Author Topic: HP-53131A Korean vs US manufacture  (Read 531 times)

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Offline stephen.x.thomas@pm.meTopic starter

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HP-53131A Korean vs US manufacture
« on: November 11, 2024, 11:10:51 pm »
I have two HP-53131As in excellent cosmetic condition that were clearly well-kept instruments. The Korean-made unit is likely newer (serial KR912007xx) with five calibrations and the US-made unit (serial 3546A092xx) has ten. Initial testing shows they are equally accurate. I did a complete tear down and cleaning for both. The capacitors look good in both units and their build quality is visually similar.  The US-made one has marginally better BNC ports, perhaps from less wear.

I planned to upgrade and keep only one but not sure which to choose.  I considered upgrading both and see if one improves more, but I thought it a fair question to ask if anyone has more experience with these units.
« Last Edit: November 12, 2024, 02:11:58 am by stephen.x.thomas@pm.me »
 

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Re: HP-53131A Korean vs US manufacture
« Reply #1 on: November 12, 2024, 06:22:21 am »
I'd keep the newer one if it passes all self tests and performance verification.
If there were any improvements made between the two serial numbers, it'll have them, and the VFD potentially won't have faded so much (depending on individual run-time, but replacement VFD's are available on ebay etc).

It's not too hard to replace the BNC's as they are still available. I replaced all the BNC's and the serial/GPIP ports on my 53132A just 2 days ago. They were damaged and rusted, now they are shiny and new. :)
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Offline stephen.x.thomas@pm.meTopic starter

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Re: HP-53131A Korean vs US manufacture
« Reply #2 on: November 12, 2024, 06:39:49 pm »
The newer one has firmware 3703 and the older unit has 3427.  Viewing side by side, the older one actually has a much higher contrast VFD, so maybe I will swap the front panels and start modding there.
 

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Re: HP-53131A Korean vs US manufacture
« Reply #3 on: November 12, 2024, 10:21:43 pm »
If you have access to a chip programmer (and maybe new chips if the ones in your instruments are PROM, not EEPROM), here is the latest firmware.

You may need to recalibrate after the update, but it's not too hard to do.
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Offline stephen.x.thomas@pm.meTopic starter

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Re: HP-53131A Korean vs US manufacture
« Reply #4 on: November 12, 2024, 11:45:24 pm »
This is great advice, thank you. The newer unit has four AM27C010-150JC chips.  I had to remove a label to identify them.  I sourced AT27C010-70JU which is a one-time write but it should be the last time these units are modded.
« Last Edit: November 14, 2024, 06:49:10 pm by stephen.x.thomas@pm.me »
 

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Re: HP-53131A Korean vs US manufacture
« Reply #5 on: November 15, 2024, 03:53:13 pm »
They should work fine.  :-+
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