HP D530 USDT power supply HP-L1520F3P

[jdTech]

Hello,

I have a HP D530 USDT (P/N: DB670AV#ABA) PC with a HP-L1520F3P power supply. This supply when down yesterday. I found about 6 swallow caps that I changed. The supply came back up but the STANDBY voltage goes from 5V to 6V when the main supply is turned on (green wire grounded). This will cause the 5V protection zener on the STANDBY line to short. Looking at the PCB traces it looks like the main supply is somehow connected to the STANDBY SMPS chip on the hot side. I have a 5 ohm load on the STANDBY line. Adding another 5 ohm load (2.5 ohm) will drop the STANDBY voltage to 5.15V. I would think a 1A load would be plenty to keep the supply happy and regulating. I also changed the 431 adjustable zener and two 10Uf/50 caps (one the cold side & one on the hot).

Any ideas?

Thanks for your time.

Jim

[jdTech]

Re: HP D530 USDT power supply HP-L1520F3P

Problem solved! Found that cap C801, a 22uF/50V was defective (read 2.2uF). This cap connect across the two traces that come from the main supply. The STANDBY now reads ~5.1V with no load, 5 ohm, and 2.5 ohms.

Later!

Jim