Satellite receiver Power supply higher voltages output

[pharaon]

This power supply output voltages is higher than it should be, what could be the cause
Standard voltage actual voltage
23V = 32V
12V = 18.5V
3V = 7 V
Next 3V = unstable 0.5 to 1.6 V
5 V = unstable 6.8V to 7V

 

[Bluejets]

How are you measuring those readings..?

 

[pharaon]

How are you measuring those readings..?

that way, if that's what you mean

 

[Cirkit]

Try measuring those voltages again with your black probe on the respective GND pins.

 

[Bluejets]

Perhaps but it might be different if you use the black probe on the reference "GND" that is adjacent to each 3v3, 5v and 12v etc.
23v is the far right, not the second as you have marked.

Which meter range are you using?

Edit...Cirkit...beat me by .......that much)

 

[pharaon]

Try measuring those voltages again with your black probe on the respective GND pins.

Done it and same results

Perhaps but it might be different if you use the black probe on the reference "GND" that is adjacent to each 3v3, 5v and 12v etc

same results as well

 

[Bluejets]

Meter on dc range..?
Meter tests ok..?
unusual for any reading to go higher than normal (within tolerances)
Input voltage/frequency match input requirements..?
Board looks to have been pretty warm around the switcher ic and associated bits.

 

[pharaon]

Meter on dc range..?

yes

Meter tests ok..?

yes

Input voltage/frequency match input requirements..?

yes

Board looks to have been pretty warm around the switcher ic and associated bits.

although it's working and there's an output voltage

i need to know the cause of the higher output voltage, cause it cause the receiver to hang up while working or give me "searching for signal" for some channels

 

[Bluejets]

i need to know the cause of the higher output voltage,

Yes I did realise that.

although it's working and there's an output voltage

I guess so but not the right values so something is amiss.

Still seems rather strange to have much higher indicated voltage levels.

Could be a fault somewhere in the feedback section.

 

[pharaon]

Could be a fault somewhere in the feedback section.

So what to check?

 

[Cirkit]

What voltage do you measure at IC1? Does the capacitor next to it have a domed top - hard to tell from the photo angle?

Have you tested all the output diodes?

 

[pharaon]

Does the capacitor next to it have a domed top

no

What voltage do you measure at IC1

at what pic exactly should i do the measurement

 

[Bluejets]

Look for details on the switcher (5L0365R) which should bring up a data sheet and a load of schematics.
Perhaps not exactly the same as your board but enough to get an idea of the layout.
I found a couple of videos but mostly Russian/Vietnamese so not much help but it does show it is a fairly common type of board.

 

[Cirkit]

at what pic exactly should i do the measurement

If IC1 is a KA431 or similar, look at the values of the two resistors closest to it. You should be able to work out the set voltage.

 

[pharaon]

If IC1 is a KA431 or similar,

how to tell if it's?

You should be able to work out the set voltage.

can you explain to me how can i?

 

[Cirkit]

how to tell if it's?

Can you read the markings off the flat side of the component?

You will need to trace the resistors that form a potential divider for that IC. Watch the video above, you are looking for the equivalent to R204 and R205 connected in the same way to IC1 on your board.

 

[pharaon]

Can you read the markings off the flat side of the component?

 

[Cirkit]

Not the controller IC. The small 3-pin component marked IC1 next to it.

 

[pharaon]

The small 3-pin component marked IC1 next to it

i also have tested the big cap 47uf 400V and it gave me 36uf, is that acceptable? and can it cause such higher voltage in the output ?

 

[Cirkit]

i also have tested the big cap 47uf 400V and it gave me 36uf, is that acceptable? and can it cause such higher voltage in the output ?

Now find the two resistors that form the potential divider for that part.

How did you measure the capacitor? Was it discharged first, in-circuit?