HP3458A restoration - Page 1
Forum section: electronics / testgear

author: Ice-Tea
author_rank: Super Contributor
timestamp: October 24, 2019, 01:54:03 pm
content: Well, got one of these, but not in the best of shapes. The front bezel is chipped, the back bezel is broken (but can perhaps be glued to an acceptable state), pushbuttons on the front are missing, as well as the rods. The banana post front assembly is wobbly. Not too worried about most of that, because amazingly you can simply order parts from Keysight. I was first hoping 3D files would be available and this would finally be a good excuse to get a decent 3D printer but it seems I won't have to..Unfortunately, it also comes with a number of errors:RAM 1 TEST LOW: I assume depleted NVRAM batteries205, "HARDWARE FAILURE - TEST VALUE OUT OF RANGE : 108"According to the ALRM, should be on the A1 assembly somewhere.110, "Calibration Required"Yeah, figured as much114, "SYSTEM ERROR - Non Volatile RAM checksum"Yeah, figured as muchOnce you get rid of the errors and warnings, unit actually seems to work: measured a coin cell voltage and current and both were OK. So, starting with the NVRAMs:Seems like one of the earlier boards. And the NVRAMs are all original (datacode 89 I think) which, in this case, is not good. I think it's safe to say the cal data is long gone, no point in trying to retrieve it and all of them need to go. I already figured ou the DS1235 can be replaced with the 1230. What I still wonder: these were also offered with more NVRAM as an option (see empty sockets):- is it worth expanding the memory?- is it as simple as plopping in 4 more chips? Will the SW recognize it?Let's see how this goes

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 05, 2019, 12:17:36 pm
content: Grpmff... Replaced all NVRAMs. Now comes up with "RAM TEST 1 LOW". Can't reset beyond that. Which one is "1", by the way? Left or right?

author: Dr. Frank
author_rank: Super Contributor
timestamp: November 05, 2019, 01:04:30 pm
content: Hello,the 1220 should be replaced with DS1220AD-120+, and both 1235s by DS1230Y-150+This RAM TEST error you still see usually refers to the 1230Y - 32kx8 nvRAMs, U121 and U122, because both form a 16 bit word, whereas the calram 1220 is 8 bit only.The 4 empty sockets U122 - U125 are intended for 62256 SRAMs (volatile), to increase the data buffer to 148kB. nvRAMs should also work, but are a waste of money.You might also update the firmware in the 6 EPROMs to latest version 8 or 9.FrankPS: RAM TEST 1 LOW should refer to lower byte, that is U121.U121 and U122 also contain the working RAM space for the processor, therefore latter can't operate at all, if there's an error.

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 05, 2019, 02:42:55 pm
content: Well, I've put in 1230ABs. Should be as good as Y's as the power supply voltage is well within range (5.138) of the AB versions. And the 1220 is a 150+ version but so was the original one.I should have socketted it.

author: bsdphk
author_rank: Regular Contributor
timestamp: November 05, 2019, 03:26:51 pm
content: You should update the firmware as the first thing, version 4.6 has "issues" which I would not want to deal with, while trying to debug the hardware at the same time.

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 05, 2019, 04:07:14 pm
content: I was really hoping I wouldn't have toI aslo thought I didn't have an adapter for my programmer, but come to think of it, the base of the programmer probably *is* the adapter in this case

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 05, 2019, 04:22:57 pm
content: Also: what kind of issues?

author: Dr. Frank
author_rank: Super Contributor
timestamp: November 05, 2019, 04:33:06 pm
content: I just named the most convenient and cheapest types, but your choice seem to work also.So maybe there's a problem with the new nvRAMs, or you have a soldering problem, or something else on the PCB is fishy.Maybe you should really desolder all three nvRAMs again, and put them on precision sockets, and then you could also swap the high and low byte - RAMs, to see if this error moves to the other byte.For testing, you might also replace them by 32kx8 volatile RAMs, you only would get some initialization errors on each boot.Ah btw., have you saved the content of the old calram, maybe?I think that its data were not yet corrupted and could be copied to the new 1220, if you own an appropriate programmer.Frank

