Is it worth the effort to build a test unit for LionChief engines since they usually from what I’ve seen is just one board. On the other hand the LionChief + engines are more complicated so could a person benefit by building a test unit for testing the boards or just the parts connected to the board? One last question , what is the type of connectors Lionel uses to connect to their boards so I can make test leads.
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I recently build test sets for the Legacy RCMC and the Legacy BEMC boards, they have been very useful for me. If you work on a lot of LionChief stuff, you certainly could benefit from a test set.
The connectors used on most Lionel boards are the JST family of connectors. JST-EH, JST-PH, and JST-ZH are the most common, but a couple of the small connectors used on some Lionel board are the Molex PicoBlade 1.25mm pitch connectors.
Here's what I'm seeing locally for repairs typically with Lionchief and LC+
#1 most common failure is related to the audio amplifier. If the speaker wiring is shorted to AC metal frame (often happens in steam engines with the drawbar system connectors and wiring) it first blows the amp and then the entire board.
#2 On Lionchief plus- a semi common failure is the smoke fan transistor. It's a BJT and thus when the fan draws more than normal current (example dry fan bearing, or overfilled smoke unit with fluid in the fan, or motor just failing). Point being, the failure is no fan function. This is best tested just using an identical known good working smoke unit from Lionel parts and the matching typical 4 pin connectors (JST-PH).
#3 Motor driver section was cheapened out or chip availability and changed on Lionchief boards from discrete H bridge transistors to integrated chip based H bridge. The problem is, this then became a weak spot in the design and a jammed motor from mechanical linkage or other problems can and easily will blow up this H bridge- when the old style one will survive. Key rating here is the P channel side of this dual MOSFET limited to 3.4A however dropping to 2.7 quickly at 70C temp. The older previous H-bridge design, it's P-channel MOSFET is 17A and 12A at 100C. A night and day difference in safety margin for current.
VS 
#4 Outright unrepairable board. I've seen a handful of the Lionchief BT boards have a failed radio module. This then shorts the regulators and the DC supply thus killing the board. Since the radio module is factory programmed and engine specific- you cannot just replace it. Again, the board just dies with no good reason. If you desolder the entire radio module- the sounds module of the board may become operational, however effectively, that board is dead and cannot be controlled or work again since the programming of a new radio module can only be done by Lionel.
By far, the most useful diagnostic bench setup I use is 3 basic things. A JST-EH connector to a 9V battery to power the board under test. An 8 Ohm speaker with JST-PH- for earlier Lionchief board, and Molex PicoBlade 1.25mm pitch connectors. Last a universal remote.
With those 3 things you are going to know if the board boots, if the amplifier is good, and can a universal remote find and connect to the board. This determines if the board is even worth trying further tests in 99.9999% of all cases I have ever experienced.
Motor drive section failures are painfully obvious with a crater and smoke from the blown ICs.
Fan drive failures may not be visible damage- but again from function- you get heat but no fan on a Lionchief + RF model- good chance it's that fan BJT.
Some fun pictures added
Thank you both for your insight into board repair and troubleshooting. This gives me a lot to think about. Again thank you both
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