Nerd2 persistent problems

[Etmar]

I have had a several Nerd2 problems (DiveCan) with rEvo. In my configuration Nerd2 is controlled by Petrel 3, which is working perfectly. I have also had Perdix and Perdix AI several years in OC and there has been no problems.

Original Nerd2 failed first time on November 2023 after 70 dives and one year from purchase. Depth displayed 'Err' (means no Depth data available). After that it was serviced twice, but same error occurred in first dives.

On March 2024 I got new replacement Nerd2 from Shearwater which in its first dive displayed same error: Depth 'Err'.

I was already very frustrated about this odd behaviour and continued to dive with new Nerd2 to find if there were root reason to be found. I did about 15 dives from March to end of May and there were:
- 6 dives with correct Depth
- 3 dives with Depth = 'Err'
- 4 dives with Depth > 200 meters and max temperature > 100C
- 2 dives with Depth about 2 meters deeper than real depth

After that I dived over 40 times from last June to end of December and Nerd2 was working perfectly.

Last month (December) problems started again. It seems to indicate that cold weather might have some effect on these errors, but I doubt it and also Shearwater does not believe that moderate cold (0C or warmer) would have effect on that.

When Depth shows deeper than real depth, error starts already on shore when going through pre-jump checklist.

It is hard to believe that depth sensor could fail four times in a row. I have thought about DiveCan cable being involved but according rEvo the DiveCan cable has no effect on functionality of depth sensor. However there must be a connection between DiveCan cable and Nerd2 at some level in order for to be able to display PPO2-readings on Nerd.

This might not be purely a depth sensor error?
If depth sensor is faulty, why it is working correctly with some dive?
If depth sensor is faulty, why is temperature reading also insane on same dives?
If Depth displays 'Err' it means that no data is received from depth sensor to mainboard, how is that related to depth sensor fault?

I have checked the “mbar now” value on Nerd2 and it is often significantly lower than in Petrel3.

I wonder if anyone has experienced same kind of persistent and inconsistent problems with Nerd2? Any hints for trouble-shooting?

My dives are in Nordic lakes in clean waters and Nerd2 is transported with care and stored inside in 22C temperature.

Other than this Nerd2 is brilliant tool in CCR diving, compass, PPO2, NDL visible all the time.

 

[beldridg]

If you rEvo is configured like a "normal" unit and the Petrel3 is the controller, they are correct in that the NERD is on a different cable than any of the DiveCan stuff. It directly reads the milivolts of cells that the cable is connected to and it is a "straight through" "analog only" cable (i.e., it is NOT on the DiveCan bus).

I'm pretty sure that the board that has the depth sensor in the NERD also has the temp sensor so it could be a faulty board. I had a depth sensor problem a while ago and the temp readings were also wacky so that tracks. Why you have had 3 or 4 of the boards fail is very strange.

When the depth sensor (or the board) fails, you get the "Err" that you are seeing.

It is only a guess, but it seems like that board keeps failing maybe because of water ingress but I can't imagine why else it would happen repeatedly. Since you are diving fresh water, it could be that once the unit dries out, it works for a while but then fails after getting wet. Again, only a guess.

If the lakes you dive in are close to sea level in terms of elevation, you could try hard coding the alititude to SeaLvl on both the Petrel3 & NERD2 and see if the resulting depths while in the water are the same.

Seems like you are going to need Shearwater to take a closer look.

Regards,

- brett

 

[Etmar]

If you rEvo is configured like a "normal" unit and the Petrel3 is the controller, they are correct in that the NERD is on a different cable than any of the DiveCan stuff. It directly reads the milivolts of cells that the cable is connected to and it is a "straight through" "analog only" cable (i.e., it is NOT on the DiveCan bus).

I'm pretty sure that the board that has the depth sensor in the NERD also has the temp sensor so it could be a faulty board. I had a depth sensor problem a while ago and the temp readings were also wacky so that tracks. Why you have had 3 or 4 of the boards fail is very strange.

When the depth sensor (or the board) fails, you get the "Err" that you are seeing.

It is only a guess, but it seems like that board keeps failing maybe because of water ingress but I can't imagine why else it would happen repeatedly. Since you are diving fresh water, it could be that once the unit dries out, it works for a while but then fails after getting wet. Again, only a guess.

If the lakes you dive in are close to sea level in terms of elevation, you could try hard coding the alititude to SeaLvl on both the Petrel3 & NERD2 and see if the resulting depths while in the water are the same.

Seems like you are going to need Shearwater to take a closer look.

Regards,

- brett

Thanks for thoughts. I've already set altitude on "SeaLvL" on Petrel and Nerd. However if Nerd measures surface pressure to be less than 965 mbar, then the Altitude setting is automatically forced to "Auto"-mode and cannot be changed. This has happen a couple of times.
Shearwater has been helpful by servicing and replacing the Nerd2, but I would like to find is there is a reason why this happens so often. Bad luck is possible, but four times in a row, hhmmmm.

