After randomly reading on here about the dreaded battery ick I pulled my A5000 out of storage. I've had it since new in the '90s.
It's an A5000 alpha, 4Mb, 33Mhz. It has a simtec 4Mb -> 8Mb upgrade in it, I have a few podules for it (including a ColourCard Gold) but none of those are currently installed while I test. It has a 72MHz CPU xtal in it to be running at 36Mhz rather than 33Mhz, this never caused any issues. I have the original xtal and the original memory controller that was removed from the socket for the simtec upgrade. The backplane is removed because I don't have it all in the case while I test.
Battery was leaking but not too awfully. With help from various of the older posts on here I removed the battery, checked continuity and was missing at least one pin from the cmos chip so removed that as well plus the crystal which had corrosion on the case.
Parts just arrived so I've cleaned everything up, repaired two traces with fine wire and attached a new battery (off board with wires to not have the same problem again). Discovered my PSU is dead, waiting on parts to try and repair that.
In the mean time I wanted to test the motherboard to see if there is anything else I need to do there. 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. Hooked up an old PC PSU to supply 5V and 12V for the motherboard and floppy.
For displays I have the old Torch colour monitor I used with it in the '90s with a custom cable. I have no idea if this still works but it powers on and when powering off I see the normal old CRT fade to a dot in the middle of the screen. I also have a 15 year old Dell LCD with an SVGA connector and svideo. My TV has a SCART input but I don't have a SCART cable for the A5000, I'll order one to test with.
I've connected the floppy drive but not the hard disk.
With a fitted cmos chip and battery I've tried powering it up with del or r or t pressed, I've tried selecting the number on the number pad to try and get it into monitormode 4... I've seen nothing on the Torch monitor or the Dell LCD.
I ran through everything in viewtopic.php?t=6179 basically.
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.
About 35 seconds later the floppy drive seeks and the keyboard lights will toggle when I press them, which implies it is running.
If I hit F12 and ^G I don't get any boop.
If I type in any commands I don't get any change (tried blind setting monitor modes, etc).
It feels like it is running but I get no audio and no video.
With no other machines to test against the displays I don't know if they are working or if the video output from the machine is toast or misconfigured.
Am I mistaken about the need for -5V? Anything I'm missing here? I have a multimeter and can do basic electronics discovery, I don't have an oscilloscope and I never got good enough to work from a diagram of something I'm not familiar with to diagnose problems. These days most of my electronics work is hooking stuff up to Arduinos, etc.
It's an A5000 alpha, 4Mb, 33Mhz. It has a simtec 4Mb -> 8Mb upgrade in it, I have a few podules for it (including a ColourCard Gold) but none of those are currently installed while I test. It has a 72MHz CPU xtal in it to be running at 36Mhz rather than 33Mhz, this never caused any issues. I have the original xtal and the original memory controller that was removed from the socket for the simtec upgrade. The backplane is removed because I don't have it all in the case while I test.
Battery was leaking but not too awfully. With help from various of the older posts on here I removed the battery, checked continuity and was missing at least one pin from the cmos chip so removed that as well plus the crystal which had corrosion on the case.
Parts just arrived so I've cleaned everything up, repaired two traces with fine wire and attached a new battery (off board with wires to not have the same problem again). Discovered my PSU is dead, waiting on parts to try and repair that.
In the mean time I wanted to test the motherboard to see if there is anything else I need to do there. 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. Hooked up an old PC PSU to supply 5V and 12V for the motherboard and floppy.
For displays I have the old Torch colour monitor I used with it in the '90s with a custom cable. I have no idea if this still works but it powers on and when powering off I see the normal old CRT fade to a dot in the middle of the screen. I also have a 15 year old Dell LCD with an SVGA connector and svideo. My TV has a SCART input but I don't have a SCART cable for the A5000, I'll order one to test with.
I've connected the floppy drive but not the hard disk.
With a fitted cmos chip and battery I've tried powering it up with del or r or t pressed, I've tried selecting the number on the number pad to try and get it into monitormode 4... I've seen nothing on the Torch monitor or the Dell LCD.
I ran through everything in viewtopic.php?t=6179 basically.
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.
About 35 seconds later the floppy drive seeks and the keyboard lights will toggle when I press them, which implies it is running.
If I hit F12 and ^G I don't get any boop.
If I type in any commands I don't get any change (tried blind setting monitor modes, etc).
It feels like it is running but I get no audio and no video.
With no other machines to test against the displays I don't know if they are working or if the video output from the machine is toast or misconfigured.
Am I mistaken about the need for -5V? Anything I'm missing here? I have a multimeter and can do basic electronics discovery, I don't have an oscilloscope and I never got good enough to work from a diagram of something I'm not familiar with to diagnose problems. These days most of my electronics work is hooking stuff up to Arduinos, etc.
Statistics: Posted by pir — Sat May 11, 2024 1:07 am