Lenovo Yoga 7 laptop - flashes the white power led three times quickly

[gadgetfixup]

How to you check for the requirement of reverse polarity when you don't have the OEM charger?

I can't remember the last time I found reverse polarity. Barrel outside is ground, inside barrel is positive and center pin is sense voltage. I don't think you'll have to worry about reverse polarity in modern laptops. These days, we require customers to bring in their chargers so we can make sure they are functioning correctly.

 

[HCHTech]

These days, we require customers to bring in their chargers so we can make sure they are functioning correctly.

We ask, but don't "require" the same thing. I absolutely get the idea, and it's a good one - we just haven't made the step where we won't work on a laptop if the customer forgets their charger. New Year's resolution, maybe?

 

[Larry Sabo]

These days, we require customers to bring in their chargers so we can make sure they are functioning correctly.

Why? One can test and fix laptops without the OEM charger, most of the time. If they bring it, sure, check to be sure it is outputting 19v. But requiring it before accepting the job?

 

[NviGate Systems]

The centre pin is both a sense wire but also one wire circuit that communicates with a chip on the charger.

For testing it's not needed as most models now will warn and reduce power when there is no signal.

It's worth to have a bag of 5.2MM barrel connector to laptop adapters, you get them on Amazon cheap, you can even use other brands of laptop adapters by chopping off the end and re wiring it with a standard barrel connector, that's what I've done. I even have a MacBook Magsafe charger that's just the wire that you can plug any charger in with the right voltage.

You can even get creative with USB C with those PD adapters that will use PD to get voltage to an analog wire, great if you want to skip the bench power supply but have a decent USB PD setup.

 

[britechguy]

Why?

For me, it's simply because the charger itself could be bad. If they're bringing a laptop, they need to bring its power supply as well.

To each his or her own.

 

[Larry Sabo]

For me, it's simply because the charger itself could be bad. If they're bringing a laptop, they need to bring its power supply as well.

Yes, the charger could be bad but in my experience, the charge is bad in less than 5% of cases. To me, it seems pointless to turn away a job where there is a 95% chance the charger has nothing to do with the problem. But as you said, to each his own.

 

[gadgetfixup]

Why? One can test and fix laptops without the OEM charger, most of the time. If they bring it, sure, check to be sure it is outputting 19v.

Several reasons:
1. Make sure the charger is good.
2. Make sure it's the correct voltage/amperage
3. Make sure it has no bent or missing sense pin that could damage a new port we install.

We used to do like you and never required a charger. We changed our policy after getting a few negative reviews that could have been avoided if we had the charger.

The straw that broke the camel's back was repairing an HP, typical busted jack and shorted protection diode. The customer took it home and called up, screaming that they had paid $150 and that we hadn't fixed the problem. I asked them to bring it back with the charger, and sure enough, the pin smashed sideways and busted the new jack we installed. We replaced the jack pro-bono, sold them an HP charger, and for our troubles? We got a negative review saying we charged $150 on a laptop repair when it only needed a charger (according to the customer). The customer's wife deduced that since it didn't charge after our repair, charged after we replaced the charger, that's all it needed. All the rest of our work was unnecessary and nothing we said would change their mind. We are a rip-off shop taking advantage of people.

We're blessed with an abundance of work all the time; if we get slow, we might change our policy, but we've avoided a few times similar problems. Gaming laptops with underrated aftermarket chargers, customers buy AM chargers, reversing the polarity, or selecting the wrong voltage. Just better for us to make sure we're giving them back something without issues.