 

[SavageSeaCow]

There is a design flaw in the nerd that leads to the pressure sensor becoming unseated. I experienced the same thing and had to send it in to Richard at dive tronix. Sounds like you are not in NA, but your local service center will need to replace your nerd. My sense from your story is that whatever fix they have done isn’t working and it just needs to be replaced.

 

[Etmar]

There is a design flaw in the nerd that leads to the pressure sensor becoming unseated. I experienced the same thing and had to send it in to Richard at dive tronix. Sounds like you are not in NA, but your local service center will need to replace your nerd. My sense from your story is that whatever fix they have done isn’t working and it just needs to be replaced.

That might be, I am just wondering if there could some x-factor explaining these consecutive fails.

 

[Capt Jim Wyatt]

Never had a problem with my nerd2. Please keep us in the loop with your problems.

 

[DS79]

I used to have similar issues with my NERD2 on my rEvo. In my setup, the NERD is even the controller with 3 of the 5 sensors linked to it.
I bought the rEvo new in 2021. In 2022 after around 100hrs, the depth sensor was broken. Furthermore, the NERD decalibrated itself during the dive (!) indicating ppO's which were completely off (by around 0.3 - it took the 0.7 at accent as 1.00). Fortunately, the rEvo has more the sensors splitted, indicating the ppO also on the Petrel.
I got a replacement, which has been working fine ever since (no at around 300 hrs in total on the unit).
Unfortunately, I don't have a single buddy who has not had at least once the presser sensor broken - Petrel, NERD, Perdix, Terric - it happens on all models (but not only), mostly within the 2yr warranty period (Europe).
I was actually hoping, that Shearwater has meanwhile solved their depth issues since we haven't had any cases recently...
That said, I still love using the Shearwaters, the usability, the well tought through information like Delta+5, GF99 etc. It's just sad that they seem to not get over their quality/ enduance problems.

By the way, I handle my shearwaters like new born babys, avoiding any kind of hits, vibrations etc. (e.g. putting the NEARD back to its case after every dive instead of keeping at on the DSV while transportation)..

 

[Etmar]

I used to have similar issues with my NERD2 on my rEvo. In my setup, the NERD is even the controller with 3 of the 5 sensors linked to it.
I bought the rEvo new in 2021. In 2022 after around 100hrs, the depth sensor was broken. Furthermore, the NERD decalibrated itself during the dive (!) indicating ppO's which were completely off (by around 0.3 - it took the 0.7 at accent as 1.00). Fortunately, the rEvo has more the sensors splitted, indicating the ppO also on the Petrel.
I got a replacement, which has been working fine ever since (no at around 300 hrs in total on the unit).
Unfortunately, I don't have a single buddy who has not had at least once the presser sensor broken - Petrel, NERD, Perdix, Terric - it happens on all models (but not only), mostly within the 2yr warranty period (Europe).
I was actually hoping, that Shearwater has meanwhile solved their depth issues since we haven't had any cases recently...
That said, I still love using the Shearwaters, the usability, the well tought through information like Delta+5, GF99 etc. It's just sad that they seem to not get over their quality/ enduance problems.

By the way, I handle my shearwaters like new born babys, avoiding any kind of hits, vibrations etc. (e.g. putting the NEARD back to its case after every dive instead of keeping at on the DSV while transportation)..

I have had a small padded pouch for Nerd when in transportation or storage but only from last summer. Attached on BOV/DSV only on divesite. I also really like Shearwater products and have only had problems with Nerd. That is a pity because it is a super useful tool especially for CCR and DPV.

 

[SavageSeaCow]

I used to have similar issues with my NERD2 on my rEvo. In my setup, the NERD is even the controller with 3 of the 5 sensors linked to it.
I bought the rEvo new in 2021. In 2022 after around 100hrs, the depth sensor was broken. Furthermore, the NERD decalibrated itself during the dive (!) indicating ppO's which were completely off (by around 0.3 - it took the 0.7 at accent as 1.00). Fortunately, the rEvo has more the sensors splitted, indicating the ppO also on the Petrel.
I got a replacement, which has been working fine ever since (no at around 300 hrs in total on the unit).
Unfortunately, I don't have a single buddy who has not had at least once the presser sensor broken - Petrel, NERD, Perdix, Terric - it happens on all models (but not only), mostly within the 2yr warranty period (Europe).
I was actually hoping, that Shearwater has meanwhile solved their depth issues since we haven't had any cases recently...
That said, I still love using the Shearwaters, the usability, the well tought through information like Delta+5, GF99 etc. It's just sad that they seem to not get over their quality/ enduance problems.

By the way, I handle my shearwaters like new born babys, avoiding any kind of hits, vibrations etc. (e.g. putting the NEARD back to its case after every dive instead of keeping at on the DSV while transportation)..

I think you’re right that the problem is with a specific vintage of nerd. I bought my unit around the same time and had roughly the same number of hours. I’m now up to around 300 ish hours on the new nerd and it’s working fine. Hopefully that means it’s “fixed”.

 

[dahab boris]

Spoken to Shearwater ?