Excellent stuff. Some thoughts:
"The A5000 is known to be particularly badly affected by this, as the battery is located close to the CPU"
I don't think that's particularly true or even relevant. The CMOS RAM is connected to IOC, not the CPU. It's pretty rare IME that a battery leak in A5000 causes any damage to/around the CPU. Much more common is the battery leak destroying IDE on an A5000, and that's then hard to fix tidily due to the location and SMT nature of the parts used.
I could write a small book just on fixing battery leak / CMOS RAM issues on the various machines. Tips include checking not just for battery voltage when the power's off, but also that the CMOS RAM is receiveing main voltage (at least 4V) when normally powered or it still won't respond... but this should all be somewhere else - is arcwiki a reasonable place to start putting such info do you think?
"Acorn machines are not generally subject to the same capacitor issues that affect eg Amiga or Macintosh"
I now think this needs caveats. The statement is true in general EXCEPT for A4, which I believe now does always need a 100% re-cap. A5000s which have the "backwards electrolytics" also need a full re-cap. RiscPCs regularly have failing capacitors on the VCO which cause "wobbly video" output - I /think/ this is worst on Mk3s. And finally the explosive C39 tant on A300 boards probably deserves a mention. Oh, and the RIFAs in everything pre-A5000, though in Arcs these still don't seem to suffer anywhere near as much as Beebs do.
Monitors
Probably worth explaining the Numpad-number-key-power-on to force monitor type - and the caveats/limitations of doing so. And Acorn's extended monitor type detection via the VGA ID pins. And separate/composite sync? Ugh.
I saw quite a bit of 'weird' chat recently about what seemed to be a perception that "A SCART" was the preferred connection method, which bears no technical merit in itself, other than that TVs which have SCART inputs will always support 15kHz on that input (and sometimes ONLY on that input)
Mice
Perhaps adapters like PS2MouseMini could be mentioned for using PS2 mice with machines that need quadrature. Or Smallymouse or TruMouse... perhaps keep it generic.
Keyboards
Pointless technical nit - A4 is a pre-RiscPC machine that can use a PS2 keyboard.
Recommended machines
Is it fair to have some sort of explanation that A300/A400/A3000 have 8MHz RAM and are not well suited to use with 'VGA' or higher resolutions? With ARM3, for games, perfectly adequate equivalent to A5000 in real terms I think.
A300/A400 - don't they -all- contain RIFAs?
A3010 Adelaide - worth mentioning that the ARM3 upgrade, though desirable, requires good SMT skills to fit the socket first?
It'd be easy to go off in to the weeds though - I like that this guide is decently consise for an easy one-sitting read-through. Good job putting it together.
"The A5000 is known to be particularly badly affected by this, as the battery is located close to the CPU"
I don't think that's particularly true or even relevant. The CMOS RAM is connected to IOC, not the CPU. It's pretty rare IME that a battery leak in A5000 causes any damage to/around the CPU. Much more common is the battery leak destroying IDE on an A5000, and that's then hard to fix tidily due to the location and SMT nature of the parts used.
I could write a small book just on fixing battery leak / CMOS RAM issues on the various machines. Tips include checking not just for battery voltage when the power's off, but also that the CMOS RAM is receiveing main voltage (at least 4V) when normally powered or it still won't respond... but this should all be somewhere else - is arcwiki a reasonable place to start putting such info do you think?
"Acorn machines are not generally subject to the same capacitor issues that affect eg Amiga or Macintosh"
I now think this needs caveats. The statement is true in general EXCEPT for A4, which I believe now does always need a 100% re-cap. A5000s which have the "backwards electrolytics" also need a full re-cap. RiscPCs regularly have failing capacitors on the VCO which cause "wobbly video" output - I /think/ this is worst on Mk3s. And finally the explosive C39 tant on A300 boards probably deserves a mention. Oh, and the RIFAs in everything pre-A5000, though in Arcs these still don't seem to suffer anywhere near as much as Beebs do.
Monitors
Probably worth explaining the Numpad-number-key-power-on to force monitor type - and the caveats/limitations of doing so. And Acorn's extended monitor type detection via the VGA ID pins. And separate/composite sync? Ugh.
I saw quite a bit of 'weird' chat recently about what seemed to be a perception that "A SCART" was the preferred connection method, which bears no technical merit in itself, other than that TVs which have SCART inputs will always support 15kHz on that input (and sometimes ONLY on that input)
Mice
Perhaps adapters like PS2MouseMini could be mentioned for using PS2 mice with machines that need quadrature. Or Smallymouse or TruMouse... perhaps keep it generic.
Keyboards
Pointless technical nit - A4 is a pre-RiscPC machine that can use a PS2 keyboard.
Recommended machines
Is it fair to have some sort of explanation that A300/A400/A3000 have 8MHz RAM and are not well suited to use with 'VGA' or higher resolutions? With ARM3, for games, perfectly adequate equivalent to A5000 in real terms I think.
A300/A400 - don't they -all- contain RIFAs?
A3010 Adelaide - worth mentioning that the ARM3 upgrade, though desirable, requires good SMT skills to fit the socket first?
It'd be easy to go off in to the weeds though - I like that this guide is decently consise for an easy one-sitting read-through. Good job putting it together.
Statistics: Posted by IanJeffray — Sat Mar 29, 2025 3:03 pm