Yingtai H81MDC-LSP has no reset repair

Yingtai H81MDC-LSP has no reset repair

Yingtai h81mdc-lsp has no reset. The 49 pin divider resistor is disassembled and connected with 50 pin. The power on test is normal and the running code is on.

Machine model: Yingtai H81MDC-LSP

Fault phenomenon: no reset.

Maintenance process: the whole board VCC of Yingtai h81mdc LSP is normal without reset, and auto power off is not restarted.First measure CPU VCC pg signal.

Yingtai H81MDC-LSP has no reset repair Figure 1.

CPU VCC chip 95812 outputs PG signal through 3 pin, often twotriodeSwitch to Nanqiao, 3.3V is normal.At this time, it is necessary to test the PG signal from IO to Nanqiao.After measurement, it was found that the PG signal from IO to Nanqiao was abnormal, and then it was found that there was something wrong with 5V Vin.

Yingtai H81MDC-LSP has no reset repair Figure 2.

5V Vin is only 1.09v, which should be 2V normally.

Yingtai H81MDC-LSP has no reset repair Figure 3.

Look at the IO product manual, 49 and 50 pin are 5V and 12V VCC respectively.

Yingtai H81MDC-LSP has no reset repair Figure 4.

For quick maintenance, the 49 pin divider resistor was disassembled and connected with 50 pin. The power on test was normal and the running code was on.

Yingtai H81MDC-LSP has no reset repair Figure 5.

Conclusion: the voltage divider resistance of VCC detection circuit is broken, which causes VCC abnormal, IO does not send PG signal and does not reset.