I'm moving my computer collection to a local museum but I couldn't resist to buy another Apple IIe to replace the one I donated.
I bought an Apple IIe (PAL version) from eBay, sold as not working wich was indeed correct, and without the lid.
The correct lid seems to be difficult to find. It's the first version ... and I have bought the last version which does not fit.
Anyway here is the repair process description.
SYMPTOM: The computer does not RESET, no BEEP, but the POWER LED is ON and there is only a clear/blank rectangle on the monitor.
Mainboard : PAL version F 607-0264 F (1982)
DEBUG:First checked the Power Supply output, and all voltages were correct.
I thought that the non-functioning keyboard lamp would be detected as faulty like in the Apple ///, but it's incorrect.
The LAMP status is not detected during the A//e startup sequence.
Anyway, I have replaced that lamp by a LED with a 120 ohms serial resistor.
A mainboard visual inspection was showing that the computer was stored in a rather humid environment.
I have removed the IC's from their socket and gently cleaned up the pins with a Dremel and a brass brush.
-> After reassembly the computer was still NOK
I have swapped a few ICS, like the processor, bus buffers, address demux etc..., to no avail.
-> No improvement at all.
A another visual inspection of the solder side did not show any issue.
That board was very nicely soldered on a wave soldering machine before the leadless solder was made mandatory. Shiny solder joints, easy to inspect.
I have then scoped both address and data bus.
There was a processor activity.
But there was also a problem on the data bus with D5.
The signal was not correct @ TTL level. About 2.2V to 2.5V
I've removed the eight RAM's, soldered sockets and changed the RAM's
-> After reassembly the computer was beeping when powered ON, but still NOK with the same display
MD5 level was OK.
Blind typing characters at the keyboard did not produce any syntax error beep after hitting RETURN.
The diagnostic sequence upon power-up could not be started.
So the processor was stuck without completing the RESET sequence.
I have decided to reprogram the CD and EF proms.
When reading the CD original ROM in my programmer (HiLo ALL-03) the checksum was not consistent.
I have programmed the two ROMs in D2764 EEPROM's and replaced them on the board.
-> After reassembly the computer was beeping when powered ON, but still NOK with the same display.(white/gray rectangle)
However, blind typing characters at the keyboard did now produce a syntax error after hitting RETURN. Cool.
The diagnostic sequence upon power-up could be started with the typical sound. I could not see the result :(.
The processor was running OK but still no video.
Scoping the video circuit was showing that the SYNC signal was OK, but with no data to display.
Just to be sure I have also programmed a new VIDEO ROM in a 27128 EEPROM.
-> NO CHANGE.
I have decided to unsolder all soldered IC in the video line : 74S02, 75LS125, 74166, 74LS164 and 74LS74
I have soldered sockets and changed theses IC's with new ones.
-> BINGO the computer beeps, and shows the APPLE // on top of the screen.
The keyboard is fully OK.
I have placed a bootable PRODOS ROM board in slot #7 and the machine instantaneously boots in PRODOS.
I have eventually isolated the faulty IC : 74LS164 (it's a PAL SYSTEM BOARD)
Here is a phot of that board with faulty IC's surround by a red rectanle. I'm not completely sure that both ROM CD and EF are faulty.
I have to further investigate why the checksum was changing in my programmer. Perhaps poor contacts.
Now, I'monitoring the web to find another cover :)!
I hope this description will help others.
Yves.