Atari Mega ST/e modernisation

Some time ago I’ve modernised my three 16 bit Atari computers – 520ST, Mega ST and Mega Ste. 520ST and Mega ST received complete PSU’s treatment – all capcitors in them were replaced.
Mega ST and Mega Ste received new coolers (standard ones were very noisy), RTC batteries were replaced, MonSTer boards were installed (for switchable / flashable TOS (up to 4 versions), 8mb of fast ram (on Mega STe only 6mb is available, because of existence of VME bus) and two IDE interfaces, so scsi drives can be replaced with noiseless, cheaper and much bigger CF/SD cards connected via IDE 2,5″<->CF/SD adapter). There are two IDE connectors, so second device could be used for easier data exchange with PC.

Below are two MonSTer boards for Mega ST and Mega STe:

MonSTer boards for Mega ST and Mega STe

Boards installation is pretty simple and only on Mega STe we have to solder several wires to renable blitter, Mega ST needs Mega Bus adapter and is truly solderless. MonSTer board (in models other than Mega ST) sits directly on CPU socket, so we have to remove CPU, put CPU on MonSTer board and plug board on CPU socket. On basic ST/e models main processor has to be desoldered if was not socketed.
Standard TOS roms have to be removed or desoldered if they weren’t socketed.
If we want to use ASCSI devices we have to connect one pin from MonSTer board to one ASCSI port pin (without soldering, cable is supplied with board).

Optionally we can:

  • two switches can be attached to rear of Atari case to select currently used ROM bank and slot (otherwise we could use jumpers, but it’s not covenient).
  • connect external IDE activity led.
  • connect external RTC module (I didn’t have to do this, because both Mega ST and Mega STe have one).

Here are some photos from inside of modernised Mega ST:

Mega ST with Noctua cooler

Mega ST MonSTer installation

Modernised Mega ST

Here are some photos from inside of modernised Mega STe:

ASCSI MonSTer connection
Mega STe MonSTer installation

For Mega ST I’ve used NOCTUA NF-A4x10 FLX cooler(40mm), for Mega STe NOCTUA NF-A6x25 FLX. Here you can see comparison of Noctua to original Mega STe cooler.

Now I’m considering further work on 520ST and 520STe models, by adding more ram to 520ST (this is more complicated, because memory has to be soldered on mainboard, simms cannot be used like in STe series), replacement of 520STe PSU capacitors, adding for it SD floppy drive emulator and maybe srgb video output (in STe, but this means removing TV modulator). For both machines I intend to install MonSTer boards too.

Here are some links if you are interested in repairing / modernising your 16/32 bit Atari’s:
Exxos LaST upgrade site / webshop
MonSTer boards by Alan Hourihane


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