Deltalab DL-4 interface to Deltalab MB-4...HELP!

[Cheezmistr]

I've owned a Delta lab model DL-4 digital delay flanger unit since 1984. They were used on early Rush in Genesis recordings. It's got a five-pin XLR connector on the back to connect to an optional memory expansion rack unit model MB-4. This increases the delay time to 2 seconds which was a lot in the late seventies and early '80s. They made very very few MB-4 memory expansion modules. I only come across one every 10 years I just snatched one on reverb but I can't get it to work. I know on the DL-4 you set the memory switch for external when using the MB-4 but I'm not sure how to set up the MB-4 switch. The MB-4 has an additional five pin XLR connection for additional MB-4s? I don't know? Either way I get no sound when connected to the MB-4 The time delay pot on the DL-4 does change the digital readout settings on the MB-4. I've been a audio Electronics technician since the late '70s so I somehow will figure this thing out. But if there's any old dogs out there that know anything about early digital delays or even just a manual for a Delta lab MB-4 I will fix my last toy!