Repaired laptop charger , is it safe to use ? - General query

[jarvis7]

Re: Repaired laptop charger , is it safe to use ? - General query

now my charging pin is physically loose .. so it could have happened because of that .. but even intentionally when i try hard to make the contact loose , it doesn't loose the charging or the charging led doesn't switch off.. so i suspect it is of bad cap.. anyways i would like to replace it.. though it is working fine now


My money says the cause was a bad connection this whole time.

Many, many times I have had continuity of 0ohms. yet it was barely making contact and therefore could not pass much current.

I had this happen on a laptop charger that failed because the wire was bad right were it came out of the charger.

Another laptop had a loose VCC(broken solder joints). I assume you know what VCC means? (where the charger plugs into the laptop)

thanks , yes sir you are absolutely right.. the wire near the charger pin was loose and was on the verge of breaking .. cutting it and making a fresh joint there, fixed it ..

though still want to replace the cap because it is a general purpose cap and it is of bad quality..

Thanks a lot for your reply

[momaka]

Re: Repaired laptop charger , is it safe to use ? - General query

my existing g luxon cap is 10 x20mm .. with hardly any extra space for diameter or height

in 1000uf 25v rubycon ZLJ i am getting 20x10mm .. in 1200 uf i am getting 10x25mm

now if i go with 1200 uf 25mm height then the cap height will be too much and top cover wouldn't fit properly .. i can duct tape it with protruding cover adjusting it somehow and managing it with protruding cover .. But is it worth it .. is 1000uf going to be detrimental to ripple and harmful for motherboard ? this is for a 15w tdp pentium 3558u laptop

Cap's have 20% tolerance anyways, so going down to 1000 uF won't cause issues in most cases.

additionaly there is Panasonic FS in 10x20 1200uf .. but this is new series if i am not wrong and untested and i would like to stick to Rubycon and panasonic costs more

Panasonic FS is basically Panasonic FM/FR shrunk down further into a smaller caps. With Panasonic FM and FR being good caps, I'm pretty sure FS would be fine too.

Of course, if that's too expensive for you, then the 1000 uF Rubycon ZLQ should be fine too.

[jarvis7]

Re: Repaired laptop charger , is it safe to use ? - General query

Thanksss a lottt sir

Just last question

i have 2 options

1000uf 25v ZLJ - rated ripple - 2500 , impedance 20c - 0.028 , -10c - 0.084

1000uf 25v ZLS - rated ripple - 1960 impedance 20c - 0.020 , -10c - 0.060

which of the 2 will output lowest ripple / will be better performance wise ? and what is the deciding factor higher ripple rating or lower impedance value

just out of curiosity, one of the low ESR series you mentioned YXJ , in 2200uf 25v capacity has a rated ripple - 2230 , impedance 20c - 0.032 , -10c - 0.11 .. it has both lower rated ripple and higher impedance than1000uf ZLJ , does that mean the 1000uf ZLJ is actually better than 2200uf YXJ and will perform better and output lower ripple ?

if yes, then aren't uf values pointless without ripple rating and impedance values ?

Thanksss !!!!

[momaka]

Re: Repaired laptop charger , is it safe to use ? - General query

which of the 2 will output lowest ripple / will be better performance wise ? and what is the deciding factor higher ripple rating or lower impedance value

There is no universal "this is better than that" answer here.

Depending on the PSU design, one cap may be better than the other. But the two caps you are comparing (ZLS and LZJ) are pretty close in terms of specs, so you would probably get very similar performance with them, regardless of which one you pick.

ESR is probably what should be used as the deciding factor. The ripple current rating is what tells you how much AC ripple the cap can take before overheating (i.e. fluctuations in the voltage/current of the circuit). In general, you don't have to be very exact with it, as most circuits should be designed to stress caps with ripple current much below their rated value. Thus, usually I think it is better to pick caps based on ESR when trying to match original caps.

However, in your case here, I am more inclined to pick ZLJ, as laptop lower adapters use flyback topology, so the higher ripple rating may help the cap stay cooler inside the adapter.

just out of curiosity, one of the low ESR series you mentioned YXJ , in 2200uf 25v capacity has a rated ripple - 2230 , impedance 20c - 0.032 , -10c - 0.11 .. it has both lower rated ripple and higher impedance than1000uf ZLJ , does that mean the 1000uf ZLJ is actually better than 2200uf YXJ and will perform better and output lower ripple ?

The ZLJ is indeed "better" than the YXJ (that is, it has lower ESR and higher ripple current). BUT! - that doesn't mean any circuit will perform better with it. There are circuits where the YXJ with its "inferior" specs may be better;

if yes, then aren't uf values pointless without ripple rating and impedance values ?

