Salvaging electronic parts - Part 3 BenQ GL2430 Monitor

Summary

This blog continues a series of salvaging electronic parts, this time focusing on a BenQ model GL2430 monitor and what components could be salvaged. 

GL2430-B  BenQ Monitor

The monitor build date was from early 2011.

GL2430 Name Plate

Salvaging
The dismantling process for the monitor was skipped. The two major and two smaller printed circuit boards (PCB) removed from the monitor were: Flat panel driver board, Power supply board, Backlight driver board and Audio breakout board.

Flat panel driver board
Shown below is the flat panel driver board, single sided multilayer circuit board. This board contains the Realtek flat panel driver IC boxed in blue. Realtek part RTD2483RD. 

GL2430 Flat Panel Driver Board Top Side

Boxed in red of the image are a mixture of five serial memory devices ranging from ST Micro 24C02 EEPROM to a Winbond 2Mbit Flash W25X20. These devices are usually very easy to salvage.

Boxed in yellow are some of the numerous inductors on the board.

The semiconductor in the top right hand corner of the image is a Diodes Inc PAM8603 - 3W stereo class D amplifier. Possibly not worth salvaging as there are parts available with lower distortion ratings.

In the bottom left hand corner of the board are a pair of TVS arrays from the manufacturer InPaq 1045QU. Again probably not worth salvaging.

The crystal on the board is common video 14.318MHz type and could be repurposed if any crystal frequency is suitable.

Remaining on the board are a mixture of connectors, passives and unidentified semiconductors. If you were really scratching to find a MELF diode or 220uF Lelon Electrolytic then this board could be added to the spare parts box.

Power supply driver board
The power supply board is populated with components on both sides, double sided with a single layer PCB design. Heavy through hole components on the top side of the PCB and smattering of glued surface mount components on the solder side.

GL2430 Power Supply Board Top Side

Boxed in red is the mains common mode choke and towards the centre of the board, the switching transformer. Both these devices are manufactured by a Taiwanese transformer manufacturer. These parts can come in handy for research and design projects and a worth salvaging.

The green boxes highlight a few resistors which could be extracted for the spares bin. There are no signs of overheating or other physical damage which may have been caused by a fault on the PCB.

In the blue boxes are the diodes and bridge rectifiers. The bridge rectifier is listed as an obsolete part on supplier's websites such as Mouser so may be good for the spare parts box. The two larger axial diodes are Vishay part UG4B; a reputable brand worth salvaging once properly tested.

The two devices on heatsinks are the mains side switching MOSFET K4101 and secondary side dual rectifier diode FMX12S. At least one of these devices has discolouration in the PCB surrounding the heatsink. Heatsinks could be salvaged for other purposes.

Remaining on the top side of the board are various connectors, mains voltage rated varistors and mixture of capacitors. Usually components which have been operating at mains voltages for an unknown amount of time can left on the PCB if the operational state of these parts is unknown.

GL2430 Power Supply Board Bottom Side

Shown above is the solder side of the power supply board. To the left of the image is the switch mode controller. Across the board are a number of other parts, all glued down with epoxy. Using epoxy to glue surface mount components in order to simplify the assembly process is standard practice. The epoxy can make repair and salvaging parts difficult.

Backlight driver board
Below is an image of the backlight driver board. The main LED driver, boxed in red, is an MP3389 from Monolithic Power. Device is worth salvaging or even the entire board itself as it is a self-contained unit which could easily be reused.

GL2430 Backlight Board Top Side

Boxed in blue is an unbranded inductor which is always good to have in the spares box.

Shown in the yellow box is a SinoPower MOSFET APM1110 which was not located on the company website. Specifications are nothing to be excited over although part would be worth salvaging for prototyping.

The remaining passives such as the radial capacitors are from Lelon making the remainder of the board a contender for the spares box.

Audio Connector board
Lastly is the small 3.5mm audio connector board. The connectors are a standard pinout and could be salvaged or the entire board repurposed for a bespoke project.

GL2430 Audio Connector Board Top Side

Design Notes
A section of the power supply mains input section was chosen for some brief notes on PCB design.

GL2430 Power Supply Board Main Input Section

Boxed in white, top left hand corner of the above image, is the one of the mounting holes with exposed long pads coated in solder. This is a good feature for eliminating star or copper washers however the electrical resistivity can suffer due to the smaller contact area and surface oxidisation of the solder. It should be noted that on the component side of the board is a through hole nut allowing direct access to the mains earth connection.

In the orange boxes are several slots on the board to improve the creep distance between component pins. Slots in the board are an effective and cheaper solution to conformal coating.

Shown in the blue box is attention to detail by the PCB designer. A small pullback was applied to the copper surrounding the two mounting holes for the IEC mains connector.

Boxed in purple is a section of silk screen showing the isolation plane between mains AC and isolated DC voltages. The silk screen for the isolation plane and most components is present on both sides of the PCB making component identification and servicing easier.

Lastly the red box shows three cascaded surface mount resistors used in series to discharge the mains input capacitor connected between active and neutral. The PCB designer was mindful of creep distance and to some degree spacing between these components.

