Instructions | CP297s

1

Start by the shorter components

First components to be soldered on the board should be the ones that are shorter in height.

Start by the resitors.

Then add the diodes
2

Then add the IC sockets

And solder the P2 Jacks
3

Next solder the capacitors

First the ceramic and polyester capacitors

Followed by the electrolytics
4

Add some headers

Add some pin headers, specially the Power Supply header
5

Plug the PSU and perform some tests

Plug the PSU to the board and test for the correct voltage (5V) at all IC sockets.
6

Test the clock

Solder the Crystal and insert U4

Power the board and check for 6.5MHz signal at pin 3 of U4
7

Test the frequency Divider

The frequency divider is It is one of the few pieces of ZX81 video generating circuit that run standalone (mostly).

Insert U5, U6, U7, U23 and place a jumper wire from pin 2 of U23 to ground.

Then check for:

3.25MHz at pin 1 of U6

A Negative going pulse of 4.6us (Hsync) at pin 6 of U4 . The HSync frequency shall tick at 15.7Hz.