Bench PSU suggestions for laptop/phone repairs - Page 1
Forum section: electronics / testgear

author: Technomancer
author_rank: Contributor
timestamp: April 17, 2020, 09:25:04 pm
content: 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.

author: Messtechniker
author_rank: Frequent Contributor
timestamp: April 17, 2020, 09:55:12 pm
content: How about some requirement specs?For powering laptops you will at least need something like19 VDC and/or 21 VDC current limited to about 2 to 3 A.Possibly also other voltages and currents dependingon the type of laptop you are planning to operate.Plus a good selection of laptop power supply plugs.There are about 40 different types.

author: Technomancer
author_rank: Contributor
timestamp: April 17, 2020, 10:26:15 pm
content: 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.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: April 18, 2020, 12:17:57 pm
content: 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 asthis $44 from eBaywould 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.

author: nctnico
author_rank: Super Contributor
timestamp: April 18, 2020, 12:27:54 pm
content: Quote from: Technomancer on April 17, 2020, 10:26:15 pmThat won't work. Many devices negotiate with their adapters about voltage and power nowadays.