Around late 1984 to early 1986, where music was performed on TV (usually mimed) if there was a keyboard it was either a DX7 or a KX5.
Formel Eins (Apr 1983 to Dec 1990), ARD
Notable for its elaborate set dressings ranging from cliché to downright bizarre, it was common to see a DX7 deployed as the generic keyboard of choice.
Prominently feaured during its first years.
Känguru (Jan 1985 to Dec 1986), ARD
Musik Convoy (Jan 1984 to Sep 1985), WDR
A large number of the acts that performed on the show brought a DX7 to have as the lone synth to mime the (many) keyboard parts.
One exception: Depeche Mode's Alan Wilder is behind a DX9 during the performance of People Are People.