Amiga 3000 cold power on issues

[Castellen]

But what are your thoughts on it just booting fine with the 68030 on board versus having issues with the CSMkII installed?

There's not enough information to say exactly what might be causing the problem.  You mentioned that the BFG9060 works reliably, but then you also said that the CSMkII "is now booting fine all the time".  There's obviously some kind of intermittent issue somewhere.

You'd need to collect more clues with the system in the fault state to draw more solid conclusions, which you can't easily do without some diagnostics tools such as a special ROM to see what's happening under normal boot conditions.

Intermittent problems are often caused by issues with connectors, and the A3000 is full of these in the form of horrible IC sockets with tin plated contacts.  In these situations it's often worth removing each of the socketed ICs, including the PLCCs, carefully brushing all contact surfaces with isopropyl alcohol and re-inserting them.  Be sure to use a PLCC extractor tool since anything else will damage the sockets.  Otherwise leave the PLCCs alone and just focus on the DIP devices.

The KEL connectors are at least gold plated, so don't suffer the same tarnishing and oxidisation problems that tin plated contacts do.  They're usually reliable except when individual pins somehow get over-compressed or bent out of alignment.  You can also brush the contacts with isopropyl to remove any surface contamination.

[Betelgeuse]

There's not enough information to say exactly what might be causing the problem.  You mentioned that the BFG9060 works reliably, but then you also said that the CSMkII "is now booting fine all the time".  There's obviously some kind of intermittent issue somewhere.

You'd need to collect more clues with the system in the fault state to draw more solid conclusions, which you can't easily do without some diagnostics tools such as a special ROM to see what's happening under normal boot conditions.

Intermittent problems are often caused by issues with connectors, and the A3000 is full of these in the form of horrible IC sockets with tin plated contacts.  In these situations it's often worth removing each of the socketed ICs, including the PLCCs, carefully brushing all contact surfaces with isopropyl alcohol and re-inserting them.  Be sure to use a PLCC extractor tool since anything else will damage the sockets.  Otherwise leave the PLCCs alone and just focus on the DIP devices.

The KEL connectors are at least gold plated, so don't suffer the same tarnishing and oxidisation problems that tin plated contacts do.  They're usually reliable except when individual pins somehow get over-compressed or bent out of alignment.  You can also brush the contacts with isopropyl to remove any surface contamination.

Thanks, sorry wasn't clear. The system was booting fine yesterday with the CSMkII, but not today, which is when I decided to test it with the BFG9060, so it's clearly some issue between the A3000 and CSMkII.

I did remove and resocket all the chips and cleaned them up, so again not that. Why does it work fine after the system has been powered on for a while? That's the puzzle, sme heat-related expansion of a bad solder or something? I'm close to just giving up at this point...

[Boing-ball]

Thanks, sorry wasn't clear. The system was booting fine yesterday with the CSMkII, but not today, which is when I decided to test it with the BFG9060, so it's clearly some issue between the A3000 and CSMkII.

I did remove and resocket all the chips and cleaned them up, so again not that. Why does it work fine after the system has been powered on for a while? That's the puzzle, sme heat-related expansion of a bad solder or something? I'm close to just giving up at this point...

Have you tried changing the CPU oscillator? Believe it or not, it could be just a simple fix as that….

[Betelgeuse]

Have you tried changing the CPU oscillator? Believe it or not, it could be just a simple fix as that….

Yes, and I just received a 50MHz one from DigiKey along with a socket. But I measured the oscillator and it is outputting 50MHz. Weirdly, heating the area in the vicinity of the oscillator with a hairdryer makes the machine boot every single time, but not other areas on the board nor the CSMkII. So maybe it is flaky in a way that is not showing up on an oscilloscope and heating it fixes it? I did reflow all solder joints in that general area but that had no effect.

[Betelgeuse]

Well, it wasn't the crystal, which was a royal pain to remove due to the large ground plane underneath, but at least it's socketed now. It may be one of the resistor arrays, as heating those alone makes the system boot up. Do those fail in this manner?

[Betelgeuse]

An update, heating RP109 makes the system boot. So it may be that component. It connects to the CPU address lines. Maybe the 030 is more tolerant of some fluctuations but the 060 or the added length of connections to the 060 in combination with the CSMkII architecture causes the issue. Will replace it once I get replacement parts and will update here for others who run into the issue.

