The following is from Per Olesen on solutions he found to problems using the MCB900. Thank you to Per for providing this for the benefit of others!
QuoteI use the TSSOP types on my boards, so it is not possible to program them in the MCB900, and then move it to the target board.
In 2 cases I had the problem that it would only program 1. Time.
Solution problem 1: I had a RS485 chip on the RxT TxT line on the target board, and with no external power on the target board, the RxT line was overloaded. I simply put a 100K resistor in serial with the input on the 485 chip, and it worked fine.
Solution problem 2: To be safe I had placed a 100uF capasitor on the VDD of the LPC, and it is too much, it kills the rise time of the VDD from the programmer. 22uF works.