Weird problem with rebooting

cozido · Joined: Aug 31, 2020 Posts: 6 Location: Spain

A friend has a non-working G1 rack and asks me to look at it. Since there is no schematic available online, it's a bit difficult to troubleshoot. The symptom is basically as follows: once the G1 runs for about 20 minutes, it would freeze up and require a reboot to function again, then the whole process repeats itself. Sometimes. the MIDI connection would drop out first (sometimes not), but it could be brought back by re-establishing the connection via the Editor, that's until the G1 freezes up.

Any tips or clues on what could be wrong will be much appreciated.

blue hell · Posted: Thu Sep 10, 2020 4:41 am Post subject:

ow yuck .. that may be hard to find ... I'd check the power supply with a scope (on the main board, not on the PSU itself, maybe it is a PSU cable issue), and there is this one memory chip in a socket iirc .. would take that out and put it in again.

Oh, and maybe reseat the PSU power connectors and the cable to the front panel too.

After that ... as it looks heat dependent .. I'd try to apply heat, with a paint stripper maybe, to places .. or cold-spray might find it too .. I'd suspect there to be a .. not so well .. soldered SMD part.

The MIDI connection dropping out .. I'd assume that to be unrelated .. as it tends to drop out in some setups anyway.

cozido · Joined: Aug 31, 2020 Posts: 6 Location: Spain

Thanks for the pointers, I will look into them and report back.

blue hell · Posted: Thu Sep 10, 2020 10:12 am Post subject:

And when it has the expansion board installed, you can get that one out, this will not break anything .. but it may be the cause of the problems.

Good luck!

cozido · Joined: Aug 31, 2020 Posts: 6 Location: Spain

Day 1 - I tried a bunch of things but sadly, there's no change in the behavior...

The NM still froze at around 20 minutes - like clockwork! The voltage rails on the main PCB seemed to be well within spec: -5V, 4.99V and 3.27V. Even though what appears to be a heat-related problem, so far, the culprit has yet to show itself. I was surprised that directing the heat to the parts did not make it crap out any sooner than before, that's weird...

More later...

blue hell · Posted: Fri Sep 11, 2020 3:40 am Post subject:

Ok, it seems also possible that certain, possibly corrupted, patches make the NM's OS hang.

https://electro-music.com/forum/topic-57873.html

cozido · Joined: Aug 31, 2020 Posts: 6 Location: Spain

Yes, I saw that. But I have already removed all the banks from the NM and re-loaded just Bank 1 from the factory patches. For testing purpose, all I am doing is turning on the NM, load one of the factory patches, leave it running for about 20 minutes and usually by that point - either the unit is already frozen or I just wait another minute or two, then try to load another patch, invariably the front panel becomes unresponsive, at which point, the unit has to be re-booted. Like I said, it's weird!

blue hell · Posted: Fri Sep 11, 2020 3:55 am Post subject:

Weird it is.

You seemed to be telling that the 20 minute thing was pretty much the same each time - that made me think of a possible software issue.

Anyway, you already tried that.

cozido · Joined: Aug 31, 2020 Posts: 6 Location: Spain

Yes, it does seem to be trapped in some kind of loop. I haven’t detect any pattern regarding the patches - I have tried many patches, loaded them in various sequences but that appeared not to matter.

I have also re-flashed the ROM to 3.03, made no difference... could it be a bad micro controller?

blue hell · Posted: Fri Sep 11, 2020 10:36 am Post subject:

I've been developing micro controller systems for like 25 years or so and only once I've seen a bad one ... and that was because it got programmed too often (which was like 1000 times or so in the early days) .. (not counting the cases where I destroyed stuff by shoritng things or applying too much voltage - which is very unlikely to have happened in a closed unit) so, I think that to be unlikely .. but can never rule it out without replacement ... but a bad soldering point is very possible. and pretty hard to find.

cozido · Joined: Aug 31, 2020 Posts: 6 Location: Spain

My friend is going to take the NM to another friend with a reflow oven to see if that helps with the possible bad solder joint, in any case, I am out of ideas, let’s see if they can get it fully functional again. Thanks for your tips and suggestions so far, they were much appreciated.