JDM Programmer debugging?

I have wired up the JDM programmer on

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for programming a 16f876a using a +-11 v RS 232 port of my PC.

since it failed, i checked the MCLR and Vpp of PIC wrt to the Vss and saw that MCLR is not being pulled up to 13v. actually across the 5.1 v zener the drop is nearly 5.1 but across the 8.2 v zener there is only a drop of 0.7 v adding to a total of 6v at MCLR

when i check the voltage bw the ground of rs 232 and the TxD pin without connecting to the circuit i am getting around 11 v but once in circuit the voltage is around 6v

is this due to loading? i tried inserting a diode pair, resistor at the various connections between programmer and serial port.. how can i avoid it?

or are the voltages ok and get corrected while programming? if so what else am i doing wrong?

will this JDM work for RS 232 with < 8.6v? only?

else can anyone tell me what all i should check to see the prorammer is working?

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cafm
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