Replaced the 555 with a new one, the output remains around 93Vdc, slightly higher than 90Vdc with previous 555. The supply voltage is 8.9Vdc, resolder some components around 555 and the IRF740. To help me diagnose the problem(I have a CRO):
1. what the is expected output at 555, it should a square wave but what peak voltage?
2. what is expected output at the IRF, peak voltage, around 210V?