Cheers Salas and Andrew,
I suspected Vgs was that measurement, but also was interested in the other readings relative to - plus felt safer with only one dmm probe near the MOSFET pins.
Have now swapped out all of the sk170s in the regulator section and both misdeed, just in case. Have not changed the c550 as didn't have a spare. Still getting the same readings across the misdeed.
When I removed the pcb I could see that the there was a small trace of solder shorting the + rail to gnd just before the B1 section
I suspected Vgs was that measurement, but also was interested in the other readings relative to - plus felt safer with only one dmm probe near the MOSFET pins.
Have now swapped out all of the sk170s in the regulator section and both misdeed, just in case. Have not changed the c550 as didn't have a spare. Still getting the same readings across the misdeed.
When I removed the pcb I could see that the there was a small trace of solder shorting the + rail to gnd just before the B1 section
Ok,
I gave up trying to get the + half of my dcb1 working. After changing all of the solid state components in the PS section, I was still getting the same error. I have now swapped another working dcb1 into the chassis and transferred the TX2575 resistors over.
Sounds fantastic - am using 1 ohm current regulating resistors now. The case is quite hot to touch, although I can leave my hand on it without discomfort
. It's going to warm up here in the UK over the next week, so it will be interesting to see how the B1 stands up.
If there is excessive heat what components are at risk? Am I looking at blown MOSFETs or are there other considerations?
Brad
I gave up trying to get the + half of my dcb1 working. After changing all of the solid state components in the PS section, I was still getting the same error. I have now swapped another working dcb1 into the chassis and transferred the TX2575 resistors over.
Sounds fantastic - am using 1 ohm current regulating resistors now. The case is quite hot to touch, although I can leave my hand on it without discomfort
. It's going to warm up here in the UK over the next week, so it will be interesting to see how the B1 stands up.
If there is excessive heat what components are at risk? Am I looking at blown MOSFETs or are there other considerations?
Brad
Didn't you find a solder short culprit the other day? Maybe you had some PCB trace killed also? Beyond Ecaps expiring faster on radiated heat, mainly the Mosfets are to die suddenly of too much heat, maybe the setting resistors too. IF its too much in the long run of course. To talk suggestions or to guess realistically we need currents through the resistors, their ratings in Watt, temperature on them and on Mosfets bodies, on ecaps. At least a picture.
Cheers Guys,
After a nights sleep I had already decided to increase the value of the current setting resistors - using 2.7ohm 5w ceramic wire wound resistors now. All of your comments pretty much reinforce what I knew, but was choosing to ignore in my quest for the F1 version of the DCB1. Now the case just gets warm to the touch. I was surprised by how much hotter the 1ohm current setting resistors made the B1.
I may revisit this and add a fan and improve the thermal interface between the MOSFETs and the chassis by removing the anodised finish where they are attached. I bet the lightly brushed anodised finish is less thermally conductive than dead flat aluminium.
Brad
After a nights sleep I had already decided to increase the value of the current setting resistors - using 2.7ohm 5w ceramic wire wound resistors now. All of your comments pretty much reinforce what I knew, but was choosing to ignore in my quest for the F1 version of the DCB1. Now the case just gets warm to the touch. I was surprised by how much hotter the 1ohm current setting resistors made the B1.
I may revisit this and add a fan and improve the thermal interface between the MOSFETs and the chassis by removing the anodised finish where they are attached. I bet the lightly brushed anodised finish is less thermally conductive than dead flat aluminium.
Brad