21fbp22 red gun advice

[mstaton]

Originally Posted by Electronic M

An isolation transformer is used to eliminate the DC path between the heater supply of the TV and the CRT heater to cure the symptoms caused by a heater to cathode short inside the tube.



I'd like to see a picture of this device as well.

I think you mean AC path. there are no DC filament voltages

[old_coot88]

Originally Posted by mstaton

I think you mean AC path. there are no DC filament voltages

By "DC path", he means the fault condition that occurs when there's a heater-cathode short. When this happens, it kills all luma (B&W signal) displayed by the CRT, while leaving the chroma display unaffected. Rapping on the neck of the CRT will usually reveal the condition, causing the luma to flash in intermittently.

An isolation booster will eliminate the "DC path" but introduces a new problem: the parasitic capacitance between the secondary and primary windings of the isolation xfmr. causes smearing-out of fine detail in the pic.