How bad about is it? 128k Mac plugged into 220v

#1 Mon, 17 Oct 2011 - 14:27 68kMLA

Is the analog board repairable? how about the logic board, is it affected? my fault i didn't notice i plugged it into 220v instead of 110v. xx(

visual inspection:

#2 Mon, 17 Oct 2011 - 16:39 68kMLA

Looks like you burned out all of those low-value resistors. The transistor might be shot too. Those will need to be replaced. Just test continuity on every component, and the ones that show an open circuit will likely need to be replaced.

#3 Mon, 17 Oct 2011 - 17:06 68kMLA

The power supply should have burned out and shut down before the voltage could be passed on to more sensitive circuits. The logic board should be unaffected, as it gets it's power well after the mains. As DogCow suggests you should be able to start replacing the burned-out PSU components, checking continuity as you go until you restore normal functionality.

#4 Tue, 18 Oct 2011 - 00:02 68kMLA

which one is the power supply? needs to be replaced too?

#5 Tue, 18 Oct 2011 - 03:04 68kMLA

pretty much everything shown in your picture needs replaced, including those 2 transistors. God only knows what else it would have taken out in the primary circuit.

#6 Tue, 18 Oct 2011 - 22:41 68kMLA

which one is the power supply? needs to be replaced too?

The power supply, also called the analog board, is the vertical board beside the CRT. It's on the left as you face the Mac.

#7 Wed, 19 Oct 2011 - 14:17 68kMLA

pretty much everything shown in your picture needs replaced, including those 2 transistors. God only knows what else it would have taken out in the primary circuit.

What about the transformer? do you think it's damaged?

#8 Thu, 20 Oct 2011 - 09:50 68kMLA

Had a few of these, back in the day.

There should be no damage to the logic board or the transformer. There will be a large number of fried components on the analog board though. Make sure you check the power supply rectifier diodes and chopper transistor as well as the obviously damaged parts.

[edit] be very careful how you power it up for the first time if you decide to repair the board yourself. Ideally, use a variac. If you don't have one, an old TV techo trick is to put a 100w light globe in series with the mains (might want to try 60w for 110v?). If "bad things" happen when you power up, the light globe will come on brightly and hopefully prevent everything getting blown up for a second time. If the globe glows dimly and the Mac boots, it's all good!

#9 Fri, 21 Oct 2011 - 03:18 68kMLA

No, the transformer should be fine. your parts blew up before anythign could happen to the transformer.

any component that looks burned, blackened, physically cracked (2 transistors) youll need to replace.

and as someone suggested, check the main chopper transistor.

#10 Sun, 23 Oct 2011 - 11:16 68kMLA

Those parts can be easily obtained from electronics stores?

#11 Mon, 24 Oct 2011 - 05:23 68kMLA

digikey, mouser, newark, mcm, to name a few.

you can use octopart.com and it searches all the mainstream ones plus oddball ones.

#12 Tue, 25 Oct 2011 - 00:28 68kMLA

Is there any manual somewhere i can download about part numbers/components of this particular analog board?

#13 Tue, 25 Oct 2011 - 04:27 68kMLA

schematics are on the web. i forget where tho.