QNAP TVS-671 Intel B85 Motherboard

[kaz911]

Hi,

I could use a bit of advice on a B85 chipset motherboard from a QNAP TVS-671.

Symptom : QNAP does not turn on as it does not enable the standby power circuit to enable the soft power button. A hard ATX power on will turn the QNAP on and all works fine.

I first traced high consumption to 5V to 3.3V voltage regulator from the standby power circuit (burning hot regulator).

So I tried to manually feed 3.3v in to the standby-circuit bypassing the regulator and now its seems like the main chip-set is absorbing the power/ heat.

But randomly the standby circuit will work fine - led comes on fine and uses 87mA. Other times circuit will go into overdrive and consume (max tested/limited) 800mA and the chip-set B85 will slowly heat up (got a heat-sink...)

Since QNAP have not responded to my support ticket yet I have not wanted to do anything destructive yet - but has anyone seen similar? And was it the chipset? The randomness could be a cap somewhere but I have not found any that looks/measures cracked or damaged yet.

It is random'ish but reproduce-able every time.

But when forced On - the QNAP TVS-671 works fine (pull ATX PW-ON to low) - and then voltage regulator will operate within normal specifications. But remove the A/C power for a little bit and problem is back. So I would like to fix it for power out situations....

/k

[Rasz]

sounds like similar problem to Asrock motherboards https://www.eevblog.com/forum/repair/what-would-cause-failure-of-4-motherboards-in-different-pc_s-within-a-few-months/msg1439544/#msg1439544