wdk450
Well-known member
Gang:
I thought I would share my experience with a recent failure of my Progressive HW (hard Wired) 50 EMS, and what I think is an improvement to the device to help prevent future failures.
I got into TT Russian River August 23 in a 100 degree heat wave. A couple of days later my EMS kicked the power off, the remote readout reporting that it was sensing 255 volts on Line 2. This raises some red flags pointing to the EMS, since I am hoked to a 30 amp, 110 volt hookup with a paralelling 30 amp to 50 amp AC adapter cable. Line 1 reported in at 120 volts at the same time. I bypassed the EMS to get the air conditioner going again after checking the incoming voltage with a DVM. A little later L2 was indicating OK, but now the EMS was giving an error code for no ground connection, so I still had to bypass the EMS. I checked ground continuity from the trailer frame to the park pedestal box, and it measured good. I called Progressive, and after they had me crawl into the storage compartment and take DVM readings, they agreed with my diagnosis that the EMS circuit board was bad. For anyone who has Progressive EMS problems in the future, the "255" reading is a digital logic red flag, since 0-255 is the full range some digital counter chips can count, and the chips will frequently fail displaying their max count, i.e. 255.
I got the exchange circuit board in just a couple of days, and found a couple of resistors near a diode on the bottom of the old board burnt out. I personally don't like the sealed enclosure Progressive uses. This is probably very good at keeping water out, but very bad in providing ventilation for hot electronic components. I drilled about 5 - 1/8 inch holes in a row above and below the circuit board location in the top cover and bottom of the EMS phenolic box for convective ventilation. I made the holes small as a compromise to minimize possible water intrusion. I spaced the box up off of the compartment floor with some machine nuts below the mounting screws.
I encountered a similar sealed electronic box in a model of radiant infant warmer in my career as a hospital electronics technician. I found that the big SCR's that were mounted to a heat sink, and the capacitors on the circuit board were having a high rate of failure. I got the Clinical Engineer at the Hospital to approve me punching 1 inch holes at the top and bottom of the metal box and inserting ventilated hole plugs in the punched holes. The failure rate for these boxes went down about 80% after this ventilation modification.
I thought I would share my experience with a recent failure of my Progressive HW (hard Wired) 50 EMS, and what I think is an improvement to the device to help prevent future failures.
I got into TT Russian River August 23 in a 100 degree heat wave. A couple of days later my EMS kicked the power off, the remote readout reporting that it was sensing 255 volts on Line 2. This raises some red flags pointing to the EMS, since I am hoked to a 30 amp, 110 volt hookup with a paralelling 30 amp to 50 amp AC adapter cable. Line 1 reported in at 120 volts at the same time. I bypassed the EMS to get the air conditioner going again after checking the incoming voltage with a DVM. A little later L2 was indicating OK, but now the EMS was giving an error code for no ground connection, so I still had to bypass the EMS. I checked ground continuity from the trailer frame to the park pedestal box, and it measured good. I called Progressive, and after they had me crawl into the storage compartment and take DVM readings, they agreed with my diagnosis that the EMS circuit board was bad. For anyone who has Progressive EMS problems in the future, the "255" reading is a digital logic red flag, since 0-255 is the full range some digital counter chips can count, and the chips will frequently fail displaying their max count, i.e. 255.
I got the exchange circuit board in just a couple of days, and found a couple of resistors near a diode on the bottom of the old board burnt out. I personally don't like the sealed enclosure Progressive uses. This is probably very good at keeping water out, but very bad in providing ventilation for hot electronic components. I drilled about 5 - 1/8 inch holes in a row above and below the circuit board location in the top cover and bottom of the EMS phenolic box for convective ventilation. I made the holes small as a compromise to minimize possible water intrusion. I spaced the box up off of the compartment floor with some machine nuts below the mounting screws.
I encountered a similar sealed electronic box in a model of radiant infant warmer in my career as a hospital electronics technician. I found that the big SCR's that were mounted to a heat sink, and the capacitors on the circuit board were having a high rate of failure. I got the Clinical Engineer at the Hospital to approve me punching 1 inch holes at the top and bottom of the metal box and inserting ventilated hole plugs in the punched holes. The failure rate for these boxes went down about 80% after this ventilation modification.
