A40000 problems after upgrade CPU

dougal

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I upgraded from an A3630 to an A3640 and now I have issues.

Seems that after some use I start getting hard drive errors which even a reboot doesnt seem to fix.

Still testing, but is there anything I may have done wrong ?

I changed the jumpers 100 and 104 from 1-2 to 2-3 or else the A3640 did not want to work.
 

fitzsteve

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Re-cap the A3640, it might help.
 

dougal

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Its already re-capped

Its also clocked (overclocked) at 33Mhz ... detected in WhichAmiga and SYSinfo

Seems after switching the Amiga off for a few minutes and everything works fine again.

- - - Updated - - -

Is it possible that I need to do some MAX Transfer settings because of the faster CPU (from 030@25 to 040@33) ?
 

dougal

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Replace 66MHz oscillator by 50MHz on A3640.

I did some more tests using AIBB and SYSspeed and playing some games on whdload and so far it's stable.

Stachu, I think it was more than just the crystal that was modded as there are some jumper wires on the card and sysinfo, aibb and whichamiga all report that it is a full 68040 with MMU and FPU.

Is the cpu supposed to be a 68LC040 without FPU?

From the results in SysInfo and AiBB there is a very nice speed boost from the standard 25Mhz A3640

Is it dangerous keeping it at 33Mhz ? Maybe if I add a fan ?
 
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fitzsteve

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You could try 28/30/32 (56/60/64) and see how you get on but mine was flaky @33mhz and finally settled with 30mhz as a reliable speed.

I might still have a 60mhz or 64mhz crystal here somewhere.
 

dougal

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Wow you seem to have quite a collection of crystals :p

I'll give it a day or two of testing. If its still problematic would you be willing to part with those crystals (if you have them and for a price of course :) ) ?

You could try 28/30/32 (56/60/64) and see how you get on but mine was flaky @33mhz and finally settled with 30mhz as a reliable speed.

I might still have a 60mhz or 64mhz crystal here somewhere.
 

Aysel

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The 3640 @ 30mhz I put in one of my A4k's gave random resets and GURU's after an hour or so use, turned out to be heat accumulation in the case and all I had to do was pop the expansion slot cover off on the rear and its been perfect since... had exactly the same with the quad doubler I've fitted to the other, that was way hotter though, could feel the heat on the top of the case... I fitted an exhaust fan to the expansion slot, again really cool and stable ever since.

A4000 desktop case is a nasty design, completely sealed unit with the PSU fan blowing into the case which is fine with the stock 030 but as soon as you start with any upgrades I would highly recommend some sort of cooling :)

People say the A3000 is worse, both mine have 3640's in them and they have never missed a beat... the way the PSU fan dips down below the chassis just seems to circulate the air so much better.
 
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cpiace64

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insert a photo, the overclocking need a mod near chip of delay

i have repaired one and i modify the delay for more stability whit standard xtal
 

dougal

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I think maybe it might need a fan.

Any recommended fans ? size, type, fitting etc. ?
 

fitzsteve

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It's actually the gals that overheat you can try to put heatsinks on them. Dopefish found that while upgrading my A3640. It's documented here on amibay somewhere!
 

Buzzfuzz

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I would turn the fan around, you are better off with having the air flowing out the case, then in.
In fact the cold air would flow from the front to back, both the A3000 and A4000 have a few holes up front that allow air to flow, but it's pretty far from perfect.

A4000 desktop case is a nasty design, completely sealed unit with the PSU fan blowing into the case which is fine with the stock 030 but as soon as you start with any upgrades I would highly recommend some sort of cooling :)
People say the A3000 is worse, both mine have 3640's in them and they have never missed a beat... the way the PSU fan dips down below the chassis just seems to circulate the air so much better.
 

Aysel

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Yeah I fitted a hydraulic silent fan in the PSU and reversed the flow, then bolted an exhaust fan to the expansion slot above the IDE interface... cool as a cucumber now :D

PA131040.jpg
 

dougal

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I've been using it and its been fine since yesterday. I have a suspicion the power lead to the motherboard got loose (it tends to do that) whilst I was installing the A3640.
 

dougal

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I have a feeling the instability is nothing to do with the hardware as such but rather the power cable from the PSU to the motherboard. Actually the plug/socket feeding power to the board.

It's a little flakey and at times the power supply will be on but no power to the Amiga or issues with the hard drive not booting or errors.

As soon as I move the wire a little it works perfectly fine.
 
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