Okay sure, yes, they do protect a circuit, technically, but ultimately, why? As you said, over current... What is the resulting effect of over current?
(Hint: things getting too hot... which leads to burning... Which leads to fire)...
Agent24
I see dead caps
Last Activity: Yesterday, 03:26 PM
Joined: 10-04-2007
Location: Hiding inside a plated-through hole
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It's not functionally equivalent either.
A fuse is ultimately used to protect against fire, basically. It is not designed to save the circuit. It is designed for your safety.
The diode here is used as what is called an "overvoltage crowbar" and IS a form of circuit protection.
It is not a fuse, and it does not work the same way, nor for the same reasons....Leave a comment:
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Install uBlock Origin in your browser....Leave a comment:
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3.5" was probably more popular too since idiots can't put it through a hole-punch and stick it in a ring binder......Leave a comment:
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No, a TVS diode should not read as 15 ohms. It is effectively shorted.
The P6KE200 has a breakdown voltage of 200 volts. You would need a current-limited supply with over 200 volts to test one....Leave a comment:
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You have to be sure there's nothing using the 60Hz AC signal from the transformer as a time/clock reference or something too, if you decided to use a DC power supply instead.
If you can't fix the transformer, two separate ones should work too.
Also have to wonder if some fault on the main board overloaded and killed the original transformer.Leave a comment:
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If it's glue under SMD ICs it's probably not the bad one. The bad glue is used to secure large parts usually, primary capacitors, transformers, etc. The good manufacturers use silicone glue.
The bad ones use nasty brown or black stuff that goes corrosive. This has been known for decades but it's still in use... clearly planned obsolescence.Leave a comment:
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Did anyone check the PSU is working properly? Maybe there is some missing voltage rail or something.
If the firmware was the issue, surely the replacement mainboard would have fixed it?Leave a comment:
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If it has 4 wires it probably outputs two different voltages.
If you analyse the circuitry it connects to, you can probably guess what the other voltage is supposed to be.
Then you could probably replace it with two different transformers supplying each the different voltage.Leave a comment:
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Are you talking about the current sense resistor under the circled mosfet, about a dozen posts ago? Makes sense that would fail if the mosfet went bad, yeah. Could also have damaged the CS input on the IC...Leave a comment:
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I recall having a similar issue in the power supply of a device, turned out the pass transistor (TIP42 or such) was dying and eventually went open circuitLeave a comment:
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I think you forgot to upload the picture. We can't see anything with a circled resistor on it here......Leave a comment:
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I swear some of these manufacturers mark their parts with colour-shift paint.Leave a comment:
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Yes, I've done it before, to recover files off old disks, but I wouldn't trust the disk afterwards, the material will be damaged to some extent by the mold, it's not reliable after that....Leave a comment:
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Moldy? Happens a lot to floppies and tapes...Leave a comment:
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You may have some kind of incompatibility? Like flash drive is too big, the file system format is unsupported, maybe even the interface USB 3 vs USB 2 is some issue?
What is the model of this device? Is there any specification about what kind of drives it supports?Leave a comment:
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You're going to need a bigger heating plate, I doubt anything USB powered would ever get hot enough, unless it's using the maximum power that USB-PD can supply, and even then, I am skeptical.
Something more like this: https://www.puhuit.com/main/page_pro...reheating.html...Leave a comment:
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I have various computers with old versions of Windows (7 and earlier) around for a handful of legacy stuff but my daily usage is Linux now.
Sick of Microsoft and all the bloatware, spyware, ads and other general GUI stupidity.
And let's not forget the "Recall" inbuilt malware idea....
I will never trust a company that thought something like that was a good idea.Leave a comment:
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Got any photos of this?
Does it have the "evil brown glue" all over it, causing corrosion somewhere like the control circuits?Leave a comment:
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Remove and test out of circuit the three small capacitors C18, C16, C8
Though C18 is the most likely to cause this issue, the others might too.
D2 could also be suspect, it maybe shorted/leaky.
Another fairly likely cause is the TOP248YN, I've seen a lot of these little integrated "offline" SMPS controllers fail, in various ways, and power-cycling is one of them.Leave a comment:
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