Desktop powers up, but no signal to monitor

Registration date
Tuesday June 27, 2017
Last seen
June 27, 2017
Recently went turn on p.c. in morning and had "no signal found" to monitor. Checked all cables in unit, reset memory cards and still nothing. Fan on power supply runs, but still no monitor. Tested power supply (under load) with a multi-meter and all voltages are good, but -12 volt (pin #14) is -10.84 volts. Is this within range? Before testing power supply, I did clear BIOS/CMOS by removing battery and moving jumper. This I may not have done properly so what is correct procedure? How do I get the mom-board to chirp a troubleshoot/error signal and where can I acquire a chart of those beeps? This is an almost 6 yr. old Acer Aspire w/ soldered on processor and I just need to nurse this thing a long until I can afford to build my own. Thanks for any and all help.