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07/05/2011 1:25 am
i've been helping a guy t/s an interm prob w/ a mont/kone miprom controller car will stop in the up dir. w/ a reset/brownout fault on the pwr supply board temp trapping people. the unreg pwr supply read 24 vdc w/ no ripple but the reg pwr supply would get back to the rack at 21 vdc. w/ no drop off while car was running up and down the h/w. had him swap out the pwr supply bd the 21vdc bumped up to 24 vdc and everything looked good. but after a few runs car had same prob. so we adj the pot on bd to 25 vdc but interm would trip off. next watched bldg pwr controller calls for 208 + - 10vac phase to phase read 218 vac & 126 vac to ground all w/ in tolerance but on 1 occ. caught the voltage at 202 vac not good. had their elec. come out he said everything checked good even w/ bldg fully loaded. so now we got the car down while the pwr company monitors the bldg pwr poss. xfmr going bad. now heres my ? is there a way to disable the brown out/reset feature on this bd. i think it clamps through a chip set not sure though any help would be great. thanks.
07/05/2011 1:56 am
Some friendly advice, if I may?
If you circumvent the UL listed controller safety features, you incur liability on yourself. The root cause needs to be fixed first. Don't put your head in a noose to please the customer.
07/05/2011 2:03 am
Check your voltage regulators on the side of the car rack. Make sure the plastic screw is not broken. Then try soldering new ones in we have had a couple go bad with all kinds of weird problems. Sometimes like the way you discribe some times no outputs. Sometimes all outputs locked on it depends if it is the 5 volt or the 15 volt.
13/05/2011 2:36 am
Hey, sccjr any news on this job?
13/05/2011 8:11 am
you should be able to check voltage from L1A to L2AX which is the power supply input to the PSC board. it should operate fine with voltages above 105VAC. If you are watching the board, if brown out led comes on, then LED2 should come on and stay on until the voltage at L1A to L2AX comes back to tolerance. then the brown out LED will stay on even though the voltage has come back into tolerance. this is why you often see the brown out led on when you look at the board, and the car is running fine. If you are seeing brown out LED1 come on, then LED2 turn on then off again you are either dropping input voltage, or something is dragging down the voltage at terminal SS. L2AX feeds SS through the S2 switch, so if SS grounds momentarily, L2AX will drop and the brown out sequence will start. However, if you are only seeing LED2 come on and then reset, you could have a bad input or output card that is dragging down the voltages of the system, causing led2 to reset the cpu. You would not want to try and disable the brown out circuit, this is a safety feature that essentially shuts off the cpu thus clearing all outputs. I have never actually seen a brown out cause a shutdown in the field. I have only seen the led on when we go to a miprom job. it is something that we have all seen and usually just reset it and go on about our business. If you guys actually witnessed brown out led come on and stop the car in flight, and the power is good, i would look at the SS line.
Last edited by Scott Davidson; 05/13/11 12:19 AM.