exxos's Atari, Amiga & retro forum

Looks like I am confirmed as some kind of idiot. RAM came off with a heat gun, did not appear damaged, everything looks perfect but now no boot, nothing from serial. I guess the cheapest thing to try is buy more RAM. On the upside, a brief check with a slower 68030 shows no change so it is perhaps not the 68030 that is dead.

Aeberbach wrote: 21 Sep 2020 12:52 Looks like I am confirmed as some kind of idiot. RAM came off with a heat gun, did not appear damaged, everything looks perfect but now no boot, nothing from serial. I guess the cheapest thing to try is buy more RAM. On the upside, a brief check with a slower 68030 shows no change so it is perhaps not the 68030 that is dead.

Mounting the ram backwards is likely to kill the RAM chips only.

However, the card will boot with no ram, if yours is not booting, there is another fault somewhere.

Which version of firmware are you using too? If you remove the RAM it should boot without it.

Did you try booting it without RAM chips?

Aeberbach wrote: 21 Sep 2020 12:52 Looks like I am confirmed as some kind of idiot. RAM came off with a heat gun, did not appear damaged, everything looks perfect but now no boot, nothing from serial. I guess the cheapest thing to try is buy more RAM. On the upside, a brief check with a slower 68030 shows no change so it is perhaps not the 68030 that is dead.

Don't be so hard on yourself, everyone makes mistakes. I have built 3 so far and have 5 more PCBs on the way. One out of the 3 that I made (the one I kept for myself of course) was initially working, but now I can't get it to boot either. I've reflowed it so many times trying to get it going again that I'm convinced I either damaged/overheated the Cpld or messed up the PCB somewhere.

Anyway, it might be worth cleaning up the board really well, get all that flux off and post some more pictures here. It looks like some areas on the PCB were scraped, but it's hard to tell if it's not just leftover flux.

Don't be too hard on yourself, I built a Greaseweazle last week and got one of the few chips it has 180 degrees out, killed the chip. It happens, it's what you do next that's important :)

Aeberbach wrote: 21 Sep 2020 12:52 Looks like I am confirmed as some kind of idiot. RAM came off with a heat gun, did not appear damaged, everything looks perfect but now no boot, nothing from serial. I guess the cheapest thing to try is buy more RAM. On the upside, a brief check with a slower 68030 shows no change so it is perhaps not the 68030 that is dead.

We have all done it at some stage, put something in back to front. Just a few months ago I put a molex plug upside down into a old IDE hard-drive. I thought it was a bit stiff when I pushed the plug home, did not have my glasses handy at the time to check (nah it will not fit in upside-down, yes they will if you push them hard enough :oops: ). Power it up, and bang!! terrible fire (smoke), 12 volts into the 5 volt line :shock:. Luckly it only blew a cheap diode, and was easily repaired. That is after 40 years of I should know better electronic/computer repair :roll:

Danoo wrote: 21 Sep 2020 14:11 We have all done it at some stage, put something in back to front. Just a few months ago I put a molex plug upside down into a old IDE hard-drive. I thought it was a bit stiff when I pushed the plug home, did not have my glasses handy at the time to check (nah it will not fit in upside-down, yes they will if you push them hard enough :oops: ). Power it up, and bang!! terrible fire (smoke), 12 volts into the 5 volt line :shock:. Luckly it only blew a cheap diode, and was easily repaired. That is after 40 years of I should know better electronic/computer repair :roll:

Did the same on a floppy drive. Step motor was toast. 12V on 5V line is not great.

I remember doing that in a SNMP modem manager system under development - a 540MB 2.5" hard drive, shockingly expensive thing back then. We only had one in the company. When connected in reverse a piece of one of the controller chips actually flew off the PCB off and smoke came out.

Anyway, after removing incorrectly installed RAM from both my TF536 boards (and binning it) and cleaning them up a bit I think I just need to order new RAM. Both Xilinx devices respond to xc3sprog on the pi and can be programmed so I am hopeful this mistake only cost me $20 or so. Still there is the possibility of CPLD I/Os being toast but it won't cost me a huge amount to find out. One board did _not_ boot with the RAM removed - the other I didn't try as I have just cleared a big mess of wires off the desk and I need to leave it all alone until the RAM arrives. Thanks all for looking and for spotting the mistake :oops:

I am still at a dead end. I have two TF536 cards that will not boot. When the TF536 is removed from the A600, DiagROM boots normally to a connected monitor and gives serial output on my terminal. Both cards look fine when inspected with a microscope. One has RAM attached - the right way round this time - and the other doesn't. Both should show some output on serial through DiagROM, errors if there is no RAM (as in the video from the first post) or just working with the RAM installed.

I have a Mac SE/30 to test my 68030s with, and they are fine.

There is no serial or other sign of life when either card is installed.

That leaves:
- the Xilinx part. How likely is it that the CPLD is dead, preventing boot? It is recognised for programming by the raspberry pi but that does not mean installing the RAM backwards did not kill the ports that RAM was attached to. Replacing one of these on a hunch is difficult, and costs $40.
- Lemaru's riser for A600. Not by design because it works for him and others but could the one I have be damaged? I have inspected it carefully and there appears to be nothing wrong, it's all passive.

Must be the Xilinx?