Need help with restoring Apple II Plus.
Apple II Plus,board p/n 820-0001-04, Non-RFI, Rev. 1 board.
What I have done,Replaced the Power Supply.Removed all cards.Removed 32K of RAM, left 16K installed.
What happens when power is applied,
Keyboard power button light is on, and a single beep from the speaker.There is a brief flicker of video showing characters, waving sync, then the screen goes black.
Pressing reset , gives a beep and a repeat of the video flicker.
Adjusted video level on board, same problem.
Next ?
Can you publish a video ? It seems your Apple II boot in self test mode. Maybe a keyboard/keyboard cable/74LS251 problem
What type of video monitor is used?
(Apple II+ doesn't have any self-test mode)
Beep means CPU, RAM, ROM, and a whole lot more are probably working! Just a video (or monitor) issue. Check RCA jack, monitor (analog CRT would be best), and then video circuits.
This is an Apple II Plus, no self test option.
For video display, connecting to an Flat Screen TV that has a composite video input.
Correction on pressing reset - Just gives a beep, No repeat of the short video flicker.
Other testing
Removed RAM memory from Row C, No beep on power up, still see brief video flicker.
Reinstall another bank of RAM chips in Row C, no change.
Started to reseat chips used by video circuits, no change in video output.
Some flat screen TV's may not like the Apple II video (especially early Rev boards). Since you do briefly see characters, I'd say it's 50/50 that the Apple II is just fine. Wavy sync could be an indication of bad video socket (RCA) or cable. Try twisting or wiggling them. Any chance you have a scope? Or an old VHS machine (you could try running Apple video through that to clean it up).
If the problem is just in the monitor, video connection or incompatible signal, then pressing Ctrl-G with all cards removed would produce a beep.
Here's another test you can try. After the wavy text disappears, unplug the video cable from yout TV. Wait 15 seconds and then plug it back in. If you see the wavy text again (even briefly) that means the computer is still outputting video but it's the monitor that doesn't like it.
You should maybe try increasing the video signal strength. Some LCD monitors will kakk out if the video signal is too low.
The video signal level potentiometer is located at position J-14 on the motherboard.