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 05, 2019, 05:10:40 pm
content: Quote from: Dr. Frank on November 05, 2019, 04:33:06 pmShould have put it on sockets right away. Stupid. But swapping is next on the list.QuoteHadn't considered that. Good idea.QuoteNo. I didn't think chances of it containing anything at all after 30 years were nihil. In addition, I didn't think they'd be of much use after 30 years of component ageing. You thihk it's worth trying to read it?

author: Dr. Frank
author_rank: Super Contributor
timestamp: November 05, 2019, 05:35:47 pm
content: The blank calram will be initialized with the default values like 7.2000V and 10.0000kOhm, so the new readings will be far off.The old RAM might still contain the old values which for sure have drifted a lot, but that will at least give you a much better reading, in first instance.Also, the RF calibration values might be preserved, which is an advantage, as this calibration otherwise requires special equipment, whereas zero, 10V and 10kOhm might be easily available from other volt-nuts.So, it's better than nothingFrank

author: Kleinstein
author_rank: Super Contributor
timestamp: November 05, 2019, 06:02:22 pm
content: The SRAMs can sometimes hold there contend even with a voltage considerably lower than given in the DS. So it is no longer guaranteed that data are still correct, but there still is a good chance the data are still there.The is a message for SRAM checksum error, but no such message for the cal RAM.

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 05, 2019, 06:26:43 pm
content: Message received. Will try to get the call data tomorrow

author: bsdphk
author_rank: Regular Contributor
timestamp: November 05, 2019, 06:56:07 pm
content: I'm not going to give you a very clear and detailed answer, because this is code which runs in a live product, and therefore by definition not a legitimate "dataarcheological" target.To be honest, I am not entirely sure what is going either.The fact that this version is named "4.6" where all other released versions are single-digit is ... strange.All the other versions have the ROM checksum code in the bottom of the low eprom pair, where also the reset vector lives, so that you can meaningfully detect problems in the other four eproms. In 4.6 everything is ordered differently, and the ROM checksum code lives near the end of the top eprom pair, meaning that 4 eproms must (mostly) work before you can even run the built in diagnostics.Looking at v2, v6 and v4.6 (anybody have v3 and/or v5 ?) the differences indicate that 4.6 was more of a side-branch than a point on the mainline.Almost as if somebody somewhere else were told "Please patch these critical bugs NOW! we can't wait for the next release..." or something.Service note 12-B has the public release notices for the firmware versions, and gives plenty of reasons on its own to upgrade to v8 or v9

author: Dr. Frank
author_rank: Super Contributor
timestamp: November 05, 2019, 10:07:26 pm
content: phk,that sounds a little bit between the lines, as if this FW 4.6 might contain errors which prevent a proper initialization of blank nvRAMs.Anyhow, if a UV eraser and programmer for these old EPROMs is available, I would directly upgrade to these FW 8 or 9, there is practically no difference between them.Frank

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 06, 2019, 07:23:40 am
content: Ah, crud. UV eraserHadn't considered I was going back that far in timeProgrammer should be OK, I'll have to find something for the UV.

author: Kean
author_rank: Unknown
timestamp: November 06, 2019, 07:39:54 am
content: Quote from: Ice-Tea on November 06, 2019, 07:23:40 amIf you don't want to buy/build a UV box, then the sun can work pretty well - it can just take a day or two of direct sunlight.

author: bsdphk
author_rank: Regular Contributor
timestamp: November 06, 2019, 11:00:08 am
content: The only differences between 8 and 9 are the version number and two changed boundary values, which are probably for a component change to a larger tolerance.

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 06, 2019, 12:59:52 pm
content: Quote from: Kean on November 06, 2019, 07:39:54 amDirect sunlight? In Belgium?Seriously, though. Ordered some cheap OTP's. So I can keep the originals around and give v8 or 9 a spin