[Baeteman]

After replacement of the Hor. Flybacktrafo by a non-original
type (HR Diemen), the set had sync probs and blurred image
for the first half hour.
300 Hz hum on +5V derived from Flyback. (pin 17)
Cause: parasitic oscillations in regulator circuit. (LM 358)(comp.7551)
Remedy: Decoupling the inverting input of the device with 470 nF ceram.