Hi all.
Thanks for the help so far. I got it repaired (kinda). I replaced the Viper and a couple of components, found there was no power reaching it.
Essentially the circuit path is mains, 25A fuse (presumably for the mechanical stuff), then feeding all the AC side of the relays, as well as a 5W 10ohm wire wound resistor that feeds to live side of the full bridge rectifier, then the a capacitor between the positive and negative rails, then through the choke positive on say channel 1, negative on channel 2, then another capacitor again across the 2 on the other side of the choke, then each rail off to the viper and SMPS respectively etc.
Ended up discovering the wire wound resistor was open, I replaced it in my second round of attempting to fix and everything was working good now (almost). As someone mentioned, the choke was stuffed, or maybe I stuffed it when I cleaned it, I'm not sure which. One channel is fine, the other is busted with a couple of breaks. I took it off the board and just put in 2 jumps in the interim which is how I was able to verify everything was operational again, however long term it probably isn't health to just leave jumps there? and I should replace the choke with a new one.
My biggest issue is I'm doing my head in trying to find out anything useful about the existing choke so I can source a suitable replacement. I'm pretty uneducated with all this so I'm not sure how people even figure out what specs are suitable for a choke. All I really know is the physical properties of the choke. I'm hoping that someone can help.
So we know the voltage coming in from mains is 240-250VAC @ 50Hz (typical Australian mains power); then is gets rectified before the choke to DC which I understand ends up being like 350-400VDC or something? from what I read. (I don't much understand it sadly).
The choke is dual channel UU type core.
The copper wire used on the winding is thin, really thin. My digital Vernier calipers said the wire is 0.1mm thick; though my calipers are pretty old and a bit unreliable, so I'm not sure how precise that is.
I unwound the broken winding; given couple of breaks I don't have a perfect turn number, but I counted 214 turns with a couple of turns either side to account for the loose unspooled breaks.
I measured about a length of 4.6m of copper wire.
The U shaped core is inserted into a plastic shroud that the winding is wound over, that shroud measures a side length of 5mm, it is a rectangular box shape, the winding is multilayered over it, which builds it up to an overall diameter of about ~8mm and the length/space it is wound out over is 3mm. all of this is obviously mirrored on the other channel with the other "U". as for the core itself, from the part of the U-core that is open
The length of the whole choke is 16mm length 10mm width. 16mm is the length of the 2 U cores end to end. Pins are 7mm apart on each channel and 8mm apart between the 2 channels.
I'm assuming since it's feeding through that rectified VDC of something like 350 or 400, given how thin the wire is it current draw must be pretty low to the viper and the SMPS? I needed both channels working to measure the inductance though. So I'm at a total loss for knowing what is suitable in terms of inductance/impedance for replacing this choke. I can find plenty that look right; basically UU chokes all look the same, but with no marking on this one I'm really struggling to find a replacement. Maybe it would be possible to determine what it should be based on the known incoming voltage, it's wire thickness as a max current, and knowing it feeds a viper and a SMPS?
Long post I know.. just wanted to put as much info as I could think of upfront if anyone can anything that can help