A4000 problems with CIA and more?

[Liqourice]

I've had my A4000 away for recapping and at the same time the Buster socket was replaced since it was corroded.

Now though I have some more issues. They were probably there before, it was very unstable the last few years before it didn't want to work anymore.

Now however it runs fine for a short while, ten-fifteen minutes or so. After that I start getting failures like these.




I ran Amigatestkit after the computer had been off for quite a while. Besides the audio not working properly, left had no sound at all but I think the rca contact have come lose somehow, I got some faults on the CIA's.





I don't know how serious these are. Since they're soldered it's not possible to just swap them like on the 500.

Question is, are these related? Can a bad CIA be the reason why my CV64/3D crashes the computer as well? How bad are these faults?

Obviously I need to replace them or at least one of them. Question is which one.

Everything else seemed ok when I ran Amigatestkit. I wonder if something is overheating because it runs well for a little while. Testing ram, though only one pass on each bank, showed no errors.

Any ideas and/or tips?

[Liqourice]

Oh, just to mention. When it's "cold" it does not give errors on boot like on the image above. THen it boots just fine.

[DigitalKeeper]

Please make some Photos of the Board i.e. Audio

No Sound or scrambled Sound -> the Audio Lines/Traces are often defective and/or broken from Leakage of the capacitors there.

I suppose, that the "Recapping" wounld'nt properly done

At the Audio Area -> check for corroded Traces, Oxyd, etc.

Before:



After:

-

.

[Liqourice]

Never been any noticable leakage around that area, it looks fine. However, after I got it back from the recap it was difficult to get the board back in, one of the rca contacts didn't quite fit through the hole in the backplate. I don't know if he did anything with them when he recapped but it doesn't seem to sit were it should.

The audio bit is the least of the issues right now though, The crashing and instability issues are more important so solve.

[DigitalKeeper]

Have a look at the RCA contacts, often there are "Black" with Oxyd, if so - cleanning would help, or new RCAs

CIA-A -> IRQ Failure -> have a look at ALL Traces from/to the CIA - they must be ok...in some cases, the 47 Ohm Resistors are faulty...this have some weird effects



->
BFE801 todlo 50/60 Hz event counter bits 7-0 (VSync or line tick)
BFE901 todmid 50/60 Hz event counter bits 15-8
BFEA01 todhi 50/60 Hz event counter bits 23-16
<-

Check Signal's on Pin 21, 23, 27 on U300 (CIA-A) with oscilloscope

[Liqourice]

That's gonna be difficult since I don't have an oscilloscope. Might need help with this since my knowledge in this area just aren't good enough.

[Liqourice]

Well. After a few years of not having either time or energy to get into this I've finally started to look into things again.

First of all, I'm pretty sure my main issues are that the 060 runs to hot. I removed the fan and heatsink I had on it, mounted with a double sided conductive tape and instead just used small pieces of the same tape in the corners of the fan and stuck that onto the cpu.

It ran a lot longer but still started crashing eventually so the problems are mainly overheating. Chucky converted my CS MkII from 040 to 060 and put a 66 MHz crystal on so I suppose my Rev 6 just isn't capable of running at that speed without proper cooling. I guess I have to get a 50 MHz crystal to use instead for the time being.

Does anyone have a suggestion for a good way to cool the CPU? I've been searching but can't really find anything that fits a 060 all that well.

[cloverskull]

I've used these to great effect: https://www.digikey.com/en/products/...xpQOQBEQBdAXyA

Bit pricey but worth it I guess.

That said, are you 100% positive you're running a rev 6? There's no way you should be overheating at 66MHz. That's pretty unfortunate if that is the case.

[Liqourice]

Originally Posted by cloverskull

I've used these to great effect: https://www.digikey.com/en/products/...xpQOQBEQBdAXyA

Bit pricey but worth it I guess.

That said, are you 100% positive you're running a rev 6? There's no way you should be overheating at 66MHz. That's pretty unfortunate if that is the case.

Yes, it's definately a Rev 6. I know exactly where it came from so I know it's not a fake.


My other thought is that there was some mistake done in the conversion from 040 to 060 so it's fed a bit to high voltage and that causes it to run hot.



A working cooler is worth a lot since I just can't use the CPU without one ATm. It's quite evident that temp is an issue since it works fine and stable for 10-15 minutes or so and then it starts crashing just opening a window in workbench.


I tried running it without anything on it, no heatsink and no fan, and it got to hot to touch after a while.

[Lunda]

Originally Posted by Liqourice

Yes, it's definately a Rev 6. I know exactly where it came from so I know it's not a fake.


My other thought is that there was some mistake done in the conversion from 040 to 060 so it's fed a bit to high voltage and that causes it to run hot.



A working cooler is worth a lot since I just can't use the CPU without one ATm. It's quite evident that temp is an issue since it works fine and stable for 10-15 minutes or so and then it starts crashing just opening a window in workbench.


I tried running it without anything on it, no heatsink and no fan, and it got to hot to touch after a while.

I haven't seen my rev 6 above 40 C with a small cooler. That's not in a closed box though.

If you really need good cooling, a thermoelectric (peltier) cooler will get the job done. See attached photos.
I don't remember the spec of the TEC, but I was testing it at 5V. Which was too much for the 060. You don't want condensation.

Have you checked if other chips are running hot?

Regarding the 040 to 060 conversion. This is something that must be taken care of:
https://eab.abime.net/showpost.php?p...8&postcount=72

[Liqourice]

Originally Posted by Lunda

I haven't seen my rev 6 above 40 C with a small cooler. That's not in a closed box though.

If you really need good cooling, a thermoelectric (peltier) cooler will get the job done. See attached photos.
I don't remember the spec of the TEC, but I was testing it at 5V. Which was too much for the 060. You don't want condensation.

Have you checked if other chips are running hot?

Regarding the 040 to 060 conversion. This is something that must be taken care of:
https://eab.abime.net/showpost.php?p...8&postcount=72

I have the lid open at the moment so it should get plenty of air. That's why I think the voltage might be to high since it's running so hot.


I didn't do the conversion of my CS MkII myself and I fully trusted the person who did it but everyone can make mistakes sometimes. I don't have the tools and knowledge myself to check.


Gonna see if my original PSU is still ok and put that back in just to see if that makes a difference. Currently I'm using an SFX supply with the Amiga-kit adapter. Perhaps that's not really doing what it's supposed to.

[Liqourice]

I haven't been able to check if other chips get hot so far, I need to more or less disassemble everything so I can access them first.

Have removed the SFX PSU and put the original back in though. That didn't change anything, the result is the same as before. I replaced the PSU back when I started getting problems with my 4000 thinking it was the cause but that wasn't it. A recap got it working again.

I've emailed the person that did the conversion of the CPU-card to ask what he thinks, if it might be that the cpu gets to much voltage.