PSoC to Tracer MPPT 1210RN 2210RN 3215RN 4210RN with Bluetooth and Datalogger

Summary
Although the early EPSolar MPPT Tracer series with remote display have been surpassed by improved MPPT models with inbuilt LCDs, there are plenty of the earlier models that remain in operation. This project is Cypress PSoC 4 BLE based and features connection to the Tracer MPPT, load control, Bluetooth and data logging of the MPPT data.

MPPT
A number of other people have used the EPSolar MT-5 display to reverse engineer the communications protocol, however there was PC software from the same manufacturer which performed all the same functions, possibly more.

EPSolar Tracer RN MPPT

At last glance of the EPSolar website the Tracer series had reached obsolescence and the PC software on the site no longer supports the Tracer series.

Hardware
Initial documentation for the MPPT connections were taken from a site by Steve Pomeroy, another two sites by John Geek. The 8 way RJ connections to the Tracer were drafted with an optional zero ohm link added such that the MPPT could power the project. Buffers were added to the transmit and receive lines, although not a necessity, to ensure some protection for the PSoC from the real world.

EPSolar Tracer RJ45 Connections

For the display an OLED or LCD capable of being powered from 3.3V for both the logic and backlight was selected. In most instances this results in the LCD contrast voltage being negative however this was generated by the PSoC using the circuit shown below.

LCD Connections

Four momentary push buttons were used instead of the Cypress Capsense feature. This solution using switches was chosen only due to the design of the hardware as the PCB was to be mounted inside a box and away from the lid.

Buttons / User Interface Connections

The power supply regulator was chosen to be small and the usual buck topology. The LMR14203 has been my default single output regulator for some time, certainly there are newer devices with higher efficiency in the low current region of operation. In the event the display that was chosen could not have the backlight operate from 3.3V, a linear 5V regulator was added for testing.

Power Supply Connections

Even though the design incorporated Bluetooth, USB was added for debugging, downloading of data and upgrading of the PSoC. Field upgrades would be possibly by using the PSoC bootloader, a program allowing the active application to be updated some time in the future. The FTDI FT230X was chosen for the USB implementation however for those looking for a similar priced and reliable solution the Cypress CY7C65213A-32 would also be a good choice.

FTDI USB Connections

The PSoC selected was the CY8C4247LQI-BL483, which features a 48MHz System Clock, 128K FLASH and the all important Bluetooth. Although the PSoC4 libraries did not support SD at the time of writing, there are a few alternatives from the PSoC Community.

PSoC Connections and Supply Filtering

Lastly bringing all the sub-sheets together is the top sheet as shown below.

Project Top Sheet

PCB Enclosure
The PCB was designed to fit into a plastic enclosure with a clear lid, no bells no whistles. A Ritec case from a local supplier was used, the Altronics H0324.

Altronics H0324 enclosure

With the enclosure size selected the PCB dimensions were set to 98mm (W) x 75mm (H).

PCB Design

For the schematic and board design Altium was chosen since the board was mixed logic with RF. This combination was always in my mind a four layer board. The board layer stack would follow the usual two middle power planes and signals on the outside layers.

There were a number of parts added to the component database although none more interesting that the meandered inverted-F antenna (MIFA) to suit the PSoC4 BLE part. The antenna design was well documented in the Cypress Application Note - AN91455. This antenna was implemented as described on Page 10 of the Application Note.

PSoC4 BLE MIFA 

The board shape was drawn and a work guide added for the position of the four push buttons, then all components were place on the PCB.

Tracer MPPT Interface Board

With some quick shuffling of parts then an idea of the layout could take place.

Tracer MPPT Interface Board Parts Placement

Parts positions were changed on the PCB with some connectors and the SD card moved to the bottom layer.

Tracer MPPT Interface Board Final Part Placement

A few hours later the final route is shown below.

Tracer MPPT Interface Board Final Route

The board in 3D shows the stacking of the LCD and logic board.

Tracer MPPT Interface Board with LCD

PCB Prototype

The PCB was hand populated for both top and bottom layer. Some last minute modifications were made to the LCD connector and backlight control because the four line LCD had to be changed to another manufacturer. LCD supply pins were swapped.

Top Layer MPPT PCB Populated

Bottom Layer MPPT PCB Populated

To mount the LCD to the MPPT board, a male pin header was soldered to the bottom side of the LCD. To space the LCD and MPPT board 12mm tapped metal spacers were used.

Spacers for MPPT PCB and LCD

USB Check
Two of the hardware connections that were used for debugging this particular project were the Cypress MiniProg3 programmer and the USB port. Certainly the LCD or on-board status LED could also be useful although the background debugger and serial port usually work sufficiently.

With the USB connected between the MPPT board and a Windows PC, the FDTI chip was configured using the FTDI application FT Prog. This application was used to disable three unused CBUS pins and reconfigure the fourth for USB bus voltage detection.

FT Prog Scan

The Scan command was issued the the FTDI device was located.

FT Prog Default CBUS Settings

From the list shown in the Device Tree pictured above, the 'Hardware Specific' item was expanded and the 'CBUS signals' entry was selected.

