I was so excited to finally get a copy of Larry Pina's Mac Repair and Upgrade Secrets. Finally I was going to be able to repair my original 128k's analogue board (I've been using a Mac Plus analogue board for a while now). Well, I've been through the book and my 128k with a fine tooth comb and have yet to find a problem to repair! I'm afraid I need some expert help now.
Here's the story: The CRT is good. The logic board is good. The analogue cables are good. The problem is, when I switch on the 128k, I get a bong, but the screen is completely dark. No static, no pin prick, nothing. Here's the kicker -- if I insert a 400k floppy, it seems to boot up just fine with the drive making all of the normal noises. I can't see anything, but when it finishes I can select Cmnd+E and the disk ejects. There is no odor, no unusual noises, nothing out of the ordinary. So, with my trusty multimeter in hand, I checked all the resistors, all the electrolytic capacitors and the rectifiers and everything else Pina suggests might be a problem. Everything tests good -- usually really good for it's age! Not one of my caps leaks if you can believe it. Guess I took really good care of the 21 year old girl. I even re-soldered several of the usual cracked solder joint areas just to be sure since they are so hard to spot and nada. I can find no evidence of a short, discolored or bulging component anywhere either. All the pins look good too, no oxidation or corrosion. The only thing I can do now is proceed with a complete Mac Plus/SE upgrade which means a few hours replacing most of the caps and a few resistors and rectifiers. Seems a shame when everything checks out, but what else can I do at this point? One hint that I thought might shed some light on the situation is that when I plug an internal 800k drive into the logic board instead of a 400k, it begins to "flup" without a bong. This happens no matter what logic board is in there ... the Mac Plus logic board works fine with a 400k drive but also "flups" with an 800k, so it's not a ROM issue. I cannot adjust the voltage to make any difference. The components that Pina indicates are responsible for "flupping" check out. Oh, I also check the 800k drive with different ribbon cables and I am definitely using the correct one for the drive. Is it possible that the 800k drive consumes more power than the 400k so as to expose the weakness on the analogue board? If so ... what is it telling me is the problem? Mighty frustrating! -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:compact.macs@mail.maclaunch.com> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- iPod Accessories for Less at 1-800-iPOD.COM Fast Delivery, Low Price, Good Deal www.1800ipod.com ---------------------------------------------------------------
