I connected the battery to the plane with the leads reversed. my RDAC isn't working, I have confirmed that power is getting to the device but it's not working. The reason this happen is I built a new cable to connect the RDAC to the xTreme which was working previously. so I'm trying to identify if I've fried the RDAC or not or the new cable isn;t working. The Xtreme EFIS does power up and appears to be fully functional except for the RDAC data is obviously not working. the RDAC is not showing any signs of life - no LED is working.
what are my options? buy a new rdac or can the old rdac be repaired.
thanks
Peter
reversed power polarity and the RDAC XF
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Re: reversed power polarity and the RDAC XF
Yes it certainly can be repaired. The RDAC has an input overvoltage protection circuit that can be destroyed with reverse polarity depending on how your grounds to the rest of the RDAC are wired.
Open the RDAC and find the part marked TR1. This is one of the larger devices with three legs and a tab soldered to the PCB. Have a close look - you may see a burn mark or crater in the device. This is a BSP51 transistor. Remove it and replace (there are many equivalent devices if you can't get this particular one). You can also risk not using it - in this case simply join the collector and emitter pads with a short piece of wire. These are the two legs closest to the edge of the PCB. This will then take the overvoltage protection out of action but the RDAC will operate.
The overvoltage protection kicks in at about 35V and is effective to about 150V - it does not clamp and is thus DO-160 compliant. Without this circuit active your RDAC will survive up to 40V but will be destroyed if you apply reverse polarity. Essentially the transistor acts as fuse for the reverse polarity case.
Open the RDAC and find the part marked TR1. This is one of the larger devices with three legs and a tab soldered to the PCB. Have a close look - you may see a burn mark or crater in the device. This is a BSP51 transistor. Remove it and replace (there are many equivalent devices if you can't get this particular one). You can also risk not using it - in this case simply join the collector and emitter pads with a short piece of wire. These are the two legs closest to the edge of the PCB. This will then take the overvoltage protection out of action but the RDAC will operate.
The overvoltage protection kicks in at about 35V and is effective to about 150V - it does not clamp and is thus DO-160 compliant. Without this circuit active your RDAC will survive up to 40V but will be destroyed if you apply reverse polarity. Essentially the transistor acts as fuse for the reverse polarity case.
Re: reversed power polarity and the RDAC XF
thank you - I'll take a look