I bought an AY-AT clone and bought the resistor and IC needed for the upgrade. But when I wanted to burn the M firmware, I found that I could not find the pre-compiled firmware that could be burned in the Windows system... It seems that it needs to be compiled and burned on the Linux system...
...I have some diodes I need to test - should I be really careful in which way around they go?
Assuming you have that particular version of the tester, my advice is DO NOT test anything on the zener test pins (K - A) until you have made the mods. You might get away with it if it is a higher voltage zener and you are fast but there is a good chance you will burn D2 and possibly damage the DC-DC boost IC.
Hi there, I've ordered 2 replacements as unfortunately being without this bit of tat sucks. Before I do the mods any recommendations? I have some diodes I need to test - should I be really careful in which way around they go?
Have you enabled HW_DISCHARGE_RELAY by chance? That would ground the TP_REF pin (in your case PA3) between probing cycles.
I've discovered a problem with the reference voltage on pin PA3 for my stock LCR-TC2. I was looking at the config.h file of the m-firmware and saw an option for defining the reference voltage so I decided to measure it on my tester but found it was only 45mV.
I've discovered a problem with the reference voltage on pin PA3 for my stock LCR-TC2. I was looking at the config.h file of the m-firmware and saw an option for defining the reference voltage so I decided to measure it on my tester but found it was only 45mV.This is not a problem, but a feature of the tester that you need to know and take into account. In this circuit, the PA3 pin of the MCU is periodically connected to ground (by software), so the reference voltage of 2.495V appears only when the measurement cycle starts for a very short time.
I also have a round GM328A(BGR)2 tester and the reference voltage stays on for a couple of seconds after pressing the test button. I'm pretty sure it wasn't with the LCR-TC2. I overwrote the Chinese firmware so I can't test it anymore to double check
/* hardware SPI in config_644.h: */
#define SPI_HARDWARE
#define SPI_PORT PORTB /* port data register */
#define SPI_DDR DDRB /* port data direction register */
#define SPI_PIN PINB /* port input pins register */
#define SPI_SCK PB7 /* pin for SCK */
#define SPI_MOSI PB5 /* pin for MOSI */
#define SPI_MISO PB6 /* pin for MISO */
#define SPI_SS PB4 /* pin for /SS */
/* ST7735 using hardware SPI in config_644.h: */
#define LCD_PORT SPI_PORT /* port data register */
#define LCD_DDR SPI_DDR /* port data direction register */
#define LCD_RES PB0 /* port pin used for /RESX (optional) */
#define LCD_CS SPI_SS /* port pin used for /CSX (optional) */
#define LCD_DC PB1 /* port pin used for D/CX */
#define LCD_SCL SPI_SCK /* port pin used for SCL */
#define LCD_SDA SPI_MOSI /* port pin used for SDA */
/* set SPI clock rate for hardware SPI display in ST7735.c: */
// SPI.ClockRate = SPI_CLOCK_2X; /* set clock rate flags */
SPI.ClockRate = 0; /* set clock rate flags - SPI2X = 0, SPR1 = 0, SPR0 = 0, SCK = fosc/4 */
/* set power management pins in config_644.h: */
#define POWER_PORT PORTD /* port data register */
#define POWER_DDR DDRD /* port data direction register */
#define POWER_CTRL PD1 /* controls power (1: on / 0: off) */
#define BUTTON_PORT PORTD /* port data register */
#define BUTTON_DDR DDRD /* port data direction register */
#define BUTTON_PIN PIND /* port input pins register */
#define TEST_BUTTON PD2 /* test/start push button (low active) */
/* set probe colors to match decal in color.h */
#define COLOR_PROBE_1 COLOR_RED
#define COLOR_PROBE_2 COLOR_YELLOW
#define COLOR_PROBE_3 COLOR_GREEN
I finally got the v1.48m firmware working on my LCR-TC2 with hardware SPI.
Hi there, I've ordered 2 replacements as unfortunately being without this bit of tat sucks. Before I do the mods any recommendations? I have some diodes I need to test - should I be really careful in which way around they go?I have a Transistor Tester just like yours where the current limiting feature of U7 failed, but fortunately I avoided roasting D2. Therefore my unit is still generates 30V, but without any current limiting. I went ahead and installed the 2k2 series resistor between the junction of D2/C14 and the K test socket pin. This limits maximum short-circuit current to about 15mA.
IMHO putting in the 2k2 series resistor alone is good enough to prevent anything from smoking.
I continue to recommend replacing U7 too. The 2k2 series resistor protects U7. Even if a direct short is placed from K to A, the 2k2 series resistor keeps U7 safe and happy. After installing a new U7, testing with the 1k resistor should display a “zener voltage” of 5-6V. This indicates U7 is properly limiting the zener test current.
<offtopic>...I have some diodes I need to test - should I be really careful in which way around they go?What do you want to measure? Zener voltage? Forward voltage? There are simple ways to measure diodes (Google it). You don't need to risk your tester.
</offtopic>
I think you have made a mistake though, the junction between D2 and C14 is the K test point so you'd be putting it in parallel with a wire. Do you mean I should knife the trace? That doesn't seem reliable.
Thanks.
Ed in an earlier post you explain this'll require cutting the trace
I can't find that manual link and I'd like to see a picture of your modifications please - I noticed the replacements but not the cut trace in a post you made 3 pages back
<offtopic>...I have some diodes I need to test - should I be really careful in which way around they go?What do you want to measure? Zener voltage? Forward voltage? There are simple ways to measure diodes (Google it). You don't need to risk your tester.
</offtopic>
This is a non-answer but it'd be nice to measure the breakdown voltage (or "the voltage" when using them as voltage regulators)