Products > Test Equipment
Video Teardown and Repair of an Agilent E4433B ESG-D Signal Generator
radar_macgyver:
@Jay_Diddy_B:
Thanks for the insights, I have an E4433B that had the same issues, it too has the '1GG3' MMICs instead of the HFETs used on Shahriar's unit. I had tracked down the loss of power to the burst modulator, as you had, and then was stuck because of the multilayer board and not being able to flip the board over (due to the output MMIC being screwed down). I noticed that the transistor where the burst mod drive signal is sourced had a dry joint (mottled gray appearance instead of shiny silver). Also, one of the diodes next to that transistor were not properly soldered (the bead wasn't formed well). After some light rework, it seems to be stable; no more UNLEVEL errors! If I were to guess, I'd say the two toroids next to the diodes were probably shielding the diodes from IR during reflow.
Thanks all!
TK:
I got an E4422B unit with the UNLEVELED error and no output. I followed different repair tips from this and other threads. I tried the 20K resistor bypass fix and I got -30 dBm signal, but unit still showed the UNLEVELED error. I also tried reflowing the area near the BURST MOD at the same time. After I removed the 20K resistor, I got consistent -60 dBm signal with the UNLEVELED error still on the display, so the "no output" error was fixed, but signal did not go higher than -60 dBm... it goes down when I set levels lower than 0 dBm, but it does not go higher than -60 dBm even when I set any level higher than 0 dBm. The output amp is OK, if I remove it and bypass the input to the output, the output level drops by 30-40dBm. Then I tried to test the level before and after the BURST MOD section by soldering 2 pieces of jumper wires, one before the first diode, one after the last diode (this BURST MOD section is just before the output amplifier section). I set the output frequency to 50MHz, level to 0 dBm and connected the scope probe (10X)... magically the generator outputs the correct level... it even goes up to near 20 dBm and no more UNLEVELED error!!! After 2.5 GHz starts to give the UNLEVELED error again... Then I decided to remove the 2 wires, thinking the generator was almost fixed, but I get the same -60 dBm signal and UNLEVELED error... I solder the wires, no error... remove them, error... solder the wires, fixed...
It is the most bizarre "repair" I have experienced... The wires are not even connected, they are not twisted... they are just hanging in the air... Only 1 wire doesn't fix the problem, I need to have both wires soldered
edpalmer42:
Transmit and Receive antennas?
Try soldering a capacitor between the open ends of your wires.
Ed
syau:
--- Quote from: TK on September 20, 2018, 01:05:33 am ---I got an E4422B unit with the UNLEVELED error and no output. I followed different repair tips from this and other threads. I tried the 20K resistor bypass fix and I got -30 dBm signal, but unit still showed the UNLEVELED error. I also tried reflowing the area near the BURST MOD at the same time. After I removed the 20K resistor, I got consistent -60 dBm signal with the UNLEVELED error still on the display, so the "no output" error was fixed, but signal did not go higher than -60 dBm... it goes down when I set levels lower than 0 dBm, but it does not go higher than -60 dBm even when I set any level higher than 0 dBm. The output amp is OK, if I remove it and bypass the input to the output, the output level drops by 30-40dBm. Then I tried to test the level before and after the BURST MOD section by soldering 2 pieces of jumper wires, one before the first diode, one after the last diode (this BURST MOD section is just before the output amplifier section). I set the output frequency to 50MHz, level to 0 dBm and connected the scope probe (10X)... magically the generator outputs the correct level... it even goes up to near 20 dBm and no more UNLEVELED error!!! After 2.5 GHz starts to give the UNLEVELED error again... Then I decided to remove the 2 wires, thinking the generator was almost fixed, but I get the same -60 dBm signal and UNLEVELED error... I solder the wires, no error... remove them, error... solder the wires, fixed...
It is the most bizarre "repair" I have experienced... The wires are not even connected, they are not twisted... they are just hanging in the air... Only 1 wire doesn't fix the problem, I need to have both wires soldered
--- End quote ---
Sorry for digging out this old thread, my unit has the same issue and I am finding a way to fix it (besides soldered 2 wire)
Bud:
I fixed mine by washing the board with isopropyl and a toothbrush. While it was also a bizarre fix, my speculation was the fault could had been caused by conductive dust or tin whiskers. The unit operates flawlessly ever since.
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