H5 C5B Development Boards

[Icky]

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

STFM_H5C5B_v1_2026-Mar-09_10-20-57PM-000_CustomizedView4662945417_png.png

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:

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[Icky]

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.

[Icky]

So removal of the audio chip using a heat gun:

IMG_1573 (1).png

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

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[Icky]

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:

IMG_1559.png

After:

IMG_1626.png

[exxos]

Very neat :thumbup:

[Icky]

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:

IMG_1627.png

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

And in place:

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[Icky]

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

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[Icky]

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:

IMG_1633.png

H5 connector with pin requiring cutting:

IMG_1632.png

Snipping the pin:

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Connector ready for STFM keyboard

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[Icky]

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.

IMG_1561 (1).png

Connectors in place:

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[Icky]

Insertion of the MFP chip and crystal:

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