HP / Agilent 53131A / 53132A VFD to LED Display Conversion - Page 1
Forum section: electronics / testgear

author: dimmog
author_rank: Regular Contributor
timestamp: December 25, 2024, 04:52:27 pm
content: This is a drop-in replacement for the VFD display used in the HP / Agilent 53131A / 53132A / 53181A counters.The new display is LED-based and requires no modifications to the counter.EEVblog forum users can use the ebay coupon codeEEVFORUMLEDfor15% OFFon the LED display for the 53131A, 53132A, and 53181A.The displays are now available here:https://hubequip.net/products/hp-agilent-53131a-53132a-vfd-display-replacement-led-display-conversion-kitor here:https://www.ebay.com/itm/326404635023

author: Tony_G
author_rank: Super Contributor
timestamp: December 25, 2024, 04:59:05 pm
content: Interesting - Is there a link to the display?TonyG

author: dimmog
author_rank: Regular Contributor
timestamp: December 25, 2024, 05:06:23 pm
content: The display module will be ready for sale soon.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 26, 2024, 11:24:43 am
content: Oh my.I replaced the VFD with a new one in my 53132A, but this has my attention... What sort of cost are we looking at?Will it be open sourced?I assume it is something like a 3D printed frame on top of SMD LED's with a 'shadow mask' overlay sticker or similar? Looks neat!

author: lowimpedance
author_rank: Super Contributor
timestamp: December 26, 2024, 02:17:51 pm
content: And presumably this same technique can be easily adapted to the 34401a as well with appropriate annunciators!Certainly very interesting.

author: dimmog
author_rank: Regular Contributor
timestamp: December 26, 2024, 10:23:48 pm
content: Quote from: TERRA Operative on December 26, 2024, 11:24:43 amThanks. We are open to price suggestions.

author: TheSteve
author_rank: Unknown
timestamp: December 27, 2024, 01:52:39 am
content: The same VFD is also used in the 58503 GPSDO.

author: dimmog
author_rank: Regular Contributor
timestamp: December 27, 2024, 06:02:34 am
content: Quote from: lowimpedance on December 26, 2024, 02:17:51 pmYes, it can be adapted, but there are currently plenty of affordable new VFDs available for the 34401A.

author: dimmog
author_rank: Regular Contributor
timestamp: December 27, 2024, 05:32:37 pm
content: Quote from: TERRA Operative on December 26, 2024, 11:24:43 amThis is not a 3D-printed frame. It’s a high-quality, professionally made LED display.The only difference from the original is the blue color instead of cyan.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 28, 2024, 04:12:59 am
content: Quote from: dimmog on December 26, 2024, 10:23:48 pmThat's not something we can answer without the full BOM, shipping, etc cost breakdowns....

author: dimmog
author_rank: Regular Contributor
timestamp: December 29, 2024, 05:10:15 am
content: The photo shows the clearance.

author: dimmog
author_rank: Regular Contributor
timestamp: January 02, 2025, 12:27:57 am
content: Here’s how we tested the prototype.

author: TERRA Operative
author_rank: Super Contributor
timestamp: January 02, 2025, 03:53:20 am
content: So, how can we get our hands on one?Any chance for green?

author: squadchannel
author_rank: Frequent Contributor
timestamp: January 02, 2025, 04:11:48 am
content: as you can see, it is a custom segment LED, and it would be impossible to change the color.can see the shadow mask on top of the segment LEDs. it would be easy to change the annunciator letters.if can make a frame of the segment with an SLA printer, it is easy to duplicate. the problem is the resolution of the SLA printer.

author: dimmog
author_rank: Regular Contributor
timestamp: January 02, 2025, 05:23:03 pm
content: Quote from: TERRA Operative on January 02, 2025, 03:53:20 amThere's not much longer to wait.Only blue color will be available, as none of the other LED colors we tested pass well through the display window/filter.Unfortunately, cyan LEDs in the needed configuration are not available.

author: dimmog
author_rank: Regular Contributor
timestamp: January 04, 2025, 10:03:44 pm
content: The first batch of PCBs has just arrived.

