Just found this while spring cleaning my Socata TB20. Previous owner didn’t inform me about it and it wasn’t working.
About 5 kg in weight, picture attached. Just one label, Becker EPU 400, 14V.
Can you see any reason why I should try to repair and keep it?
Usually it only needs a new battery, but – why would one use one of these power supplies? Their current capability is limited and most of modern avionics in need of an EPU do have their own internal batteries. I would toss it in the garbage bin or donate to a flight school.
I did a google but found nothing decent. What does it actually do? Does it sit on the bus and provide a battery backup? You could presumably get the same effect by having a bigger main battery.
I have no idea, but I suspect it’s a backup or auxiliary battery for tHe EDM 930 engine monitor.
However, it seems to be from a totally different era, maybe an emergency power supply for a Becker radio?
On the pilot side I have an EPU on/off switch, but it never seemed to do anything.
Update: There are 2 battery cells inside, photo attached.
That piece is far older then any EDM …
Yes, there should be two lead batteries inside and you can get replacements from i.e. RC toy shops, they should be standard sized. A looooooong time ago these EPU were meant to have emergency power for instrument flights. My former aircraft had two of them to power HSI and the ancient GPS in case of power failure.
Have a close look at the capacitors on the circuit board – they are usually due for replacement as well, if you really want to keep the outdated crap. If they look like the Zener diode does, I suspect you would have to replace all electr(on)ics parts ;-). Is this the version with self-charging capability or without?
I dont know about its self charging capability, but everything inside is very corroded, and one piece that looks like a power thyristor is half eaten by rust.
I think the best would be to remove everything related to it and save a hefty 5-6 kilos in weight…
Re-purpose it !
Googling around suggests this was a backup power supply for specific avionics; probably a COM radio.
So there will be extra wiring installed behind the instrument panel.
