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Intellitec EMS 760 board fried


mandms59
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Hello,

We pulled into Ogallala, NE. for the night...when wife went to start rear A/C after I finished hooking up surge protector and 50 amp power, she smelled electrical smoke from rear of coach.  she immediately turned off A/C at control panel and called out to me outside.  

I came in and noted the EMS remote panel was blank but we had power still to the refrigerator and microwave.  I turned the main 50 amp breaker of at rear panel and went outside again to ensure that there was nothing wrong at transfer switch (no electrical fire burnt smell).

After some further T/S and turning power off at the pole, I pulled off the panel cover and sure enough I could see where the board had fried where the power wires came into board for rear A/C unit; with the power still off I took a look at some of the wiring in vicinity of the melt down... it looks like I may need to have a couple wires replaced in addition to the circuit board.

A couple of questions -

(1) Is there a way to isolate the EMS board so that I can charge the batteries and run a couple electrical outlets to run box fans (its 98 deg outside)

- e.g. kill breakers to everything except 50 amp and inverter in rear panel box // remove rear a/c wiring leads on control board where they were fried??

(2) My understanding of the way system works ... I cannot run generator either until board/wiring replaced - as power goes from gen thru transfer switch to Rear Panel/EMS control board. 

(3) It looks like I need 00-894-200 control board... hopefully I can only order the control board and not the whole 760 kit upgrade.

Thanks in advance  for advice/assistance

R/

Mark

 

 

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The EMS system is somewhat independent of the rest of the coaches electrical system.  It simply controls the circuits it is wired to shed when it senses 30 amp shore power, in my case AC1, AC2, Water Heater, and Washer Dryer.   It has a sense wire from the generator 12 volt circuit that tells it that the generator is running and that there is no need to shed power. 

You can simply disconnect the wires going to the EMS from each of the breakers it controls and then using the wires on the outgoing side wire them into the individual breakers.  Make a schematic as to how everything is currently wired and take some pictures first.  You can then replace the EMS board in the future. 

I had a lightening strike take out my EMS board, no visual damage so it was internal.  It was winter and I needed only one AC unit so I bypassed the EMS system for that circuit.  Took me about a week to get a new board, I actually had to upgrade since my board was obsolete.  I got my board from M&M Electronics, they worked with me to confirm my board was bad and then provided me with the required parts to upgrade.  More importantly they shipped to a destination I was going to be at!!!!

From your picture you have the 750 model and it will have to be upgraded also, meaning new upgraded board, new load sensor, and new pigtails.  Not a hard upgrade, just make sure to read the instructions.  When I first wired mine in I accidentally switched the pigtail locations, luckily the board is protected so no damage done, just had to redo my mistake. 

 

Edited by jacwjames
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Jim,

Thanks for the quick response & excellent directions.   

I  free-handed a wire diagram & photographed current installation.  As the wires were so stiff,  I had some wire nuts available in my repair tool box - so I connected the two wires together for each system running thru EMS control board for the night (my wife thanks you for getting the AirCon back for the night)

I will make a better temp repair tomorrow in the daylight.  Will check with M&M tomorrow I had them bookmarked when I started researching my options for repairing the problem earlier this afternoon.

R/

Mark Meyer

 

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Jim is correct. Unfortunately the heftiness of the relays used in the EMS board are not built for the amps and loads that need to go through them. SO what happened to your board is quite common. Luckily you discovered it without having any major damage to the coach.

As long as none of the 120 VAC wires have been compromised as Jim stated you can simply bypass each of the relays to restore power.

When I upgraded my board on my 2002 Windsor I had to purchase a new display along with the upgraded board plus new pigtails for each end of the wiring harness. Not a difficult installation providing you pay attention to the exact wiring details. Make sure you crank down on the connections to make sure they are solid. Also it is highly recommended to inspect and re-tighten those connections yearly.

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The cover for your panel shows a model 750 but the board itself shows a 760, so your system may have already been upgraded and you may only need the board.  I upgraded from a 750 to a 760 board.  There is a number stamped on the board, do a search and if you can find a compatible board it would indicated it's been upgraded. 

