All mopar boxes are nowdays prone to fail. IT SEEMS the power transistor is the culprit, but more from Transistor manufacturer than Mopar itself. They seems to be cheap replacements from the original designed transistors ( not anymore Motorola made, but a cheaper manufacturer with their licenses ). I have got 2 in a row chromed boxes damaged. One of them just last long 2 weeks
FORTUNATELLY I found 2 NOS ( when I mean NOS I really mean Old Stock it seems from 80s ) which will be soon to replace the existant transistors on my damaged ECUs. I got them from Germany on ebay!!!!
It seems lates lates lates ECUs got a diff Transistor manufacturer by I could advertise from some pics I found on ebay stores, but also IT SEEMS the Mopar ECU boxes are being discountinued due the poor quality they are coming out. You can check Summit is out of stock of these since long time now. INCLUDING the Dist and ECU full kit.
The problem about transistors seems to be affected to Don at FBO, since he stopped to produce the GREAT A688 ECU stock appearence he had and began to make HR688 ( which we found was a chevy module built into the Mopar look alike box ) then replaced by the HRR688, totally new module
So it seems we will have now just regular replacements like Standard LX100 and 101 which I have heard good things about them, some other being sold on Rockauto and some HiPo aftermarket pieces, like the one from FBO I mentioned, same as one box Rick Eherenbergh ( sp? ) offers on ebay as a Hi-Rev 7500, and the wonderfull but not cheap Rev-N-Nator ( also kinda out of stock at this moment, hope to be restocked soon )
OR, get one used MP unit and take care of a soon GOOD transistor replacement
about the melting back on ECU... how your charging system ? do you get lot of back and forth ammeter gauge needle readings ?
a lack of power from alternator can be as far my theory the culprit for this fail, allong with a sooner ECU fail. This lack of power can overheat the electronic components inside the ECU, requesting a load the alternator is not able to give