.:madworm:.'s photos
LED warner in action
Unholy relay wiring
| |
|
These two relays have the same switch state when the whole power supply is of or if it is in offline current set mode. If the control logic looses power (blown fuse), the relays internally short + to - and all the power gets pumped into the power transistors. A lot of heat...
I thought fuses were used to make stuff safer, but here... Once the fuse for the control logic has blow, 75W get pumped into the heatsink. I call that a possible cause of fire and or burned fingers. I don't want to think about that it was running in this condition for several hours - unnoticed.
My digital power supply
| |
|
The left two fuses were blown, having a very unfortunate effect.
Also what bugs me a lot is that the screws used to keep everything in place are made of a particularly soft iron. They literally 'melt' away when loosening them with a standard (and matching) screwdriver. I'll have to replace all of them.
Overheated shunt resistor
| |
|
The left one got too hot. It was running a few hours at maximum current (about 2.8A). As I found out later, it ran in unregulated mode, as two fuses were blown. The power to the microcontroller was cut off.
After replacing the two 100mA fuses with 160mA ones it works again. I just happened to have them, but I'll need to get proper ones. The shunt resistor will have to be replaced as well, as its insulation is breaking down. I've measured it to be 0.4Ω, but I can't trust that value. Maybe the manufacturer will tell me the correct resistance.
Overheated shunt resistor
| |
|
Overheated shunt resistor
| |
|
Removing a relay
| |
|
At first I thought one relay was broken, but it turned out to be a classical "failure by design". More on that on my blog.
Digital power supply
| |
|
BMOW.
The bottom right chips are two DACs. Either they're used to drive the power transistors, or (which would be a sad thing) they're used to drive the LC displays on the front.
The two green relays are used for two thing: a) connect/disconnect the voltage from the screw terminals on the front, b) short + to - for offline current adjustment. This plays an important role when the fuses for the microcontroller blow.
Both relays are SPDT. One is connected as "normally closed", the other one as "normally open".
Bad solder job
| |
|
95% of the board are OK...
On the other side there are two terrible cases of "wire doesn't fit through pad".
Bad solder job
| |
|
Bad solder job.
The rightmost pad should have been as large as the left ones. The wire diameter on the other side of the board is the same for all three of them.
C20 just doesn't fit
| |
|
C20 was added at the bottom of the PCB. Seems like they had some problems with space.
Malmö - Sweden
Copenhagen
Copenhagen
Somewhere in between Malmö and Copenhagen
Copenhagen
Copenhagen - Horse Arse
