Several days ago one Dell 760 came to me. Not turning all at all, they said that before this for some time sometimes it turned on fine and then refused or just restarted sometimes without user intervention.
The diagnostic lights on the front panel - blinking digit 3. After some testing and removing the CMOS battery, I had orange blinking power button - just one time and then back to blinking digit 3.
3 if you look at the diagnostic lights description is connected with the CPU.
The BIST test on the CPU ran just fine. BIST is a feature of DELL PSU-s, which initializes power supply test. Fans spinning, HDD spinning - everything seemed ok with the PSU. So, Dell technician will probably say that this is Mobo problem and will offer expensive repair. They will refuse to disassemble the PSU.
Well, in fact I am DELL and HP certified. But... Neither the error code nor the BIST were correct. When I opened the PSU, I saw 10 bulging Lelon caps - all 2200 uf and all failed. And one 100uf cap bulging between the transf and some radiators of other components. It was extreme PITA to replace the caps without complete disassembly of the board assembly. They have one main board, on which there are 4 boards using soldered pin connectors and rotated 90 degrees of the main board.
I had no spare PSU, because the PSU uses nonstandard power connector, not the normal ATX power connector like some decent SFF PC-s.
It was a PSU problem. Because of the caps, the PSU provided out of spec power to the mobo. Even if the BIST ran just fine and voltages were okay, measured with multimeter. I did not have my portable oscilloscope with me to check the quality of the provided power, not just the voltages.
Always suspect the PSU first in this SSF systems and always take it apart to check for caps and anything suspicious.
Now the system works and works stable. I uses Sancon 105C caps. And when there is 16V, I like to use 25V. Where there is 25V, I like to use 35V.
The diagnostic lights on the front panel - blinking digit 3. After some testing and removing the CMOS battery, I had orange blinking power button - just one time and then back to blinking digit 3.
3 if you look at the diagnostic lights description is connected with the CPU.
The BIST test on the CPU ran just fine. BIST is a feature of DELL PSU-s, which initializes power supply test. Fans spinning, HDD spinning - everything seemed ok with the PSU. So, Dell technician will probably say that this is Mobo problem and will offer expensive repair. They will refuse to disassemble the PSU.
Well, in fact I am DELL and HP certified. But... Neither the error code nor the BIST were correct. When I opened the PSU, I saw 10 bulging Lelon caps - all 2200 uf and all failed. And one 100uf cap bulging between the transf and some radiators of other components. It was extreme PITA to replace the caps without complete disassembly of the board assembly. They have one main board, on which there are 4 boards using soldered pin connectors and rotated 90 degrees of the main board.
I had no spare PSU, because the PSU uses nonstandard power connector, not the normal ATX power connector like some decent SFF PC-s.
It was a PSU problem. Because of the caps, the PSU provided out of spec power to the mobo. Even if the BIST ran just fine and voltages were okay, measured with multimeter. I did not have my portable oscilloscope with me to check the quality of the provided power, not just the voltages.
Always suspect the PSU first in this SSF systems and always take it apart to check for caps and anything suspicious.
Now the system works and works stable. I uses Sancon 105C caps. And when there is 16V, I like to use 25V. Where there is 25V, I like to use 35V.
Comment