07-07-2016, 09:22 AM
I've just had a very similar fault on a Grundig (my post is a couple down the list). Turned out to be an intermittent 25pf cap in one of the IFTs.
I tracked down the faulty stage by tuning into the 10.7Mhz IF on a scanner then enabling/disabling each stage by pulling the valves till the fault disappeared. Once the faulty stage was identified many components could be ruled out as they were used on AM only, this just left a few components to check . However I appreciate this may be difficult with your set if it has series heater valves, but maybe you could disable each stage some other way. It saved alot of time in the end.
Mark
I tracked down the faulty stage by tuning into the 10.7Mhz IF on a scanner then enabling/disabling each stage by pulling the valves till the fault disappeared. Once the faulty stage was identified many components could be ruled out as they were used on AM only, this just left a few components to check . However I appreciate this may be difficult with your set if it has series heater valves, but maybe you could disable each stage some other way. It saved alot of time in the end.
Mark
