Datron 1071 repair - Page 1
Forum section: electronics / general

author: feedback.loop
author_rank: Frequent Contributor
timestamp: August 25, 2016, 06:06:44 pm
content: A vintage metrology grade meter was repaired, calibrated and tested for stability. Not much was wrong with it: a couple of faulty caps, a stuck switch, and corrupt calibration data. The display is bad as well, but usable, so it can be tolerated for now. The loss of calibration is, of course, a big deal since I don't have appropriate equipment to calibrate a 7.5-digit meter, but I have done what I could given the circumstances. Then I run the meter together with HP 34401A for about 28 hours taking measurements of 10V from Fluke 341A calibrator over GPIB and plotting the data using Octave 4 with instrument-control package. The results look good: just a few ppm of drift over a wide temperature range, and the meters stayed within about 2.5 ppm from each other.Datron 1071 Service Manual:http://www.ko4bb.com/manuals/66.228.162.56/Datron_1071_Multimeter_Cal_and_Service_Handbook.pdfhttps://youtu.be/jcCC867gKXE

author: bitseeker
author_rank: Super Contributor
timestamp: August 25, 2016, 06:21:26 pm
content: Thanks for making another repair vid. I look forward to watching this tonight.

author: The Soulman
author_rank: Super Contributor
timestamp: August 25, 2016, 07:21:41 pm
content: Thanks for sharing!Are you sure the display itself is broken and not some of the driving circuitry?There is to much of a pattern for my taste, I don't know, just a guess..

author: Vgkid
author_rank: Super Contributor
timestamp: August 25, 2016, 07:52:38 pm
content: Thanks, will watch tonight.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: August 25, 2016, 08:13:43 pm
content: Quote from: The Soulman on August 25, 2016, 07:21:41 pmI am not entirely sure, but I couldn't find anything wrong with driving circuitry. And I vaguely remember seeing some posts about replacing such displays with ones from broken donor units.

author: Dr. Frank
author_rank: Super Contributor
timestamp: August 25, 2016, 09:30:39 pm
content: Nice story telling. Good pace.I also would think, that there are some bad solder junctions, or so, as the display shows too many correlated faulty segments.Good luck for the repair.You sound similar to TiN (which both is quite pleasant),Do you also have an origin from Russia, or from neighboring states? (no degradation intended!)Frank

author: feedback.loop
author_rank: Frequent Contributor
timestamp: August 25, 2016, 09:52:34 pm
content: Quote from: Dr. Frank on August 25, 2016, 09:30:39 pmWell, I will try to look again into the display circuitry, but it looked fine on the first glance.Yes, I am from Russia originally. Same accent. It is hard to get rid of the accent if one learns a second language as adult. And I am sure I make mistakes from time to time with grammar and pronunciation.

author: bitseeker
author_rank: Super Contributor
timestamp: August 25, 2016, 09:56:02 pm
content: Some accents are very heavy. I find yours easy to understand. Keep up the good work!

author: lowimpedance
author_rank: Super Contributor
timestamp: August 25, 2016, 11:15:50 pm
content: I thought the voice sounded familiar ! , I had seen your fluke repair on youtube before.As for the display I thought I had seen another couple of threads relating to cathode poisoning on these panaplex/nixie displays in the past, so see here:https://www.eevblog.com/forum/beginners/gas-discharge-display-of-datron-4000-problems/?nowapNote Gilbenl s reply with some links that may be useful.And given you have replaced the HV cap I suspect it is indeed a worn out display.

author: Vgkid
author_rank: Super Contributor
timestamp: August 25, 2016, 11:38:38 pm
content: Nice job on the repair so far. I think I have heard of someone replacing the panaplex display with a LCD display, though that might be for arcade purposes.

author: macfly
author_rank: Contributor
timestamp: August 28, 2016, 12:01:59 pm
content: > It is hard to get rid of the accent if one learns a second language as adult. And I am sure I make mistakes from time to time with grammar ...Thank you very much for this report - and don't worry about your accent. Your English is very good understandable.Some of the native-english speaking fellows talk so fast and with dialect, which is sometimes absolut incomprehensibil for those, who learnedonly Oxford English at school (sorry fellows).Regards,macfly

author: guenthert
author_rank: Frequent Contributor
timestamp: August 28, 2016, 05:19:30 pm
content: Thanks for sharing and sorry for not being able to help with the repair of the display. I was wondering instead about those diodes you identified as voltage reference in the DMM. Is this the Williams' 'ring of two' configuration (there should be a NPN/PNP transistor pair nearby)? I got away with the impressions that surface Zener diodes generally are noisy and age poorly, so I'm surprised to see them used as reference in a long-scale DMM. Do subsurface, discrete Zener diodes exist (in a two-terminal package)?

author: TiN
author_rank: Super Contributor
timestamp: August 28, 2016, 06:49:14 pm
content: Nice work, hope to see more on this box in future. Overall concept of design seem to be very similar to higher end 1271/1281.