[beller]

I was having similar issues with my A1200.  Wouldn't boot at first startup but would eventually start and run fine.  Tried sorting it out but never did.....untill I pulled out my Blizzard '030 and replaced it with a PiStorm. Any boot issues vanished.  Could be your processor getting old...

[Betelgeuse]

I was having similar issues with my A1200.  Wouldn't boot at first startup but would eventually start and run fine.  Tried sorting it out but never did.....untill I pulled out my Blizzard '030 and replaced it with a PiStorm. Any boot issues vanished.  Could be your processor getting old...

Thanks, it is possible something on the CSMkII is causing the issue, but it's not the CPU as I have several and the behaviour is the same with different revs of 68060. I'll replace the resistor pack I'm suspectful of today and we shall see if it makes a difference.

[Boing-ball]

It’s worth a shot. Don’t forget these Phase 5 / DCE accelerator cards are getting older now. You never know.
I have a slightly temperamental MK1. Took me a couple of months finding out after 9.5 and over cycle tests on ATK, that I had a failing RAM Simm. Since swapping that out, it’s been pretty stable. Have had the odd Guru still. So maybe it’s software or another SIMM about to fail.. 🤷🏻‍♂️ Arn’t Amigas great.. 😳🤣🤣

[Castellen]

An update, heating RP109 makes the system boot. So it may be that component.

Good find to narrow it down that far.  The resistor networks are usually fairly reliable, I've only seen them give problems as a result of corrosion damage.

You can test it easily enough.  With the system in the fault state, and powered off, measure the DC resistance between 5V (or pin 1) and pins 2 - 9 of the resistor network, they should should all be around 1k Ohms.  Some variants use 2.7k or 3.3k for address bus pullups.

To further test the heating theory, you can confine heat to a single component by putting your soldering iron against the component body for 5 - 10 seconds.  That means you'll be heating only the suspect component and not anything else in the area around it as the hot air does.

[Betelgeuse]

Well, I've spent the entire weekend on this thing and it's starting to drive me boing! I replaced the oscillator, no change, replaced the 2 resistor packs near the ROMs, no change. The old ones tested OK, which I expected as I've never seen those go bad. BUT, pressing on the ROMs, either one, makes the machine boot, as does heating them. So I replaced those sockets, and it is more reliable but after a long power-off period it still won't boot, pressing on the ROMs quite firmly makes it boot. The sockets are new and connections seem to test out ok, and it always boots with the built-in 68030, so I think those are fine. I looked all around that area and see no issues. But, how many layers is the 9.2 rev A3000 board? Could it be a bad via or a trace in the board that's wonky? So frustrating!

[Castellen]

how many layers is the 9.2 rev A3000 board? Could it be a bad via or a trace in the board that's wonky?

It's a 4-layer board.  A majority of the signals are routed on the external layers, with the internal layers mainly used for 5V and ground.  Internal layers do contain signal routing in congested areas, such as around the 68030.  It's a decent quality PCB and faults are rare except when there's physical damage or corrosion.

Since you were able to make the fault go away with localised heating, that's still a good lead to follow.  Though I'd suggest trying to use heat in much smaller areas.  For example, heat a component body using a soldering iron.

Once the system is in a state where it's not showing the problem, you can try using an aerosol can of freeze spray to provide localised (spot) cooling to see if you can make the fault re-appear on demand.  That might get you a lot closer to whatever is causing the problem.

[Betelgeuse]

Thanks! It seems that the issue is in the corner area near the ROMs so I'llf focus on finding what the cause is. On possibility is U354, which is a 74LS174 flip-flop, not sure what else in there could be causing the issue but I'll troubleshoot with localized heating and see if anything can be located.

[Betelgeuse]

Figured it out, should've thought of that at the beginning so I feel pretty dumb about it, lol! One of the EPROMs that has Kickstart 3.2.2 doesn't like being cold in combination with CSMkII, hi-rom specifically. Not sure why, both are identical and I replaced previous 3.1 ROMs with these. Warming just U181 makes the machine boot every time. Putting in original 3.1 ROMs also makes it boot every time with the CSMkII, even from cold boot. The combination of this particular EPROM and 3.2.2 and CSMkII makes it not work when cold booting. So nothing wrong with the A3000 itself thankfully! What an annoying issue!

[Betelgeuse]

Final update: Replaced the hi-rom EPROM with a new one and the problem is solved. It was just a bad EPROM.