[SOLVED] 820-3115-B Pulsing charger light

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Japtastic

New member
Very new to this so may be an obvious one.

Corrosion around the area pictured.

Fuses and resistors in this area test ok.

Have replaced:

C6991
Q7030
Q7035
Q7630
Q7080
C7030
C7035
Q7931

Pulses the green charger light the same as it did before the swaps. Fans spins for between 0.5 - 3 seconds every 1-2 seconds. If you listen very carefully, a tick.. tick....tick noise is coming from somewhere over the side of the board where the corrosion was, at least that's where it appears to be coming from. When the fan is spinning the tick...tick.tick disappears. This was still audible when all of the above components were off the board. Any clues please.

Cheers

Stewart
 

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Japtastic

New member
Thanks for the reply. Unless the donor U7000 is also faulty, no joy with replacement. Back to the same situation. Ticking persisted even with U7000 off the board. C7020 and C7050 don't test as shorted...
 

Japtastic

New member
PPBUS_G3H = 3.6v while pulsing/ticking 11.65v when fan spinning
PP3V42_G3H = 3.45v Constant

U7000:

Pin1 = 16.3v Constant - 0.1-0.2v drop when fan starts
Pin2 = 16.3v Constant - 0.1-0.2v drop when fan starts
Pin3 = 3.9v Constant - 0.1-0.2v drop when fan starts
Pin4 = 3.42v Fan off, 0v Fan Spinning
Pin5 = 0.2v Fan Off, 2.8v Fan Spinning
Pin6 = 3.45 Constant
Pin7 = 0.7v Fan Off, 2.8v Fan Spinning
Pin8 = 0.44 Fan Off 1.63v Fan Spinning
Pin9 = 0.03v Constant
Pin10 = 3.45v Constant - 0.1-0.2v drop when fan starts
Pin11 = 3.45v Constant - 0.1-0.2v drop when fan starts
Pin12 = 3.45v Constant
Pin13 = 3.14v Constant
Pin14 = 2.36v Constant
Pin15 = 0v Fan Off, 0.05v Fan Spinning
Pin16 = 2.8v Fan Off, 10.02v Fan Spinning
Pin17 = 2.8v Fan Off, 10.72v Fan Spinning
Pin18 = 3.5v Fan Off, 11.4v Fan Spinning
Pin19 = 5.02v Constant
Pin20 = 5.02v Fan Off, 4.96v Fan Spinning
Pin21 = 0v Fan Off, 1.22v Fan Spinning
Pin22 = 0v
Pin23 = 3.5v Fluctuation Fan Off 14.6v Fan Spinning
Pin24 = 3.5v Fluctuation Fan Off 16.2v Fan Spinning
Pin25 = 4.53v Fluctuation Fan Off 14.6v Fan Spinning
Pin26 = 14.6v Fan Off, 14.3v Fan Spinning
Pin27 = 0v
Pin28 = 0v
 

aprendiz

Moderator
Resistance between pins 17 and 18 should be about 3ohm and between 27 and 28 should be 20ohm, check if those values are true in your board please....
 

larossmann

Administrator
Staff member
I don't buy "no resistance" between pins 17/18 and pins 27/28. Please do not use meter in beeping mode, it beeps even at 50 ohms. Read resistance off it and check again!
 

Japtastic

New member
Thanks for the replies chaps. I've just had another go to be sure and it's definitely the same results as before. OL between those pins. I even changed the battery in the meter. So I understand the train of thought here, what will these results tell us?

Any idea what the ticking noise is that I can hear?
 

Japtastic

New member
Sorry, my bad, lack of experience and lack of decent, unbroken sleep meant I ballsed up the terminology.

Pins 27 and 28 have continuity to R7021 and R7022 are correct at 10ohm
Pins 17 and 18 have continuity to R7051 (2.5ohm) and R7052 (0.3ohm)

Any clues on ticking noise?
 

larossmann

Administrator
Staff member
We mean resistance between the pins themselves, not to the resistors. Measure with one probe on pin 17, the other on pin 18, in resistance mode, and te same again for 27/28. This will tell us if there is a break in the current sensing circuit. if the machine an't sense how much current the battery or the charger is using it will turn it off, which is why you get a flickering light. Noise no idea, probably something switching on and off. Fix current sensing first.
 

Japtastic

New member
Tested again just now. No reading between Pins 17 and 18 or 27 and 28. So a break in the current sensing circuit then?

Again, apologies for the balls up and appreciate the patience.
 

Japtastic

New member
:(:( OL is open line, the exact opposite of no resistance. Check all the resistors between those pins and check continuity between them.
Ok, so I retested the continuity. Same results.

Pin 27 has continuity to C7020, C7022 and R7022 which tests correctly @ 10ohm
Pin 28 has continuity to C7020, C7021 and R7021 which tests correctly @ 10ohm


Pin 17 has continuity to C7050 and R7052 which tests @ 0.3ohm, schematic says 0...?
Pin 18 has continuity to C7050 and R7051 which tests @ 2.5ohm, schematic says 2.2...


I'm a little lost of where to check next. I can't understand why, if the components are testing fine and continuity is fine why I'm not getting a reading between pins 17+18 and pins 27+28. Is the only explanation that the U7000 from the donor board is also bad or is there something else to check?
 

Japtastic

New member
Have always been testing from the pins. Just checked at higher zoom and no line breaks. Continuity confirms this also, tested between pins and pads and every combination.
 
I don't know how many other ways there are to tell you the same thing. Either you are using your multimeter incorrectly or you're looking at the wrong thing on the board.

Look at the schematic and find the two current sensing circuits, CSI and CSO. Trace them out and back into the ISL with your finger. Measure the three resistors for the correct resistance. Then measure that there is no resistance between each resistor along that path that you traced with your finger. Do the same for both circuits.
 
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