This is a listing for 2 complete circuit board sets for the MLC-20A-SIC Conrol Unit, and a 3rd partial set (circuit boards available individually). Used. Boards removed from working machines. The first set is pictured in this listing; circuit board model numbers for this set: 
PX52-11837 (3 boards - Rev. A1, A2 and A3) / YWA3148*A 
PX52-11839 (3 boards - Rev. B1, B2 and B3)  / YWA3147*A 
PX52-11840 Rev. E1 / YWA3155*B 
PX52-11842 (4 boards - two of Rev. A1 , two of Rev. A2) / YWA3149. 
The second circuit board set was removed from a later model machine, however part numbers are identical (different Rev nos.).  The third/partial set includes the following circuit board model numbers:  
PX52-11840 Rev. E1 / YWA3155*B 
PX52-11842 (4 boards - two of Rev. A1 , two of Rev. A2) / YWA3149.