Wubs GP32 - Nand replacement.

[rubber_jonnie]

I'm surprised the NAND was faulty rather than having just lost it's contents. It might have worked had it just been reprogrammed?

I'll likely try and re-flash it when I get my TSOP adapter, see if it works. In any case I'll return it to Wub even if it's dead.

Either way simpler to fit a new one to prevent a re-occurrence.

[alexh]

Either way simpler to fit a new one to prevent a re-occurrence.

How long was it powered off? Some NAND flash parts have a retention period of less than 5 years unpowered. It may simply have lost it's contents because it was switched off for so long?

I think the chips that were used in the earlier units were sub-standard and tended to lose the data over time if the unit is not kept with batteries in.

That is not "sub-standard" it's just NAND I'm afraid. Not suitable at all for cold storage.

[rubber_jonnie]

Either way simpler to fit a new one to prevent a re-occurrence.

How long was it powered off? Some NAND flash parts have a retention period of less than 5 years unpowered. It may simply have lost it's contents because it was switched off for so long?

I think the chips that were used in the earlier units were sub-standard and tended to lose the data over time if the unit is not kept with batteries in.

That is not "sub-standard" it's just NAND I'm afraid. Not suitable at all for cold storage.

Look, I'm no Nand expert, I'm just the repairman, but from what I've read so far Nand can fail, just as other IC's fail (MT RAM is one that I'm thinking of right now), and by that I don't mean they have the same mode of failure, I mean that they fail to do their job as designed. I've run into a lot of dead IC's over the years and they've failed for one or more reasons probably, but they do stop working. That includes mask ROM failures.

From what I've read it seems to be that the Nand used in some GP32's is like the equivalent of MT RAM or MOS IC's in Commodore and other machines, they fail over time and fail more than other brands, and whilst I don't disagree that perhaps long term 'cold storage' may be the cause, I think manufacturing quality could also play a part.

Ultimately it's Wub's machine, I'm doing what he's asked as I have the necessary tools and skills to repair it, so that's what I'll do. If it doesn't fix it then perhaps we can look elsewhere, but I am going to try and reprogram the old Nand, though I'm certainly not going to refit it if it can be reprogrammed as I'd feel it would be untrustworthy and could fail again.

Of course if it can't be re-programmed then that should answer the 'Is the Nand really bad' question. Just need my adapter to arrive...

[wub]

Well, it's a very interesting question but I'm in no way qualified to have an opinion on it either way. If these chips are not designed to retain data over a long period then that could well be the cause of the problem for the unit Jon is working on.

I was under the impression that the chips were of questionable quality but that was entirely based on what I remember of conversations I read on a forum 20 years ago, and that information may well have been wrong in the first place.

When I was researching the problem more recently all the discussions I read were about finding a replacement for the IC and, more importantly, finding the correct usb data cable from a specific late 90's phone to use for making one end of the JTAG cable.

I can see that now it would have been helpful to try re-flashing first, but I honestly didn't even consider that the chip could be ok! Another lesson learned and I'm certainly sorry if I've wasted Jon's time with this.

[rubber_jonnie]

Well, it's a very interesting question but I'm in no way qualified to have an opinion on it either way. If these chips are not designed to retain data over a long period then that could well be the cause of the problem for the unit Jon is working on.

I was under the impression that the chips were of questionable quality but that was entirely based on what I remember of conversations I read on a forum 20 years ago, and that information may well have been wrong in the first place.

When I was researching the problem more recently all the discussions I read were about finding a replacement for the IC and, more importantly, finding the correct usb data cable from a specific late 90's phone to use for making one end of the JTAG cable.

I can see that now it would have been helpful to try re-flashing first, but I honestly didn't even consider that the chip could be ok! Another lesson learned and I'm certainly sorry if I've wasted Jon's time with this.

I certainly don't see it a a waste of time, I love doing this sort of stuff and have no issues either way.

[alexh]

You're absolutely right. ICs can fail and NAND more so than others. They have a lifespan, PE (Program Erase) cycles, i.e. they wear out.

Also very early NAND were extremely susceptible to environment.

You wouldn't believe how error prone the underlying technology is and the extreme error correction that goes inside them just to make them work reliably when new.

Certainly can't hurt to replace it and is probably good practice (if you have the skills) rather than waste time with a potentially broken IC.

P.S. I wasn't questioning the legitimacy of replacing it, just a hint that NAND chips can loose their contents when not powered. Less so early NAND where there is only 1-bit per cell but 3-bits per cell and higher definitely.

[rubber_jonnie]

P.S. I wasn't questioning the legitimacy of replacing it, just a hint that NAND chips can loose their contents when not powered. Less so early NAND where there is only 1-bit per cell but 3-bits per cell and higher definitely.

Totally get that and having discussions like this is always great IMHO because finding out other perspectives is always useful.

On a side note, I've had my own GP32 for a really long time and can remember long periods of time where it was stored with no batteries (I was more worried about battery leakage) but mine is a later back lit model (BLU) and it's never had any issues like Wub's has had.

Out of interest I still have my boxes:

IMG20240904093132.jpg (159.65 KiB) Viewed 124 times

Including the GP32 Link device which is basically BNIB since I never used it as I was the only person I knew who had a GP32.

[rubber_jonnie]

Dammit.

This arrived today:

IMG20240906113812.jpg (203.17 KiB) Viewed 95 times

Great I think, but wait. I ordered the wrong sized zif, and it's too wide. Time to regroup and shout bah humbug a lot.

[alexh]

Was it expensive? This one might be useful for Xbox OG?

[rubber_jonnie]

Was it expensive? This one might be useful for Xbox OG?

Not particularly, no. TBH it is a two part item, so I just need to find the correct adapter to plug in, so I won't send it back since I'm always glad of the tools.

Might have to be one that you solder the Nand to though, something I wanted to avoid.

That reminds me, I need to find my other small TSOP solder on adapter for use with PS4's. I put it somewhere safe and now I can't find it...