Fixing a broken APEX Classic main unit

[theatrus]

A few weeks ago my APEX Classic (it wasn't classic when I bought it!) had failed, in a disastrous way: the system had effectively locked up and did not respond to inputs or control any outputs. Upon further debugging, it was even latching up after rebooting, usually a short while into the boot process.

I swapped it with a spare "Lite" unit I had kicking around from a planted tank (really, how much control do those need anyway?) and at least was back in business for the most part.

If you have ever opened up the unit, you'll know there isn't much there:

- LPC2368 main CPU
- NatSemi Ethernet PHY
- An ATTiny for each of the isolated sensor channels (it uses an optoisolator to communicate unidirectionally)
- Maxim CAN transceiver (AquaBus) (MAX3059)
- Various power supply bits (MC34063 DC/DC)
- Atmel "DataFlash" AT45DB161D SPI flash unit

After dumping the unit in the ultrasonic bath (flux everywhere, also some years of salt splash took out one of the VDM connectors), and probing voltages there wasn't much really going on. The unit would reliably hang after about 30s at boot, and now to the point it wasn't even displaying anything sensible on the remote display unit.

This roughly left two options:
- Main MCU had bit the dust. I don't think Neptune ships the bootloader used for this with their firmware update files, so recovering this part would be a hard.
- The data flash had developed a fault due to years of data logging to it.

I went for option 2: DataFlash was dead in some way. Thankfully replacements are easy to source:

https://www.digikey.com/product-det...gies/AT45DB161E-SSHD-T/1265-1034-1-ND/3847271

I pulled the old DataFlash off the board - a mere 10s with hot air, even easier as Neptune did not use lead-free solder here. I attempted to read-back the unit with a handy TL866A universal programmer, and ended up with valid data for many portions, and was able to successfully blank the chip (erase to FF), however programming in one area of the flash back to 00 was failing. Bingo.

Swap the new part in (which is _smaller_ than the original in width - the wider one is no longer readily available), and... it lives! The smaller width requires some careful alignment to cover the existing old pins.

Location of the DataFlash for those interested:

Old flash above the board, new one installed. Back to the races.

Notes:

- I removed the battery for this picture (it won't wash well )
- You need to use the firmware update utility to reload the "web pages" (which are stored here as well)
- Doing this will obviously wipe all settings out.
- I haven't tested Apex Fusion functionality since doing this.

 

[Maggie321]

Was it luck you had the universal programmer? Fate? Or proper planning... I don't think I would have one of those laying around.

 

[theatrus]

Was it luck you had the universal programmer? Fate? Or proper planning... I don't think I would have one of those laying around.

If you dabble in random electronics bits they are extremely handy. You could also use an Arduino, Bus pirate, etc.

In this case there was no need to preload the external flash with any data - the APEX firmware self bootstraps.

 

[AllSignsPointToFish]

Very cool! I might try this repair on the failed unit with all of the c-virus downtime I have on my hands!

 

[kyleinpdx]

I know this is an old thread, but I just saw it pop up.

Kudos, great job man. This type of thing is what got me into my career (enterprise IT infrastructure), when you know the rules of the game, you can begin to bend them to your outcomes. Its nice having a hot air rework station at home. I used to have a Weller WHA3000 w/ a heated build plate as well for reflowing BGA graphics chips in the mid 2000's.

Did the repair hold up?

 

[theatrus]

I know this is an old thread, but I just saw it pop up.

Kudos, great job man. This type of thing is what got me into my career (enterprise IT infrastructure), when you know the rules of the game, you can begin to bend them to your outcomes. Its nice having a hot air rework station at home. I used to have a Weller WHA3000 w/ a heated build plate as well for reflowing BGA graphics chips in the mid 2000's.

Did the repair hold up?

Yup, still running! I expect several more years before salt eats the uncoated boards or the flash wears out again

 

[BZOFIQ]

Great work, Did you replace the battery while at it?

It's my understanding that hey tend to go bad on old units and not hold time when losing power. Have a LITE brain on the shelf with that exact problem and no time to address.

 

[theatrus]

Great work, Did you replace the battery while at it?

It's my understanding that hey tend to go bad on old units and not hold time when losing power. Have a LITE brain on the shelf with that exact problem and no time to address.

Probably not. It literally just acts as a pH for Ca reactor and heater/chiller controller so I wouldn’t notice if the time was very wrong

 

[BZOFIQ]

Probably not. It literally just acts as a pH for Ca reactor and heater/chiller controller so I wouldn’t notice if the time was very wrong

Haha...true

 

[GlassReef]

Theatrus, what do you use in you ultrasonic cleaner?

Thanks

 

[theatrus]

Theatrus, what do you use in you ultrasonic cleaner?

Thanks

Branson EC concentrate.

Note: don't use this with aluminum boards as it will etch them.

 

[JohnP68]

Hi Theatrus, mine was broken too and I followed your instructions.
Works fine now and saved me €450.

Thanks Thanks Thanks

JohnP
Netherlands

 

[theatrus]

Hi Theatrus, mine was broken too and I followed your instructions.
Works fine now and saved me €450.

Thanks Thanks Thanks

JohnP
Netherlands

Excellent! Glad it’s helping others.

 

[Rhythmmakers]

i pulled out the atmel data flash, check it on a programmer and got nothing.
so does the new atmel chip need to be programed before installing?
if so where would i get this information?

 

[theatrus]

i pulled out the atmel data flash, check it on a programmer and got nothing.
so does the new atmel chip need to be programed before installing?
if so where would i get this information?

it’s been awhile since going through this process but from what I remember it does not. You will need to reload the webpages, but the firmware appears to be able to initialize its own file system.

 

[Nomadic1]

I'm pretty sure this is my issue with my now "classic" unit, based on the symptoms. I've disassembled it but for some reason cannot get the PCB out of the housing so I can desolder the flash in question. I don't see any additional screws holding the PCB to the casing. Is there a trick to getting it out (I'm trying to avoid flexing the PCB and affecting all the surface mount components).
Thanks!

edit: Figured it out. It's held in with some strong double sided foam. Sustained, light to medium pressure with a plastic prying tool made it release.

 

[theatrus]

I'm pretty sure this is my issue with my now "classic" unit, based on the symptoms. I've disassembled it but for some reason cannot get the PCB out of the housing so I can desolder the flash in question. I don't see any additional screws holding the PCB to the casing. Is there a trick to getting it out (I'm trying to avoid flexing the PCB and affecting all the surface mount components).
Thanks!

edit: Figured it out. It's held in with some strong double sided foam. Sustained, light to medium pressure with a plastic prying tool made it release.

That’s a new one. A lot of APEX modules are held in with just hot glue, haven’t seen foam tape yet.

 

[Nomadic1]

Thanks for this info...it helped me repair mine.