That appears to be a full-wave bridge rectifier so it looks like you can feed it with an AC or a DC wall-wart... That's cool... I have all DC wall-warts so I'll eliminate the bridge rectifier and simply install a jumper... It looks like there's a 78L12 just to right of the large filter capacitor and two 1N4148 diodes below it for developing the regulated 13.2 volt VPP supply...
I guess I've looked at plenty of Serial ICD2 Clone schematics and they're all pretty much the same... The MAX232A circuitry is a "no brainer"... The regulated 5v power supply and PIC 16F876(A) connections, also a "no brainer"... The Power, Busy, and Error LEDs are well documented (Pwr=Vdd, Busy=RB3 active high, and Error=RB2 active high)... As are the transistor circuits for driving the target MCLR line to VPP from RC0, or to VDD from RC1, or to ground from RC2... I used 2N3904's and 2N3906's on my prototype board instead of the BC548's and BC558's... The target PGD and PGC lines are driven from PIC pins RC3-RC5 using the five (5) resistors just to the left of the 5-pin ICSP connector on the top right corner of the board...
Please check out the ICD2 schematic at stolz.de.be... I'm sure it'll clear things up for you... And I have a copy of the modified bootloader for 16F876A devices if you don't have a 16F876 handy...
Regards, Mike