faulty You normally have to go through a series of fault finding procedures to decide what the problem could be 9 out of 10 its normally the built in Tripler unit that supplies the eht to the tube
Routine standard checks
Isolate smps from TV check v out from power supply
Have you removed the fly back transformer from the PCB ?
If so have you connected a 100watt dummy load to the HT supply rails ?
If you then switch the set on is the HT rail correct across the load or near enough correct
Have you checked line drive and line oscillator on a scope ?
If that’s correct have you checked The line output Transistor or in some cases Line output Fet ?
Turn A1 right the way down so as not to burn the tube
Remove each of the secondary rails in turn off the LOPTX and check V out making sure that your 12 volt line and 30volt line are Ok
Have you checked the Frame stage supply rail ?? typically 25 volts to 50 volts depending
Check east west correction North south Correction stage You are looking fro leaky or short circiut east west correction diodes , possibly modulation circuitry Normally Fet or similar plus possible transformer (EW)
Have you checked the RGB final output stage 150V to 200V approx
Have you also made sure that any protection circuitry feedback to the CPU is dis connected?
Can you also upload a circuit diagram please
Mark www.harrington.force9.co.uk