No.
The capacitance and voltage rating determine how much energy a capacitor can store. The ESR simply tells you how "easily accessible" that energy is when going from/to the cap. When a cap has really high ESR, energy (current) cannot come in / go out of it very fast, and that can make the cap appear "useless" to the circuit. So in that sense, YES, when the ESR is too high (due to faulty cap, not due to specs), then the capacitance becomes irrelevant.

[jarvis7]

Re: Repaired laptop charger , is it safe to use ? - General query

Thankkk you so much sir !!!

it got delayed a bit but now Ordered ZLJ as per your recommendation

Thanks once again for all the help

[jarvis7]

Re: Repaired laptop charger , is it safe to use ? - General query

Thanks Momaka sir

as you know I got the caps replaced with Rubycon ZLJ and Nichicon HE , i don't know if this is a cause of concern or not ..

When i plug in earphones , i can hear some very low background noise in earphones , that varys in pitch if i put load on CPU .. This only happens when laptop is running through adapter , and noise disappears when it is running from battery , noise is slightly louder when i just simply touch earphone jack to USB or HDMI or VGA port


Does this indicate very high ripple coming from PSU ?

Adapter is made by Lite On

Thanks

[momaka]

Re: Repaired laptop charger , is it safe to use ? - General query

When i plug in earphones , i can hear some very low background noise in earphones , that varys in pitch if i put load on CPU .. This only happens when laptop is running through adapter , and noise disappears when it is running from battery , noise is slightly louder when i just simply touch earphone jack to USB or HDMI or VGA port

What kind of noise is it? 50/60Hz line buzz (like from a transformer) or just random squealing when the computer is doing something?

The latter may be normal. I have seen a lot of laptops and (some) desktops with noisy audio. So I wouldn't worry about that.

If the noise sounds like 50/60 Hz (or rather 100/120 Hz) buzz, maybe there was a grounding wire/circuit that wasn't installed properly when the tech serviced your laptop. The only other thing I can think of is if the input capacitor in the charger is starting to go bad (low capacitance).

Also, could this noise been something that you just never happened to notice before? (But was there even before the recap?)

In any case, it doesn't sound like a big issue (if at all). As long as the adapter has good caps on the output, it won't be able to misbehave too much.

[jarvis7]

Re: Repaired laptop charger , is it safe to use ? - General query

Thank you sir ,

Yes it is like 50hz sound pattern.. i just noticed this a few days ago , maybe it was there before also , ..

i also tested this on my other 2nd laptop ..it isn't audible normally , but when i put my finger/skin on earphone jack and then touch it to any metal part of port i can hear it slightly

on this 1st laptop , it is audible without touching skin.. and when i touch skin it gets much more louder..

the other 2nd laptop's noise maybe is only 20-25% of volume of noise of this 1st laptop i.e - this 1st laptop's noise is much higher

Input capacitor looks fine as with 82uf primary cap and llikely around 15 watts of load of my laptop under cpuz stress , this is able to give me a hold up time of more than 100-120ms

should i leave it as it is if it's nothing or should i open the charger up if it is harmful and fix grounding wire ?

Thankss

[Th3_uN1Qu3]

Re: Repaired laptop charger , is it safe to use ? - General query

Charger may not be at fault here (buzzing noise problem), maybe you are plugging it into an outlet with no earth?

[jarvis7]

Re: Repaired laptop charger , is it safe to use ? - General query

Thank you The unique sir ,

yes i don't think i have an earth in my outlet , is this something to worry about ? and does this have negative effect on laptop's life ?


Thank you

[Th3_uN1Qu3]

Re: Repaired laptop charger , is it safe to use ? - General query

It should not have any negative effect on the laptop. It may tingle you a bit though if you touch a metallic part of the laptop and an earthed appliance or another earthed object such as a water pipe.

There is a way of getting rid of the buzzing noise - just remove the Y capacitor(s) in the charger. They are colored blue and go across the isolation barrier between primary and secondary of transformer. Doing this may cause the charger to generate other kinds of interference though, but it will not affect its operation in any way so you can try it out and put it back if it gets worse.

The Y capacitor in your photos of the charger is the blue blob with heatshrunk leads, near the input AC socket.

[jarvis7]

Re: Repaired laptop charger , is it safe to use ? - General query

thank you sir , Then i'll leave it as it is if it doesn't have any negative effect on laptop

noise is very low , so it isn't irritating or distracting ..

Thank you !!