Reusing power sources to power devices of different voltages: voltage converters

42V DC Power 19V 2A regulated DC to charge a laptop that spends 3A

In this post we will see how to feed these appliances we have at home, whose power supplies had stopped working and left, forgotten, in a drawer.

For example, that portable power supply can have a second life and continue feeding any device that requires a power exceeding the capacity (watts) of the transformer. While we maintain the amps equal or exceeding the needings by the apparatus we want to power, we just have to make sure that the voltage output is the same or little less of your device needs.

If for example we need an  e-bike charger, or need a charger of a given voltage, we can adapt economically the output voltage: This is where the boosters and converters come into play modifying voltage DC to DC.

Repairing a Chinese Li-ion battery charger 42V "Rait" brand

The circuit: in one UF1004 dissipating diode and a MOSFET 600V N  MDP11N60 (left)

A collegue had broken his battery charger, he told me that he had left running, hitting an explosion when going to charge his battery 20Ah scooter for the last time .

Normally when a small explosion sounds, it is that any electronic component has gone to hell, so I checked the components and at first sight there was nothing broken, not even the MOSFET had been damaged.

It is  quite simple transformer of 180 / 240VAC to 42 Vdc with 5A load capacity (although the actual output voltage 40,7V are even better for the longevity of the battery), of unknown Chinese brand that came with the battery of 20Ah Chinese acquired.

In reviewing the tracks below, we see what happened: the track that connects with the departure had not stood the peak intensity of the moment to connect to charge the battery (capacitors can deliver a significant current at the time of connection); It is that by design has 3 tracks (possibly to put resistors as a fuse in the Tinned areas) but only one was connected.

Changing the hard drive of a Lacie Network Space 2

A couple of years ago I bought this super NAS (Network Storage) Lacie with Linux operating system, good performance and very low power consumption (you can set it to shut off at 20 min. without use, very convenient for longer life of your hard drive).

The disc It had got too small, so using Clonezilla, I opened the box (to do only handle in the area led out all the cover up), and I cloned the 1TB disk to another larger than 2 TB. To exploit its full capacity, we have to resize the XFS partition data to use all the free space remaining with the Gparted (free Linux program).

The Gparted allows us to do all sorts of operations on partitions (image of their web)

The plotter fails to recognize the cartridge: Repairing a 500-800 HP Designjet 42 "

We had a problem with our plotter; it marked "unrecognized cartridge" error before finishing of each printed plan; when we repositioned the cartridge the problem was solved for a while, but it seemed a problem of poor contact with the cartridge chip (it was produced when the motor axis ink supply was activated).

To repair it, you have to access the module cartridges; first of all we need to remove the cover of Control, it is a matter of finding and removing all the screws, simple task and which information is on the internet, so that I refrain from commenting;)

Repairing a tape backup LTO 2 unit: HP Ultrium 448 with broken tape

In a unit Ultrium Fujitsu (HP) for backup, the tape had broken, being useless as the mechanism for capturing the tape was inside it. To repair the unit is complicated, recommended only to those who have already dealt above with similar mechanisms (VHS, glory times). 
To repair it is necessary to understand the method these units use (and many other models are based on the same principle), a curious way to save space by having a single drum in the cartridge and in the unit, where the tape passes from one side to another as information is stored, until it ends.

These LTO (Linear Tape Open) are optimized for capacity, and the latest versions, able to store 2.5TB of information in one cartridge that costs about 20 €, making it very competitive in terms of price and space currently.

After this brief introduction, let's go to the subject.

Repairing and Adflo Speedglas battery ref 837621 with LI-ION 4.2V Cells

Lately I have been repairing multiple wireless devices whose NI-MH batteries have deteriorated ; usually get considerably cheaper make you the battery pack with a new charger is to buy it new; in this tutorial I will show how to build a battery of 4500 mAh 12.6V and 3 packs of 3 cell li-ion parallel each to replace a battery 10.8V and 4000 mAh NI-MH (9 batteries in series 1.2V) with just 32 € (charger not included).

Update: I uploaded how I repair them to youtube:

HD version

And slim version.

