AFAIK, the only FM synths with an even halfway complex layout were the DX7 series, which divvied up the sound-generation responsibilities between two chips (one for envelope generators, one for the actual operators) and the requisite DACs. Past that, they pretty much made all their FM stuff as single-chip solutions (although outboard DACs were still commonly required,) which I'm sure had a lot to do with the popularity of the things in arcade boards and Japanese home......
Actually the FB01 is the module version of the DX27/DX100 the 4 Operator versions of the DX7 without the filters. But it still sounds great. I especially remember the Orchestra, Drawbars and a slider ping/pong sound I cant remember the name of.
Pity about the sound issue.
It could be the Caps...
