Oscilloscope HP 54522A self test fail DAC ADC Acquision  error etc. - Page 1
Forum section: electronics / repair

author: slowolitus
author_rank: Newbie
timestamp: May 28, 2025, 11:49:19 pm
content: There is a wonderful device - oscilloscope HP 54522A. Came with a problem - the computer does not start. After replacing the battery, the device turned on. Then it turned out that the input attenuators of both channels do not work correctly - I have disassembled the attenuator relay, washed the gold-plated lamellas in citric acid and rubbed the pin contacts with polishing paper. After that, both input channels successfully passed self-calibration.The device works, shows the waveform, but does not pass self-test. See the photo.What was done - both hybrid ADCs were removed, the printed circuit board under them was cleaned. The contact frame with tiny pogo-pins was cleaned in a ultrasonic bath in isopropanol. But no success.The power supply has been checked - all voltages are normal, no pulsations. The power supply is generally in very good condition.Unfortunately, there is no publicly available schematic for this oscilloscope. There is only a service manual with a block diagram.I don't know what to do next and I can't figure out if this is a software or hardware problem.Acquisition RAM FailedAnalog Trigger FailedD/A Converter FaiiledA/D converter FailedPlease help!greetings from Stuttgart

author: Haenk
author_rank: Super Contributor
timestamp: May 29, 2025, 10:44:31 am
content: You have followed this?https://damien.douxchamps.net/elec/equipment/hp54542a/acq_ram_fail/I could imagine the DAC ADC both use this RAM. So maybe the bad connections on the RAM module cause the following errors.However, just guessing here.

author: slowolitus
author_rank: Newbie
timestamp: May 29, 2025, 11:15:10 am
content: Haenk], yes i know this link. It was first what i done - two times cleaned pcb and pogo-pins frame under this hybrid ADC/RAM modules. But no success. What is really wondering -scope seems to be working, i gave him different types of signals and triggering works well. But every time if i change input channel i have to switch triggering source manually. I do not knoe if it normal or not..

author: Runco990
author_rank: Frequent Contributor
timestamp: May 29, 2025, 07:41:43 pm
content: Make sure you load the default calibration first. Then try again.I had one of these, it's a work of art! Beware the power supply!

author: slowolitus
author_rank: Newbie
timestamp: June 02, 2025, 12:40:44 am
content: Runco990, i have made defaul calibration, after that calibrated both channels without any problem and faults. BUT software shows me four channes have to be calibrated, despite of fact that channes 3 and 4 are physically missing in 54522A. Could it be the problem? maybe it is wrong firmware installed in my 54522A?And "Ext" triggering input is missing too in software, but it is present in my scope

author: slowolitus
author_rank: Newbie
timestamp: June 02, 2025, 12:09:50 pm
content: I have cheked power supply, it is ok.I have flashed newest software version T3.33, problem persistsCan someone show here how service menu looks like in 54522A. Is there 4 channels too, even in 2- channel model of the scope?

author: slowolitus
author_rank: Newbie
timestamp: June 04, 2025, 01:54:59 pm
content: Poblem is solved!!!I have removed resistor R408 from the bottom side of the mainboard and now I have 2 channes and Ext input in the service Menu instead of 4! All tests are passed!R408 configure the model of the scope. Missing resistor - 54522A, present - 54542AThanks for all!

author: Runco990
author_rank: Frequent Contributor
timestamp: June 04, 2025, 02:50:45 pm
content: The power supplies on these scopes tend to have leaking capacitors, which isn't always visible until it's too late. If the power supply fails, it is VERY difficult to repair it. I would really consider doing a re-cap on it if you plan to keep that scope. Some people have built a new power supply from off the shelf one's. I think it's documented here. Don't ignore this! You need to open it and CAREFULLY check it. I'd desolder a few of the output filter caps and look underneath.The resistor thing....... well, I'll be damned.... never seen THAT one before! Good troubleshooting!!!I wonder if that was a production error?These are nice scopes. Not great without digital phosphor, which I need, but have a lot of math functions and a good FFT. I had both the 2 and 4 channel one's. Eventually I sold them with a bunch of gear prior to moving 3 years ago. But since I got a Keysight 2000 series scope, I don't miss them.COLOR is nice!