A3640 advice

Tajmaster

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Hi All

I have an A3640 CPU card installed in my A4000. I dont really use the A4000 enough to justify spending 200+ quid on a new CPU card so I was wondering, is it worth overclocking the A3640?

I think its rev 3.1 and as far as I am aware nothing has ever been done to it. Ive read that to overclock it some soldering would be required which Id rather not do so Id like to know whether its worth it and if so find someone who is willing to do it for me :)

Thanks

Taj
 

Justin

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yarp, well that's what Zetr0 told me anyway, he said 33mhz is a cool performance increase, so once again, yarp


Hi All

I have an A3640 CPU card installed in my A4000. I dont really use the A4000 enough to justify spending 200+ quid on a new CPU card so I was wondering, is it worth overclocking the A3640?

I think its rev 3.1 and as far as I am aware nothing has ever been done to it. Ive read that to overclock it some soldering would be required which Id rather not do so Id like to know whether its worth it and if so find someone who is willing to do it for me :)

Thanks

Taj
 

Zetr0

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I would recommend the following


1. Good quality single core Kaynar wire (jump wire)
2. A 33 or 40 Mhz 68040 Component
3. Fresh set, or recently repopulated correctly orientated capacitors
4. Gold plated turned socket pins for the Oscilator port
5. Heatsink / Fan combo

Your milage will vary pending on the glue logic, but the above is the ingredients I would suggest to use to get the best performance from the card.

Technically as the GAL logic is avaialble, one could buy very fast GAL chips program them, its quite possible to get 40Mhz from the unit - however this would require some in-depth knowledge of the card and its timmings - logic propagation delays etc as this will effect and impact on what you put on the card - this info is available on the net with a good google search and on AmiNet I believe.
 

MagerValp

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Being a former owner of an overclocked A3640, I'm also saying go for it. A 33% performance increase across the board for very little investment is a great deal.
 

Tajmaster

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Thanks all for the replies, it looks like its worth the effort then eh :) Ill need to take it out of the A4000 and then see if there is anyone willing to do the job for me cos my soldering sucks :oops:
 

Tajmaster

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Its been a while but I finally managed to pull my finger out and remove the A3640. Ive got a pic attached below, what Id like to know is:

What work requires doing on it?

Is anyone (preferably in the UK to keep costs down) willing to do it? As my soldering skills are poo :D

Id need to know the full cost before as the A4000 is used very little so Im not wanting so spend loads on it :)

Thanks all (y)

BTW, it came with a HSF and the processor is socketed if that helps :)
 

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Cosmos

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I'm working to repair my :DX-Calibur:D today... Héhéhéhéhé ! :)

(y)(y)(y)
 

Zetr0

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@taj

most certainly - great link - I will be buying one myself me thinks =D

heres what the modifications involve

Under the heatsink and Fan combo is a FULL CORE (MMU & FPU) 040 rated for 40mhz



The unit has had the Timing Line modification (in Commodore Blue 30 Awg)

a3640-001-hack.jpg


this involves cutting one track on the PCB and wiring a small bit of jump wire from the delay ic and the clock feed

After removing the xtal from the card I soldered Turned (gold plated) socket pins for changing of the Oscilator (crystal) from 50Mhz to 66Mhz

a3640-003-hack.jpg


I sold mine to magervalp a while back when it was set at 50mhz (25mhz operation), MagerValp
took the opportunity, replaced the Capacitors (i do recommend this) and added a 25Mhz fall-back mode - with these mods the unit operated at 66 Mhz

a3640-002-hack.jpg


hope that helps.

heres the results that MagerValp was able to achieve
 
Last edited:

Cosmos

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>Would I also need to purchase a 33Mhx 040 CPU? Would this one do?

No, all 68040@25 works at 32 or 33 Mhz (y)



@all

I have an X-Calibur :p
 

Tajmaster

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Hmm, thanks Zetr0 :) So I do the delay thing and then put a socket in for the oscillator, I think I will give it a go (y) Im going to go for the 33Mhz 040 too I think. I assume I can get an oscillator and the socket things off eBay?
 

Cosmos

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On some A3640, 33 Mhz is a bit to much, and the A4000 don't boot... So try at 32 !


@all

Maybe you don't know, but I found an X-Calibur :LOL:
 

Tajmaster

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On some A3640, 33 Mhz is a bit to much, and the A4000 don't boot... So try at 32 !


@all

Maybe you don't know, but I found an X-Calibur :LOL:

I take it it is quite rare?
 

AndyLandy

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Thanks all for the replies, it looks like its worth the effort then eh :) Ill need to take it out of the A4000 and then see if there is anyone willing to do the job for me cos my soldering sucks :oops:

The A3640 is a nice little CPU card and is often an inexpensive way of getting an '040 into an A4000. It's even better if you can track down the X-Calibur, I wonder if anyone on Amibay has such a board? :nod:
 
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