| Electronics > Repair |
| Another blown Agilent 4263B |
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| Astralix:
Hi! Thank you for these very informative run through of previous 4263B repairs. Really appreciate that work as it gave me some hints where to start and to look first. I got ripped-off by an eBay seller (Unit removed from working test setup... bla bla bla) as not only he stated that the unit was working till the last day, but I now have evidence that the someone had the remnants of the accident that killed the unit carefully removed on the top layer. But he forgot to do that on the bottom layer. Unfortunately I had the unit sitting on the shelf far too long to take any further actions besides repairing the unit. Pictures of previous repairs in this forum already helped identifying, if the so cleanly removed trace under the Z6010 diode was a factory mod. No it wasn't it was carefully removed and cleaned to hide what happened. But I have still two questions: The Z6010 Diode below the connector B was blown on my unit and one of the 77G too. But around the blown Z6010 two traces have been vaporized and one through-hole has sort of exploded. As your photos show, I need to replace the trace on the top side. But I cannot see where the through-hole connected before on the bottom side. All of the through-holes there look like they connect to the inner layer but they don't do so. Any idea which of all the through holes do connect to that barely visible inner layer? Current status of the unit is: With all diodes removed and the trace to Hcur bridged to the 3 in parallel 100R resistors, the instrument does give stable readings, but they are far out of target. So a 560uF cap, tested for 530uF gives around 43uF on the 4263B and a 1% 100R metal film resistor gives 18M Ohm with X being far away from 0. It is not really conclusive that, with such a big bang going through the inputs, only two traces and a 100R resistor on the Hcur Output had been damaged. Someone mentioned some 51R resistors on one of the hybrids. I will check these too. But I would be really glad if there are more suggestions and especially if there is an update on firmware, calibration software and whatever. Some of the threads on repairing these units are so old now, all the helpful links start to fade away... Best of all Astralix |
| TERRA Operative:
I wrote a Python script that will do a self test and unlock both options automatically. https://github.com/JaredCabot/HP-Agilent-4263B-Option-Unlocker You'll find the latest firmware image there too. It can be written to the instrument via GPIB with the correct commands if one were to write a Python script to do so, but I think it's safer to just pull the socketed chip and stick it in a chip programmer. As for the damage to your board, I'll take some photos from my instrument later tonight that might provide some clues to help you out. Looks like no schematics are available AFAIK, but the service manual has some troubleshooting info and block diagrams that might help a little. https://groups.io/g/HP-Agilent-Keysight-equipment/files/All%20HP,%20Agilent%20and%20Keysight%20instruments%20in%20folders%20by%20part%20numbers/4000%20to%204999/4263B%20LCR%20meter%2010%20Hz%20to%20100%20kHz |
| Astralix:
Hi Jared! Thanks! My unit shows a date of February 2nd 2000 with firmware 1.06 with Options 001,002 installed. So the unit was bought with these options or someone already used your script? I cannot tell. However the self-test seems interesting but isn't that available thought the menu as well? That one passes on my unit without any fault. I have read the service manual and by that I understood the basic working principle. That manual also lead me to the conclusion that there must be more "down below" as I could trace the sinusoidal test signal from the opto-switch through the 100R resistors and then disappearing. However, there are some open contacts around that one Z6010 Zener Diode that are unclear to me of where they should go. |
| picburner:
Nice bang! In my instrument all the points indicated by the black arrows are connected to GND (Chassis). If you are still missing some other tracks, just ask. |
| TERRA Operative:
--- Quote from: Astralix on September 30, 2024, 12:10:11 pm ---Hi Jared! Thanks! My unit shows a date of February 2nd 2000 with firmware 1.06 with Options 001,002 installed. So the unit was bought with these options or someone already used your script? I cannot tell. However the self-test seems interesting but isn't that available thought the menu as well? That one passes on my unit without any fault. I have read the service manual and by that I understood the basic working principle. That manual also lead me to the conclusion that there must be more "down below" as I could trace the sinusoidal test signal from the opto-switch through the 100R resistors and then disappearing. However, there are some open contacts around that one Z6010 Zener Diode that are unclear to me of where they should go. --- End quote --- Looks like you have the latest firmware and all options unlocked already, so no problems there. Here are some photos of my board, it seems that the burnt anode side of that diode connects to the local internal ground plane. Luckily the adjacent diode also connects to the ground plane at its cathode, so installing the diode from the undamaged hole at its cathode end and then connect the anode end directly to the cathode of the adjacent diode would get the job done. See the drawing on your photo to see what I mean. Hope that helps. I'll leave my instrument disassembled for the next day or two just in case you need more photos. |
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