This only applies to PowerCab that were produced between March 2013 and December 2013 and are all shipped with V1.65 software.
Digikey part link http://www.digikey.com/product-detail/en/ERJ-2GEJ104X/P100KJCT-ND/146730
This article from Mark Gurries site-
PROBLEM: A limited production of the NCE PowerCab were shipped with an incorrect chip installed that created communication problems with any device connected to the Cab Bus. DCC accessory controllers are not effected.
1) DESCRIPTION OF PROBLEM
NCE buy parts from multiple vendors that are interchangeable. There was a limited run of PowerCab which have installed a chip which is incompatible with the Cab Bus. This was not caught right away resulting in a limited quantity of PowerCab shipped around the world that will unfortunately not work with any compatible NCE cab bus expansion device.
2) WHAT DEVICES CAN BE AFFECTED BY THE PROBLEM?
Basically any device that plugs into the NCE CAB BUS.
Cabs: ProCab, Cab04, Cab05 and Cab06 all versions.
Radio: RB02 which is require to work with any radio based cab.
Accessories: USB adapter, MiniPanel, AIU
3) HOW CAN I TELL IF I HAVE A PROBLEM?
You can only tell if you have a problem by plugging in a NCE cab bus device. Although the device powers up, it will not work correctly no matter what you do. The failure will take place when there is an attempt by the PowerCab to talk to the device. Examples of a failure.
a) ProCab: Powers up and you can set cab parameters but the display never gets updated for train operation.
b) USB adapater: PC recognizes the USB device but cannot talk to the PowerCab.
c) NCE Minipanel: Minipanel attempts to work flashing LEDs but nothing happens.
d) Engineer Cabs: Does not work. You can set cab parameters but when you exit, no control of anything.
e) 2nd PowerCab used as a ProCab: 2nd PowerCab may power up in PowerCab mode with normal display and appears to work but there is no control no matter what you do. Otherwise it will act like a ProCab.
4) HOW CAN I IDENTIFY A POWERCAB THAT MIGHT HAVE THE PROBLEM?
The Problematic PowerCab were produced between March 2013 and December 2013 (10 months) and are all shipped with V1.65 software. There is no way to tell from looking at the outside the PowerCab itself if it has a bad chip installed. If you purchased a brand new but older PowerCab with any version of software V1.28 or older, you are not effected. Upgrading it to V1.65 software will not cause any problems.
5) WHAT IS THE SOLUTION?
If you have identified your PowerCab has a problem with NCE, NCE will send you a brand new modified PCP panel for free. PCP = PowerCabPanel. NCE part number 524-222. No need to send anything back to NCE nor pay any money. However if you can solder resistors, you can fix it yourself too and save your self some time. Read on.
The solution/modification requires installation of two simple low cost 100K resistors on the PCP panel. Only the PCP panel needs to be modified. Standard UTP or expansion cab panels do NOT need to be fixed nor modified in any way. This modification will NOT effect a normal working PowerCab that does NOT need the resistors nor any other NCE cab bus device. This is an Install and forget solution.
6) WHAT DID NCE DO TO FIX THE PROBLEM?
What is the modification? Look at the photo on the left and notice there are two small white colored diagonal "0805" surface mount resistors installed. The are shown in the center of the photo circled.
Can I apply this modification to my PCP panel even if I do not have a problem or are unsure if I do? YES.
7) HOW CAN I FIX THE PROBLEM MYSELF?
Yes. Two ways
a) You to can install the same "0805" surface mount 100K resistors like NCE did as shown above.
b) You can use two standard 100K 1/4W resistors you can find at any electronic parts store.
Do you have to use exactly 100K resistors? No. Value that are 50% lower will also work. However, do not go higher. 100K is a very common value that you should be able to get easily. If you are going to use a different value, check the value with a Ohm Meter before you install it.
There is no tolerance accuracy of the resistors required. Any 100K resistor will work if you can fit it to the board. There are multiple locations where the resistor connections can be done but it must be done exactly as shown in the schematic found at the bottom.
If you buying 100K resistors, the color code is: Brown, Black Yellow. The forth or Gold (5%), Red (2%) or Silver (10%) band is not important.
If you buying 100K 1% resistor, the color code is: Brown, Black, Black, Orange. The offset fifth band will be brown (1%).
Below are some resistor installation examples done by NCE users.
Using 1/4W 100K 5% resistor. Photo courtesy of Jim Exler
Using 1/4W 100K 1% resistors.