author: Cyclotron
author_rank: Unknown
timestamp: January 05, 2025, 08:00:31 pm
content: Quote from: dimmog on January 04, 2025, 10:03:44 pmThey are very nice-looking boards. I'll take two.

author: Cyclotron
author_rank: Unknown
timestamp: January 05, 2025, 08:11:03 pm
content: Any chance your work might be something that could be used on HP 34410A, 34411A DMMs?I've been hunting VFDs for a bit and have no luck.

author: dimmog
author_rank: Regular Contributor
timestamp: January 05, 2025, 09:31:56 pm
content: Quote from: Cyclotron on January 05, 2025, 08:11:03 pmThe VFD in the 34410A is a more advanced unit with built-in logic, not just a simple display. Converting it to an LED display would involve extensive reverse engineering.The 34410A/34411A aren’t very common DMMs and the costs of development and production for such a project would likely outweigh its benefits.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 05, 2025, 11:18:31 pm
content: yep the 34410a 34411a have their drivers inside the vfd ... i know their prices have gone up from the mere 35$ ea i paid for 2 of them ...but i would still buy the vfd ...not sure, but i think someone worked on the data decoding between the main and vfd board ?? it was done for the 34401a

author: pqass
author_rank: Super Contributor
timestamp: January 06, 2025, 12:24:08 am
content: Quote from: coromonadalix on January 05, 2025, 11:18:31 pmSeeherefor an alternate display for the 53131A/53132A (doc/protocol_desc.txt).Seeherefor an alternate display for the 34401A (protocol.md).

author: dimmog
author_rank: Regular Contributor
timestamp: January 08, 2025, 05:33:46 pm
content: Longevity testing in progress: this unit has been running continuously for 35 days, 24/7.It has endured a temperature range of 26°C (from 4°C to 30°C) and a humidity variation of 50% (40% to 90%).

author: dimmog
author_rank: Regular Contributor
timestamp: January 13, 2025, 11:04:25 pm
content: The displays are now available here:https://www.ebay.com/itm/326404635023

author: Cyclotron
author_rank: Unknown
timestamp: January 14, 2025, 12:33:43 am
content: Quote from: dimmog on January 13, 2025, 11:04:25 pmOrdered one to put in my 53132A and if that works out well I'll put one in my 53131A too.Thanks

author: dimmog
author_rank: Regular Contributor
timestamp: January 16, 2025, 04:07:51 pm
content: Easy to connect - only two extra wires: +5V and GND.

author: artag
author_rank: Super Contributor
timestamp: January 16, 2025, 04:59:38 pm
content: The ebay listing of destinations doesn't include UK or Germany in either 'ships to' or 'excluded'.Do you expect to change this ?

author: dimmog
author_rank: Regular Contributor
timestamp: January 16, 2025, 05:38:05 pm
content: Quote from: artag on January 16, 2025, 04:59:38 pmeBay International Shipping is blocking several categories from being shipped from the USA to the UK, citing new UK regulations as the reason.You could try using a shipping proxy or forwarding service - they're widely available.

author: artag
author_rank: Super Contributor
timestamp: January 16, 2025, 07:09:43 pm
content: ebay shipping is weird. The forwarders are very expensive and, if this is correct, would also have this problem. Germany is affected too. These are both important markets for this product.There are many suppliers who have no problem. It seems you have to get the right category and then it will work.One supplier was able to arrange UK shipping by putting his items (logic analyser ground clips) in"Consumer Electronics>Radio Communication>Parts & Accessories>Coax. Cables & Connectors". I'm not sure what they were in previously but probably some more generic spare parts - the categories having problems are rather arbitrary. You might try a category like 'displays' or something that avoids any implications of meeting electrical or consumer standards.

author: dimmog
author_rank: Regular Contributor
timestamp: January 16, 2025, 07:52:29 pm
content: Quote from: artag on January 16, 2025, 07:09:43 pmI believe I found the category for the UK, but not for Germany yet. Please check.

