Apollo 1240 Issues

[stefcep2]

I had a similar problem http://www.amiga.org/forums/showthread.php?t=37909&highlight=apollo+stefcep2

the solution was

1. a 40 mhz crystal got the 68040 to work at 40 mhz (strange as it worked with an 80 mhz crsytal before)

2.  Sent it to PG and upgraded it to a 68060, which also runs at 40 mhz.  

Wierd i know but its worked for more than a year now faultlessly with the 68060.

[stefcep2]

If you use 40mhz chrystal with 040 your card will run 20mhz

40mhz 040 has a 80mhz chrystal

Yes, but not in the case when the card has some sort of fault.  Like I said, I had the exact same symptoms as the OP.  Put a 40 mhz crystal and the 040 ran at 40 mhz (AIBB) benchmarks), whereas with the original 80 mhz it just black screened.  It SHOULDN'T work that way but it did.  When I decide to upgrade it to a 68060, the card would black screen with the 50 mhz crystal, but works fine with a 40 mhz crystal and is (on AIBB) about 25% faster than 40 mhz 68040.

Apollo 1240's did not solder the crystal to the board, and it could easily come loose.  I've been told that its possible to fry the CPU if the crystal has worked loose and you power up.  I know in my case I did power the board with the crystal not properly inserted, more than once, and we put the board failure down to that.

Allways check power issues, even if your amiga works without turbocard with current psu

Thats sensible advice.

However, I was running it on an A500 power supply for years, I then swapped power supplies for another A500 which ran a friends Apollo 1240 so we knew it wasn't the power supply.

s