Re: Compaq T2400h UPS Repair Advice

The video was quite a large file, so I trimmed to 5 seconds of noise and saved to a smaller (4.5MB) file.

[url]https://drive.google.com/file/d/1FSYCh8PjTQDLme87QKGhcrdsINUgZ3dy/view?usp=share_link[/url]

I'm thinking it might be some sort of "out of phase" situation that's causing the transformer coils to rattle. Maybe one of the NPN/PNP gate drive transistors is not at full health, and it's driving some of the power mosfets out of sync to the others.

That's a wild guess, and so hard to work...

Hello !

I have a Compaq branded UPS, model T2400h.

It's making curious unhappy rattling noises when running on battery.
Batteries are brand new and fully charged, and also tested on another identical unit.

I grabbed a video of the noise (starts at 00:18 on the mp4 video at the Goo link below), and also took a couple o'scope shots of the waveform, both on-mains and on-battery.

The scope connection is via a small 12VAC transformer, just to explain the scaled voltage readings in the scope photos. We are on 240V-ish mains here....

Re: New Members - please post your introductions here

Hello to the BadCaps forum from a very wet and windy Hungary!