AP7750 ATS will not carry load on Source B

[tuxman]

Hey all, this is a long shot but I'm wondering if anyone has seen this before. 

I have an old 7750 ATS that was working fine (as far as I know) for years in one location.  We recently pulled it and moved it to another location.  When powered up both A and B Sources appear to be ok.  the ATS says they are both ok anyway.  If The ATS is set to B preferred and we loose power to B it switches to A no problem. However if the feed is on Source A and it fails, it very briefly "clicks" over to B (and I very briefly see the LED arrow switch to B and then the entire unit dies. 

From the ATS Terminal connection itself the only event that seems to be logged is SPIKE/DROPOUT
I've tried this with different sources, UPS's , straight commercial power, combination of both, nothing seems to matter. It simply doesn't want to stay powered on Source B.

I also tried switching it from narrow to wide VRMS range to see if that would make a difference, it doesn't

I'm at a bit of a loss, I know the unit is old, but there is zero indication that I can see that the unit thinks there is something wrong?

Any comments/suggestions are welcomed. 

[Teken]

Given it’s age there is a internal component failure which is common in this model.

If the ATS is monitored by a NMC you’ll want to review what the 5, 12, 24 volt power supplies. You’ll probably see random variations in the above.

Lastly, there was a firmware update that addressed a few specific issues with the 7750 / 7750A ATS.

I call this out because it wasn’t really a fix vs trying to resolve a bad design!

Regardless, I would not recommend a firmware update as this point given the out of warranty and the fact there’s a 75% chance of bricking the entire system! 🤢👎

Regardless of all the above I updated all of ours to the latest (last) 3.9.4 / 3.9.3 ATS firmware due to compliance reasons.

Relays were replaced in many systems due to contact arcing (poor APC design) with higher quality or wider performance.

Other components were replaced such as capacitors with lower ESR and higher temperature ratings and wider voltage ratings. 

All the above has allowed tens of thousands of these units to operate fine in 2024! 🤟

The vast majority are being staged for replacement now and into the future due to security and compliance with insurance and certification requirements. 

[tuxman]

I'm not totally surprised with your reply.  You're right it's old.. no question, and components don't last for ever. 

I did check the voltages,  they all seemed ok with the exception of the 24v, it seems a little low at 20v, and I did think hmm. 
24 VDC PS 20.0
+12 VDC PS 12.0
-12 VDC PS -12.0
5 VDC PS 5.0

at this point trying to update the firmware can't really make things any worse, it's either pooched already or maybe the firmware might help.. maybe..

Is there really a 3.9 version of the firmware for the 7750 ?  I did see reference somewhere of one for the 7750A but I wasn't sure it was compatible with the 7750 

[Teken]

Apologies I misspoke the v1 NMC goes up to 2.6.X firmware. You can not use the 3.XX firmware platform. 

You’ll need to reach out to APC Technical Support to obtain a copy if available. Prior to doing so either all the loads must be disconnected or the (B) secondary power disconnected from the wall.

If you ignore doing so the hardware will be bricked! 🤦‍♂️🤢 As stated earlier if this hardware is out of production and you simply want to test your luck give it a shot.

If however this is in production I would recommend you just retire the hardware and upgrade to the AP4450A or any competing ATS hardware.

The NMC 1 does not support anything related to a modern browser in terms of encryption and certs. It’s beyond slow to even load even when this hardware was new! 🙄👎

Rebooting and waiting for any of the services on that box. A person could have replaced three components by then! 🤣

Let me know how it all turns out good / bad. If you obtain the last firmware release please do share a download link for others to use. 👍