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help fixing satellite receiver power supply circuit
- Thread starter pharaon
- Start date
Start by checking the input:
Is there a rectified input voltag eacross the electrolytic capacitor (marked red)?
Is the fuse conducting or open?
Is there a rectified input voltag eacross the electrolytic capacitor (marked red)?
Is the fuse conducting or open?
Sir pharaon . . . . .
Is your DC voltage being somewhat in the order of + 320---340 across the BIG BLUE main filter capacitor ?
If so, then that voltage passes to the corner terminal of the power transformer primary and comes out of the winding as the third down . . .of the four terminals on that side of the transformer and that terminal then feeds into the nearest corner of the 8 pin " all in one " power IC for the system.
The IC's power return to ground is thru the 0.51 ohm resistor on the other side of the IC to the negative side of the BLUE cap.
There is being the single power FET switching transistor built within that IC and the involved internal control electronics.
I am expecting that the FET shorted and if severely overloaded might have shown plastic case damage or bulging.
Also the 0.51 may now be open circuit.
Pass back the part numbering on the 8 pin IC . . . . . and it may be a Viper series unit. . . . . of one manufacturers products.
Once the IC gets its initial "kick starting" it then uses its other separate primary winding to feed thru the 11?ohm resistor and get rectified by D5 to feed C7 / 8 to develop the normal run voltage supply for the IC with a littlle regulation assist from the ZD1 and 2 zener diodes.
ANY of those could ALSO be your BASIC problem instead of the IC.
If the R5 0.51resistor is not blown, you could get some what of an initial analysis of the units basic switch mode circuit operation by placing a mini pocket AM transistor radio right atop the power transformer .
The radio is to be tuned off of any station and its volume is at max.
Then plug in your power supply and see if the radio sounds off like a TEXAS size mosquito. If not . . . .no pulse switching activity is being generated.
If uncertain of the above procedure, initially bring the radio up to the face of an operating TV or monitor and then play around with the positioning of the radio to find the most sensitive direction of signal pick up. Apply that then learned positioning importance, to the positional alignment to the power transformer.
PLUS, by that initial familiarization , you will then DEFINITELY know what you are expecting to be heard.
Thaaaasssssssit . . . . . fer now . . . .
73's de Edd . . . . .
Now, I just have to ask you . . . . is it all right for a vegetarian to eat animal crackers ?
.
Is your DC voltage being somewhat in the order of + 320---340 across the BIG BLUE main filter capacitor ?
If so, then that voltage passes to the corner terminal of the power transformer primary and comes out of the winding as the third down . . .of the four terminals on that side of the transformer and that terminal then feeds into the nearest corner of the 8 pin " all in one " power IC for the system.
The IC's power return to ground is thru the 0.51 ohm resistor on the other side of the IC to the negative side of the BLUE cap.
There is being the single power FET switching transistor built within that IC and the involved internal control electronics.
I am expecting that the FET shorted and if severely overloaded might have shown plastic case damage or bulging.
Also the 0.51 may now be open circuit.
Pass back the part numbering on the 8 pin IC . . . . . and it may be a Viper series unit. . . . . of one manufacturers products.
Once the IC gets its initial "kick starting" it then uses its other separate primary winding to feed thru the 11?ohm resistor and get rectified by D5 to feed C7 / 8 to develop the normal run voltage supply for the IC with a littlle regulation assist from the ZD1 and 2 zener diodes.
ANY of those could ALSO be your BASIC problem instead of the IC.
If the R5 0.51resistor is not blown, you could get some what of an initial analysis of the units basic switch mode circuit operation by placing a mini pocket AM transistor radio right atop the power transformer .
The radio is to be tuned off of any station and its volume is at max.
Then plug in your power supply and see if the radio sounds off like a TEXAS size mosquito. If not . . . .no pulse switching activity is being generated.
If uncertain of the above procedure, initially bring the radio up to the face of an operating TV or monitor and then play around with the positioning of the radio to find the most sensitive direction of signal pick up. Apply that then learned positioning importance, to the positional alignment to the power transformer.
PLUS, by that initial familiarization , you will then DEFINITELY know what you are expecting to be heard.
Thaaaasssssssit . . . . . fer now . . . .
73's de Edd . . . . .
Now, I just have to ask you . . . . is it all right for a vegetarian to eat animal crackers ?
.
323.5 DC
On the buzz mode it's open circuit, but on ohm scale it give me 0.59 ohm
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are you sure it should be turned off?
It should be turned " off " . . . . . meaning not tuned into any station, so that the radio can then only
pick up the switch mode signal harmonics that would be emitted, IF, the unit is working.
pick up the switch mode signal harmonics that would be emitted, IF, the unit is working.
Couldn't hear any difference really since AM frequency is loud noise anyway but not the same noise i hear when i close the radio to the TV, is there any other way to test it
Last edited:
the resistor is alright
which one exactly?
do you mean R5 ,R6? or the two diodes 06,05
but will they cause the Ic to not work at all?
anyway i'll change them and see
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