Near Hopeless Laptop Repair

When it comes to polarity I've found there is no guarantee. Check the board on both the brick and on the computer you might get lucky and see a polorized cap or diode or some indication of polarity on either the center pin or the outer contact.

Beyond that you know what to do I'm sure.. You have posted the skills often enough.

Yay! Mex save the day! Again :).

Glad it worked out, sorry about the lousy shipping and customs issues.

Success!
Thanks to your help. The old Compaq brick was labelled 19.0 volts but powering the laptop voltage was 19.55

I realize it doesn't make any difference but am surprised at the sloppy treatment of labeling accuracy. The new brick is almost one ampere greater power. Should last him a long time. Soldered directly to tip conductors. No tangs or solder ports provided. Then came six layers of adhesive shrink tubing. Fat for finger gripping, and strong for strain relief.

At the moment Alicia is up to her rear in alligators preparing taxes. The late fee fine is 148% of tax due, meaning one minute late = 148% of $56,000 pesos (at 17 to the dollar). I get to play the part of "hero" today.

Thank you. Tomorrow if you should see a mushroom cloud on the horizon and hear "Yipa! Yipa! Yipa!" You'll know something went wrong.

To determine polarity on the laptop connector, simply remove the battery, and using a reliable digital multimeter, measure continuity from the negative battery terminal to the charging port connector. The negative side will measure 0 ohms to the negative side of the connector. The negative connector wiring will always be common, not going through any regulator, etc. Most always the outer ring is negative, but this method will remove any doubt.

The price is not an issue. ADUANA. Mexican CUSTOMS has every and all last method of shipping diverted to Mexico City. No PC's are allowed only laptops. There is a hundred dollar allowance made for personal items. After that it's full bore right up the chute. The 329 dollar computer would become five hundred dollars after taxes, and the nearest ANYTHING office is A THOUSAND MILE ROUND TRIP. Using Mexican mail would cause a massacre. Seven or eight people would be trying to kill the others to get their hands on the Postal Laptop (after it clears customs in Mexico City - but it would never get there by mail. Try four or five miles afer crossing the border. It is REALLY discouraging.

I had to use intense magnification and a direct beam of a 30 watt LED lamp to make out the 19.5 volts. The pin polarity orientation had been rubbed completely off.

The store taxes are on the hard drive and they can't even access their cloud account. Federal tax is infinitely more cumbersome than any USA tax. It takes hours and hours to complete. When someone goes a THOUSAND ROUND TRIP MILES they will pick up a computer.

When I asked the store manager at Costco Morelia Michoacan WHY a computer that cost four hundred dollars in the USA cost almost seven hundred dollars in COSTCO. Here is his verbatim reply:

"This is not the USA"

The computers were absolutely identical. They were PC's.

There is absolutely no way to get around the mail / commercial carrier 10-day detour to Mexico City.

Think this is bad? Aduana assessed a THREE HUNDRED PERCENT TAX on a tourist's Honda axle shipped direct from Japan (the only source).

Flip a coin time. I'm going to solder the old tip onto the Compaq's brick with center pin positive and hope for the best. After cutting off the injection molded plug sleeve, I am left with manufacturing a sleeve using multiple layers of 3/8" 4/1 heat shrink tubing.

Can you imagine a cell phone store selling a used 1.0 GHz 2008 laptop with Windows XP Espa?ol for TWO HUNDRED DOLLARS? The battery is no good. And it's only a 155 mile drive distance.

But to put this issue to sleep, may I say I am supremely pleased with the information about polarity and the compatibility of a 19.0 volt brick from my old Compaq. I know you folks cannot know about the hassles of shipping stuff in (My new BiPAP masks worth $400 were seized in 2008).

I grin and flippem-off driving through Customs at the border when contrabanding merchandise. My LED lights are being sold at prices affordable to Mexicans. On top of everything else, the fishing cooperative here employing 800 in a town of 3,000 went bankrupt last February.

Thank goodness the USA has Canada and Mexico as neighbors instead of Iran and North Korea.

But a minor but important miracle was achieved thanks to you. Happy New Year! ¡Prospero Año Nuevo A Todos!

The laptop is OLD. The nearest place to buy a 400 dollar replacement for 800 dollars is a 600-mile round trip.

B&H in NYC ships to Mexico and they have the Dell 15.6" Inspiron 15 3000 Series Notebook for $329 .

MEXICOWANDERER wrote:
WAY WAY south of the border.
UPS, mail, computer parts a thing of dreams.

An OLD laptop works fine. Dead battery. Power supply 19.5 volt brick burned its circuit board. 2.8 amps @ 19.5 volts. Battery says 10.0 volts.

I have a spare 19.0 volt 3.8 amps power brick

But the laptop plug is larger on the bad brick laptop.

Zero continuity on the OUTER plug conductor. This plug is darned near the size of a RG6 coax fitting with no threads of course. It is merely big.

Question. No way to determine polarity orientation. Is the center wire connector ALWAYS the positive conductor? Meaning the outer ring is the negative connector?

The original umbilical is bad I assume at the plug. If I scalpel cut the plug strain relief am I going to find something I can heat and wick the solder off? Attach a replacement cable (the replacement brick) then run several layers of adhesive heat overtop?

The laptop is OLD. The nearest place to buy a 400 dollar replacement for 800 dollars is a 600-mile round trip.

The computer is used for a small business not for pleasure.

Any help or comments will be greatly appreciated. I am by no stretch of the wildest imaginatiin a "computer tech". Thanks In Advance!

One thing I have learned over the years as an electronic tech is to NEVER "assume" anything..

There is no hard and fast rule as to how a low voltage plug is wired, it could be pos inside or it could be pos outside. Generally it will be pos on the inside BUT one should always verify the actual polarity before engaging a potential display of smoke.

I know this is not the answer you were looking for BUT I would recommend SKIPPING this power brick you have and BUYING a new UNIVERSAL laptop power brick.

The Universal Laptop bricks come with a multitude of specially made adapters, one should fit your laptop. Secondly, the some Universal laptop bricks will also CORRECTLY MATCH THE VOLTAGE for the adapter selected and others have a manual switch. Just pick the correct adapter, set the voltage and you are done..

The 19.5V at 2.8A is a 56W brick so you can use any 60W or greater universal laptop power supply..

HERE is a 70W with adapter tips for $13.. as an example..

Mex,

I get to do this sort of lash-up more than I like, but I have usually been successful. You have a good brick, that is one hell of a good running start. In my experience, the 19.5 vs 19.0 will make no difference. The supply voltage is usually above the required to operate and charge the internal battery to make battery charging faster.

If the dead brick does not have the polarity on it, you can possibly get probes into the connector and find a polarity. You should also look at the label on the bottom of the unit, I have found connector specifics there as well. Then, there is always the manufactures website that might be help.

Barring those, remove the cable from the dead brick. When you plug that into the unit, you may be able to put it in the good brick.

If none of those are good, come on back. I have more, but some are not simple.

Matt