FT Prog Updated CBUS Settings

The settings were modified as shown above which enabled voltage sensing for the USB - VBUS_Sense. All other CBUS pins were unused and therefore tristated.

FT Prog Program

To save the CBUS settings changes using FT Prog, the 'Program' command was used. As shown in the capture above a 'Program Devices' dialog allows for confirmation of the Program process then subsequent programming.

RealTerm Loopback Test for MPPT Board

In order to test the USB a dummy PSoC application was made to loopback the Tx and Rx pins, P0.4 and P0.5 respectively. RealTerm was then used to test the loopback at 921600 - no issues were noted.

Software - Prototype
After the initial hardware checks of the boards power rails some initialisation code was written to check the LCD, buttons and communications. Below is an example of the initialised LCD.

Initialised LCD for Testing

A prototype project, certainly with some bugs, is available for download below.

Prototype Tracer PSoC MPPT Interface

The prototype project implements communications to the Tracer MPPT and display of current MPPT readings to LCD. Some of the current MPPT readings are also sent to the USB port for logging.

Serial Data Logging
The data logging 'USB output' was rather raw code with the sole purpose of providing a console output capable of being imported into Microsoft Excel. The UART Update function was called every minute and send some basic information to a terminal application.

void UART_Update() 
{
    char UART_Buf[20];
    uint16_t UART_temp;

    UART_UartPutString(LINE1_PV);
    UART_temp = MPPTPanelVoltage;                           /* Temp memory to modify for display */
    sprintf(UART_Buf, "%d.%02d%s%c", (UART_temp/100), (UART_temp%100),"V",0x9);
    UART_UartPutString(UART_Buf);
    UART_UartPutString(LINE1_BV);
    UART_temp = MPPTBatVoltage;                             /* Temp memory to modify for display */
    sprintf(UART_Buf, "%d.%02d%2s%c", (UART_temp/100), (UART_temp%100),"V ",0x9);
    UART_UartPutString(UART_Buf);   
    UART_UartPutString(LINE2_BI);  
    UART_temp = MPPTBatteryCurrent;                         /* Temp memory to modify for display */
    sprintf(UART_Buf, "%d.%02d%s%c", (UART_temp/100), (UART_temp%100),"A",0x9);
    UART_UartPutString(UART_Buf);
    if (System.MPPT_Load_Is_On == true)
    {
        UART_UartPutString(" Load On\r\n");
    }
    else if (System.MPPT_Load_Is_On == false)
    {
        UART_UartPutString(" Load Off\r\n");
    }

}

Shown below is an example of the data output to a terminal application.

MPPT Example UART Output

The output panel voltage displayed in the terminal window was also used to verify the position and angle of the solar panel. Moving the solar panel a few degrees off axis to the sun appeared to make no appreciable difference in the readings.

MPPT Protocol
The protocol was verified and confirmed in another of my blogs which can be found at http://electronicmethods.blogspot.com.au/2017/03/tracer-mt-5-to-mppt-communications.html

SD Card
The SD card implementation was scheduled to use the Element 14 community project #50 implementation for the PSoC4, which uses a modified version of the Segger / Cypress EmFile. In early part of '18 an article appeared Hackser.io with an implementation using Segger libraries by Hima from Cypress allowing SCB (Serial Communication Block) or UDB's (Universal Digital Blocks) for communications to the SD card.

Downloading and compiling the example from Hackster illustrated how easily the project could be changed between SCB or UDB's. Another feature buried in the API's are related SD card functions which are non-blocking. For full details see the Hackster.io site with credit to Hima. Note the Segger library license requirement.

In the capture below, are the two additional directories for adding the SD Card libraries to the MPPT project.

PSoC4 SD Card Libraries Compiler Entries

Similarly the Linker references one additional directory.

PSoC4 SD Card Library Linker Entry

To test the SD Card the appropriate File System header file was included and blocking writes were made to the SD card - a snippet is shown below.

#include <FS.h>
...
...
if ((pFile) && (SD_Removed_Read() == false))
    {      
        UARTCrLf[0] = 0x0a;UARTCrLf[0] = 0x0d;

        FS_Write(pFile, PV_string, strlen(PV_string));
        FS_Write(pFile, "," , 1u);
        FS_Write(pFile, BV_string, strlen(BV_string)); 
        FS_Write(pFile, "," , 1u);
        FS_Write(pFile, BI_string, strlen(BI_string)); 
        FS_Write(pFile, "," , 1u);
        FS_Write(pFile, TE_string, strlen(TE_string));
        FS_Write(pFile, "," , 1u);
        FS_Write(pFile, LOAD_string, strlen(LOAD_string));
        FS_Write(pFile, UARTCrLf , strlen(UARTCrLf));

    }

The rather inelegant code above was for testing opening of the log file written to the SD card, by Excel, Libre Office or another similar application with CSV capabilities. Shown below is a sample of the log from the SD card.

0.00V,13.34V,0.00A,25C,OFF
0.14V,13.34V,0.03A,25C,ON 
0.14V,13.32V,0.02A,25C,ON 
0.14V,13.32V,0.02A,26C,ON 

Next up scheduling control of the SD card....