After my post ‘ZX Spectrum 48K (Issue 3B) with video issues (Part 1)’ I spent some time researching the issue and done some testing on the motherboard
- Schematics and layout for the Issue 3B Motherboard
- Found information on the ‘weird’ modification
- Measured voltages on the ULA, CPU, ROM and lower RAM chips
- Measured temperatures for the ULA, CPU, ROM, lower RAM chips (IC6-IC13) and upper RAM chips (IC15-IC22)
Time to try my luck on another ZX Spectrum repair, this time a ZX Spectrum 48K with an issue 3b motherboard.
The RF module has already been modified to output a composite signal, so it was easy to connect it to a TV set.
When I fixed the ZX Spectrum 128 +2B machine I simply replaced the non-working keyboard with a known to be working keyboard. If should be fairly straightforward to get this keyboard working again.
Cleaning the parts
On eBay I bought a set of four untested (which usually means broken) joystick interfaces for the ZX Spectrum, based on the pictures provided they all looked fine. Although one seemed to be missing the keyway peg at pin 3.
The set consisted of the following interfaces
Several months ago I had won an auction for a ZX Spectrum 128 +2B of an unknown state and no big surprise the machine was not working properly. This is what I saw after booting up the machine
Black screen with a white border
building (a raft) with...
types of coffee
This blog is powered by Blot