Hi,
I’ve purchased about four broken Fluke 233 meters and repaired/ resold them. I think the first thing I’d check on your meter, is to look at the window on the plastic housing of the display and base unit. On the last meter I repaired, it had a couple of open traces because of battery corrosion, but, after I repaired those, I tackled an issue where it worked when the base was disconnected (remote mode), but not when it was connect to the base. After further inspection, I discovered the plastic window on the display unit for the rf signal to pass through was partly eaten /corroded from a chemical or something from the previous owner, which prevented the signal to pass through. Regarding the test points, I attached some notes (scribbles) of when I was doing some of my troubleshooting/testing of past meters. Maybe it will help you. Where there is red ink, those were measurements of bad voltage readings. The black ink, is good voltage readings.
I agree with you, about seeing the red dashes, and red LED staying on, that it hasn’t booted up completely. It doesn’t sound like the cause is any of the M430F449 chips. Your PCBs look pretty clean too.
Another thing to check is the voltages at DS202. One side should be tied to the “-“ PCB terminal, and the other should read about 35mV. ( I had another 233 meter where the lead that connects to the “-“ PCB terminal was open, which caused dashes). All my voltage readings were referenced to the “-“ terminal on the PCBs.
Keep us posted of your progress
Hello, Thank you very much for the response
. It was really DS202's negative terminal. Although I am sure I checked it before, today when I checked it again, there was no continuity and it was the cause. And whoala, it is working now with attached display.
BUT another problem occured . Wireless transmission is not working. It is possibly caused by me after several desoldering and soldering the RF IC
(because its contacts looked oxidized to me and I saw that they are not soldered well (this is only mine opinion)). Here is what is the situation now:
I measure 35mA to 45mA current of the display module while trying to establish connection;
In the same time there is no more than 1mA current consumption on the base unit;
In the base unit I can see, that after detach the display the SPI communication is started (there are MOSI, CLK and CS transitions). Also RST pin goes high. No transitions on MISO pin! The whole process takes about 1 to 2 seconds and RST is again held LOW and no more SPI transitions.
So in this situation probably I think the RF IC of the base unit is damaged, as it not responds to SPI master via the MISO pin. I also checked its input voltage and there is 3.3V. I did already purchased the RF IC when I received this DMM, so now waiting for it...
If you have any advice I will really appreciate this.
Once again thank you very much for the help.
Greetings from Bulgaria.