author: Mouse69
author_rank: Contributor
timestamp: January 17, 2025, 05:37:33 pm
content: Ordered mine this morning via ebay.co.uk for my 53131A.Go a message this afternoon it's been dispatched.

author: artag
author_rank: Super Contributor
timestamp: January 17, 2025, 05:50:07 pm
content: WinIt appears they're looking for some sort of CE/UKCA declaration for items which would have that - which would be mains powered (yeah, I know those are not just for power but that's all that seems to bother ebay). But they don't actually care what the item is, they just apply it to categories of items which are mostly mains powered, such as test equipment (which, of course, is industrial equipment and didn't use to require CE approval).

author: dimmog
author_rank: Regular Contributor
timestamp: January 17, 2025, 08:21:39 pm
content: Quote from: artag on January 17, 2025, 05:50:07 pmIt seems they also look at the item title. I have a listing under 'Soldering & Rework Stations' that is visible in the UK and Germany, but when I assign the same category to another listing, it disappears everywhere except the US.

author: salvagedcircuitry
author_rank: Regular Contributor
timestamp: January 17, 2025, 09:29:29 pm
content: This is a very neat mod. Nice job on the replacement part! This should keep these units working well into the future

author: artag
author_rank: Super Contributor
timestamp: January 18, 2025, 01:42:16 pm
content: Quote from: dimmog on January 16, 2025, 07:52:29 pmIt might be this :https://www.ebay.co.uk/help/account/regulatory/extended-producer-responsibility/extended-producer-responsibility-selling-germany?id=5336

author: hp3310a
author_rank: Regular Contributor
timestamp: January 18, 2025, 06:30:00 pm
content: Quote from: dimmog on January 16, 2025, 07:52:29 pmDoesn't work with a ship-to address in Germany but works just fine with an Austrian address. That's a bit weird.

author: dimmog
author_rank: Regular Contributor
timestamp: January 18, 2025, 09:48:04 pm
content: Quote from: hp3310a on January 18, 2025, 06:30:00 pmYeah, I really don’t know how to make it available in Germany. I’ve tried everything.

author: Cyclotron
author_rank: Unknown
timestamp: January 19, 2025, 08:25:21 pm
content: Horray!!I got my display in yesterday and swapped it out today. WOW! My VFD was in pretty good shape, but this new one is beautiful.I wanted to post some before-and-after shots. I didn't realize this display's refresh cycle would mess up my photos. Anyway, I like it. I will use it for a bit and decide if I will replace the one in my other unit.I think this included the best set of directions I've ever seen in a non-OEM replacement component. That's a pro move.Oh, one more thing. I was assembling my system and ensuring everything was clean when the film covering the LCD pealed. At first, my stomach sank, thinking I'd messed up something, but I then realized it was a protective film over the LCD.You might want to note the film cover in your directions.

author: dimmog
author_rank: Regular Contributor
timestamp: January 20, 2025, 03:36:13 am
content: Quote from: Cyclotron on January 19, 2025, 08:25:21 pmThank you for your feedback! I mentioned the protective film in the instructions, but only your display was sent without this information. Sorry about that.

author: dimmog
author_rank: Regular Contributor
timestamp: January 21, 2025, 08:18:07 pm
content: Quote from: dimmog on January 18, 2025, 09:48:04 pmIt looks like I’ve finally fixed Germany in the U.S. eBay listing. If anyone from Germany could check whether this listing (https://www.ebay.de/itm/326404635023) appears on eBay.de and if it’s actually possible to purchase, I’d really appreciate it!

author: dimmog
author_rank: Regular Contributor
timestamp: January 24, 2025, 07:54:57 pm
content: The first Agilent 53131A on eBay featuring an upgraded LED display:https://www.ebay.com/itm/126890560572

author: bson
author_rank: Unknown
timestamp: January 31, 2025, 10:39:35 pm
content: This very cool. Just have no illusions that blue LEDs won't fade with age...

