max485 problem with comm

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regards ...
i made this circuit [plz consider just the max485 only ...but when i used it it didn't received any thing although transmission was all good, then i tried some debugging and found that on removing r14,r15,and r18 it works..
although i get a character y' all the time when i change from transmission to reception ...

plz help me why i get this..

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With no data, pin 1 of the max485 should be at a logic 1. According to your circuit, the bias resistors will make it logic 0. Reverse the bias resistors and it should work better.