Lecroy 454 intermittent shutdown  - Page 1
Forum section: electronics / repair

author: dbach
author_rank: Newbie
timestamp: August 20, 2025, 03:06:09 pm
content: Hello,This is my first post to the forum so correct me if I made any formatting errors.I have a Lecroy 454 wave surfer oscilloscope, bought for parts or not working on ebay with the description of "Does not power on". In testing the device does in fact power down but intermittently shuts off, usually in 30 seconds to 2 minutes. Windows Embedded boots, and I have made it into the DSO program once (for a few seconds).I have never worked with windows embedded and I am thinking this is a problem with the computer and not the the power supply or something like that. If anyone could give me some advice on a likely culprit, or things to look for I would appreciate it. As far as I can tell everything is seated correctly and plugged in. I have uploaded a photo of it booting and I have a video of one of the failure but i'm not sure how to post that.https://cdn.teledynelecroy.com/files/manuals/ws-om-e_rev_b.pdfThanks you so much,Davis

author: inse
author_rank: Super Contributor
timestamp: August 20, 2025, 03:13:25 pm
content: How does it shut down?Bluescreen or just off like you pulled the plug or other?You could upload your recording to this video platform who‘s name I‘m not getting…

author: d-el
author_rank: Regular Contributor
timestamp: August 20, 2025, 03:16:00 pm
content: You can connect multimeter to power supply rails and monitoring voltage.And make visual inspection electrolytic capacitors.

author: dbach
author_rank: Newbie
timestamp: August 20, 2025, 03:40:45 pm
content: Its shuts down like I pulled the plug, video attached (it expired in 2 days unfortunately)https://streamable.com/yngpglPower supply does not open easy, I inspected it before I powered the device on and all the caps looked fine and it was clean (although looks can be deceiving)

author: dbach
author_rank: Newbie
timestamp: August 20, 2025, 03:43:37 pm
content: Quick update, powered it on a few more times to see if I could catch the boot process and I got a lsass.exe errorIm thinking maybe hard drive problem or some other malfunction but I am really not well versed in this sort of thing

author: inse
author_rank: Super Contributor
timestamp: August 20, 2025, 07:15:05 pm
content: Does it only happen when the DSO application is started?

author: dbach
author_rank: Newbie
timestamp: August 20, 2025, 08:50:36 pm
content: No, it is pretty random. often 30 seconds to a minute after startup but has also happened immediately or after a few minutes. I am going to do a full motherboard scan and check all the caps and power supply rails. I think ill likely have to fully recap the motherboard.

author: bombcat
author_rank: Contributor
timestamp: August 21, 2025, 01:28:24 am
content: If it looks like a similar failure to your computer, it is recommended to check the cooling system and memory. Thermal imaging can be used if available.

author: sprit
author_rank: Regular Contributor
timestamp: August 21, 2025, 05:49:50 am
content: Looks like the problem is temperature related, make sure the mobo or acq board is not overheating. Have you tried re-applying cpu paste?

author: Uunoctium
author_rank: Frequent Contributor
timestamp: August 21, 2025, 08:29:47 am
content: What happens if you don't try to launch an application from the Windows Start screen yourself? Does the oscilloscope load the application automatically, as described in the instructions?

author: inse
author_rank: Super Contributor
timestamp: August 21, 2025, 05:05:15 pm
content: A hairdryer may be helpful confirming or rebuting the thermal hypothesis.You can try to start XP in safe mode by pressing F8 key to see if any driver might cause the issue.

author: dbach
author_rank: Newbie
timestamp: August 21, 2025, 09:03:50 pm
content: The seller had clearly already been inside the unit, not sure what the original problem was cause them to do this but upon inspection of the cpu the heatsink was installed incorrectly. Scope works fine now, I’ll post photos and details soon.

author: dbach
author_rank: Newbie
timestamp: August 21, 2025, 10:42:11 pm
content: Now the scope works as expected, however, every third turn on or so the video signal is messed up and loads very zoomed in and skewed left. This is a issue ill have to track down in software i'm sure.I attached an image of how I found the heatsink, flipping the retaining bar fixed this.

author: TinLethax
author_rank: Regular Contributor
timestamp: August 22, 2025, 12:05:41 am
content: Shut down could be thermal related problem. Can you take the PSU apart and check the PTC fuse (if there was any). Also I believe you can disconnect power from the acquisition board and left only PC side so you can isolate the problem.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 22, 2025, 02:05:32 pm
content: Quote from: dbach on August 21, 2025, 10:42:11 pmsure it did not help the cpuif it restart, try killing the scope application by doing crtl alt del (task manager) and see if it continue to run fineis the psu same as an computer model IE : atx 20 or 24 pinsthermal problems, psu problems ? check the cpu motherboard capacitors if they are buldged / leakingXP embedded can be replaced with an normal xp, sure you need all the drivers and software ... do an hdd backup / cloning before loosing anythingthere was a teardown here :https://www.eevblog.com/forum/testgear/lecroy-454-teardown/sadly some photos have dissapearedhttps://www.eevblog.com/forum/repair/lecroy-454-repair/https://groups.io/g/LeCroyOwnersGroupmay be of helpare you up to date when it works ?https://www.teledynelecroy.com/support/softwaredownload/documents.aspx?sc=12