hp 3325b  the repair from hell and full calibration  - Page 1
Forum section: electronics / repair

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 06, 2023, 07:17:09 pm
content: The story started on Sunday suddenly decided not to work no display.I opened the power supply A22 board and found a dead 6.2 volt zener diode. Looks like new.There is still no display. I did a diagnosis for the provider without loadThere were voltages 15 plus 15 minus 5 plusStrange. It took me a while to realize that the problem is in the standby circuittransistor. npn q301 which is part of the standby start-up circuit was shorted.I didn't have exactly the same one in size to-92I had a c945 model which is closeBut the leg of the base is not in the middle.I twisted the small leg to the middle. I isolated me with a shrink nancyThe provider went back to work with a bunch of errors.010026039013There was no voltage the device output correctly did not receive negative voltage with error 010The frequencies were shocking, nothing wrong, it registers 2 volts and comes out 7Writing minus 5 volts outputs 2.4 volts.In short, the generator was seriously ill.It took me another day to realize that the problem was in the doubta 15 microfarad 20 volt tantalum resistor to die in such a way that I thought a cockroch was electrocuted in the device.I did thinking it can't towards.I understood that a single cable from the power supply transfers minus 15 volts in a single thin cable to the A14 boardAnd actually the power supply broke down, the voltage was the unstable 24 volts from the track. That fried the tantalum and 3 more resistors12 ohm3.9 ohm100 kilosIn the area where the negative voltage was 15 volts to transistor Q2092 capacitors10 nanofarad ceramic changed to 10 nano np015 microfarad tantalum was replaced with a 22 microfarad polymer3 resistors were replaced12 um which I measured exactly 12100 kilos tooAnd 3.9 ohms that I didn't have, I created through 2 samples in parallel 5 ohms in parallel with 22 ohmswhich I physically measured 3.95 ohmsI did point to point threading for everything and cleaned up.And the generator returned to full lifeI did full recalibrated the 3225And the generator is now as accurate as ever

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 06, 2023, 07:18:38 pm
content: more photos after cal

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 06, 2023, 07:21:59 pm
content: more photos

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 06, 2023, 07:22:33 pm
content: more photos

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 07, 2023, 09:55:27 am
content: hp3325b calibration

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 09, 2023, 11:21:30 am
content: hp3325b test after repair and calibration

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 12, 2023, 02:52:33 am
content: more project photos

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 12, 2023, 02:55:00 am
content: more project photos

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 12, 2023, 03:02:52 am
content: more project photos

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 12, 2023, 03:08:10 am
content: more project photos

author: DavidAzulay5000
author_rank: Regular Contributor
timestamp: April 12, 2023, 03:11:48 am
content: more project photos

author: Swake
author_rank: Frequent Contributor
timestamp: April 04, 2024, 12:32:57 pm
content: Thanks for this extensive write-up.I might have to work on one of these soon and this will certainly help me.