Overclock A3640 in an A3000

[Sandman]

Hello all,

I posted this awhile back on amiga.org but thought that I would seek out help here also.

I am trying to overclock my A3640 for the shear fun of it but I am not having much luck.

I replaced all capacitors on the card and socketed the oscillator.

I also did the delay line modification as described here: http://members.iinet.net.au/~davem2/...ock/a3640.html

ver. 3.1 A3640 card works great @ stock 25mhz with both XC68040-25 & XC68040-40 cpus that I tried but won't boot at either 30mhz or 33mhz as is mentioned should be attainable.

I have checked and all voltages are good. No battery damage to the A3000 mb. 16mb of 70ns ZIPs.

The A3000 MB chips are as follows:
Ramsey is -4
SuperBuster -11
SuperDMAC -02
WD -08 (chip was just upgraded from -04)

Also the 74F08@U103 was replaced with 74HC08 and managed to boot one time with an 62mhz oscillator (for a 6mhz overclock) but locked up soon after with corrupt graphics.


I know that the problem is with SCSI as machine will boot overclocked just fine without any SCSI drives connected and just a terminator at the end of the SCSI cable.

Sorry for the long post but any help would be greatly appreciated.

Thanks!