author: dimmog
author_rank: Regular Contributor
timestamp: February 01, 2025, 01:19:32 am
content: Quote from: bson on January 31, 2025, 10:39:35 pmThe LEDs are driven with a limited, pulsating current at a very conservative operating pointto minimize thermal stress and maximize long-term reliability.The display brightness is about half of its maximum.

author: dimmog
author_rank: Regular Contributor
timestamp: February 10, 2025, 09:53:54 pm
content: The next batch of displays has just arrived.We offer a discount for bulk orders.

author: dimmog
author_rank: Regular Contributor
timestamp: February 19, 2025, 05:15:58 am
content: Many thanks for your review, Dave!

author: kloetpatra
author_rank: Regular Contributor
timestamp: February 19, 2025, 09:00:32 am
content: Impressive! Would love to see this for the keithley 2000/2015/2016 (all have the same display).

author: vaualbus
author_rank: Frequent Contributor
timestamp: February 19, 2025, 09:12:01 am
content: As you are now "expert" on this I would suggest you to also to replacement for other VFD instruments such the Agilent 33120A function generator and 34401A multimeter.I recently burned the VFD filament of my 33120A as I am an idiot and connect the main power supply the wrong way around sending 24V to the filament and burned it.Luckly the instrument survives but the VFD was a Christmas tree.

author: lowimpedance
author_rank: Super Contributor
timestamp: February 19, 2025, 09:54:10 am
content: Another happy customer here aswelltwo 53131's back in action from collecting dust due to unreadable VFD's. A very neat solution for the long term.Ps If you did produce one for the 34401 , I would buy one....or two..

author: SHF
author_rank: Regular Contributor
timestamp: February 19, 2025, 11:14:16 am
content: I would like the color green better, it is also easier to read

author: Kean
author_rank: Unknown
timestamp: February 19, 2025, 11:23:12 am
content: Quote from: SHF on February 19, 2025, 11:14:16 amApparently not when you take the commonly available green LED wavelengths and put them behind the existing display filter.

author: Kean
author_rank: Unknown
timestamp: February 19, 2025, 11:24:52 am
content: Quote from: lowimpedance on February 19, 2025, 09:54:10 amMe too, or three...And I'll upgrade my future 53131A/2A when I finally get one.

author: dimmog
author_rank: Regular Contributor
timestamp: February 19, 2025, 04:15:29 pm
content: Quote from: lowimpedance on February 19, 2025, 09:54:10 amThank you!The initial investment for LED display production is quite high, so we're not sure if we'll be able to take on another similar project in the near future.Many new low-cost VFDs are available for the 34401A, making an LED project for it unprofitable from the start.

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: February 19, 2025, 10:18:32 pm
content: Quote from: dimmog on January 02, 2025, 05:23:03 pmCyan would have been perfect, I'm not a fan of the blue but it sure beats the alternative of not being able to read the display. Great productIs the brightness user-adjustable (trimpot or resistor swap)? I could probably handle it being just a fraction dimmer, for my personal preference.

author: dimmog
author_rank: Regular Contributor
timestamp: February 19, 2025, 10:46:30 pm
content: Quote from: Geoff-AU on February 19, 2025, 10:18:32 pmThanks.We designed the display to require no modifications to the counter, which comes with certain design limitations. As a result, there is no built-in brightness adjustment. However, you can reduce the brightness by slightly lowering the 5V rail using a parallel resistor.

author: TheSteve
author_rank: Unknown
timestamp: February 20, 2025, 06:13:03 am
content: Still pondering if I want try one in my 58503B.The original VFD is dim but not horrible after more than 7 years of 24/7 use.The LED's would look quite nice I'm sure.

author: dimmog
author_rank: Regular Contributor
timestamp: February 20, 2025, 11:52:11 am
content: Quote from: TheSteve on February 20, 2025, 06:13:03 amVery interesting! I haven't seen the display board in this unit before.It seems to have some differences compared to the 53131A/32A.I haven't come across any photos online either.

