Experimental Engineering

Posted on November 11, 2021May 11, 2021 by The Engineer — Leave a comment

Clone DCB090 DeWalt USB Battery Adaptor Teardown

Since I got my new DeWalt combi drill, I needed a way to charge the batteries without having to resort to sticking blade terminals into the pack connectors – I didn’t purchase the branded charger, mainly due to cost. I also have a very capable multi-chemistry charger that handles multi-cell lithium packs with no issues, so I saw no need to replicate things. This little gadget was ordered just for it’s main pack connector; I can then use this to make up a charger adaptor cable. What this normally does is allow the use of DeWalt XR battery packs to charge mobile devices via 5v USB outputs, so there’s going to be some kind of DC-DC converter in here. There’s also a “charge level indicator” built in, which doesn’t actually do anything sensible – even on a flat battery pack, showing a single LED on it’s charge indicator shows the full 3 LEDs on this unit.
The remaining feature is a trio of white LEDs to function as a torch, but it’s less than stellar in the brightness department. Given that there’s not much in the way of control inside the battery packs themselves, I reckon this unit could actually overdischarge a pack, causing damage.

The top of the unit has a large label with windows in for the various LEDs, and a pad covering the tactile switch to operate the torch function.

The label on the side indicates the unit will operate down to 10.8v, good for the 3S packs, as well as the 18/20V packs.

Here’s what I was after – the battery pack connector. This has the full compliment of pins for all the balance taps too.

Removing a label, and a single screw gives access to the internals. There’s not much in here apart from a large PCB, with a few components.

The PCB is pretty sparse. There’s a microcontroller in the top right corner that does the torch LED switching, and the “battery indicator LEDs”. This is completely unmarked, which is very common now for Chinese microcontrollers. The only way I’m identifying this one is via a decap operation on the IC!
The USB ports have MOSFETs in their negative pin paths, probably to switch off the ports if they’re overloaded. The data pins are bridged together on one port, and connected to the DC-DC converter on the other port.

The main DC-DC converter IC is in the bottom right corner of the board, next to the input pins. This is an IP6503S multi-protocol USB charging converter, with a 24W power limit. This explains why the data pins of one of the USB ports is connected back here – it’s doing some communications with the connected device for fast charging. Chinese datasheet below.

IP6503S Datasheet

1 file(s) 757.25 KB

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Posted on October 15, 2021July 7, 2021 by The Engineer — Leave a comment

Yellow Jacket Titan P51-870 Digital Manifold Teardown

New tool time! I figured now I’m a fully ticketed member of the F-Gas community, I’d treat myself to passing the course by buying a decent set of refrigeration gauges. This is the Yellow Jacket P51-870 Titan manifold, a fully digital unit with all the useful functions built in. Basically an electronic module attached on the top of the standard Titan manifold, this unit performs all the regular functions I’d normally need either a calculator for, or other tools. The front of the unit has just a power button, LED & a large resistive touch TFT panel for display.

The rear panel has the ports for charging the internal battery, which is micro USB – this is also used to download log data to a PC from a system processing run. There are 4 3.5mm jacks for the external temperature probes, and vacuum sensor.

Removing 4 Torx screws in the back panel allows the clamshell case to come apart, showing the mainboard, and the pressure transducers screwed into the manifold. The aux jacks & the USB charging & data port are supported on small vertical PCBs plugged into the mainboard via 0.1″ headers.

With the pressure transducers unplugged from their looms to the mainboard, the module is free from the manifold section.

The muscle of the operation here is a Freescale (now NXP) Kinetis K2 Series MK22FN512VLH12 ARM microcontroller. With a Cortex-M4 core at 120MHz, there’s a bit of beef here. The LCD & touch overlay is controlled by a Bridgetek FT810Q Embedded Video Engine. The video controller communicates with the microcontroller via SPI, and the LCD via parallel RGB. There’s some SPI Flash memory up on the left, for log data storage, a Winbond W25Q32JV 32Mbit part. Just under that is a pressure sensor, which I’ve been so far unable to pull a part number off. This is required to assist in calibration of the main pressure transducers.

NXP Kinetis MK22FN512VLH12 Microcontroller Datasheet

1 file(s) 1.05 MB

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Bridgetek FT810Q Datasheet

1 file(s) 1.25 MB

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Winbond W25Q32JV 32MBit SPI Flash Datasheet

1 file(s) 2.68 MB

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In the top right corner of the board is a 74HC595 shift register, with quite a few discrete transistors & diodes hanging around it. I suspect this is used to switch between two vacuum sensors when both are plugged in – from looking at the waveforms present on the sensor interface, the power does appear to be switched ON/OFF on a single sensor at about 1Hz.

My guess at the moment is that the sensor communications are over I²C, by the 4-wire connection, and the very obvious clock & data line on the connector, but I haven’t yet looked deeply into this.

Next to the battery connector (the battery itself is a single LiPo pouch cell, double-sided taped to the front shell, behind the display), are a selection of DC-DC converters, providing all the required voltage rails. No doubt there’s lithium charging control going on here too.

Wireless connectivity is provided for by a Silicon Labs Blue Gecko BGM111A256V2 Bluetooth 4.2 SoC module. These are also fairly powerful parts, with a full ARM Cortex M4 microcontroller hiding inside, clocked at 40MHz. There are as a result two programming headers on this board, in the top left corner, for both this part & the main microcontroller.

Silicon Labs BGM111A256V2 Blue Gecko Bluetooth SoC

1 file(s) 3.89 MB

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+10

Posted on September 12, 2021April 12, 2021 by The Engineer — Leave a comment

HP 5087-7048 Directional Coupler Teardown

Time for some more RF component teardowns, here’s a very high quality Directional Coupler from HP, I believe this was part of a Vector Network Analyser at some stage. The main body appears to be made of Brass, but the entire unit looks like it’s Gold plated – the shine is far too good to be just Brass! Connections are via SMA connectors.

There isn’t much on the label to explain what the specifications are unfortunately. Nothing that can’t be found out with a quick look on a VNA though.

After removing the 6 Torx screws securing the top cap of the coupler, the internal components are revealed. There is no RF gasket or seal on the top cover, and relies on flat machining for an RF seal.

The internal construction of this unit is a little different from what I’ve seen before in directional couplers. The arrangement is usually parallel copper tracks on a suitable RF substrate, but in this case, HP have used a very small diameter Coaxial cable, covered with ferrite sleeves on the outer shield. The large square block in the middle is rubber, and may just be to stabilise the assembly. It may also be loaded with ferrite powder to give some RF properties too.
The ferrite cores are secured in place with beads of black silicone, again probably to prevent movement under vibration.

The input of this coupler is AC coupled via a capacitor, and then fed into the centre core of the Coax. The forward power output pin, visible at the top of the track, is coupled to the centre core of the coax by a tiny carbon track making up a resistor, via another ceramic capacitor. The track is more directly coupled via another carbon trace to the outer shield of the Coax. I believe this coupler is damaged, as the carbon trace that goes via the capacitor has a break in the centre, but the coupler does seemingly still work.

The other end of the coupler is very similar, although with no main line coupling capacitor, it’s direct fed to the SMA here. The reverse power output is connected the same way as the other, with a network. The carbon trace here though doesn’t have a break.