DS918+ not booting up (blinking blue light) unless switched off for hours

[bluewave]

My DS918+ (out of warranty) had to be rebooted and now it does not start anymore unless been switched off for few hours without power.

When I press power on the blue power button blinks and fans start - but nothing else, not even output from UART unless the RAM is removed.

I have removed all drives, changed the CR2032 to fresh one, obtained new PSU and even replaced the USB DOM using new one with VID/PID update and cloned contents.

However, if I leave the unit unpowered without PSU connected and press then power button, the unit UART will output the entire boot process, the blue light stops blinking, the green led is lighted and the unit is accessible normally from network using browser - like it should normally boot.

Essentially, the PSU, USB DOM and BIOS must be thus functional, but obviously some problem in the motherboard is present.

In case I switch the unit off, it will not boot and keeps blinking the blue led - but again, if switched off without power for several hours it is again booting normally.

Does anyone have similar experience or any idea what is the actual problem? I would appreciate any expert advice.

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[Jan Janowski]

Does that with both power supplies? If so it’s not supply.
Had issue: a VTR (VPR3) once where cap on CPU Watchdog Timer circuit was effectively open, and therefore would only allow boot under wierd power up circumstances. I had schematics, and scoping that line was first hint of what real cause was. I had already unsuccessfully swapped CPU ( lucky me, it was in a socket).. Good old days…. When schematics (and spare parts) were the norm!

 

[ragnarok]

My DS918+ (out of warranty) had to be rebooted and now it does not start anymore unless been switched off for few hours without power.

When I press power on the blue power button blinks and fans start - but nothing else, not even output from UART unless the RAM is removed.

I have removed all drives, changed the CR2032 to fresh one, obtained new PSU and even replaced the USB DOM using new one with VID/PID update and cloned contents.

However, if I leave the unit unpowered without PSU connected and press then power button, the unit UART will output the entire boot process, the blue light stops blinking, the green led is lighted and the unit is accessible normally from network using browser - like it should normally boot.

Essentially, the PSU, USB DOM and BIOS must be thus functional, but obviously some problem in the motherboard is present.

In case I switch the unit off, it will not boot and keeps blinking the blue led - but again, if switched off without power for several hours it is again booting normally.

Does anyone have similar experience or any idea what is the actual problem? I would appreciate any expert advice.

Sounds complicated, like the power rails are not delivering the required voltage due to bad voltage regulators, worn capacitors or other defects on their route. You may need assistance from a professional for further diagnosis...

One suggestion: Wire the DOM to an USB cable/adapter and try to boot from the front USB port - just to rule out a badly seated DOM or a defect in the motherboard DOM socket...

 

[bluewave]

Does that with both power supplies? If so it’s not supply.
Had issue: a VTR (VPR3) once where cap on CPU Watchdog Timer circuit was effectively open, and therefore would only allow boot under wierd power up circumstances. I had schematics, and scoping that line was first hint of what real cause was. I had already unsuccessfully swapped CPU ( lucky me, it was in a socket).. Good old days…. When schematics (and spare parts) were the norm!

I also wired 12V directly from ATX PSU to exclude the PSU and the result was the same. So it's not PSU.

 

[Telos]

Essentially, the PSU ... must be thus functional,

How so?

 

[bluewave]

Sounds complicated, like the power rails are not delivering the required voltage due to bad voltage regulators, worn capacitors or other defects on their route. You may need assistance from a professional for further diagnosis...

One suggestion: Wire the DOM to an USB cable/adapter and try to boot from the front USB port - just to rule out a badly seated DOM or a defect in the motherboard DOM socket...

Thanks for the suggestion. Unfortunately this did not help. USB DOM itself should be fine as booting from it works when the NAS has been powered off for several hours - but even immediate rebooting fails and NAS has to be powered off again for hours.

 

[Jan Janowski]

Hmmm... so you didn't try a second supply in the unit? If this is an internal supply not an external, it might have a second or 3rd supply in it... I would say bridging a 12V supply across where 12V outputs from main supply is not good enough...
There could be other power up circuits on main supply, too... You wouldn't know this for sure without a schematic... If you haven't purchased a new supply, I think that is still an option here...

 

[bluewave]

How so?

At least the PSU is not the problem as replacing it does not help - neither wiring 12V from ATX PSU.

 

[Jan Janowski]

Is this an internal supply? or external? Your reference to ATX would seem to indicate internal... adding 12v across 12v may not be enough...

 

[bluewave]

Hmmm... so you didn't try a second supply in the unit? If this is an internal supply not an external, it might have a second or 3rd supply in it... I would say bridging a 12V supply across where 12V outputs from main supply is not good enough...
There could be other power up circuits on main supply, too... You wouldn't know this for sure without a schematic... If you haven't purchased a new supply, I think that is still an option here...

I borrowed and tested DS920+ supply from functional unit and that made no difference.

 

[bluewave]

Is this an internal supply? or external?

DS918+ has external PSU with 4-pin connector. 12V 8.33A 100W.

 

[Jan Janowski]

OK, then the 2nd/3rd supply comments do not apply.... ATX references threw me off...

For Grins.... Re-Seat the RAM module.. and try again?

 

[Jan Janowski]

If all else fails, and you are comfortable doing so.... What I would do: is get it to where you have access to main board..
FIRST: Do the "Sniff Test"! Smell anything burned? Examine board carefully: Any Burned components, indicating: STOP! Not worth continuing! ???? If board still looks good: get a can of freeze mist, with nozzle to hit small locations, not broad areas... Power it up with it failing to boot... carefully hit small caps ... with small blast of freeze mist.... not too much, you don't want to hit large area, just the device, individually, letting 30 seconds go by after each 'hit'... If nothing happens (obvious boot, or such) after 30-45 seconds, move to next component...
This way you might find the bad cap..... or other device.... Cold usually works better than heat on components...
You are out of warranty, it's not power supply, coin battery, loose connections, or drives loading down boot, they sell no replacement boards, AND you have no schematics!!!.... What are your other options?