author: TheSteve
author_rank: Unknown
timestamp: February 21, 2025, 04:28:12 pm
content: Quote from: dimmog on February 20, 2025, 11:52:11 amThe front plastic and VFD are the same as the 53131/132/181, the front label that covers the plastic is different as are the keypads buttons.

author: dimmog
author_rank: Regular Contributor
timestamp: February 21, 2025, 05:18:55 pm
content: Quote from: TheSteve on February 21, 2025, 04:28:12 pmI believe they also relocated the DC/DC converter to the display board, which may add an extra step for removal and replacement when swapping the display.

author: Zucca
author_rank: Unknown
timestamp: February 21, 2025, 06:39:59 pm
content: Quote from: dimmog on February 19, 2025, 04:15:29 pmVFD don't last, LED do.You can easily charge $120 or more for a 34401a LED drop in replacement.I don't agree it will not be profitable... quite the opposite.I fell there are 10x more 34410a on this planet benches than 5313xA.Also why not sell it outside from ebay and make 10% more profit?

author: dimmog
author_rank: Regular Contributor
timestamp: February 21, 2025, 07:34:55 pm
content: Quote from: Zucca on February 21, 2025, 06:39:59 pmOkay, I've added the poll about 34401A to the thread now.BTW, eBay now charges a 13% fee. But I'm not a fan of the idea of creating a separate store for just one product, as it would increase the workload for order processing and shipping.

author: lowimpedance
author_rank: Super Contributor
timestamp: February 23, 2025, 11:09:32 pm
content: Quote from: dimmog on February 21, 2025, 07:34:55 pmThanks for the poll, would probably get greater exposure if the thread title mentioned the 34401 specifically for a possible LED display version.

author: artag
author_rank: Super Contributor
timestamp: February 23, 2025, 11:43:04 pm
content: Quote from: dimmog on January 02, 2025, 05:23:03 pmWhite seems like an option, since it could be more effectively filtered. Was that one you tried ?

author: dimmog
author_rank: Regular Contributor
timestamp: February 24, 2025, 06:04:54 pm
content: Quote from: artag on February 23, 2025, 11:43:04 pmWe tested these different colors, but some were declined for aesthetic reasons. In the end, we selected blue as the best option.Code:+----------------+-----------------+----------------+------+| Emitting Color | Test Condition | Wavelength, nm | △λ |+----------------+-----------------+----------------+------+| Amber | IF=18mA | 600-605 | 30 || Super green | IF=18mA | 565-575 | 30 || Super red | IF=18mA | 630-635 | 20 || Ultra red | IF=18mA | 621-623 | 20 || Ultra red 2 | IF=18mA | 620-625 | 20 || High red | IF=18mA | 638-660 | 20 || Yellow green | IF=18mA | 570-580 | 30 || Yellow | IF=18mA | 580-600 | 35 || Blue | IF=20mA | 465-475 | 40 || Pure green | IF=20mA | 515-525 | 40 || White | IF=20mA | - | - |+----------------+-----------------+----------------+------+

author: dimmog
author_rank: Regular Contributor
timestamp: March 03, 2025, 06:52:10 pm
content: EEVblog forum users can use the coupon codeEEVFORUMLEDfor15% OFFon the LED display for the 53131A, 53132A, and 53181A.https://www.ebay.com/itm/326404635023

author: Runco990
author_rank: Frequent Contributor
timestamp: March 04, 2025, 02:21:44 am
content: I'd have to see one of the displays in person.... I'm excited about the prospect, but I really don't like these (dark) blue LED's everywhere. Blue is the hardest color for our eyes to focus on. The "Coolness" of blue led's wore off for me years ago. I HATE seeing them in audio gear lighting the VU meters, for example. This weird "hyper blue" just kills your eyes!

