Duo / DuoLE Vu-duo is Dead

For those whose duo is still not working after replacing c807 here is the solution.

duoAO1212ok.jpg

If you don't change c807 on time, and if you play and experiment with bricked duo with power switched on, the regulator (No3 on photo) will die. On duo it's marked Pz 1021ai and universal name isAOZ1212, there are 3 exactly the same regulators on duo (see photo), but note that all are outputing different voltages, this is from memory (measure before changing anything):
1. gives 2.5v
2. gives 1.25v
3. gives 1.15v

If you can find a spare (which is extremely difficult) just replace it and duo will work like new.

And if no spare is available don't worry there is a solution. Here is what we did:
We found manual schematic for DIY regulator that converts 5v to 1.25, and we made it
Took out the working regulator from position 2 on photo and istalled it into position 3 in place of defect regulator.
We manualy injected 1.25v from theDIY regulator directly into the output pins of 2nd regulator and whouala the DUO works like new.


Now the cause of this is simple, prolonged exposure to heat makes condensator c807 break, which can than break regulator. The position of c807 is very near HDD which creates heat especially if used extensively. Or if you have fan problems this can reduce the amount of air circulating which can be also cause. Or simply the batch of condensers used in some duo mainboards is not so good. In my case, it was after 2 and a half years of extensive use. And the new condenser costs just 5eurocents and the regulator costs 1 euro.
 
Thanks @Alpa
excellent explanation
In a time of many components are manufactured in China
because my company supplies many of the components in China.
so that it is not difficult but sometimes you have to wait longer or shorter
If you can not find locally.
short search with Google immediately gave a few good links.
 
To look back once again on this topic
since coming summer days.

My advice
Cooling down VU boxes as well as possible will certainly reduce the number of failures and problems.
 
Matrix10 said:
To look back once again on this topic
since coming summer days.

My advice
Cooling down VU boxes as well as possible will certainly reduce the number of failures and problems.
Click to expand...

thanks for suggest.... whwre can buy c807 ecc. ? I can't find .....
thanks in advance
 
paperino61 said:
thanks for suggest.... whwre can buy c807 ecc. ? I can't find .....
thanks in advance
Click to expand...
replace C807 220uF 16v with a new 330uF 16v on the motherboard

It can be bought in almost any electronic parts store
and it costs less than a euro for the best.
Replacement still needs to make someone who understands even a little in electronics.
 
Matrix10 said:
replace C807 220uF 16v with a new 330uF 16v on the motherboard

It can be bought in almost any electronic parts store
and it costs less than a euro for the best.
Replacement still needs to make someone who understands even a little in electronics.
Click to expand...

A friend of mine made the operation for me using 330uF 35v and all works now.
Thanks to all for help in explanation the cause of problem and solution.... I am completely stupid in electronic and the only solution for me (without help of forum people) would be to sent the box to the seller and pay a lot of money for that
thanks thanks thanks
g.
 
ALPA said:
For those whose duo is still not working after replacing c807 here is the solution.

View attachment 7601

If you don't change c807 on time, and if you play and experiment with bricked duo with power switched on, the regulator (No3 on photo) will die. On duo it's marked Pz 1021ai and universal name isAOZ1212, there are 3 exactly the same regulators on duo (see photo), but note that all are outputing different voltages, this is from memory (measure before changing anything):
1. gives 2.5v
2. gives 1.25v
3. gives 1.15v

If you can find a spare (which is extremely difficult) just replace it and duo will work like new.

And if no spare is available don't worry there is a solution. Here is what we did:
We found manual schematic for DIY regulator that converts 5v to 1.25, and we made it
Took out the working regulator from position 2 on photo and istalled it into position 3 in place of defect regulator.
We manualy injected 1.25v from theDIY regulator directly into the output pins of 2nd regulator and whouala the DUO works like new.


Now the cause of this is simple, prolonged exposure to heat makes condensator c807 break, which can than break regulator. The position of c807 is very near HDD which creates heat especially if used extensively. Or if you have fan problems this can reduce the amount of air circulating which can be also cause. Or simply the batch of condensers used in some duo mainboards is not so good. In my case, it was after 2 and a half years of extensive use. And the new condenser costs just 5eurocents and the regulator costs 1 euro.
Click to expand...
Thank you for the good explonation.
The only part I didn't understand is , you have replaced Regulator 3 with the second one in the middle .
So you didn't have to solder new regulator in position 2 , the receiver will opersate with only 2 of them ( 1 and 3) ?
 
The receiver cannot operate with only two, I put DIY regulator on position 2 (because I could not find new aoz chip regulator), I switched the positions of 2 and 3 bcs the schematics I managed to find for DIY regulator was with appropriate voltage for position 2 only.
 
thanks for the information guys,
just to confirm did you guys have this problem after updating kernal, or did it happen randomly.
as mine happened randomly this week. i updated kernal 3 months ago
nothing comes on[no fan , no light on external hd]
only red light on front panel comes on
thanks
 
I was having trouble with the duo as well not to the extent of the above post,
the Duo dose not respond to any USB sticks or hard drive, but after a while a found that it will respond to a powered USB stick.
is this the start of some thing that gonna fail?
 
Did you manage to power up the red light problem? I had the same problem and changed a transistor on the power supply and worked fine,
 
replace C807 220uF 16v with a new 330uF 16v
was getting my old box alive again thx for the info in this tread all br:sat
 
Hi,

My C807 went really in FIRE today (smoke coming out from the box). I hope that my motherboard will not be dammaged. Box 2 1/2 year old (also intensive use) and the box was very hot since a few days, even in standby (not deep standby), the temperature did not go down. The box shutted down/restarted alone more and more frequently.
I am still surprised that the problems began with the new image 3.0 update. May be coincidence. (2 1/2 year or new bootloader??)
I will try to replace the C807 220uF with a 330uF 16v.
Am I right with that?
Can it be that the power supply is defective? Because normally in stand by, the box should have cooled. And this was not the case.
more question, when I look at the c807, it has 8 pins, while the 330uF 16v only 2. Where do I connect the 2 pins? If somebody has a picture, should be nice.

Thanks
 
Hi ,

Is there a nice person that could tell me how to replace this AOZ1212 with the 330uF 16v?
Thank you

AOZ1212 description :
1 LX 8 VBIAS
2 BST 7 VIN
3 GND 6 EN
4 FB 5 COMP
Pin Number Pin Name Pin Function
1 LX PWM output connection to inductor. LX pin needs to be connected externally. Thermal connection
for output stage.
2 BST Bootstrap voltage input. High side driver supply. Connected to 0.1μF capacitor between BST and
LX.
3 GND Ground.
4 FB Feedback input. It is regulated to 0.8V. The FB pin is used to determine the PWM output voltage
via a resistor divider between the output and GND.
5 COMP External loop compensation. Output of internal error amplifier. Connect a series RC network to
GND for control loop compensation.
6 EN Enable pin. The enable pin is active HIGH. Connect EN pin to VIN if not used. Do not leave the EN
pin floating.
7 VIN Supply voltage input. Range from 4.5V to 27V. When VIN rises above the UVLO threshold the
device starts up. All VIN pins need to be connected externally.
8 VBIAS Compensation pin of internal linear regulator. Place put a 1μF capacitor between this pin and
ground.
 
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