Hi Everyone,
I have a Matek FCHUB-6S PDB. It has 3 to 6s battery input voltage, supports up to 27 volts. I have been using it as a power regulator for a while since its the only thing I have that has a 5v and a 10v regulated output. It was powered via another PDB: Holybro PM07 power module. This one supports up to 12s batteries.
Matek's main power cables was soldered to one of the ESC pads of the PM07. Everything was working fine untill I made 2 changes. At first, I changed the power connectors of my battery packs' and PM07's to XT90s antispark plugs. Tested and the system worked fine +20 times. No sparks at all. And then I decided to add an electrolytic capacitor to Matek's main power input for extra protection against voltage spikes.
After that, antispark plugs started to spark! Even the contact points of XT90s' got darker in 4 plug ins and outs. I was trying to figure out why they started to spark. At the 6th plug in, I saw a huge bright spark came out from Mateks new capacitors legs and smelled that something has burned out. I immideately unplugged the battery from PM07.
I thought electroliytic cap was the one that burned but it wasnt. I seperated the capacitor from matek for investigation. The smell was coming from the board, the cap was fine. I checked for any shorts on the Matek with a multimeter. It doesnt make a beeping sound but it shows a value: 57 ohms. Regarding to its manual if it shows a values over 50 ohms it should also beep. I am confused about that. So I guess there is no shorts but something on it doomed. Couldn't find what that is though. I am attaching its before and after pictures. The before picture is the one with the blue rubycon cap on, also its in a case. The after pictures are the bare board pictures without the cap and close-ups.
Can a capacitor cause something like this? It should have protected the circuit, instead did it fry it? Or did the resistor in the antispark plug burned and its spark caused Matek to burn? I am open to any ideas about what might have happened or done wrong. I will try to find a power supply and a better multimeter to conduct better tests on it.
By the way, all other equipment is healthy. And the cap was 470uF 35V with 0.073 impedance.
Thank you,
Ipek