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Satellite receiver Power supply higher voltages output

pharaon

Oct 28, 2014
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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.
you mean those two resistors?


What type of meter did you use to measure it? Ideally, you need to measure the ESR. The capacitance is slightly lower than what it should be.
UT61E
 

Cirkit

Oct 28, 2015
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you mean those two resistors?

Possibly, you need to trace if they are connected in the same way as the resistor numbers I mentioned above in the video.

There are two other resistors close to the KA431 which could also be the potential divider for it.
 

Bluejets

Oct 5, 2014
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C1 (104) cap looks weird...next to ic pin 2.

Still think that switcher has copped a lot of heat.

What does it look like underneath the board?
 
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pharaon

Oct 28, 2014
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Possibly, you need to trace if they are connected in the same way as the resistor numbers I mentioned above in the video.

There are two other resistors close to the KA431 which could also be the potential divider for it.
ok i changed the big cap and measure the voltage under load and now everything is fine , although i don't understand what would be the relation between the big cap and the output voltages , someone told me the cause might be the Optocoupler
 

73's de Edd

Aug 21, 2015
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Sir pharaon . . . . .

Pull out your large unabridged ENGLISH - to- ARABIC DICTIONARY . . .and . . . .

Having a run on Saddle -Light receivers powder supplies-es-es are we ?

Upon evaluating the info you have given us . . . . .I suspicion this . . . . .

This AP-134 unit is being a like variant of your last one, but with this based upon Fairly-childs FSL0365R . . .SMPS in a chip.
I have it YELLOW boxed . . . . and nearby is located its kick start 400K resistor, also YELLOW boxed, with it being fed from main B raw supply . . .it only comes into play after a power failure or unplugging.
That was being your conundrum on the last power supply encountered.. . .not so this time

With your present voltage vacillations and unstable regulation and looking at the
PINK boxed info . . .of 2010 manufacture . . . I believe that your present situation will be related to a gradual decline and onset of . . . . " E-cap atrophy " .
But with this case , you being physically clueless . . .in not having the bulging capacitors that even some techno " DUMMIES " rely upon in being able to guess at a possible clue for a solution.
The typical situation is filtering degradation, declining in effectiveness down to the threshold where bonker effects start showing up on the equipment.
Potentially, that's being noticeable by the unit not working on initial power up, and might take an extra power turn on attempt, or possibly even more.
However, once started up, and with the warming up of components, it tends to run until the unit is being turned power off.
Then there is that degree of failure such as you are now experiencing, and then, eventually, the downright failure of its capability to even stay powered up.
You are not yet into that full no-workee-workee stage yet, but if one has just found equipment, being right at that threshold of degradation I have found that pulling out a hair blowdryer used in its heat position and distributing its heat all around equally to all of the units E-caps and bringing their cases temperatures up to the level of the HOTTEST tea or coffee that you are able to tolerate.
As is being equated by finger tip testing to the tops of their cases bare alumininny-yum-yum shells.
( Thats NOT being heated up to the temp that melts and curls / or / pops their outer plastic sleeve surrounds ! )
If you had a /or/ some marginal caps . . . then . . . . .surprise . . . . .when you then try a power up, the unit comes on and plays all the way until your purposeful power down.
This equates to a similar situation of a cars lead storage battery being overnight in SUB zero weather and the next morning
it cranks up and the engine sputters ALMOST to a running state . . .until that final weakened GRR
RRRRRRRRRR of the starter.
Then you pull the battery and bring inside, to place atop a warm stove to bring up its temp. Then when at a raised tempeature taking it out and resinsttalling it, then results in that final OOOOOMPH to get an engine start up.

What do I do now ?

Well I would be checking all of the capacitances and voltage specs on all af those caps that I have preassigned Alfa I.D.'s to.
I suspect the use of 470's ,1000's and possibly a 2200 or 3300 thrown in, for " C through K " and do take note of the highest and lowest voltage, with consideration that the highest voltage rating found could be used in all cap positions for sub in testing.
Now the one capacitor that gets CONSTANT use is being the "A" unit that provides power to the controller I.C..
It is powered by a secondary single PALE BLUE winding that initially passes thru a low value series surge " cushioning " resistor and thein into the H F rectifier diode that continually supplies it with fast rising high frequency square waves that really makes it feel like it is being continually hit with a . . . jackhammer . . .

Mechanical-Hammer-90578.gif


Thats HAMMERING being to the tune of 10's-100's of thousands times per second.
That results in heating and less electrolyte wetting and gradual onset of E
quivalent Series Resistance . . . and that ends up with even exponentially geater developed ESR and filtering + bypassing and effectiveness declines.

