exxos's Atari, Amiga & retro forum

Hi,

I recently picked up an Atari Falcon 030. Standard US TOS 4.04. EXXOS 14MB memory upgrade. SD to HD adapter. FPU installed. Original NVRAM.

When I first booted turned on the machine it did boot from the HD and pretty much worked. Two HD partitions found. Both could be read and written to. I let the computer run uIP (NetUSBee) for several hours as a I loaded software onto the HD.

Upon exiting uIP the machine hung. Power cycle reboot showed several XXX during the memory test.


Machine now consistently shows 2 bombs upon boot. (bus error)

While booting, holding down the CTRL key will bypass the two bombs and I can get to GEM desktop with floppy displayed. I can open the floppy drive and see directly listing, read a file, etc., but if I attempt to close the file dialog or perform pretty much any menu action like setting preferences the machine bombs with 4 bombs. (illegal instruction)


I have removed the FPU, the HD, and the floppy drive and the same behavior is repeated. Memory errors during POST, two bombs, bypass two bombs with CTRL, GEM desktop bombs out with four bombs.

I have also removed and reinserted all socketed ICs and the memory board. No change in behavior.

I've looked at the main board and don't see any obvious damage other than the FPU PLCC socket is cracked, but GEMBench did recognize the FPU prior to the machine failing.


Any ideas what might have failed?


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Firstly I'd remove the FPU entirely. Replace the socket. But it's most likely an issue with the RAM board. Get another RAM board to see if it solves the issue.

Please read this topic: viewtopic.php?f=23&t=6442&p=103844

Ask exxos about the number of returns he's had for his 14MB RAM boards.

I believe he thought they were being destroyed perhaps by faulty stock PSUs.

In fact I believe he recommends that all Falcon030 PSUs are either serviced (recapped?) or replaced to prevent premature death of unobtanium Falcon030 chips susceptible to voltage/current issues.

I wouldn't try to replace the FPU socket unless you have experience doing something like this.

A failed memory board is the current front runner in terms of failure modes. The RAM board in the Falcon is an Exxos 14MB with directly soldered memory (the older memory board). I've ordered an original Atari 4MB memory board in order to test the theory that the 14MB memory board was damaged by over voltage on the data / address lines and will go ahead and order the new Exxos Falcon memory board which uses a standard 72pin SIMM. I haven't read all of the info on the 72pin version, but is there a specific brand of DRAM that should be used with new 72pin SIMM memory board?

The PSU in the Falcon is an Exxos ST/STE/Falcon replacement supply so the power supply should be well regulated with acceptable ripple.

I've can do the surface mount repair of the FPU PLCC socket, but my plan is to install a CT63 once they are back in stock. So, the FPU socket isn't a priority unless it is shorting out something.

Yeah just take the FPU out entirely for now. The FPU sockets aren't very reliable in the best of times and a half-connected FPU can cause some random issues with the system.

JoeFloyd wrote: 07 Feb 2024 07:27 I have removed the FPU, the HD, and the floppy drive and the same behavior is repeated. Memory errors during POST, two bombs, bypass two bombs with CTRL, GEM desktop bombs out with four bombs.

My FPU socket broke exactly like that back in the late 90s. Took me 20 years to have a go at fixing it. I lifted several pads (luckily n/c) and decided to just solder teh FPU directly to the board after that (I did evenually do it properly about four years ago).

https://www.atari-forum.com/viewtopic.php?p=319176

Anyway having an FPU in a socket like that is a guaranteed intermittent fault, so definitely leave that off until the socket's addressed.

I'd suggest putting YAARTTT in an AUTO folder on a floppy and booting directly to that (hold down Alt). See if it can a) run and b) do a memory check.

Those DRAM chips are pretty sensitive to dodgy power rails, I believe.

BW

The fine gentleman who sold me the Falcon went above and beyond and sent me the original 4MB Atari memory board. Once this board was installed no more bombs.

I ordered replacement PLCC sockets for the FPU, but will hold off on doing that rework. The CT63 accelerator is back in stock and I'm going to upgrade the 030 to an 060. No irreversible changes.

Thanks for the info regarding the issue I experienced.