author: coromonadalix
author_rank: Super Contributor
timestamp: March 04, 2025, 03:21:11 pm
content: sadly same comments as @Runco990 not bashing this projectthe blue is too intense and too bright in some cases, for me too, i have a pc with b lue leds and believe me when the room is dark, i have a pretty strong blue effect / aura, annoying at some pointfor the repaired 34401 i had the new vfd was fine,i would need to see it live too before purchasefor the ebay link and shown images, sadly i would never buy itat 1st knowing this led variant exist, i would tend to buy an vfd instead even if its priced way higher than the led versionthe red green or blue as they are a way too intense, you would need to have rgb leds and adjust them at lower brightness or non pure primary colors by mixing other colors, to get a light blue, a light red or green .... add some slight yellow in it ?but the bezel color and thickness in some instrument for sure kill some intensityebay link again, the lower function markers are less intense for sure than the main digits, it would be a killer for me, sorryamber could be nicer i think ? my 2 centsand the poll tests price does not fit the ebay one ? i put vfd as an answer

author: dimmog
author_rank: Regular Contributor
timestamp: March 04, 2025, 05:13:57 pm
content: Quote from: coromonadalix on March 04, 2025, 03:21:11 pmVFDs for the 53131A/32A/81A are no longer available. The two Chinese sellers on eBay listing them for around $200 will either cancel orders or send a different display.Before starting this LED project, I attempted to purchase VFDs multiple times on eBay and AliExpress, but without success.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: March 05, 2025, 10:45:50 am
content: if, instead of the text annunciators, there was just down-pointing triangles (like on some other HP gear), would one of these displays be usable as a drop-in replacement for a 34401A? ie, is the wiring the same irrespective of text?cheers,rob :-)

author: dimmog
author_rank: Regular Contributor
timestamp: March 05, 2025, 05:09:13 pm
content: Quote from: robert.rozee on March 05, 2025, 10:45:50 amThe 34401A display is slightly different, with fewer pins that are offset compared to the 53131A display pinout. Additionally, the 34401A display board doesn’t provide a 5V supply with enough current. While addressing this issue and designing a compatible display wouldn’t be difficult, the main issue is the low demand for it.

author: lowimpedance
author_rank: Super Contributor
timestamp: March 06, 2025, 02:41:03 am
content: Quote from: Runco990 on March 04, 2025, 02:21:44 amI have this LED conversion to replace the unobtanium VFD in my 53131, and I do not have difficulties with the brightness and color particularly with my aging eyes where bright light causes tiredness.Yes, I too hate super bright blue LEDs, but once this display is installed behind the panel filter I find it viewing it right for me. I can actually use the instrument again !As for the 34401, I wonder just how reliable those clones are and how many times owners of these meters are willing to rework the FP PCB.Also to get one here they still represent a 'not insignificant' cost investment, and trust that it will work...properly.

author: dimmog
author_rank: Regular Contributor
timestamp: March 06, 2025, 02:46:56 am
content: Quote from: Runco990 on March 04, 2025, 02:21:44 amTo @coromonadalix and @Runco990It comes down to personal preference. I've received a lot of positive feedback from people who have replaced the display or seen it in person. Many, myself included, like the blue color - especially since, as I’ve mentioned many times, it’s the only color that passes through the filter well without a significant loss of brightness.

author: dimmog
author_rank: Regular Contributor
timestamp: March 20, 2025, 08:27:00 pm
content: Thanks so much for the review, Nick! I really appreciate it!

author: dimmog
author_rank: Regular Contributor
timestamp: April 20, 2025, 03:01:01 am
content: The LED display is now on sale!Grab it for just$71.91using coupon codeEEVFORUMLEDhttps://www.ebay.com/itm/326404635023

author: yo0
author_rank: Regular Contributor
timestamp: April 20, 2025, 04:12:28 am
content: Quote from: kloetpatra on February 19, 2025, 09:00:32 amYes I like the idea very much! Lots with dimmed displays out thereBest regards

author: dimmog
author_rank: Regular Contributor
timestamp: April 23, 2025, 02:37:02 am
content: Quote from: yo0 on April 20, 2025, 04:12:28 amAlright, we'll think it over and see where it goes..

