Need help to fixe SV8000hd

[skywalker999]

Need help fixing SV8000hd v1
here is the problem the receiver started to freeze every second on sat 97w free channels
so before removing the stb i checked the signal quality and it was a bit low around 50 even at 50 SQ it should work fine
so i removed that receiver and replaced with another sv8000hd and it's
working just fine SQ on that one it's about 30 percent better and no freezing

So now I'm trying to fix the bad receiver and so far no go i thought
it was the power supply, replaced the power supply with a brand new one and the problem is still there
I checked the voltage on the power supply with out the mother board connected
and they checked ok except for the two 22v rails and the 38v rail
they are only active when the mother board is connected the two 22v rails read
at 28v and the 38v is reading 28v also

so my question is what part of the mother board controls the 22v and the 38v


2500025001

[jvvh5897]

I can see 4 three terminal devices that are likely regulators. One is on a heat sink near the tuner and two others are right around the tuner as well. The last one is over on the lower left side of the board near what I'm guessing is the power connector. Any of those three are likely to be what you are looking for--they might regulator ICs or they might be transistors or some sort. You could test the voltages around them. You could note the markings on the devices and look them up. As far as I know there are no public schematics or service guides for the SV boxes.

[Terryl]

What I can see from your photos is a small area that has been discolored, this may be to some overheating of some components.

If you look at the bottom right area of the photo of the bottom of the PCB you will see a darker spot, now looking at the top side it looks to be in the area of the large chip in-between the white header on the left, and the heat sink in the middle.

What is this chip? Can you get a number off it?

It may have something to do with the DC power, we need more info.

25008

Look at the area circled in white

[Terryl]

If it is what I think it is, it may be the adjustable regulator that runs the LNB, this looks like you have been running something that has exceeded the DC current spec's for that unit.

How many and what type of LNB(s) do you have attached to this setup?

[skywalker999]

Thanks Terryl and Jvvh will post closeup pictures of dose parts so far i
changed the one on the heat sink (F G47 KA317) for A (LM317T)
and now SQ goes up to 50 75 90 then nothing every second

terryl my setup is 3 legacy double output lnbs for 119 118 110 and 97w then connected to
3 chieta 3x4 Multi-switch then to 3 CHieta Diseqc switchs and that goes to 3 SV8000hds
i already found out that one diseqc switch is bad and right know it's not a good time to go up
to the roof of the house with one foot of snow and minus 16 Celsius maybe minus 30 with the windshield
Here a voltaged reading of one good working SV8000hd receiver
2.2v power on
4.8v
11.8v
gnd
3.2v
3.2 v
5.1v
5.1v
29.1v
29.1v
gnd
30.8v

Here some pics of the power regulators

250112501225013

[Terryl]

OK, here is what I suspect, the last photo is a dual voltage regulator used for microprocessors, it looks like it may have over heated (the burnt look to the PCB around it) at some point.

It may be the problem as to why your unit is not working.

More info on that chip.


http://datasheetz.com/data/Integrated%20Circuits%20%28ICs%29/Voltage%20Regulators%20-%20Linear/576-1229-datasheetz.html

[skywalker999]

Thanks Terryl will see what i can do but though it was the transistor BC647 next to that mic49300wr that had gone bad
anyway what is the best way of removing that thought china made solder
and i will see if i can find dose peaces local or on the net