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From: lui@CS.UCLA.EDU
Newsgroups: comp.sys.mac
Subject: Power from the Mac+ and Mac SE modem port (for a MIDI interface)
Message-ID: <8573@shemp.UCLA.EDU>
Date: Mon, 12-Oct-87 10:58:29 EDT
Article-I.D.: shemp.8573
Posted: Mon Oct 12 10:58:29 1987
Date-Received: Tue, 13-Oct-87 05:31:38 EDT
Sender: root@CS.UCLA.EDU
Reply-To: lui@CS.UCLA.EDU (Stephen Lui)
Organization: UCLA Computer Science Department
Lines: 27

The original Mac provided +5V and +12V from the modem port. I believe the Mac+
only provides +12V. What about the SE? I've been trying to use a Passport MIDI
interface on my Mac+ w/o success. I checked my modem port and it supplies +2.4V
on pin #6. If the Passport interface expects to get +5V or +12V, then it's out
of luck and that's why it doesn't work.

I measured the voltages from the modem port on a SE... Nothing!

Does anyone have the modem port pin-outs for the Mac 128K, Mac 512K, Mac 512KE
Mac+, and Mac SE?

I also have one of the very early Mac 128K's that's been upgraded to a Mac+.
I think I have one of the old power supply boards. Could that be the problems
with the 2.4V on pin #6?


	Stephen Lui
	UCLA Department of Computer Science and

	Hughes Aircraft Company
	2000 E. Imperial Hwy.
	El Segundo, CA

	(213) 305-2085

	ARPA:  lui@cs.ucla.edu
	UUCP:  ...!{cepu,ihnp4,trwspp,ucbvax}!ucla-cs!lui