Hi group,
I realise that this is an old thread, but I thought it was a good idea to keep all the ESG-D repair information together.
I have an E4432B ESG-D with options 1E5 and UN4. The symptoms are No output and UNLEVELED indicator when the RF is turned on. Having read this thread I was expecting to be change a dead amplifier in the signal chain.
I have confirmed that the problem is on the A9 Output board assembly, by swapping the module from a good generator.
First the board is very different to the one in the video:
I have tracked the break in the signal path to the 'Burst Modulator'.
I did this by soldering wires to the board and running the ESG at 270MHz and monitoring the signals with a scope and 10x probes.
Here is a partial block diagram for an output board (option UN3 and UN4):
And here is a picture of the 'Burst Modulator' on the PCB:
I suspect that the circuit is something like this:
I have confirmed that the right end of the diode string has an inductor to ground. I would expect the that the left hand end would be positive about 6V if the "burst modulator' is on.
If I twist the wires together, to form a small capacitor, to bypass the 'Burst Modulator', the generator seems to work fine, except the 'Burst modulation'. The UNLEVEL indication is gone and I have output.
The questions is where on the board is the 'BURST MODULATOR DRIVER'?
Thanks for your help with this challenge.
Regards,
Jay_Diddy_B