kenh@pogo.WV.TEK.COM (Ken Hillen) (02/21/90)
The +5 volt power supply on my old MacPlus is starting to act funny. If I adjust it above ~4.8V the screen blanks and the speaker goes tick-tick-tick. If I adjust it below ~4.6V the reset generator starts resetting continously so the speaker goes ding-ding-ding. When I set the voltage to ~4.7V the Mac will usually boot OK, but due to what appears to be poor regulation it will occasionally start resetting (ding-ding-ding...) or going overvoltage (tick- tick-tick...). I would like to get a schematic of this board if anyone has one so I can attempt repairs. Alternately, does anyone have any suggestions for fixing this problem? Ken Hillen kenh@pogo.wv.tek.com
gordon@milton.acs.washington.edu (Gordon Davisson) (02/22/90)
In article <8582@pogo.WV.TEK.COM> kenh@pogo.WV.TEK.COM (Ken Hillen) writes: >The +5 volt power supply on my old MacPlus is starting to act funny. If I >adjust it above ~4.8V the screen blanks and the speaker goes tick-tick-tick. >If I adjust it below ~4.6V the reset generator starts resetting continously >so the speaker goes ding-ding-ding. When I set the voltage to ~4.7V the Mac >will usually boot OK, but due to what appears to be poor regulation it will >occasionally start resetting (ding-ding-ding...) or going overvoltage (tick- >tick-tick...). I would like to get a schematic of this board if anyone has >one so I can attempt repairs. Alternately, does anyone have any suggestions >for fixing this problem? By far the most common cause I see of this problem is a bad connection on the cable from the analog board to the motherboard. You can check this by looking at the +5V supply at the analog board end of the cable (if you count the missing pin as #2, #6 is the +5V line and #7 and #9 are grounds). Some voltage loss across the cable is normal, but it shouldn't be more than 0.2V. Also, try looking at the +12V line, since it's the one that's really regulated (the +5V is scaled off it by the ratio of windings in the transformer secondary). If it looks like this may be the problem, you'll have to clean and respring the contacts in the cable. Just pull the cable completely out, then pull out the contacts on the blue wire (#6, as I said above) (you'll have to use a jeweler's screwdriver or something similar to hold in the catch as you pull). Scrape any dirt or corrosion off the contact, and straighten the bend out slightly (to get more pressure on the contact area). It's a good idea to fix the catches before reinserting the contacts, so they'll stay in. Oh, yeah, and be sure to plug the cable back in... -- Gordon Davisson Westwind Computing (206) 632-8141 4518 University Way NE, Suite 313, Seattle WA 98105
baum@Apple.COM (Allen J. Baum) (02/23/90)
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I just read in MacWeek yesterday that Sams Photofacts is now selling
a set of prints/troubleshooting guide for the Mac+ & 512k. I don't
know about other models. Check it out....
--
baum@apple.com (408)974-3385
{decwrl,hplabs}!amdahl!apple!baumpaul@spinifex.eecs.unsw.oz (Paul Antoine) (03/02/90)
In article <38875@apple.Apple.COM>, baum@Apple.COM (Allen J. Baum) writes: > I just read in MacWeek yesterday that Sams Photofacts is now selling > a set of prints/troubleshooting guide for the Mac+ & 512k. I don't > know about other models. Check it out.... Great, but as I live in oz, I haven't the faintest idea who Sams Photofacts are, or their address/'phone number (and remember that o.s. people can't use 800 numbers). So could you post the address etc to the newsgroup for those unfortunates such as myself who live somewhere other than the U.S. of A.? (Yes I know it's difficult to believe, but there's a whole world out there... :-) Paul (Who just loves hacking his Mac!) ---------------------------------------------------------------------------- Paul Antoine ACSNET: paul@spinifex.eecs.unsw.oz.au Departmental Programer UUCP: ...!uunet!murtoa!eecs.unsw.oz!paul Computer Science Department BITNET: paul%eecs.unsw.oz@uunet.uu.net University of New South Wales JANET: eecs.unsw.oz!paul@ukc Sydney Australia VOICE: +61 2 {697 4026, 664 1428}
ostroff@Oswego.EDU (Boyd Ostroff) (03/03/90)
In article <527@spinifex.eecs.unsw.oz> paul@spinifex.eecs.unsw.oz (Paul Antoine) writes: >In article <38875@apple.Apple.COM>, baum@Apple.COM (Allen J. Baum) writes: > >> I just read in MacWeek yesterday that Sams Photofacts is now selling >> a set of prints/troubleshooting guide for the Mac+ & 512k. I just got the SAMS 1990 catalog a couple weeks ago, and under Apple they only list: Apple II & //e Apple //c Disk II Monitor /// Monochrome monitor Imagewriter Imagewriter II No mention of Macintosh..... At any rate the address is: Howard W. Sams & Co PO Box 7092 Indianapolis, IN 46207-7092 USA > So could you post the address etc to the newsgroup for those >unfortunates such as myself who live somewhere other than the U.S. of A.? >I know it's difficult to believe, but there's a whole world out there... :-) Sorry, but (800) 428-7267 is the only number listed in the catalog. You could try calling (317) 555-1212 for Indianapolis directory assistance. --- Boyd Ostroff - Tech Director - Dept of Theatre - SUNY Oswego -- --- The CallBoard System - (315) 947-6414 1200/2400 baud -- --- !rochester!kodak!gizzmo!cboard!ostroff -- --- ostroff@oswego.oswego.edu --