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I have had trouble with this machine a lot but i need a little help. I noticed some broken solder mask and broken traces but i know those traces are not important because they go to the battery compartment. But i need to know why wont it start. When i turn it on it makes a Hi voltage sound. Like a Click-THUMP sound and then nothing happens. Sometimes it does it over and over again or just once. When i power it off after the sound/s then power it on again the sound does not happen and there is no sign of life! SYMPTOMS: A HI Voltage Click-thump sound , no startup BONG, No video or sound , and a black screen. Also can someone give me the list of capacitors on the analog board? Update (09/16/2019)
These are some broken traces NOTE: not my image!
It’s a common issue for these to have bad solder joints due to their age. This isn’t difficult to repair, but you really should go over the entire board and refresh all of the joints to keep the rest of them from failing as well. J4 on Pin 1 is notorious for this problem, so that would mean in theory all of the original solder should be considered suspect and redone. HOWEVER, you need to take precautions with these Compact Macs as they use CRTs. These are the ~15k volt ones since they are B&W (and have a bleeder resistor), but you need to know how to safely discharge it. The best way is a proper CRT discharge tool like the Apple CRT tool (076-0381) or a rubber handle flathead screwdriver with thick jumper leads on a grounding point to discharge it. DO NOT trust the bleeder resistor in any of these M68k Macs since it’s probably long since burned out. Keep one hand behind your back as well just in case, so the charge doesn’t go to your heart and kill you. It shouldn’t even be trusted in the PPC Macs, but you at least know it probably works. As far as the capacitors go, this site has a list. The 128/512/Plus use the same analog board, with the only difference being the motherboard and case markings. If the capacitors fix nothing, you will need a flyback transformer which is harder to find then a replacement board that is sold cheap but needs work or is recapped by the seller (which WILL cost more).
You’ll need to search out the service manual out on the web to help you troubleshoot. The biggest problem will be finding parts for this system. Most parts houses have long since disposed of what they had. A high pitch whine is a failing flyback transformer. In addition most cases the electrolytic capacitors have rotted out in the power supply as well.
