| Electronics > Repair |
| Agilent E4421B RF generator restoration project |
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| nctnico:
My E4421B has thrown me a nasty curve ball today. It starts but when it gets to the splash screen I hear a loud click from one of the RF modules and it seems to reset into the splash screen. This cycle keeps continuing :-BROKE Just as I wanted to make some measurements on my new HF differential probes. :rant: :rant: Just what I need. Maybe it is karma. A few days ago I have bought a different RF generator which hasn't arrived yet. Hopefully that is in a somewhat workable condition. |
| Samogon:
Looks 5V power rail has an issue, fail at load, making reboot cycle. That is first thing i would check. Then if 5V ok, remove all boards except digital and check it |
| nctnico:
The 5V looks ok with a DMM. I also see the diagnostic LEDs keep counting in a binary sequence. With all the RF modules removed the behaviour is the same. Maybe I need to try and reflow the SRAMs. There is a message about the RAM but it isn't clear if something is bad or not. It says: Start = 0x300000 End = 0x3F9800 Errors =0x0 With the 'local' button pressed during power on, the E4421B won't start the firmware so the self test result stays on screen. |
| nctnico:
I made some progress. When it is cold and no RF modules are installed it will start succesfully. I tried using freeze spray but so far no joy. |
| Samogon:
Thermal camera? Measure cold and warm current consumption on 5V rail |
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