Hello guys,
Here i am again with another question. Someone called me because his fish radar on his boat wasn't working anymore. He didn't use it for years because is broke down and now he needed it again. It's a very old computer system from 1986, and the computer broke down. The power supply circuit in the computer shorted and took the 24V -> 12V converter with it. (all unfused ofcourse
)
I got the computer up and running again with a new transistor and a new power converter. The old converter was repairable but the salty sea air already ruined the pcb of it, so reliability was a long shot for it. This old power converter was rated at 10A.
So i went to the local and bought a new 10A power converter. But this one immediately goes into overcurrent mode. Only after replugging the computer around 5 times the power converter works and everything is fine.
Now my theory is that:
The old computer of the fish finder has got some reasonably big 220V caps in it, so if those caps are discharged they draw a big current for a short time.
And the old converter didn't have any (fast) protection so it didn't mind that current spike. But the new one has got some goofy digital overcurrent protection that immediately kicks in. And probably because of the current spike from the charging caps at that moment.
After replugging the computer a couple of times the caps are charged from the small bits of power the power converter delivers before it goes into protection mode and the power converter doesn't go into protection mode anymore because there is no current spike.
When using the computer for more than an hour the power converter barely gets heated up so i think that computer is drawing way below 10A continuously. It also got no heatsinks so i think it's pretty damn difficult to get rid of over 100W of heat without ventilation in there. The casing also doesn't heat up while using it.
I've attached some pictures of the power converter. The side of the coil is the 12V out, the side of the fuse is the 24V in.
The model number of this power converter is: HQ-CONV.DC10A
The model number of that 8 legged (PWM/CPU/FLASH?) chip is: Microchip 12F615
Do you guys know how to disable or loosen the overcurrent limit?
By the way, that modded ATX PSU for my 3D printer is still working great!
Here i am again with another question. Someone called me because his fish radar on his boat wasn't working anymore. He didn't use it for years because is broke down and now he needed it again. It's a very old computer system from 1986, and the computer broke down. The power supply circuit in the computer shorted and took the 24V -> 12V converter with it. (all unfused ofcourse
) I got the computer up and running again with a new transistor and a new power converter. The old converter was repairable but the salty sea air already ruined the pcb of it, so reliability was a long shot for it. This old power converter was rated at 10A.
So i went to the local and bought a new 10A power converter. But this one immediately goes into overcurrent mode. Only after replugging the computer around 5 times the power converter works and everything is fine.
Now my theory is that:
The old computer of the fish finder has got some reasonably big 220V caps in it, so if those caps are discharged they draw a big current for a short time.
And the old converter didn't have any (fast) protection so it didn't mind that current spike. But the new one has got some goofy digital overcurrent protection that immediately kicks in. And probably because of the current spike from the charging caps at that moment.
After replugging the computer a couple of times the caps are charged from the small bits of power the power converter delivers before it goes into protection mode and the power converter doesn't go into protection mode anymore because there is no current spike.
When using the computer for more than an hour the power converter barely gets heated up so i think that computer is drawing way below 10A continuously. It also got no heatsinks so i think it's pretty damn difficult to get rid of over 100W of heat without ventilation in there. The casing also doesn't heat up while using it.
I've attached some pictures of the power converter. The side of the coil is the 12V out, the side of the fuse is the 24V in.
The model number of this power converter is: HQ-CONV.DC10A
The model number of that 8 legged (PWM/CPU/FLASH?) chip is: Microchip 12F615
Do you guys know how to disable or loosen the overcurrent limit?
By the way, that modded ATX PSU for my 3D printer is still working great!
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