Enduring problems with A1200 busboards

[miles]

Has the 2b board had timing fixes done?  What power supply are you using and does the Z4 board have a power connector on it?  As the boards show up on the early startup menu there can't be much wrong, a jumper setting?

[miles]

For the 2b timing fixes have a look here:

http://ftp.uni-bremen.de/aminet/dirs/hard_misc.html

http://ftp.uni-bremen.de/aminet/dirs/aminet/hard/misc/A1200_fixes.lha

Short:    All A1200 motherboard modifcations
Author:   ICStedman@techie.com (Ian Stedman)
Uploader: ICStedman@techie.com (Ian Stedman)
Type:     hard/misc

A complete guide (text and pictures) of all the A1200 motherboard modifications.
It includes the timing fixes and wire mods done to some later 2B motherboards.

http://www.ianstedman.co.uk

[miles]

Eyetech states

Quote from website: In general these 1.D.4 & 2.B defects only make themselves felt when the A1200 is expanded by the addition of an '040 (or above) accelerator, high performance IDE hard drive/CDROM subsystems, Zorro slots or I/O expanders (PortPlus etc). Often any one such accessory will work, but two or more will not work in combination. Typical symptoms are an accelerator exhibiting instability problems, a graphics card failing to be recognised or a CDROM failing to show disk icons.

http://www.eyetech.co.uk/addbar.php?Address=/PRODUCT/PAMAC/AMIGA002.HTM

It might be the problem, but you will only know by doing the mod .  It looks to be a hardware problem and not software.