exxos's Atari, Amiga & retro forum

Vypr wrote: 26 May 2021 21:44 After replacing the oscillator again I have found something new. I can boot to DiagROM if, and only if, I put pressure on the 68000 socket area.
Once it has started booting I can let go and DiagROM boots fine and all tests pass. CIA & IRQ tests OK, keyboar dis fine, 64Mb FAST RAM checks out OK, I can even CTRL-A-A and it will reboot fine but if I power off and back on again without pushing down on the board, it won;t boot.

I'm very confused now.

Sounds like a 68000 socket issue. are you using a relocator ?

terriblefire wrote: 26 May 2021 21:56
Sounds like a 68000 socket issue. are you using a relocator ?

No, got it stacked onto spare 68000 turned pin socket which lifts it high enough over the ROM chip, same one I used on my TK card.
Even without the socket there is enough clearance but the same issue. I tried resoldering all the pins in case one of them was a cold joint but no joy.

I take it it's normal that the 'Test Detected FastRAM" option fails? Since Manual test of the memory range 40000000-43000000 passes with no issues.

Sounds like a bad connection/broken trace.

@Vypr humour me with this, try pushing down on the motherboard itself and not on the TF536, it could be a bad a500 cpu socket or like my 500+ had, a bad rom socket.

PhilC wrote: 27 May 2021 08:29 @Vypr humour me with this, try pushing down on the motherboard itself and not on the TF536, it could be a bad a500 cpu socket or like my 500+ had, a bad rom socket.

I did try that, A bit awkward as I have an Indivision plugged into the Denise socket which makes getting something down there to push on the board tricky but there was no joy. I might add that the issue is replicable on another 500 board.
The old A500 board has the older style socket while the 500++ has turned pin sockets, both exhibit the same issue.

I've noticed that it is pressure at the bottom end where the IDE socket is that affects it the most so I am going to try removing the buffer chips and replace the resistor networks to see if that helps.

We have a winner! Looks like it was an issue with the buffer chips.with IC4, IC5 & IC6 removed DiagROM boots up without needing to have the board pushed down.
Replaced the ROM chip with a 3.1.4 and succesfully booted into the System Test disk. All memory is seen and tes OK. I cna live without the buffered IDE, worst comes to the worst I have a spare IDEFix board I can plug into it.

Thanks you to everyone who helped and offerred advice, Much appreciated!