[sdiy] Sequential Pro-FX 500 schematics

Tom Wiltshire tom at electricdruid.net
Sun Sep 11 13:32:12 CEST 2022

Hi All,

There are schematics/preliminary service manuals floating around for *most* of the modules of the Sequential Pro-FX programmable rack effects system from the early 1980's, but information on certain modules is extremely sketchy. Here's a review, if you're curious:


Does anyone have schematics or more information on these, please?:

	510 Phaser
	518 Reverb (spring tank mounted in a 1U 19" rack)

	522 Flanger / Chorus
I've got info about these others:

	512 Distortion

	514 4x2 Mixer

	516 Parametric EQ

	520 Transpose / Sync

	524 Digital Delay 

They're interesting designs because they're very much at that transitional period between fully-analog and more-digital. There's quite heavy use of the 7524 8-bit MDAC for digital level control (and more), but there are also lots of examples of CA3280's doing a similar job, and filtering provided by CEM3320s and so on. It's a right old mixture!!

Thanks for any clues or help you can offer,


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