Greetings. If you've been following my previous thread (Apple II Plus Bad Memory/ROM? - The saga continues), you'll recall that I recently purchased an Apple II Plus motherboard with the intention of using it to replace the faulty motherboard I already had. Unfortunately, it turned out that the eBay motherboard was even less functional than the one I already had. I was ultimately able to get the original board working by swapping a few chips from the eBay board, and I now have a fully-functional II Plus.
Now, I am trying to see if I can repair the motherboard I received from eBay. The seller claimed it was a working pull, and I have no reason to assume they were lying; it is entirely possible that it did indeed work when they packed it up, but then something happened in-transit to damage it. It was wrapped in bubble wrap with no other anti-static packing material, so it is possible static got it, or rough handling. It's hard to say.
When the board is powered on, the power light does turn on, but there is no beep, and the screen either shows nothing at all (The TV I'm using for a monitor simply says "No Signal"), or it shows random garbage, as seen below:
This occurs regardless of whether the disk controller card is installed or not. When it is installed, there is no disk activity at power on. The board arrived missing the 9334 chip at F14, but swapping in the 9334 from my working motherboard doesn't make any difference. I learned by accident that my working board will still boot without a 9334 chip (It just won't display "Apple II" at power on), so I presume the same should apply to the faulty board.
Here are high-res photos of the motherboard. As with my previous thread, I'll apologize for the poor lighting.
Do note in the above photos that the E8 ROM is one of the bad chips I had tried on my other board. I installed it to fill the space, and to at least allow the system to boot into diagnostics once it reaches that level of functionality.
There is also a jumper wire on the bottom of the board. It is located behind the small "741" chip located at K13, connecting one of the pins to the resistor located immediately beneath it.
And here are the date/revision markings on the board:
-Date code is 4881
-Revision code is 820-0044-C
-Near the revision code is the stamped code "8487 0"
-Behind the expansion slots are the two stamped codes "606-X548-F" and "A8142"
So, where should I begin?