Hi, Mr. Mickle.T,
Thanks a lot!
I will try to check it tonight. I took off the pcb last night, but confused with the track as it was multilayer PCB than 2. Many track were under the top or bottom layer. But I am sure the shunt ,900k and 90k res , were connected to MAX327 and others connected to relay. So it is really like 3458, but the FET were replaced by MAX327.
In my case, the MAX327 might have been damaged and have more leakage than normal, leading to zero offset of lowest range in DCI mode . I will find a replacement for it.
BTW, I got a question that where is the boot point connected to in 3458 circuit and what is the purpose? I also saw the same layout on 6581 PCB ,but hard to find the connection.
It is strange that I can not login last night and it note that my account is banned forever. But now is fine.
Best Regards,
szszjdb