In this archive attached 4 pics that explain exactly what to do
so u can convert Humax VACI-5300 to IRCI-5400 and here modifies  (sorry about my BAD Englizi)

============= pic1: =============================================================================
1. in 5300 reader socket placed at JP332 , need change it's place to JP330
2. remove L337--L348
3. at L330 & (L332--L347) >> need place fuses or simply short them
4. C331,C330 place 2 CAPACITORs (I take any randomly CAPACITORS)
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============= pic2: =============================================================================
this is very important AREA
1. U170(IC SAS004) is not exist at 5300 so need to find it (I take it from damaged 5400)

2. as u c SAS004 surrounded with CAPACITORs (C173,174,C171,C175,C180,C178,C177,C170,C179)
3. place a resistor at R170 value 472
4. PR171,PR172,PR173= should removed in 5300 boards
5. PR174,PR175,PR176 = place an resistors value=102 and also C172,C176
6. PR170 place with value=103
7. PR178,PR177,PR179 = should be value=272
8. place U171(SB61L256AS-12) and also C181 CAPACITOR
9. place a fuses (L170--L178) or short them
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============= pic3: =============================================================================
1. place R241 & R242 = value(472)
2. U223 place IC-74HC04 
3. palce  <<< C243,C248,C249 ,R237=(105) >>> , short L223 
4. place Y220=12,000MHz
5. need short R240 or simply value zero
6. R238 should be (472)
7. U224 place an IC-74HC05
8. L221 should be shorted
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============= pic4: =============================================================================
5300 SMARTCARD Reader..modifies
finally need shift R713...and place it at R714
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Caution: 1st of all u have to know what u do ...I am not responsible if any damaged OCCURRED
so be careful also u need good tools to avoid any damage (Hot-AIR..etc)

plz refer to pictures


regards

AjeeB
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More details are available at humax-zone.net Forum
http://www.humax-zone.tv/forum/viewtopic.php?t=3336
and at TuningsOnHumax Board
http://www.toh.humax-zone.tv/board/viewtopic.php?t=2591

CrazySat