Zx spectrum diagnostics

derekfountain·zx-spectrum-diagnostics·pcb_pga2040/zx-spectrum-diagnostics.kicad_pcb

About the Zx spectrum diagnostics PCB

Zx spectrum diagnostics is an open source RP2040/RP2350 PCB design by derekfountain, published on GitHub under the GPL-3.0 license. It is a 2-layer board measuring 99.9 × 98.2 mm, with 21 components from 12 distinct parts.

Its main chip is the Pico, from the RP2040/RP2350 family. Other key parts include the PGA2040. By type, the board carries 7 resistors, 5 connectors, 3 ICs, 3 diodes, 2 switches and 1 transistor.

It belongs with the test & measurement and displays & leds designs in this gallery.

From the project

A hardware diagnostics board for the 48K ZX Spectrum

This is a hardware diagnostics board for the 16K and 48K ZX Spectrum, based on two Raspberry Pi Pico microcontroller boards.

The idea is that given a Spectrum of unknown provenance (an eBay purchase maybe), this device can quickly tell you what potential issues the Spectrum might have. It's limited to what it can see on the rear edge connector, so it can't detect broken tracks or things like that, but it can report a fair amount of useful information. There are no guarantees, of course.

Zx spectrum diagnostics, from the project README — From the project README

Main components on the Zx spectrum diagnostics

Pico PGA2040

Zx spectrum diagnostics bill of materials (BOM)

21 components, 12 distinct parts.

Qty	Part	Footprint	Refs
2	Pico	RPi_Pico_SMD_TH	U101, U102
1	PGA2040	PGA2040	U103
1	PMBT2222A	TSOT-23_HandSoldering	Q101
1	Conn_01x04	PinHeader_1x04_P2.54mm_Vertical	J101
3	Conn_01x20_Female	PinSocket_1x20_P2.54mm_Vertical	J201, J202, J203
1	ZX48Bus	Spectrum_Edge_Connector	Z101
2	SW_SPST	SW_PUSH_6mm_H4.3mm	SW101, SW102
1	D_Schottky	D_1206_3216Metric_Pad1.42x1.75mm_HandSolder	D101
2	1N4148	D_SOD-123	D102, D103
5	1K5	R_1206_3216Metric_Pad1.30x1.75mm_HandSolder	R101, R102, R103, R104, R106
1	5K6	R_1206_3216Metric_Pad1.30x1.75mm_HandSolder	R105
1	1K	R_1206_3216Metric_Pad1.30x1.75mm_HandSolder	R107

Zx spectrum diagnostics design files

The KiCad project lives in the derekfountain/zx-spectrum-diagnostics repository on GitHub; these links point at the commit this page was built from.

Layoutpcb_pga2040/zx-spectrum-diagnostics.kicad_pcb
Schematicpcb_pga2040/zx-spectrum-diagnostics.kicad_sch

Zx spectrum diagnostics: common questions

What microcontroller does the Zx spectrum diagnostics use?

The Zx spectrum diagnostics is built around the Pico, from the RP2040/RP2350 family.

How big is the Zx spectrum diagnostics PCB?

The Zx spectrum diagnostics measures 99.9 × 98.2 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Zx spectrum diagnostics?

21 components, from 12 distinct parts. The full bill of materials is listed on this page.

Where can I download the Zx spectrum diagnostics design files?

From the derekfountain/zx-spectrum-diagnostics repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the Zx spectrum diagnostics design in my own project?

Yes, under the terms of its GPL-3.0 license, which derekfountain chose for the repository.

Can I test firmware for the Zx spectrum diagnostics without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug RP2040/RP2350 firmware against it before you order a PCB.