Eddie Van Halen

In the music video for Van Halen's Jump, Eddie Van Halen can be seen [at 2:34] playing the Oberheim OB-Xa. According to this Keyboard magazine feature, he played the OB-Xa on "1984", "Jump" and "I'll Wait" on the 1984 album. On the former two songs, the OB-Xa was recorded direct in stereo, while on the latter the synth was run through a pair of Music Man amplifiers to make it sound nastier. Eddie Van Halen did his own programming on the OB-Xa: "I just know that if I twist the knobs enough, I'll hear what I like".

Live, the OB-Xa had to be replaced by the newer OB-8:

When we were getting ready to tour [for the 1984 album], I went out to buy four or five OB-Xas, because you need backups in case something breaks down. That's when I found out they didn't make the OB-Xa anymore. I didn't even know they made the OB-8, but I got a couple of them instead and tried to reprogram them. Now I only use my own programs.

During studio session for the band’s third album, ‘Women and Children First,’ Van Halen surprised Templeman by playing a Wurlitzer electric piano through a Marshall stack while the band tracked the anthemic ‘And the Cradle Will Rock … ’ Eddie later explained to one interviewer that fans “might not even notice” the keyboard on the finished track, because “it sounds like my guitar.” In other words, the band and Templeman let Van Halen add piano to the song precisely because it didn’t sound like piano.

Eddie Van Halen used the DX7II on OU812as a contrast to the 'fat analogue' sounds of early records.

Eddie had come up with a cool new riff on a Minimoog synthesizer and shared it with Templeman and Roth. Soon after, the pair hijacked Eddie’s synth composition for “Dancing in the Streets,” a cover song that Van Halen disliked. In the end, Van Halen told Guitar World, “Ted and Dave were happy -- and I wasn’t.”

This scan of a Keyboard magazine feature mentions Eddie Van Halen using two Oberheim OB-8 synths onstage instead of his Oberheim OB-Xa:

When we were getting ready to tour [for the 1984 album], I went out to buy four or five OB-Xas, because you need backups in case something breaks down. That's when I found out they didn't make the OB-Xa anymore. I didn't even know they made the OB-8, but I got a couple of them instead and tried to reprogram them. Now I only use my own programs.

Eddie Van Halen on using the OB-8 live for the solo on "Jump":

I have to play it on the keyboard. On the record the Oberheim plays a single-note line under the guitar solo. Mike can play it, but I can't switch from the guitar to the OB-8 to play the keyboard section that comes after, so I'm stuck with playing it on the keyboard, even though I don't like doing it that way. I've been jumping around playing guitar all night long, then all of a sudden I've got to stand still and try to do a solo on the keyboard. I'm not good that that... yet.

In this article, Eddie Van Halen mentions using a Prophet-10 synthesizer to write "Jump". Eventually he had problems with the fuses blowing out whenever he got the sound he wanted on the right hand section of the keyboard that he had to get an Oberheim OB-Xa instead to get the same result.

In this video Edward's keyboard tech shows some of the synthesizers that he used during the OU812 tour. Included are 2 Roland D-50's. (Mentioned around 13:30) A Roland D-50 can also be seen in a photograph from the July 1988 issue of Keyboard World magazine, which showcases Edwards keyboard arsenal.

Eddie Van Halen used a variety of synthesisers on the album OU812, including the SQ Prophet VS.

In this Keyboard magazine article, Eddie Van Halen mentions having a Prophet-5 synth. Here's what Eddie had to say about the Prophets:

I actually had a Prophet-5 years ago, but for some reason those things don't like me. I swear to God, I went through five of them, and whenever I got the sound I liked out of them, they started smoking. They burned up! I went through about three Prophets before I finally decided we just weren't going to work together. That's when I got the [Oberheim] OB-Xa.

Used for "Sunday Afternoon in the Park", as showcased in this January 9, 2015 Instagram post by his son Wolfgang.

Sunday Afternoon on a Friday #FairWarning