[Updated: 5 May 2021]
I created this page to store commonly known issues after assembling the board, and what you could be doing to solve these.
It’s extremely rare that a part that we included does not work.
We source from reliable suppliers mostly, and we test all (discontinued) parts that are sourced from e.g. China.
Check chip orentations
Make sure all chips are put in, in the correct orientation.
Especially on 128K boards, some chips are ‘the other way around’ compared to most chips on the board.
The notch on a chip should correspond to the notch on the silk screen (white printed layer outlining all chips).
Check solder contacts
Always carefully check (if possible with a magnifying glass or so) all solder contacts.
99.9% of problems were solved after reflowing solder contacts, or removing solder bridges.
Check voltage lines
Check if there is 5V on the parts.
Most 74HCxx parts have 5V on the upper right pin (highest pin number) and ground on the lower left pin (‘halfway’).
Check for problems in IC sockets
The IC sockets we include are new, but if you insert something in it that widens the metal pins, it could cause a chip not to make contact on that pin.
More info in this video:
Problem: garbage on screen or no video output
Check if the board does boot to e.g. BASIC
First thing to know, is if there is any logic working, if it’s booting to BASIC.
If so, it’s only a video output problem, and we can focus on that.
You could test if it boots to BASIC by checking the MIC output (mono on Harlequin 48, stereo on Harlequin 128) for clicks when you press keys.
Will add more tips and hints later!