Author Topic: Bench PSU suggestions for laptop/phone repairs  (Read 273 times)

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Offline Technomancer

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Bench PSU suggestions for laptop/phone repairs
« on: April 17, 2020, 09:25:04 pm »
Hello folks,

Sorry for another "PSU suggestions" thread but I could use some advice. I am looking to get a bench PSU to do some board work on laptops, phones and probably some other things to as I get more into it. I am a complete n00b, however, when it comes to PSUs like some of the ones you guys talk about here.  I have seen several posts about the Rigol 832(a) that some people seem to like but just as many extolling the virtues of buying one from a better brand such as Agilent or Keysight. Being fairly new this I don't really know what would be considered under-performing or overkill for types of repairs I was mentioning. I don't really have a budget per se but as I am just starting out with this I am not looking to break the bank on a unit that I would likely never fully use to its potential. Any suggestions you can offer (and reason why you suggested it) would be greatly appreciated.
 

Offline Messtechniker

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Re: Bench PSU suggestions for laptop/phone repairs
« Reply #1 on: April 17, 2020, 09:55:12 pm »
How about some requirement specs?
For powering laptops you will at least need something like
19 VDC and/or 21 VDC current limited to about 2 to 3 A.
Possibly also other voltages and currents depending
on the type of laptop you are planning to operate.

Plus a good selection of laptop power supply plugs.
There are about 40 different types.  :palm:
« Last Edit: April 17, 2020, 09:56:48 pm by Messtechniker »
Agilent 34465A, Siglent SDG 2042X, Hameg HMO1022, R&S HMC 8043, Voltcraft VC 940 and M-Audio Audiophile 192
 
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Offline Technomancer

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Re: Bench PSU suggestions for laptop/phone repairs
« Reply #2 on: April 17, 2020, 10:26:15 pm »
18.5v to 21v is the right range for the laptops. As for the chargers, I am most likely going to be looking at MacBooks and devices with USB charging ports which I assume you can just take the ends off of the cables and wire directly to the lugs on the PSUs but as I mentioned I am a n00b so if I am way off base with that, please let me know.
 

Offline Gandalf_Sr

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Re: Bench PSU suggestions for laptop/phone repairs
« Reply #3 on: April 18, 2020, 12:17:57 pm »
If all you want to do is provide power for a laptop or phone then the DP832 or DP832A is way over spec; it's a triple output supply and costs $450 or more (street price).

You might consider something simpler like a 30V, 5A single linear supply (you need at least 5A as many laptop PSUs these days are over 100W (power is volts x amps so 20V x 5A is 100W).

You can set up a lead that plugs into your laptop with bare wires at the other end that you connect to the PSU but it would be better to make up a cable that has banana plugs  on it to plug into the PSU; don't plug it in backwards or you will likely mess up the laptop!  Some laptops have special power supplies that 'talk' over the DC supply line so you won't just be able to connect to a bench PSU and have that work. And no, even fancy bench PSUs like the DP832A don't do that stuff.

Something as simple as this $44 from eBay would be a sensible, basic, linear supply and for $100 you would have many to choose from. Don't buy a switched mode one, they are horribly noisy (electrically) on their outputs.
If at first you don't succeed, get a bigger hammer
 

Offline nctnico

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Re: Bench PSU suggestions for laptop/phone repairs
« Reply #4 on: April 18, 2020, 12:27:54 pm »
18.5v to 21v is the right range for the laptops. As for the chargers, I am most likely going to be looking at MacBooks and devices with USB charging ports which I assume you can just take the ends off of the cables and wire directly to the lugs on the PSUs but as I mentioned I am a n00b so if I am way off base with that, please let me know.
That won't work. Many devices negotiate with their adapters about voltage and power nowadays.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 


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