Korg Poly800/EX800 Users

Many years ago I read on a magazine about a very simple mod I made on my old Poly-800: it consisted in extracting a 24ppqn analog timing pulse signal (to sync old drum machines) directly out from a pin of an IC on the synth main board: it's the same clock pulse leading the internal sequencer (and being then converted internally to MIDI digital time sync out messages). Today I got a Poly-800 mkII again but, unfortunately, I don't remember what pin and what chip were the right ones: can anyone help in telling what is the right pin to connect? Then, it's easy to join by a small wire that IC's pin to a free side pin of a (midi) DIN port, so it can work as a midi port or as a din sync port (cause earth is in common on the central pin)! One good choice could be the MIDI IN port, allowing it being used even as a din sync out port, so you could use the Poly-800 as a master timing sequencer with a din24 sync out and a midi sync out working together for non midi and midi machines. Now, please, remind me: what is the IC's pin on Poly-800's board giving internal sequencer's tempo analog pulse?!