Keysight 34461A - Page 1
Forum section: electronics / repair

author: sergioag
author_rank: Unknown
timestamp: April 07, 2019, 06:24:51 am
content: I have a Keysight 34461A which I bout about 4 years ago. I used it very little, with no issues. About 6 months ago, I put it on storage together with my Rigol DS2102A. About a week ago, I took it out from storage because I needed to use it. My surprise was that, while it powered on and booted, it didn't work at all. Let me elaborate.It boots normally, except that it takes longer than normal. No relay clicks are heard. Then it goes to the measuring screen, but it doesn't show numbers, only "+. ... ...". On the top right shows "Error". The interface responds normally when it finishes booting until about 20-30 seconds thereafter. Afterwards, it's mostly unresponsive.I've taken it apart and there's nothing evidently wrong with it. Besides some dust, all is ok. I made all the measurements mentioned in the Keysight's manual ("Power Supplies") and all are normal.About leds that are turned on, in the mainboard there is a led, DS902, labeled FPGA that it on. But the one next to it, DS901 and labeled uC, it's off. In the display board, there's DS200 that seems to be a two leds in one. Both are on. Other than these, I don't see any other leds inside the device.No self-test finishes: they hang. I've removed the battery and there has been no change (not that I expected anything, but who knows...). Current firmware version is 2.17.Since the problem seems to me to be in the mainboard, I've focused on it. I've checked power and reset pins in the LM3S1D21 microcontroller on the bottom of the board. Still, nothing seems out of the ordinary. I've focused specifically on this part because the uC led is off, which is kinda weird IMHO.Any ideas or anything that I could be missing? I would really appreciate any help here.Thanks!

author: mr.fabe
author_rank: Regular Contributor
timestamp: April 08, 2019, 02:40:15 am
content: Check and verify the warranty status on the unit through the Keysight website. There were a few conditions where Keysight extended the warranty coverage by an additional year and you might be covered. If not, check out this link...https://www.eevblog.com/forum/repair/agilent-34461a-display-failure-suggestions-please!/

author: wraper
author_rank: Unknown
timestamp: April 08, 2019, 02:47:29 am
content: Try updating firmware and resetting to default settings before doing anything else.

author: sergioag
author_rank: Unknown
timestamp: April 08, 2019, 06:40:54 pm
content: Quote from: mr.fabe on April 08, 2019, 02:40:15 amJust checked the warranty status and it seems to be just on the last legs of its warranty! Already in contact with Keysight for this! Thank you!

author: sergioag
author_rank: Unknown
timestamp: April 08, 2019, 06:41:48 pm
content: Quote from: wraper on April 08, 2019, 02:47:29 amTried that. No luck. Now it says "Firmware update failed" upon startup. Otherwise the same.

author: mr.fabe
author_rank: Regular Contributor
timestamp: April 08, 2019, 07:00:16 pm
content: Quote from: sergioag on April 08, 2019, 06:40:54 pmAwesome! Glad you took the time to check the warranty status. Even though it may just be a corruption in the firmware, you will at least have peace of mind when it leaves Keysight that all functions will be working as designed. Keysight has really good service and I'm sure you won't be disappointed.

author: LapTop006
author_rank: Unknown
timestamp: April 11, 2019, 04:18:28 am
content: Quote from: mr.fabe on April 08, 2019, 02:40:15 amYep, always do this. I've previously missed out by just a few days on getting something I picked up *very* cheaply as used/broken repaired by the vendor (my delay, had I checked the day it arrived they'd have done it for free).

author: Neo2199
author_rank: Contributor
timestamp: July 09, 2022, 09:34:46 pm
content: I am not sure if to start new thread, but I do have exact same problem on the 34465A. On top of that it displays Firmware update failed on boot up. I have tried flashing all available FW versions from Keysight, but no luck. Any advice?I have also reached out to Keysight and no help from them either. They just asked for $1300 and that's about it...

author: Traceless
author_rank: Frequent Contributor
timestamp: July 09, 2022, 10:17:38 pm
content: @Neo2199: How old is your meter? Maybe you're suffering fromthisissue. Check if your serial number is in the affected range.Cheers Traceless

author: Neo2199
author_rank: Contributor
timestamp: July 09, 2022, 11:25:16 pm
content: It is quite old meter. MY54503780. I have tried to push the bracket with hands to emulate screws but no help.I actually think the issue is related to LM3S1D21 which has some memory issue as mentioned in another thread.https://www.eevblog.com/forum/testgear/keysight-34465a-reliability/The uC LED is not lit and all the power and reset seems to be in correct state. I can also see plenty of +320 Slave processor communication error: command returned error status and communications restart failed.Is it possible to get the firmware from the microcontroller? I could try to flash it. If it just forgot a firmware which is possible. The instrument was part of lab equipment and I am not sure how long it stayed off.And one more thing: Firmware: A.02.17-02.40-00.00-00.00-00-01So looks like for sure issue with communication with microcontroller and the lack of uC LED on tells me something with that micro.

author: Traceless
author_rank: Frequent Contributor
timestamp: July 10, 2022, 07:35:11 am
content: Quote from: Neo2199 on July 09, 2022, 11:25:16 pmSorry to hear that, I know the thread you've linked, LM3S1D21 would have been my second guess a lot of older revisions seem to have that problem.Quote from: Neo2199 on July 09, 2022, 11:25:16 pmThe Firmware is availablehere. Disclaimer: I have no experience with patching a bricked unit. For the standard USB-Stick update the instrument would need to be in working condition but the page also mentions updates over GPIB not sure if that could work without the MC. A lot of newer PC motherboards have features that enable you to flash the bios without CPU or memory being installed (see video below). I somehow doubt though that Keysight impemented such a feature, so you might need an external programmer. After a quick search I foundtheseones which are not exactly cheap but the LM3S1D21 is listed as supported MCU. I have no idea if/how well these programmers work. If you own a programmer, can find a cheaper one or find someone on the forum who lives close to you and has owns a compatible programmer I'd say just give it a shot and try to reprogram it. I'd be curious to know if/how KS DMMs with a faulty LM3S1D21 can be recovered.