Greg

Most commented posts

  1. MyFitnessPal weight importer — 23 comments
  2. Commodore VIC-20 35K Expansion — 13 comments
  3. Repairing the ZX Spectrum Coil — 6 comments
  4. Netware 3.12 on the Raspberry Pi — 4 comments
  5. Building TZXDuino — 4 comments

Author's posts

23XX Adapter

I’ve been trying to repair a VIC-20 with missing ROM’s. Unfortunately the original ROMS are getting more and more difficult to find and if you do find them they are way overpriced. Luckily with a few mods you can use newer EEPROMs or EPROMs like the 27C256 which are still available and cheap enough from …

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Repairing the ZX Spectrum Coil

For the past few days I’ve been trying to get the DC-DC circuit working on a ZX Spectrum Issue 3. The problem was TR4 kept drawing too much current which damaged the transistor. The DC-DC circuit is really a horrible design. Even after applying the DC-DC mod which makes the circuit more stable I still …

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ZX Spectrum Diagnostic Board

After buying a few faulty ZX Spectrums on eBay which were having memory issues I decided to build a diagnostic cartridge to help troubleshoot the RAM issues. After looking through various internet sites I eventually found a schematic and diagnostic ROM by Dylan Smith. The original site however is no longer online but I did …

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Repairing PS4 Controller

Bought a faulty PS4 DualShock controller off eBay which has a issue with some buttons not working. Opened up the controller and after inspecting everything found a problem with the flex ribbon. Looks like some liquid damage to the controller and something has eaten away one of the pcb ribbon connectors. The pin in the …

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Commodore 1541 Troubleshooting

Trying to fix my first 1541 which I got off eBay.  Turning the 1541 on while not connected to the C64, the green LED comes on then the red LED and after 2 seconds it turns off. The spindle however keeps on spinning. Also no moment on the head.  Checked the 12V and 5V. Both …

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Commodore Plus 4 PCB 310162 Rev D

Commodore Plus 4 component layout

Inchworm ICD2 Programmer

Busy with a project where I needed to program a 16F629. I dug out my Inchworm programmer which I built many years ago. Unfortunately the original website is closed down so I struggled to find the documentation on how to connect this thing up. Eventually found the hello world example and assembly instructions. Downloaded and …

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Wiring up Atari 2600 to SCART

I recently replaced the RIOT chip on the Atari to fix a joystick issue. Fired up the Atari today for a game and the audio has now stopped working. After reading through various forums it looks like a common problem with either the inductor L201 going open circuit or the polystrene caps C206/C207 going faulty. …

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Commodore VIC-20 35K Expansion

After getting my Commodore VIC-20 working with SD2IEC  (Was a blown 7406 hex inverter) it’s now time to build a 35k expansion. Found a great write up on Ruud’s Commodore site.   A schematic is provided which gives the  VIC-20 35k of expansion memory using 62256  (32k x 8 RAM) and a 6264 (8k x 8 RAM)  …

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SD2IEC for Commodore 64

After winning a cheap bid on a Commodore 64 off eBay  the other day I’ve looked into  building a SD2IEC. The SD2IEC is a storage device using an SD card and interfacing with the IEC bus using a ATMega644 microcontroller. I used most of the information from 16 Bit Dust .  Looking at the schematic I already had …

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