At 09:13 PM 4/26/2002 -0700, you wrote: >I have noticed that all ribbon cables are marked down one edge with a >red band. I have been examining all of my computers, both mac and PC, >and it seems that there is a convention to the way they must be >attached, both on the board and on the device they power. so far I >seem to deduce that the red edge always seems to face towards the inside >of the machine and also face the plug where the power supply wires go >into the device as well.
The red line indicated Pin 1. As it so happens, 99% of drives have pin 1 towards the power connector. I've run across a couple that don't for some reason, but most of them do. >for that matter, it appears that the four-wire power plugs, ( those >having one yellow, 2 black in the center, and one red), always orient >so that the red is to the interior of the machine, and the yellow is >oriented to the outside, nearer the 'skin'. Haven't noticed whether or not there's a rhyme or reason to this one, though I guess there could be. >what does the red band down the edge of a ribbon cable stand for? is >that 'positive'? Pin 1. >is there a notation on the logic board or the the back of the device >that I should look for, that indicates which side the red band should be >on when it plug in? what should it say? Most things these days are keyed so they'll only go in one way. On things that aren't, just remember that the red wire is pin 1, so connect it that way. >I did notice that there are not actualy 40 pins on the ribbon: there are >39, and one blank space. I matched up the missing pin with the filled in >space, and figured that was the clue to the right way to plug it in. Yeah, there's a pin missing. I've occasioanlly seen it used as another keying system, though not all ribbons/drives are missing that pin. >A question about grounding: >the add-on cards fit more tightly in the new case, and in some places, >it looks as if the collars around the dongles touch or rub against the >cutouts in the back, where you screw them to the case. is this going to >be a problem, with grounding or making good contact, etc? Any decently designed electrical system would have the collars and everything external be ground, so it shouldn't be an issue. ><snip> >mystery is: when I plug these into the logic board, to give it its >powersupply, which way do the bank of them face? Every PC mobo I've ever seen has it set up so they'll only go in one way. Or at least, they'll only go in one way without forcing. I once accidently plugged them in backwards on an old XT I was playing with an a cap literally exploded. >Problem is, I can't figure out whether to turn those tabs towards the >high side of the socket, the 'wall' side--or whether they face the low >side, and snap in. The tabs should go over the "wall", IIRC. But they really should only go in one way without forcing. >the old power supply was 250 watts. the one in this box is 300 watts. >Should that hurt anything if I have connected it up right? The Wattage is a capacity, not a pure output, so it wouldn't affect anything unless you needed the extra capacity. >-a DB-25 female dongle [for--??] Sounds like a Printer/Parallel port. >the old one was set at 115 volts [for american]. this one is set at 110 >volts [for american] Devices seem to be rated from 110 to 125 volts with no issues. Should be fine. Hth :) Scott Holder -- Vintage Macs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Enter To Win A | -- Canon PowerShot Digital Cameras start at $299 | Free iBook! | Support Low End Mac <http://lowendmac.com/lists/support.html> Vintage Macs list info: <http://lowendmac.com/lists/vintagemacs.shtml> The FAQ: <http://macfaq.org/> Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/vintage.macs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
