Vu+ Solo4K Voltage measurements.

It's always a pity when a receiver stops working, especial if it's such a nice piece of machine as these Vu+ Solo4K.
But if the guarantee has expired then you could check some voltages on these motherboard to see if it's can be repaired.
And so, here it is, nearly all the voltage measurements of these motherboard to do a attempt to fix it.

Click on the picture for a full view.


Be carefully with some measurements, use a needle probe to prevent more damage.
Good luck and have fun...

 

I think that you have a 3.3v issue but at this moment I can not say for sure which Dc to Dc regulator is responsible for this voltage.
It could be the U819 sot23-5 with in my case a marking code 71203 A600 or it is 712Q3 A600 but I could not find a datasheet for it.


Tomorrow I could make some measurements to be sure if this is the source for the 3.3v.

 

I've checked this circuit from the U819 to see if it can be responsible for the loss of the other voltages and came to the conclusion that it could.
It seems not to deliver the 3.3v according your measurement and is in contact with your other missing 3.3v parts.
The loss of the lower voltages is because the U158 Vin not gets the 3.3v, therefore it also looses the 1.1v

And thus, it has a good chance if you replace the U819 with marking code 712Q3 but since I can't find the data sheet from it I can't say it will really solves the problem when it's replaced.
I think, check this 3.3v circuit with Ohms measurements, in my case it gives between this circuit and the ground a Ohm value of 1597 Ohms.

As for the U131 8p chip marking code 6178D-1 the missing voltages.
It has the 5v input, but the outputs are a bit strange, however since I also not can find the data sheet from it to see if it has a on/off switch pin I can not say if there is a issue with it.
But since the U819 output goes also to the U131 resistors R485/R487 and after the resistors to this ic then I think it is just switched off.

 

In that case seems the marking code A600 but still I'm not be able to find a seller or datasheet from it.
And to swap it with the U818 seems to me not a option because I think you will loose the 5v delivery which may result is an complete death box because most of the dc to dc circuit parts needs this 5v to operate.

And thus, if the U819 smd ic can not be found or bought somewhere and the circuit which loss the 3.3v voltage has a healthy Ohm reading between the ground and this spot, then you could consider to disable this U819 leg from the circuit and feed the circuit with a 5v to 3.3v regulator.
Nevertheless, in most cases this can be done as a alternative solution, but keep in mind that if this 3.3v circuit has some issues, the 3.3v from the U819 may drop.
So, it's important to know if this circuit is healthy before thinking to solve it with a alternative solution.

 

Ohm value of pin 5 should be 1597 Ohms.
This low ohm value could be caused due the U819, or from the 3.3v circuit self.
The only way to know from which side it happens is to remove the inductors F103/F102.

 

Basically not so bad as it seems to be, it may possible that the U819 still works.

Now you need to figure out which circuits parts are connected to the F103 which you can see on the drawing.
One, or more of them may connected to the F103 output.

 

It's not really wise to cut tracks because you always have the risks that you also cut some internal layer print tracks.
In the earlier day it was not a problem because the motherboards had only the top and bottom print tracks but nowadays they are sandwich boards with several internal layers.

In any case that you also measure allot of spots on the print side is logic due the short to ground.
That you measure allot of inductors (Fxxx parts) on the print side which are in contact with the shorted track scare's me because this could mean that you have a shorted cpu.
Strangely that you also say that you don't measure on both side the F116/F158, which could mean that both are interrupted.
However I assume that it is a measurements mistake since they both have a healthy color, not burned.

Normally I see this kind of measurements when the box has hit by a lightning strike but since I don't know the history of this box I may assume that this were not the case.

I think, check if the U165 near the Actel chip is related to the shorted track, check also if there the 1.5v output is in contact with the ground.
Remove it when there are some reasons to think that this part may caused it.

 

Yeah, it looks that way, and the only way to know that is to remove the cpu and then to see if the short has solved.
But, in some cases the solder pcb dots are so damaged, that it can not be solved.
But when it is still possible to add a new cpu, then (I think) finding/buying a new cpu will be difficult.

 

I think that it does not have to be a hardware issue, rather a issue with the nand flash chip or the software on it may incorrect.
See with a terminal as putty, or a windows hyper terminal if the box still has some terminal output.

Search with google to Vu+ solo 4k rs232 or see this howto picture.
It's for the Vu+ Zero, but the basics should be the same.

Click on it if you like a full view...