author: dimmog
author_rank: Regular Contributor
timestamp: May 01, 2025, 08:25:15 pm
content: Many thanks to Per H from Sweden, who has successfully completed the VFD-to-LED display replacement on an HP 58503A GPS frequency reference unit.Both the 58503A and 58503B with option 001 use the same VFD display as the 53131A/53132A.Although the display board (part number 58503-60010) is completely different, it is fully compatible with the LED display.The key difference is the +5V connection point for the LED display positive wire, which should be connected to the C2 tantalum capacitor.Check out all the photos kindly provided by Per H.

author: dimmog
author_rank: Regular Contributor
timestamp: June 18, 2025, 05:42:23 pm
content: If you know you know.I'll create a new topic for this display project.

author: dimmog
author_rank: Regular Contributor
timestamp: June 18, 2025, 08:26:03 pm
content: Quote from: dimmog on June 18, 2025, 05:42:23 pmhttps://www.eevblog.com/forum/testgear/keithley-2000-2015-2016-2001-vfd-to-led-display-conversion/

author: the Chris
author_rank: Regular Contributor
timestamp: June 27, 2025, 11:48:43 am
content: A new arrival in Germany. Thanks dimmog for offering this alternative!

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 03, 2025, 06:57:35 pm
content: Yup, I just bought one of these too. 5 minutes after ordering the 53132A.

author: the Chris
author_rank: Regular Contributor
timestamp: July 06, 2025, 06:34:30 pm
content: The replacement is really well documented. I was motivated to remove the old VFD intact, but there is so much solder from the top side as well that in the end, I fell back to the suggested clipping of pins. Not a huge loss as the VFD was really dim anyway.Works splendid. Got a few upgrades from snickers (https://www.eevblog.com/forum/profile/?u=440481) along the way as well

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 11, 2025, 12:00:30 am
content: This thing works great, and it was a simple install. Good stuff!Thanks,Josh

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 20, 2025, 04:12:25 pm
content: Is there any way to manipulate the refresh rate?I would like it to be easier to take photos with a cellphone.Thanks,Josh

author: TERRA Operative
author_rank: Super Contributor
timestamp: September 20, 2025, 04:43:45 pm
content: I think it is just running at the same referesh rate as the original display, that is the LED's are being driven from the original VFD signals directly with some sort of transistor or level shifting going on. I doubt there are any 'smarts' between.To take photos with a smart phone, I tend to use 'Pro' mode and drop the ISO down to 50, set the shutter speed to remove the flickering, then adjust the scene lighting to get good exposure. You'll need a tripod or stand of some sort, but it works well besides being a little effort to set up.I do the same for taking photos of the TDS500/600/700 colour displays with the shutters, they are really hard to take photos of with the camera in auto mode.

author: dimmog
author_rank: Regular Contributor
timestamp: September 20, 2025, 04:59:33 pm
content: Quote from: KungFuJosh on September 20, 2025, 04:12:25 pmThe refresh rate of the display can't be adjusted. You'll need to fine-tune your camera settings instead.I took this photo on an iPhone by adjusting the exposure, and in my case, some LED lighting also interfered with the shot.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 20, 2025, 05:19:31 pm
content: I took the photo above with a real camera, and it's much easier to control those settings that way vs. a cellphone.Is the refresh rate of the panel controlled by the panel, or by the counter? If the latter, I assume there is something setting or restricting it.

author: dimmog
author_rank: Regular Contributor
timestamp: September 20, 2025, 05:45:18 pm
content: Quote from: KungFuJosh on September 20, 2025, 05:19:31 pmThe counter manages the refresh, as TERRA Operative mentioned. It might be adjustable with extra timing logic between the counter and the VFD driver IC on the display board. For example, the 34401A DMM's VFD refreshes at a lower rate than the 53131A, even though both use the same VFD driver.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 20, 2025, 06:47:09 pm
content: Hmmmm... 🤔

author: Mrt12
author_rank: Regular Contributor
timestamp: September 29, 2025, 06:56:57 am
content: This is a very nice mod. How does it work, is there a schematic somewhere to see how it works? I assume the high voltage logic outputs from the display dirver U2 on the front panel board are used to switch on the different LED segments, right?