LITHIUM battery types depending on their composition

The Lithium-ION technology has improved a lot as  the advantages of having no memory effect and higher energy density per kilogram than any other current technology , we can add that  depending on the type of materials used , allows different power / energy densities; we can have instantaneous powers from 1C (2A / time to a cell 2000 mAh) of the LI-Cobalt portable typical 5C of manganese (LiNiMnCoO2) or 15C for the past employed in Automobiles (LiNiCoAlO2) or 30C with LiFePO4 .

Repair of electronic tracks on an old keyboard: Conductive silver liquid

In this post we will repair CNC keyboard that is no longer being manufactured

Contacts on the keyboards have evolved from mechanical systems to more modern with membrane. In this case we will repair an intermediate type; this keyboard from a Gemini 8050T FAGOR around 15 years old carries a screen printed aluminum membrane for tracks and graphite contacts, on which a metal piece with flexible concave shape closes the contact when pressed.

The technology of switches on keyboards usually are of two types: contact , where some kind of spring (metal or plastic or flexible rubber, etc) keeps separate tracks of the conductive surface (graphite or other) of the button, which when pressed blend tracks; and secondly, the induction, where pressing the button, a small magnet creates a small electrical pulse in the coil of the membrane (ultra durable modern musical keyboards).

Repairing first type of keyboards often requires all your ability of "handyman"; some with copper tracks like TV remotes are often easier to repair welding on the tracks a small micro-switch if the button is completely useless, but most cases are plastic membranes that can not be welded and we can use either glue threads on them as in this entry, or use the useful liquid silver, and you will always get a more professional work to build the appropriate cable connections.

Equipment needed

1. Cutter to open the damaged contact (in other keyboards will not be necessary).
2. Cleaning liquid or solvent which does not attack the material of the keyboard; I used Ardrox 9PR5 or you could use isopropyl alcohol.
3. Liquid silver conductive, with which "will draw" deleted / damaged tracks with a fine brush after cleaning them well.
4. A tester to verify that the track drawn conducts electricity.
5. Scissors, PVC tape to cover the contact again, brush, permanent marker to draw the button again, etc.

Building your own High Quality CREE LED lamp with 700 lumens and spending only 6W

Mounted lamp with recycled parts

In this post we will see how to build a LED lamp for your house with 700 lumens with only 6W power consumption using 3 chips CREE XML T6  fed pure white 166 mA each (6W / 12V = 0,166A) a controller 220V with 6W 12V output power, and something like this cap , but I used a recycled sink another LED lamp 7W (thermally conductive plastic) and a fine of an old E14 energy saving lamp. Total Cost: € 18

The CREE LED chips are expensive but give much light per watt, high quality and durable, enduring the worst working conditions.

By making LEDs work well below their rated power (only 25% according to its spec sheet ) get more light per watt, while also reducing its temperature and lengthen your life until after 30,000 hours . A bulb in which the driver will break down before (10,000 hours estimated by its electrolytic capacitor life) before the LED. Furthermore the CRI (color accuracy) increases the lower the current.

Repairing an LCD screen: Replacing blown capacitors

The capacitors are famous for electrolytic fail when subjected to long time of use, temperature and stress, swelling and bursting the top cover where release of the electrolyte liquid inside. Many basis of old computers that had this type of capacitor plates ended up failing after 2 years, and now they are substituted for polymer electrolytic capacitors aluminum, stronger and more durable.

IMPORTANT : Before you throw a screen away because you think beyond repair, ask before budget in an electronic workshop , it may be a small thing (every day are cheaper and sometimes costs more to repair, but still not worth more than a new repair, convenient repair, you are recycling, less waste and investing in local labor).

In this case I was left a screen which two seconds to light the lamps emitting a like a very low "zzzzz" buzzing sound turned off. The sound was probably the vibration of capacitors stage transformation frequency of 50 Hz which is the AC, that being in poor condition that sound emitted.

Changing the display cable on a laptop

Acer Aspire 5930G with the display cable fixed

Earlier I commented that in several ACER laptops the picture failed by the cable, and the solution to tighten the connection area does not give permanent results, so sick of the problem, ordered a new cable from Ebay. 15 days later it came to me:

In this post we will see the steps to take to change the cable screen (make that is the problem before changing; it is not the most common).

This guide will give us the necessary guidelines to disarm any screen, since all are constructed similarly.