K8029 flashing when 100% duty cycle


I have a K8029 for some time used as a stand alone in TIMER mode, connected to a standard (old-type) filament lamp.

Recently, due to a short in the cabling, I needed to replace the shorted triac. Since I could source the original TIC206M locally, I tried two alternatives: BT137-800E and also BTA08-600C.

In both cases, the connected filament lamp starts to flash (oscillates) during the time T1 in TIMER mode (when the lamp should be at 100% duty cycle).

The lamp lights up correctly (without oscillations) when T2 kicks in (during the dimming off).

Do I really need to use the original TIC206M? Could there be something else that I’m missing?

Thank you.