Consult the unit markup below and take note that the right sides cold side minor supplies ( 12 & 23VDC ) has its VIOLET wired one that seems tto be laid out logically.
I surmise that what seems to be the 23(4)VDC minor supply with its smaller profile diode receives the VIOLET wire from the secondary of the power transformer via the initial low value " cushioning " resistor and into the high speed rectifier diode and then its outputted pulsating DC goes into the "F" filter capacitor. This is the first of a pi section filter consisting of an E-cap then a series inductive filter and then a final E-cap . . ." K" .
The very first F cap catches a REAL HAMMERING from those DC pulses hitting it, whereas the intermediate inducive filter dampens the remnant ripple out from the F cap on into the K . . . E-cap, much akin to the way a Mercedes SL350, whipping along at 160 mph on the Autobahn, is tempered down by the confront of encountering a hairpin U curve.
That connection routing would be for your 24VDC minor power supply .

I then might surmise that The B LUE path of the supply to the E-cap will be for the 12VDC supply of another minor supply.
Without seeing the bottom of he board I must stop at that point of wiring progression.

THEN the real MAJOR supplies of interest would be the GREEN and RED supply lines and their MUCH larger current capacity diodes and their outputs of the 5VDC and 3.3 VDC, real workhorse power supplies of the unit.
I also must stop with their connections at the points shown, but I am assigning their functions in accordance to both . . . their arrangements on the output connector PLUS the logical position of the +5VDC supply is being physically aside to the TL431 adjustable zener associated with sampling one of the power supply outputs.

NOTE . . . you speak of TWO 3.3VDC supplies . . . . do you not see the BLACK wire on the J2 / CON end connector having a bare wire jumper that establishes another GND at the side of the marked 3.3V connection ?

I am seeing that the RED supply line uses the HEAVY diode to feed into the inittial "C " E-cap for the first of the 5V supply origin . . .then I need foil confirmation of which GREEN 100uh filter inductors that it feeds into . . . but, suspicioning the top one.

Sooooooooooo this 5VDC supply is aditionally sampled and fed into a resistive voltage divider bridge , associated with the TL431 precision adjustable zener. It then feeds into the PC817 family of photo couplers internal LED .
The other half of the 817's photransistor responds to the light output of the other sides LED illumination to feed to the control pin of the "365 IC . If it determines a 5VDC voltage pull down from loading, it incrementally widens the outputted drive pulse to the internal power FET to increase the power to normal. If detecting a rising voltage (that's you ) it is supposed to decrease the drive pulse width.

TESTING PROCEDURAL . . . . .

Now I am expecting 3 associated E-caps to be relevant with your PRIMARY problem.

There is the EVER taxed " A " capacitor that runs ALL the time. Now, if that is being the 47 ufd unit that now tests as 36ufd . . . .that is a good clue of a cap having time/use/heat developed multi ohms of internal ESR , and ACTUALLY may only be presenting the actual filtering / bypassing functionality of its actual resultant 5-10-22 ufd ofcapacitance.

Back at the " B " E-cap, it is being associated with the time constant of the regulation correction. If having declined from its 1 ufd on down to O.1 ufd it might have the supply so hair triggered, that it would be bouncing up and down on voltage change.

Lastly, there is the very first "well hammered" "C" input E-capacitor of a pi filtered C-L-C network of the 5VDC supply.
It is also MOST suspect, since any pulling down of it by loading will mess up your source input referencing into the previously explained regulator circuitry.

See if subbing in new /good A and C's E-caps . . .and a possibly slight suspicion of " B " . . . . will not get you operating again as normal.
If so then you KNOW that ALL of the units E-caps need replacement with PWEMIUM . . 105 degree temp grade units .
That units SAM YOUNG ( Sami Yung) certainly sold a lot of caps to Original Equipment Manufacturers, but they weren't particularely known as being PWEMIUM BWEWED units.

POST ADDENDA . . . .
Just now caught your final "big cap" comment and if that is being my "L" marked unit, that is being an AC line derived, main high voltage supply, but is also critical in providing GOOD decoupling / bypassing through the unit.
As the POWER FET within the "365" is pulling high current pulses from it at a high run fequency. With a time developed high ESR it will cause the "365" to run
hotter than is being the norm.
Its sole heatsinking is being the foil plane that a few redundant pins of the IC is soldered onto.


MARK UP REFERENCING OF POWER SUPPLY UNIT . . . .


Sat-Rec-P-S-2.png




ADDITIONAL PLEA . . . . .( Plus, also, all of the E-caps voltage and capacitance values.)
upload_2020-4-22_13-10-31.png


73's de Edd . . . . .


I bought a new vacuum cleaner for my wife six months ago and so far, all it's been doing is gathering dust, OUTSIDE, instead of INSIDE of it .


.
 
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73's de Edd

Aug 21, 2015
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Certainly not directed at me . . . .as I only see Tattoo . . . doing any SHOUTING . . . .and as far as any. concern to that situation . . . .he is in long time R.I.P. . state.
 
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