exxos's Atari, Amiga & retro forum

This thread is to follow the process of building out 3x H5 C5B boards as development boards for @exxos, @ijor, and I.


I intend to blog as detailed as possible getting these boards working and in a state to accept the Phoenix Boards such as Phoenix BLUE, Phoenix MMU and Phoenix Shifter. Ultimately being a test bed of the Phoenix Nexus.

This won't be as easy as building up a board as normal as there will be desoldering and other tweaks. However, once complete the board will allow the plugging in and out of boards in a robust manner. For example we all know the turned pins used for some boards are very easily broken as we are looking at a more sturdy connectivity.

So, these arrived the other day and now I need to take stock of the end goal and where to start. Possibly with the warning note to rotate the amplifier IC first:

So these are going to be the areas of focus as I build out these boards:

• Desoldering
  - Desolder Amp chip and re-orientate
  - Desolder Shifter socket - for Phoenix Shifter testing
  - Desolder BLITTER / GLUE and MMU sockets - for Phoenix BLUE and MMU board testing
• Soldering
  - Oscillators
  - Reset Switch
  - 68K Sockets
  - HD headers
  - Power headers
  - 3V3 header
  - Misc signal header taps and the snip of the key pin in the keyboard header
  - Header sockets for PLCC chip locations
  - Edge connectors - MIDI, Cart, Printer etc.

I'll be documenting and providing detailed pictures as I go. Some of these steps may help builders of a non-dev H5 C5B board.

So removal of the audio chip using a heat gun:


Audio chip oriented correctly and Shifter socket removed (not required if building a normal board)

PLCC68 sockets removed for BLITTER, GLUE and MMU to allow sockets for the Phoenix BLUE and MMU boards. Will add sockets after a few other parts to sort.

Before:

After:

Very neat :thumbup:

exxos wrote: 14 Feb 2026 16:30 Very neat :thumbup:

Slowly, slowly getting there. Next: adding in the missing 5V to 3V3 volt translator for dev purposes.This allows using an onboard translator to put signals through for testing / debugging etc.

Chip ready for soldering:

Anyone wanting to do the same update the chip is a GTL2010PW

And in place:

3V3 area finished. Each section posted is done on all three boards.

Don't forget the keyboard!

The STFM keyboard has a blocked hole in the connector as a key. However the H5 needs a pin cutting to allow the keyed socket to fit.

STFM Keyboard connector with key slot filled in:

H5 connector with pin requiring cutting:

Snipping the pin:

Connector ready for STFM keyboard

And now the HDD headers. These headers are the Mega STE HDD connector and internal ASCI connector. In addition is the HD INT line for Trudie IDE board.


Connectors in place:

Insertion of the MFP chip and crystal: