32-bit acorn hardware • Re: Yet another partly dead A5000

It has a 72MHz CPU xtal in it to be running at 36Mhz rather than 33Mhz, this never caused any issues. I

My experience trying to overclock Alphas is to the negative - they don't, at all. YMMV, but I'd put the 66Mhz back in if you do still have it - at least for testing - you want the most basic standard machine config you can get to.

I *think* I remember reading on here that the A5000 motherboard doesn't use the -5V and 12V lines, they just get passed to the podule bus.

Yeah, the board will start up and can be used with just 5V applied.

When powering up the power LCD comes on, I get a couple of clicks on the speaker (no boop), the keyboard lights flash.
The floppy drive light does not flash.

Normal. But the keyboard LEDs flashing means nothing - that's all automated by the 8051 in the keyboard itself.

About 35 seconds later the floppy drive seeks and the keyboard lights will toggle when I press them, which implies it is running.

Yes, "toggleability" means RISC OS is running.

No floppy flashing could mean that the floppy / bus isn't working, and with that amount of delay it could be that it's trying to flash.

RISC OS will "run" without CMOS RAM working, but generally in a very degenerate way, with most of its modules missing, and not knowing what video configuration to be.

Check that you have continuity from the CMOS RAM chip I2C pins to the IOC pins. Check you have power across pins 4 and 8 of the CMOS RAM chip when the machine's on.

Be sure you're doing the DEL-startup correctly. Hold DEL. Then power on. Keep it held for a full minute so you can be sure it's passed the '35 second delay' mentioned above.

It's also possible (somewhat likely, IME) that the chip itself has died, so you may need to replace it.

Also worth checking that you've got the two shunts fitted on the 'GENLOCK' LK6 connector near VIDC - the two toward the rear of the machine should be fitted 1-2 and 3-4. You mentioned that you had a colourcard fitted, so that would have been fitted on this connector originally, so you may have forgotten to put the links back after removing colourcard? These set the video clock (1-2) and the video sync input (3-4).

Statistics: Posted by IanJeffray — Sat May 11, 2024 1:45 am

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