> Before I replaced the failed potentiometer (new one seen top left) the > display looked like its horizonal hold had gone so I reasoned that's what
OK... The TDA1180 is the horizontal oscillator, etc, IC. It's well-known. Start by getting its data sheet. Indentify the horizontal oscillator components connected to pins 12, 13, 14, 15 of that IC. Typically you will find a pot that controls the DC voltage on pin 15 (slider of pot to pin 15 through a resistor). That sets the free-running horizontal frequency Now try adjusting it. If you can get the oscillator to run both too fast and too slow (lines sloping both ways) that that part is most likely fine and the fault is in the sync circuit. If not, then the oscillator components have problems. Are you getting a sync pulse at pin 8 of the IC? If not, trace back from there to the connector to the logic board and if necessary to the video IC. Are you getting a flyback pulse at pin 6? The horizontal control circuit is basically a phase-locked loop comparing the incoming sync pulses with flyback signal from the horizontal output stage. -tony
