12 October 2021, 19:53 | #1 |
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Any PCBs available to re-house a 68040?
I have a very dead Apollo 1240, the battery severely leaked into 74F74 and when I removed it, pretty much every pad lifted, there is corrosion through the vias, etc, etc. It is certainly beyond saving (unless someone has a schematic?).
I was wondering if there are any PCBs available in which I could transfer the important parts over including the 040 chip in order to build a replacement accellerator? If there's a blank Apollo PCB, that would be even better, but I'm probably expecting too much there. I just feel it's a waste of a good 040 chip which I would like to see running in my A1200 |
13 October 2021, 12:03 | #2 |
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Guessing there is nothing available...
If anyone has a Apollo, and can map out the destinations of the pads from the 74F74 with a continuity checker, that way it can hopefully be bodge wired back into existence... I really don't want to give up on this. |
13 October 2021, 18:47 | #3 |
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I have done a complete replacementpcb for apollo. but as I promised I will not release the files for it. but I can help you with that area.. will try to dig up a photo of that part.
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13 October 2021, 18:59 | #4 |
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13 October 2021, 20:48 | #5 | |
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Quote:
Thanks for the PCB layout image that's extremely kind of you. Do you sell the blank PCBs? |
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15 October 2021, 04:22 | #6 |
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Quick update, I installed a replacement 74f74 took the +5V from the top of the bypass cap and did all the bodge wiring to reroute the pins to the necessary connections, but when I try to boot, the A1200 is dead, no action from the CF card or the floppy. just a blank screen.
I'm at the stage now where I probably need to scrap this idea and find another way to speed this A1200 up. Unless anyone has any other suggestions? |
15 October 2021, 07:10 | #7 |
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have you tested all traces from the 74F74?
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15 October 2021, 11:05 | #8 |
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Hi Chucky, thanks for your reply. As I mentioned in my opening post, most of the pads are lifted and missing (I have anchored it on with the 5 remaining pads), the vias are corroded so I cannot use the traces, instead I have used bodge wires in their place, and yes they now all go to the connections on the layout you provided (continuity checked), although there seems to be a layer missing in your image with the ground and +5V is, so I took a chance and used the +5V feed from the top of the bypass cap, although without the bottom trace shown, I'm only guessing this is the correct +5v feed. I also tried a different known working RAM stick in case that was the issue.
This card came inside an Amiga which I bought a few years ago as a job lot and has never worked, so I'm wondering if it even has the appropriate crystal oscillator in; the chip is rated at 25MHz and the crystal is 56MHz - seems a strange jump up in frequency. I have ordered a new crystal, but it's shipping from China, so could take a few weeks. Did you ever manufacture PCBs for this? If so, do you have any available to sell? |
15 October 2021, 13:04 | #9 |
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I have sent you a PM about that
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16 October 2021, 02:58 | #10 | |
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Quote:
So bus runs at 50mhz but the CPU only runs at half that. There were Apollo 040’s at 40mhz running 80mhz crystals. Have owned both. |
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16 October 2021, 03:45 | #11 | |
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It currently has a 56MHz installed so it will surely struggle to divide down. I'll order some 50MHz crystals from ebay now. Thanks for the info |
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