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Author Topic: A2630 Rev 9 CPU Clock Module (Oscilator)  (Read 3706 times)

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Offline melangeTopic starter

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A2630 Rev 9 CPU Clock Module (Oscilator)
« on: February 19, 2007, 03:08:40 PM »
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?
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Offline cv643d

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #1 on: February 19, 2007, 03:10:36 PM »
I have used my 2630 with a 24 and 25 MHz osc and it worked fine with booth, perhaps your board is broken?
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Offline melangeTopic starter

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #2 on: February 19, 2007, 03:18:42 PM »
Thanks for the fast reply, yes, I think you might be right.  I'd like to unbreak it however.  :-D
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1 x A2000 030@25Mhz
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Offline Oli_hd

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #3 on: February 19, 2007, 03:36:39 PM »
Yeah your crystal should be just fine, as should the 16Mhz one though (Although I guess you could get memory refresh problems)
Have you checked if all the jumpers are correct?
there is one for memory size, what OS your booting and some others.
Any missing chips or anything?
Have you tried removing the 68000 off your A2000 board? (Only needed in german A2000's but you can do it to any A2000)
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Offline melangeTopic starter

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #4 on: February 19, 2007, 03:42:50 PM »
@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.
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Offline melangeTopic starter

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #5 on: February 19, 2007, 03:46:19 PM »
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:
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Offline melangeTopic starter

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #6 on: February 19, 2007, 04:14:43 PM »
@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?
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1 x A2000 030@25Mhz
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2 x A500
 

Offline Oli_hd

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #7 on: February 19, 2007, 05:51:44 PM »
Quote
How could a 16mhz OSC give the 25mhz processor what it needs?

Simple, it would run at 16Mhz, the whole board would clock at the same speed (if any of the PAL's actually use the system clock, I have the service manual and user manual so I could have a look) and you can underclock a CPU the same wasy as you can overclock one.
It wont give you 25Mhz though.
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Offline melangeTopic starter

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #8 on: February 19, 2007, 05:59:35 PM »
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    :-)
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Offline dbrads

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #9 on: February 20, 2007, 09:01:27 AM »
Hi Melange,

 I have an A2630 that also will not work, I have replaced the ROMs and no change, the really wierd part is that if I remove the 68000 from the MB the system still works perfectly but @ 7MHZ :-?  I am sending the board to Tahoe to test for me, maybe its my MB that has the problem.

 The A2630 is fitted with 4MB of RAM but that will not work at all no matter how I configure the system/card :cry:
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Offline Oli_hd

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #10 on: February 20, 2007, 09:33:02 AM »
hehe, strange problem you have there.
I wonder where the CPU is getting that 7Mhz signal from... any wires running from inside the shield to the edge connector? What does the crystal say on it? (7Mhz?)
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Offline melangeTopic starter

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #11 on: February 20, 2007, 04:07:35 PM »
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  :-)
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Offline Lemmink

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #12 on: February 20, 2007, 04:29:37 PM »
The PALs are a good starting point. Just remove and reseat them one by one. I once had an A2630 with the same behaviour. I turned out that it was a contact problem with one ore more PAL.
After the described procedure the card ran fine.
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Offline melangeTopic starter

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #13 on: February 20, 2007, 04:48:41 PM »
@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
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Offline DamageX

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Re: A2630 Rev 9 CPU Clock Module (Oscilator)
« Reply #14 on: February 21, 2007, 06:59:53 AM »
ROMs:
http://www.hyakushiki.net/junk/a2630lo.bin
http://www.hyakushiki.net/junk/a2630hi.bin

try holding both mouse buttons when you power it on and see if you get the 68000/68030 screen
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