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Control Board Repair for Big Boy and Latching Relay(s)

Frank McElroy

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I just uploaded a new file explaining how I repaired an Intellitec Board that controls the operation of Big Boy and the battery disconnect Latching Relays.

In the mid 2000’s Monaco models Dynasty and above coaches, used an Intellitec PCB in the Rear Run Bay (RRB) (also referred to as RRB PCB #6), to control both the Big Boy relay to connect the chassis and house battery banks together and the Latching relay(s) for the battery disconnect switch (salesman switch) near the PS entry door.

Unfortunately, this circuit board is now obsolete and almost impossible to find in a salvage yard at any reasonably price.

But you do have options.

Some folks have decided to upgrade the system to Blue Sea ML-ACR automatic charging relay to replace the problematic Big Boy, the Intellitec control board, and bypass the battery disconnect latching relay(s).

However, the Blue Sea unit does require additional wiring to work with a dash switch control.  Others just want the original PCB repaired to work properly.

This document explains how I repaired the RRB PCB#6 for a fellow member to enable both the original Big Boy and Latching relays to work with readily available parts.


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As our coaches age, it's getting harder to find circuit board replacements.  Boards like these used to cost about $100 15 years ago.  Today they are over $400 if you can find them.  So I decided to look to see if the board components are readily available at a decent price and yes they sure are.

Just wanted to provide folks with options if a critical circuit board fails and you can't find a replacement.  One option is to replace the defective board components.  That's what I did in this case for under $5 in parts.

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What I did can basically apply to a lot of other obsolete boards in our aging coaches.  Defective board replacements are becoming harder to find especially on higher end coaches. 

But in many cases, replacing a defective component on the board is very cost effective.  The trick is to know which component to replace.  That's why I posted the file.

My next project is to find the defective component on my old smart wheel control board.  These modules are now becoming very hard if not impossible to find.  I want a working spare since I replaced mine many years ago but kept the defective unit. 

Stay tuned - another how to repair file will on the way...

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