Circuitrocks

<r>Board comes in with one bulging cap. Do I replace just that one, or all electrolytics (shotgun)?<br/>
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<B><s>[b]</s>My rule:<e>[/b]</e></B>
<LIST><s>[list]</s>
<LI><s>[*]</s>One bulged in a monitor/PSU from same era: shotgun all same-value caps, they age together</LI>
<LI><s>[*]</s>Random ...

<r>Most common bench job: laptop wont turn on. Systematic flow saves hours vs random probing.<br/>
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<B><s>[b]</s>My sequence:<e>[/b]</e></B>
<LIST type="decimal"><s>[list=1]</s>
<LI><s>[*]</s>Check adapter output with multimeter (dead brick is 30% of cases)</LI>
<LI><s>[*]</s>Measure voltage at ...

<r>Customer brings PHP 800 multimeter. "Battery dies in 2 weeks even when not used."<br/>
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Diagnosis: auto-off feature broken. Meter idles, drawing ~3mA continuously. 9V battery (500 mAh): 167 hours = ~7 days continuous, faster with high-load measurements.<br/>
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<B><s>[b]</s>Fixes:<e>[/b ...

<r>See 1-2 swollen battery laptops/phones per week. Customer reaction: "tuloy lang gamit, dahan-dahan lang."<br/>
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No. Swollen LiPo is failed thermal runaway waiting to happen. Bag near it, sleeping with phone charging, anything.<br/>
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<B><s>[b]</s>How I explain now:<e>[/b]</e></B>
<LIST ...

<r>Every week, 5-10 customers blame device when culprit is cable.<br/>
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Top failures:
<LIST><s>[list]</s>
<LI><s>[*]</s>Internal shield break near connector strain relief, intermittent</LI>
<LI><s>[*]</s>GND wire frayed, charges slow or device says 'not authentic'</LI>
<LI><s>[*]</s>Cheap ...

<r>Common repair: lifted pad from rough rework. Customer brings board, pad torn, trace exposed. Save 70% of these now.<br/>
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Tools: flux paste, 30AWG kynar wire, hot air 280C, microscope/10x loupe, UV mask.<br/>
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Steps:
<LIST type="decimal"><s>[list=1]</s>
<LI><s>[*]</s>Clean trace with ...

<t>Daily-driver pa rin Fluke 117 sa shop. Hindi ko maipakita yung pera difference sa customer, pero yung peace of mind when probing a board na hindi mo alam yung max voltage, walang katumbas.<br/>
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Yung Aneng AN-870 yung dressier-than-it-deserves cheap option. PHP 1200, 4-1/2 digit, true RMS ...

<r>Common repair: lifted pad from rough rework. Customer brings phone or board, pad torn off, trace exposed. Throw-away rate dropping kasi here is how I save 70% of them.<br/>
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<B><s>[b]</s>Tools:<e>[/b]</e></B> flux paste, fine kynar wire (30AWG), hot air at 280C, microscope (or 10x loupe), UV ...

<r>Sharing yung patterns na nakita ko sa shop. Cheap phone chargers and small wall warts ang pinaka-common na PSU failures we get.<br/>
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<B><s>[b]</s>Top 3 failure modes (most to least common):<e>[/b]</e></B><br/>
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<B><s>[b]</s>1. Capacitor failure<e>[/b]</e></B>, yung mga electrolytic ...

<t>Customer brought in a project last week, claims his 5V regulator is "fluctuating". Showed me his multimeter reading 4.9V → 5.2V → 4.7V randomly. Naka-charged yung battery ng meter, decent unit (Fluke 17B+).<br/>
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Nag-probe ako with my own scope side by side. Scope: rock-stable 5.00V flat ...