If you have all the circuits bypassed you could take your time on replacing the EMS board.  As long as you limit your power consumption and/or use 50 amp shore power you don't need the EMS repaired immediately.  Just depends on what you are comfortable with. 

Edited by jacwjames
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From the time I first looked at that board in my 06' Windsor, I did not like the relays and believed they were too small, could heat up and damage not only the relays themselves but the surrounding circuit board. Sure enough, one night years later everything electrical in the coach when crazy. All the lights flashing rapidly, noises and so many other things happening I've forgotten. Immediately, I depower everything by disconnecting shore power and turning off both battery switches. There I was at night with a totally dead coach.

Troubleshooting showed that a large area of the EMS board was fried and smelled just like you said. One of the relays was severely damaged as well. Thus, the reason for the failure.

FORTUNATELY, because I never liked it from the beginning, I had purchased a spare board! After replacing the bad with the new, everything operated normally. I ordered another standby spare which I still have.

Hopefully, to prevent the same thing from happening in the future, when installing the replacement board, I made a slight change to the ac connections. Instead of the power coming from an ac breaker then going through the small relay and out to the coach, I placed both wires on the same terminal of one side of relay so that the relay is not carrying any load. Each ac relay is simply a connection terminal where the incoming power from the ac circuit breakers is directly connected on the same side of the relay and then out to the coach. Doesn't matter which one of the relay's 2 terminals are used to join the 2 wires.

I could have simply connected the coach circuits directly to their appropriate circuit breakers and eliminated the EMS board relays all together but decided to go the way I did in case at some point in the future I wanted to go back to the way it was originally wired. In that case all I would need to do is move one of the 2 ac wires on the same terminal of each relay to the other side of the relay so the power then again flowed through the relay.

Of course, the way I am wired now, if the EMS circuitry decides the ac system is becoming overloaded and opens one of the relays, that will not shed anything. I'm always careful about overloading the shore power and never had the loadshedding capability of the EMS system come into play. Even if I do overload, a circuit breaker will trip just like it would without the EMS as is the case with all the coaches that were build for years without load shedding.

No doubt there will be those who disagree and will respond. If that happens, then you will have additional opinions to consider and make an informed decision as to what you eventually decide.

Gary K

 

 

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The only time the EMS board plays a role is when you are on any shore power which is LESS then a 50 amp connection. Such as it will shed loads in whatever order your EMS board is setup for before reaching the maximum amps available. If you never use any power connections less than 50 amps then it makes sense to bypass the relays especially on the two AC's and the water heater which those can draw some hefty amps. My water heater draws 12 amp and each AC draws about 12-15 amps each. My four shedding devices are: #1 - Electric Assist Water Heater, #2 - Rear AC, #3 - Washer/Dryer, #4 - Front AC. When these devices are on a bypass mode you simply monitor closely how many amps you are using then start turning stuff off that is not needed.

It would be great if the manufacturer would design the boards with heavier relays that can handle the amps which those devices easily draw. Until then these boards are considered a consumable.

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Doug,

My manual states the same as yours. However, it depends on how the EMS was wired. I have come across boards that have completely different device shedding orders.

The EMS board is capable of shedding four 120 VAC devices and two 12 VDC devices. My board does not have any 12 VDC devices attached to it and I believe that Monaco chose to NOT use the 12 VDC relays to control the AC thermostat because it would disable both AC's at the same time leaving you with no AC at all.

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56 minutes ago, Dr4Film said:

Doug,

My manual states the same as yours. However, it depends on how the EMS was wired. I have come across boards that have completely different device shedding orders.

The EMS board is capable of shedding four 120 VAC devices and two 12 VDC devices. My board does not have any 12 VDC devices attached to it and I believe that Monaco chose to NOT use the 12 VDC relays to control the AC thermostat because it would disable both AC's at the same time leaving you with no AC at all.

Richard  Thanks for the explanation.  Someday I'll have to take a look and see how mine has been wired.

 

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Doug,

If  you haven't had the cover off your service panel it may be worthwhile to do a general inspection and check all the wiring connections for tightness.  Same thing with the transfer switch etc.  As much moving and bouncing the coach does it pays to do this on a regular basis.

