Hallo,

Since some time I have problems with my AmigaOne XE.
It appears that CPU stops to react to the changes of dip switch no 1
treating it as switched off permanently. In consequence for switching
combination [ON ON OFF ON] (speed multiplier x7) computer behaves as if it was [OFF ON OFF ON] giving multiplier x4 (533MHz in other words).
I have tried some other combinations of CPU board switches but always switch no 1 was ignored and it decreased multiplier value.

First step in order to find solution was deassembling computer and unplugging CPU board. Professional electrician stated that switches work well. He measured also the resistors placed on the opposite side of the card nearby the pins of the switching unit. And these resistors are good as well. On the other hand one of the resisitors placed above and marked R63 has value 10 kOhm whereas the rest of them ie. R64, R65 and R66 have equal resistance value 1.5 kOhm.
I have no idea whether such values are proper or not.
Electrician stated that R63 is connected to the switch no 3 which works well and not to the strange switch no 1.

After reassembling computer and turning on the frequency achieved 933 MHz,
but only one time. Second time it was again 533 MHz.
Then I have replaced power supply unit and battery on the motherboard. However that way of acting didn't yield any perpetual success. Incidentally only one time computer started with 933 MHz.
In desperation I reassembled computer once more and screwed the CPU card tightly. In effect after first turning on, the computer achieved 533 MHz and after executing diagnostics option in U-boot it achieved 933 MHz. During all the day when it was switching off and then switching on the computer achieved 933 MHz. I was thinking that problem had gone away.
However next day the computer turned on with 533 MHz. From that moment on the computer behaves waywardly: ca. 60% cases that it starts with 933 MHz. However every time it behaves unstable.

It seems that after reading the operating system in several tens of seconds the CPU load increases to about 50% (according to CPU Clock Docky) and then very rarely this state dissapears. CPU load falls and then computer works well. In most cases however after more than dozen of minutes
with such CPU load the system freezes and the only way is to do a hard reset.

Second most irritating symptom is the very moment of starting.
In most cases I can see black screen instead of U-boot or else U-boot hangs on while initiating drives. And again the only way is to do a hard reset.
I don't know what to do in order to resolve described problem so I need help
of people familiar with hardware issues of Amiga One.

Additional information:
VCore settings 1.59v (on off on off) and for 2 and half years I didn't changed it Lately after problems have emerged I've tried set it to
1.79 i 1.84 and nothing happened.

My CPU is Motorola G4 7455
RAM: Kinston ecc registred 256MB
gfx: Radeon 7500
msx: SB Live 5.1
ATA: Sil 0680
drives: 2 x HDD 40GB + CDRW + DVDRW


kind regards

@Mufa

I assume that the “dip switch” is not properly attached to layout of your CPU card; maybe you know some one whit how knows how to hand solder it.

I did have problem like that whit one of capacitors that where not attached on the CPU card, I fixed it my self.

Last edited by NutsAboutAmiga on 13-Jun-2006 at 04:11 PM.
Last edited by NutsAboutAmiga on 13-Jun-2006 at 04:10 PM.

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@Mufa

Note that you should probably down clock your CPU to 800 or 866Mhz when you get dips working… or replace the CPU fan whit a better one, A1’s are sold as 800mhz systems the CPU fan is too poor for any thing else.

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@Mufa

You could hand solder jumper-wires to test the configuration but I have that feeling that your multiplier is playing tricks.

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Quote:

I have that feeling that your multiplier is playing tricks

Yes i agree. Have you tried to contact an expert dealer like Guru Meditation or Soft3?

Ah about vcore... 1,69 should be enough for 7445 933. You can try 1,74 as well if you have problems but 1,79 (and 1,84) is way too high, you can overheat your cpu.

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ikir

@Mufa

I have exactly the same problem! My A1-XE has run quite happily at 933MHz for almost three years. I have the vcore set at 1.79V. A couple of months ago I suddenly noticed that it was running at 533MHz and I couldn't get 933MHz to work again. I'm running at 800MHz now. I'm glad you've been able to do some diagnostics on the cpu module as I can't think of anybody around here who would be interested in investigating a special G4 cpu module.

It does seem odd to have our A1 dipswitches fail in the same way?!

@RedMelons

I must degrade my G4 933Mhz to 800Mhz. Very harm

@RedMelons

99% its a dip-switches fault. When that kind of switches fails, there no other way to replace it. (a DMM continuity check doesn't helps)

Last edited by Framiga on 16-Jun-2006 at 05:43 PM.

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@Framiga

Quote:

99% its a dip-switches fault. When that kind of switches fails, there no other way to replace it. (a DGM continuity check doesn't helps)

You could always sort the relevant connections manually with your friendly soldering iron.

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@ikir

Quote:

Ah about vcore... 1,69 should be enough for 7445 933. You can try 1,74 as well if you have problems but 1,79 (and 1,84) is way too high, you can overheat your cpu.

I don't know if I can say this politely or not, but I think you have given bad advice based on incorrect facts and wrong assumptions.

- You DO NOT KNOW what the correct voltage for his chip is, because he has not told us enough to identify his specific chip down to the full part number suffix. I do not think all 7455s shipped were the same.

- 1.79 and 1.84 is NOT 'way too high', in fact some versions of the chip REQUIRE this voltage level to be stable. I have a suffix -PC 7455 in my A1, and it did not run for days without lockup until I raised the VCC to 1.79. I have upgraded the CPU cooler and added 2 fans to the case and raised it to 933MHz and it runs warmer than it did before, but is uptime 1month+ stable.

- I think we can agree that the stock cooler is inadequate and certainly inadequately mounted, and I would recommend it be upgraded, especially if you have a chip for which a higher vcore is recommended. A temperature monitor is not a bad idea too.

I refer again to SG's article on Intuitionbase as a correct starting point and work from there.

Scott Woodall

@swoodall

Yes as officially stated you must identify your cpu, but usually a1 are sold with same modules and since that guy was running it at 1,59 without lockups, 1,84 is way too high for sure.

BTW what you say is correct.

Last edited by ikir on 16-Jun-2006 at 06:36 PM.
Last edited by ikir on 16-Jun-2006 at 06:29 PM.

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ikir

@AMiGR

"You could always sort the relevant connections manually with your friendly soldering iron."

as provisional testing purpose, yes why not! The most important thing (for Mufa) is do not use the system running in that way.

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its buggy hardware so what do you expect... after a while something was gonna happpen... it dont come as a surprise...

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