Ursprünglicher Beitrag von: ZFix ,
Really very bad situation :( I can give you an idea to do following: It's look like a short circuit, and you must to find where is the problem: 5V or 12V. You know - 5V is for the electronics, 12V is for the motor. Check unit's main board for a burned line or element. This can guide you to the problem. Next, you can check the HDD SATA Power pinouts for a short circuit. You have 4x identical drives and you can found the difference. Now you can disassemble the motherboard from the HDDs. It will be a miracle if you find the scheme manuals for this. Here is a picture from the mother board (yours must be similar). http://www.storagereview.com/seagate_nas_hdd_review Concentrate on the components which are soldered to a thick strips (if you have a problem element with low power consumption, this element will burn and will cut the line, but after this bad smell you have again short circuit). As you see from the picture, this can't be memory i.c. or SATA controller (biggest i.c.), may be the problem is with the third one - square BGA one (78087). I'm not sure, is your board the same, I'm thinking this is a motor controller i.c. and normally this i.c. have higher consumption. Other problematic element can be diode or capacitor. Check them with a multimeter. Check everything with magnifying glass or better with a microscope. You have a smell, this means you must have or burned element or burned line on the board (more likely - element because after burned line everything will stop). Sorry for my english and do not be angry if I'm instructive. P.S. Compare the readings from the motor flex cables too. I know it's hard to find the problem without scheme manual. I wish you success.