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Just as a tip, whenever replacing your Intellitec board it is a good idea to replace the corresponding breaker as well. We just had a Dynasty in with a failed Intellitec board. The previous service company replaced it but didn't replace the breaker. The breaker became weak when the original fried and it shorted and took out the new board. We replaced the board and breaker and had no more problems.

After much discussion between our tech and Dave Pratt we instituted a new practice that when replacing the board we also replace the breaker. Breakers are cheap folks.

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5 hours ago, Doug Hoegh said:

Richard  Thanks for the explanation.  Someday I'll have to take a look and see how mine has been wired.

 

Doug,

If your 06 Diplomat is like mine it has relays on the EMS board that open the AC power to the air conditioners, water heater, and washer/dryer. On ours the first load to be shed is the water heater, then the rear air conditioner, next the washer dryer, and as a last resort the front air conditioner. A number of years back the relay that controls the rear air conditioner on ours failed so I just moved the input and output wires to the same terminal. That means the EMS cannot shed the rear air conditioner but we do not depend on the EMS to manage power so no big deal for us. The terminals at the front of the EMS board were the AC power is fed in and out of the relays is one of the locations that I check the tightness of the screws once each year. If they get loose they will over heat the board and lead to failure. I also check all the terminals in the AC distribution panel and the transfer switch each year for the same reason.

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9 hours ago, jacwjames said:

Doug,

If  you haven't had the cover off your service panel it may be worthwhile to do a general inspection and check all the wiring connections for tightness.  Same thing with the transfer switch etc.  As much moving and bouncing the coach does it pays to do this on a regular basis.

Jim

Definitely planning to check this week. I replaced my IOTA last year so I know my new transfer switch also needs it’s yearly checkup. Thanks.

4 hours ago, Bob Nodine said:

Doug,

If your 06 Diplomat is like mine it has relays on the EMS board that open the AC power to the air conditioners, water heater, and washer/dryer. On ours the first load to be shed is the water heater, then the rear air conditioner, next the washer dryer, and as a last resort the front air conditioner. A number of years back the relay that controls the rear air conditioner on ours failed so I just moved the input and output wires to the same terminal. That means the EMS cannot shed the rear air conditioner but we do not depend on the EMS to manage power so no big deal for us. The terminals at the front of the EMS board were the AC power is fed in and out of the relays is one of the locations that I check the tightness of the screws once each year. If they get loose they will over heat the board and lead to failure. I also check all the terminals in the AC distribution panel and the transfer switch each year for the same reason.

Bob. Thanks. Will be doing a check up next week.

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21 hours ago, throgmartin said:

Just as a tip, whenever replacing your Intellitec board it is a good idea to replace the corresponding breaker as well. We just had a Dynasty in with a failed Intellitec board. The previous service company replaced it but didn't replace the breaker. The breaker became weak when the original fried and it shorted and took out the new board. We replaced the board and breaker and had no more problems.

After much discussion between our tech and Dave Pratt we instituted a new practice that when replacing the board we also replace the breaker. Breakers are cheap folks.

Chris,

Thanks for the information.  Confirms my plans on replacing A/C CB's  before installing the new control board. 

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22 hours ago, Dr4Film said:

Chris, are stating that if the EMS board relay for AC#1 had gotten fried destroying the EMS board then the circuit breaker in the EMS Power Panel For AC#1 should be replaced also?

Do I have that correct?

Yes sir, that is correct. Your older breaker may or may not be weak but for the cheap price of a replacement breaker it isn't worth rolling the dice and frying a new board. On the Dynasty that we just worked on the breaker was weak which fried the replacement board the other service company replaced. We replaced both the breaker and board together. Dave Pratt and I just had a discussion yesterday about this and his procedure is the same as ours, when something fries, go upstream and start checking and or replacing other components that may feed the system you work on.

I should mention this is a standard procedure in aircraft maintenance and repair.

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Until you get it fixed , bypass the relay that is blown. Put both the in and out black wires which are next to each other on the same lug. If it’s one of the ac units the black wires need to go on the input to the relay lug . Not to worry if you put them on the wrong lug it likely won’t work. After you get it right the 750 won’t be able to shed that ac so you will be managing that one on your own. 

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