I've got an old phone charger which cannot hold voltage, it goes from 5V to 4V the fault only seems to happen when charger has been on for a while e.g. when warm. Fault happens when high current or low current is being drawn from charger. I've checked capacitors for capacity and ESR and I think they are still good, I've even replaced a cap to get better ESR. Fault still happens it goes slowly from 5V to 4V then interrupts power and restarts. Because it performs on high current (0.67A) and low current (20 mA) the same way I'm guessing it's not the caps but more likely the switching IC. However I cannot find the part number on whole internet. To me it reads Nb2 L5HHKA
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sounds more like a bad diode maybe.
when the output drops i wonder if it is dropping before the output diode or if it's going high resistance.
if you run it with a good load and left the output drop the bad part may get very hot - and be simpler to find - unlug it before touching stuff
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Great advice, I'm going to do that and then I'm going to measure the diode in circuit before and after fault. Life saver
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I did some in circuit measurement and forward voltage drop for output diode is 1.18 V stable. Isn't it suppose to be more like 0.5V or is it skewed because in circuit measurement? Thank you so much stjComment
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I'm answering my own question but in circuit you cannot get higher resistance and thus voltage drop than by measuring component apart so it results diode is faulty. Am I correct 💯 ?Comment
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I've replaced the diode with a beefier one, now the voltage stays between 4.95 V and 5.11V which it didn't do before. Will test it some more. All thanks and praises go to stjComment
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Just to be specific I replaced ss34 diode with sb1045l diodeComment
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After more testing, I must proclaim it fixed. I will get a lot more use out of it instead of it going to the dump. Million thanks stjComment
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nice.
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The bq24745 bq24745RHDR bq24745RHDT is a high-efficiency, synchronous battery charger with an integrated input-current comparator, offering low component count for space-constrained, multi-chemistry battery-charging applications. The input-current, charge-current, and charge-voltage DACs allow very high regulation accuracies that can be easily programmed by the system power-management microcontroller using the SMBus interface. The bq24745 charges two, three, or four series Li+ cells, and is available in a 28-pin, 5-mm x 5 mm QFN package.
The bq24745 features dynamic power management...10-23-2024, 02:50 AM -
The ISL88739 & ISL88739AHRZ are a highly versatile combo battery charger
configurable for operating as either a Hybrid Power Boost (HPB)
charger or a Narrow VDC (NVDC) charger, supporting 2-, 3-, or
4-cell batteries. Both configurations allow the battery to work with
the adapter together to supply the system load when it exceeds
the adapter capability, referred to as system Turbo mode. HPB
charger configuration reverse-boosts battery energy to the system
bus to help the adapter provide the system power in Turbo mode.
NVDC charger configuration...11-05-2024, 03:28 PM -
My multimeter has developed this fault, a few months ago. I tried to fix it, but had no success.
The fault is that on the current ranges it never shows 0. Does not matter if the probes are open or shorted.
As you can see from the pics, the offser is the same (just multiplied for other rages):
-4.9 uA
-0.49 mA
-0.49 A
I don't know what exactlly caused the fault.
The meter had a battery leak before I noticed the fault, but I am not sure if the fault was present before that happened. I just did not noticed. The battery leaked... -
I have two TCL A30 phones.
Old Phone: This phone worked fine for years, then stopped charging If you plugged a charger into it, the phone would make the charging sound, the phone would tell you it is charging, but the battery icon would not have the charging symbol in it and the battery would not charge.I tried new battery, same behavior.
New Phone: Works fine, bought as a donor board to try and repair Old Phone
My interest here is to repair Old Phone, using components parts off New Phone if needed. I am not interested in replacing Old Phone with New Phone.... -
To you programmers out there I want to know if it is possible to put a new OS on the Sonim XP5s phone? I only need this phone to make calls, receive calls, have a list of contacts and be able to call voice mail.
I bought this phone new Sep.2021 as an unlock phone from a third-party seller. The phone worked fine until Jan 2022. I then had intermittent problems with the sound setting resetting itself. One of the settings, outdoor, would go to silent all by itself. When in silent mode it does not indicate a call has come in. I missed very important phone calls. All the other setting in sound...
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