Electronics > Repair
Agilent E4421B RF generator restoration project
Mosaic:
This one: 252448189801 specifies no RF and unlevel error...which precisely matches what I had.
I'd suggest that if you're interested that you ask for verification that the coherent output is alive, which then means the A9 board is the fault as mine was.
The other says dual arb error which is the UND option, which can be removed. But may be a voltage issue which makes it an easier fix.
Samogon:
Oh i must be blind, reading description carefully explains errors. Sorry
SoundTech-LG:
Just a heads up...
I followed the fix shown above adding the 20k resistor, also touched up several questionable soldered areas in that circuit. Voila! works great. Then I said to myself, remove the resistor to prove that fixed it, not the touch-up soldering. Removed the 20K resistor. Voila! Still working fine! Chances seem good there are issues with solder, not circuit values (at least with this E4432B).
SoundTech-LG:
Had this E4432B running about 36 hrs. w/no problems. One of our engineers took it away to his lab, and used it under load for about 4-5 hours, then brought it back complaining "it's broke". Noticed the supply for the output amp IC was shorted to ground, then noticed all the pins were shorted to it's integral heatsink/mounting. Noticed one of the screws for mounting was loose. Looks like this is another fried 1GM14201 because of poor heatsinking, and mounting. Thanks Agilent! :--
TK:
This thread is old but I think it is worth keeping any repair hints together.
Recently I acquired this signal generator and had missing columns on the bottom half of the LCD. After replacing the LCD, the problem persisted. While trying to map the LCD pins to the correct part on the motherboard, I used a continuity meter to map the pins. It shorted one or both HM628512BLFP-7 SRAM chips (I think they are called BootROM RAM) and the motherboard did not want to boot, resetting every 3 seconds due to the power supply being shorted. I then realized that the motherboard has a 3V lithium battery to keep some configuration alive and I passed the test probes over pins while they were powered by the Battery. When I removed the SRAM chips, the board was back alive, but stopped with LED diagnostic code 2, and the manual says it is checking for BootRAM RAM, which of course were removed. After soldering new SRAM chips, the motherboard booted correctly passing all the self diagnostics. The LCD problem is still there, and I traced the problem to the Video RAM (HM514260CJ6) next to the Chips F65510 VGA controller (The controller seems to be OK because I can measure signals changing on all 8 bits that goes to the LCD). I am waiting for the Video RAM chip to arrive and I will post the results
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