ACA620 Stability Help

[solarice]

Right i think i'm running out of ideas in this so hoping someone can help.

A bit of history.

When it was first installed it would last about 30 mins with the case on.

I then put some heat sinks on the board which took it up to / above the hour mark with case on.

Since putting on a fan i can get it to about / above 2 hours of running with the case on before it'll black screen on something.

Now from what i've read most people claim they have no issues...which is annoying (only because there's no possible solutions).

Having only heard about rev 2d issues i figured it wasn't a concern, but recently i did find mention of possible problems on a rev 1.5 board with the gayle 391155-02 chip (which happens to match mine). A larger power supply seemed to fix that in the one test, so maybe a coincidence.

When the system is cool everything is great. The aca620 is 100% in contact with the chip and all pins are clean etc etc.

Is it just a heat issue (if there is such a link) or is there a compatibility issue with the motherboard in mine.

Heat wise it never gets too hot, only warm to touch.

The a600 power supply seems to be well within limits, based on info online so i don't believe its that. Issue happens regardless of hdd availability.

When it does lock up waiting a few mins or opening the case for 30secs or so and you can fire it back up and load the same game that crashed without problems for a brief time. Leaving the case off it seems to be fine for ages.

Just looking to try and find something i've possibly missed or get the give up now signal to save my hair as i've been at this months now.

Any ideas? apart for fitting a massive fan haha.

[bubbob42]

Attach it to the mainboard (hd frame holes) with two small screws. This will improve ground connection and increase stability.

And did you replace the caps of the machine already?

[solarice]

Yeah caps already replaced.

I wouldn't have thought it'd be a ground issue, as it runs fine with the case off. But it is one of the last few things i've yet to try.

[Photon]

With the SMD chip piggyback ride, temperature changes will always be an issue I think, if Individual Computers used the same plastic socket as for ACA630. If the traces around the caps were damaged before the swap, the damage could take effect with heat expansion and cause a leak current or short. The only solution I think is to get the heat directly out of the case. Remove any heatsinks and put a fan on the inside of the case grille.

[demolition]

It could well be a compatibility issue with your Gayle. If it is just on the border of being stable and the timing then changes a bit due to the temperature increase, it becomes unstable. Not because the ACA620 overheats, but because it was just borderline stable to begin with.

You do have a revision 2 of the ACA620, right?

[solarice]

Yeah the case is so damn tight to get anything in fan wise...while keeping the noise down.

Gayle compatibility would be a bit of downer, especially as there's no real mention / warning about it, hopefully its not but it does kinda look like it might be.

Double checked sysinfo and on boards its says serial number 2 so i believe that's proof its a rev 2 board (its supposed to be).

I'll keep at it...thanks so far for the ideas.

[bubbob42]

I placed both a 50mm and a 40mm fan below the grille. The smaller one is always running, the larger one is being activated by a switch which overclocks the card to 25mhz via a little circuit at the same time.

Silent and rock stable (Subway USB and Indivision are fitted as well)

[Photon]

Yeah just put a fan under the grille, heat rises and the air is blown out through the grille (i.e. it doesn't have to be over the CPU or anything).

[solarice]

I've had the fan in the few places where it would fit, to varying degrees of success. Even on the grill it would freeze up eventually (I know that will all depend on the final fan specs).

As a test I mounted it directly to the card (figured if it still froze, then there wasn't much else i could do) but so far so good. Far too loud, but if i can get it squared away i'll swap it for something a lot quieter.

Thanks for the help so far.

[Amiga1992]

Weird, I have run the ACA620 in ridiculously hot conditions (external temp too high) and it worked fine. Are you sure your card s fine? Did you do the earthing recommended beforehand?

[bubbob42]

I bet it's a ground issue - use screws.

[solarice]

Sorry for not replying before guys. As far as i know the card is 100% fine and the connections were always a tight fit.

Well i've got it setup as follows. One 5v fan mounted directly on the card pulling the hot air away and pushing it over to the left and then i've got a 12v case fan mounted to the grill to push the air out of the case.

Machine runs super cool and super quiet and since having it setup this way its been 100% reliable (hope i haven't jinxed it haha).

Maybe the issue is the gayle version or something else tbh i'm not 100% sure, but its stable now and that's all i was concerned with.

I will confess to not having tried the ground screw option so i can't confirm or deny if that would have helped...mainly as i wasn't convinced it'd be a ground issue, yeah i know i should have tested just to eliminate it.

Tbh i'd have thought vibrations from the card mounted fan would have exaggerated any ground / connection issues and as there haven't been any signs i still don't believe there were any, plus once the fans did the job playing games took priority lol.

Thanks for the help / ideas.

[fitzsteve]

You're not the only one to have issues, I've read a few posts in the past and spoken to people with the same problems such as Woodycool over at Amibay, his would work for some time then become unstable.

Mine was always fine, what I think these problems are caused by are fractures in the soldering on the legs of the 68k, you could try to reflow them or try another Motherboard if you have one available (or can find one)

[Photon]

Yeah, if that's the real issue and not overheating then 5 minutes with a 20 EUR butane soldering gun would be something worthwhile trying.

[solarice]

I had considered reflowing the solder...If it starts acting up again it will probably be one of the first things to try. For now i'm keeping the case shut or i'll spend even more time tinkering and less time actually using the machine.

Without the card its never been a bother (its the same machine i've owned from new, so i know it hasn't been mistreated). I don't have access to any other Amigas, so i'm limited in my testing.

However the way its setup at the moment i've had full days of use without any issues, so its a million times better...certainly worth a try if anyone is having the same issue and has tried everything else.

[TjLaZer]

I have an ACA620 that also locks up after a few minutes of use. Machine has new caps on it. I installed a heatsinc on the card and that did not help. Will grounding it solve the issue?

[Amiga1992]

I don't think it needs a heatsink, everyone with an ACA620 SHOULD ground it as explained, if not just for the grounding, also for the stability of the connection. My unit kept popping off the CPU with the slightest move on transport and it was fricking annoying.

[turrican9]

using grounding screws is essential for the ACA 620. Without them it will not be stable.

[demolition]

Originally Posted by turrican9

using grounding screws is essential for the ACA 620. Without them it will not be stable.

Don't tell that to my ACA620. I never used the grounding cable and it is perfectly stable..

Edit: But if I had stability problems, I would definitely attach the cable as it won't make matters worse and some times can help.

[TjLaZer]

Added grounding cable and it helps a bit, but still get lock ups. Where can I get the grounding screws? I noticed the holes on the card are small and no screws I had would fit. Would be nice if there was a kit for this. Amikit did not send me one when I bought this.