A2630 Rev 9 CPU Clock Module (Oscilator)

[melange]

Hi folks, have just landed myself an A2630 Rev 9, with a 25mhz 030 and 25 Mhz 68882.  The card came without the 2MB Zip RAm and also without the 68882, I just happened to have the ram and fpu lying around.

Problem is she don't work.  One thing I did notice after looking here...

 http://www.amiga-hardware.com/download_photos/a2630_1_big.jpg

Is that the Oscilator on my card is only 16mhz, whilst the OSC on the card in that pic is 25mhz.
I found a 25.175 mhz Crystal, but still no go.

How exact does the timing have to be?  The one in the above picture is 25.000mhz.

Anyone know?

[melange]

Thanks for the fast reply, yes, I think you might be right.  I'd like to unbreak it however.  :-D

[melange]

@Oli_hd
Nah, I haven't tried removing the 68000 as it's not a German 4 Layer board.  Have checked all jumpers carefully.  It has a rather odd set of ROMs, with "Amiga Technology Aust" 390282-07 & 390283-07.  Nothing like the pics I'm seeing online.

Anybody got the ROM code that's compatible with 3.1??  I can blow a new set if I can get my hands on the code.  I have a programmer handy and the correct EPROMS.

[melange]

Glad I wrote that down there, coz I just rubbed my finger on the sticker as I attempted to lift it off and the ink came off the sticker.  Home made ROMS for sure me thinks   :lol:

[melange]

@Oli_hd
Come to think of it, I don't get it.  I know that on the A500 for instance the 28.xxx OSC feeds the agnus which in turn provides the 68000 with the 7.1x mhz signal.
How could a 16mhz OSC give the 25mhz processor what it needs?

[melange]

Cheers,

I'm starting to think that the processor might be stuffed.
I have a 68020 @ 25mhz.  If I was to put that on the board for a quick test would I fry it?

EDIT: Ignore that, I see that the are not at all compatible now    :-)

[melange]

HI dbrads,

Wow that's really strange!  I have read the roms off my card and unified the file, and found that the bytes were not swapped, as  I believe they are supposed to be for a motorola processor.  I remade them with the bytes swapped but still no go. I feel very strongly that the processor is dead, but of course it's just a hunch.  Looking out for a replacement processor ATM, to see if that's it.
Failing that I can't see what more could be done.  The card is absolutley loaded to the hilt with PAL chips, which I think would probably be near impossible to replace now.  I could replace caps and the garden variety logic chips, but it could be a whole lot of effort for nothing.

Thanks for your reply, let me know if you get it going, would be interesting to find out what's wrong.

Cheers  :-)

[melange]

@Lemmink

Thanks, I will give that a try.  I'm very concerned about the ROMS still however, as I believe they were programmed incorrectly.  I have to wonder if the version in use on the card is even correct for it.  Would love to find a source of binaries so I could try some other versions.

The manual states that the card can take 64K Roms expandable to 128K.  The board has 256K Roms on it, which I know to be compatible, however in past experience it's been necessary to repeat the code (or copy it to) the later half of the chip 0x4000 to 0x8000 as well.  depending on how the board was designed it may only read the data from the latter half of the chip and ignore the beginning half.

Whomever programmed my ROMS did not do the above, nor did they perform a byteswap before programming the chip

[melange]

Wow, thanks everyone so very much.  I now have enough to play with.  

Still convinced its the processor at the moment, and have ordered a stack of 68030's off ebay.  Can't be sure if they will be the correct speed though.  Even if they are slower they should be compatible providing I match the speed with the crystal.  If they are faster than 25mhz, then I should be able to drive them slower with the current 25mhz crystal.  Is that a fair assumption, or have I got it all wrong?

[melange]

@eslapion

If your correct then I have a real task on my hands.  Lots of tracing can take a long time to decipher, but the schematics are there so I might see what I can find.  I notice that a earth trace has been added between two of the logic chips on the board so perhaps your correct.  I will have a look and see if I can find anything obvious.  Cheers  :-)

At least the processors are cheap so will make good spares for things in the future.

[melange]

Thanks slazzer, I have 2 or 3 different versions to work with now.  Tried them all and no difference.  I have pulled every socketed chip from the board and reseated it.  Tried a host of different things.  Now I'm looking for broken traces.