I've checked voltages using the schematics, I'm getting 5V through R13, R14 and R12.Īlso noticed that the 5V (instead of 0.7) coming from pin 7 of the LM311 goes to pin 4 (RESET) of the NE555 which might trigger it. Oh so these chips will never prevent my IIc from booting right, they do serve as a warning purpose ? I don't think I'll be able to get my hands on one of these and that the external power supplies are faulty.ĭo you have specific points where I should check for right voltages ? (Already checked the rails) One thing I don't understand is why are there IIc logic boards where these chips are completely absent ? Probably there are some other issues which influence the power supply. In your first posting you wrote that this Apple IIc was never working before. So you should look at the incoming voltage from the exernal power supply and the 5V on the mainboard. And this seems to be not a static issue but a dynamic. So I think there is something wrong with the power supplies. With a dead LM311 the LED would blink but the IIc would start normally. I have exactly the same voltages for the LM311 (which might be faulty?), nothing going through R13, R14 and R22. Hm, can you use a lab power supply or something like that? This should display the actual current upto 2A. Just received the new external power supply, unfortunately it is still not functional. That situation would definitely cause your symptoms. Try your IIc with another power supply! 15VDC are good. My first thoughts are that since the 3.46Ghz 6-core processor wasnt an official Apple feature, there is a possibility that the installation of the aftermarket processor didnt properly get the heat sink to touch the power regulators along the side of the CPU. Since the 2009 MacBook Pro, the way in which Apple has attached their keyboards into their laptops has been made much more difficult than in the early. or total failure (which on many models exhibits as a complete failure of the machine, since the power button is not functioning).
I think there is the cause of your problem: either the LM311 is dead, the 5V supply of the internal voltage regulator, or your external power supply is faulty. Mac Pro 2006-2012 - Label on the back panel of the machine. If you don’t have a removable battery: Press and hold shift+control+option on the left side, then hold the power button at the same time for ten seconds. If you have a removable battery: Remove the battery, then hold the power button for five seconds. I think the NE555 does the blinking and the LM311 watches the incoming voltage (called "+12VIN" but really accepted around 15VDC). Shut down your MacBook Pro and unplug the power cable. They are responsible for the flashing power LED. At the bottom there is a NE555 and a LM311. Go to the schematics of the IIc to page 4. Means: go to your Apple dealer and buy a new one. Above all, do not use the disk drive when the power light is flashing this may damage the computer." Find out what caused the condition (such as a brownout) and remedy it before turning the computer on again. If the power light flashes on and off, turn off the computer immediately.
Read the "IIc Reference Manual Vol 1", chapter 1, page 6! And remember, we are the only ones offering an up to 12 months guarantee in any repair.I see the trace coming from the power switch, is that where the problem is ? You can also visit us at our repair centre during office hours. In case the card is irreparable, we can offer the customer a new motherboard, with warranty.Ĭontact us by phone 933 900 524, or by filling out the form in the Contact section.
Other factors may indicate faulty graphics card, but they are usually motherboard failures.