author: dacman
author_rank: Frequent Contributor
timestamp: August 28, 2016, 07:52:11 pm
content: I believe that those orange plasma displays have a voltage rating of 220 V peak max.

author: Johnny10
author_rank: Frequent Contributor
timestamp: August 29, 2016, 12:49:15 am
content: Thanks for another interesting video.I believe I have watched all of them!It would seem you are collecting a good assortment for your lab.Would be great to see your whole setup.

author: zlymex
author_rank: Frequent Contributor
timestamp: August 29, 2016, 03:15:24 am
content: I once own a Datron 1071 and the reference is dual zener based(D59, D60). They didn't say anything about the maker and type, but I can see from the teardown photo that they were 1N829A.My questions are:Is 1N829A a subsurface Zener by any chance?Do subsurface, discrete Zener diodes in a two-terminal package exist? (repeat)I don't have any 1N829 for test, but one of my friends has tested a 1N829 by his 3458A when power up. I don't recall any parameters(such as the current, NPLCs for 3458A) but here is the chartI calculated the stdev in excel for 100 consecutive data to be 0.038ppm, which is good.

author: Andreas
author_rank: Super Contributor
timestamp: August 29, 2016, 04:31:59 am
content: Hello Lymex,the 1N82x series is a temperature compensated zener(standard surface zener combined with a normal diode to compensate for T.C.)There is a "zero TC" current (between 4 and 11 mA) where the T.C. is nearly zero over a 10 deg C temperature span.So you will have to adjust the current individually after having sorted out the unstable zeners.At least I dont know any discrete subsurface zeners.I know them only as part of a integrated cirquit (LM329, LM399, LTZ1000, AD586, LT1021 ...)With best regardsAndreas

author: zlymex
author_rank: Frequent Contributor
timestamp: August 29, 2016, 05:52:06 am
content: I had several batches of 2DW23x that are also temperature compensated Zeners. The datasheet doesn't tell anything about the type neither, but the LF noise is much smaller than the best commercial Zeners (such as LTZ1000). That's why I suspect that there is any relationship between Zener type(such as whether buried or not) and the noise.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: August 29, 2016, 06:23:41 am
content: Quote from: guenthert on August 28, 2016, 05:19:30 pmRegarding the configuration: there is a dual reference supply +-6.37 V. See the attached schemaitc

author: feedback.loop
author_rank: Frequent Contributor
timestamp: August 29, 2016, 06:28:37 am
content: Quote from: dacman on August 28, 2016, 07:52:11 pmYou probably mean to say why the capacitor was rated for 450V. I later found in the service manual that it must be 350V. Someone replaced it with 450V one.The display segments are driven from +5V to -175V.

author: Gyro
author_rank: Super Contributor
timestamp: August 29, 2016, 10:06:29 am
content: Replacement selected 1N82x reference diodes from Datron were supplied as a matched zener and resistor pair. I don't know if the resistor was simply selected to set to optimum zero TC zener current, or whether there was any resistor TC matching involved too.

author: dacman
author_rank: Frequent Contributor
timestamp: August 29, 2016, 10:51:19 pm
content: Quote from: feedback.loop on August 29, 2016, 06:28:37 amI happen to know that there is (usually) about 280 Vdc across that capacitor. The voltage gets dropped down to -175 Vdc with a series transistor regulator. It's referenced to the +5 Vdc digital power supply.What I was getting at, is if the display is suffering from cathode poisoning and it was desired to fix it by using double current or more for a time, then it seems to me that this would need to be accomplished by doubling the voltage, which I would not want to do with the display in the unit. I'd also want to monitor the current draw in case the current increase was not linear.

author: gilbenl
author_rank: Regular Contributor
timestamp: September 01, 2016, 12:23:31 pm
content: Haven't had a moment to watch the video, but the 1071 is a great meter. Mine lacks the GPIB interface, which I plan to add at some point. A ROM dump from the GPIB board would be appreciated!Regarding the display--I have a 1062 with the same fault. Unfortunately, I could never undo the cathode poisoning. There's very good info in the service manual regarding the display workings and a retrofit with a modern alternative should be doable, however, I haven't attempted. Alternatively, there are NOS and salvage Panaplex displays on ebay. They're not the purpose made datron units, but should be a serviceable replacement.Theres a very slight chance that the issue is not with the display itself, but with the PS or driver board. Check the caps if you haven't.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: September 20, 2016, 04:22:40 am
content: Teaser

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: September 20, 2016, 04:28:38 am
content: Looking forward to it.I have some Datron gear with broken displays but I have no time to fix them.

author: Vgkid
author_rank: Super Contributor
timestamp: September 20, 2016, 06:38:43 am
content: Can't wait to see an update. Those display's are what has always kept me from pursuing Datron gear.

author: Nuno_pt
author_rank: Frequent Contributor
timestamp: September 20, 2016, 07:22:30 am
content: +1 for this display, I've one that need a display, so it's on the unused box, seems like it's time to start cleaning the dust.

author: Johnny10
author_rank: Frequent Contributor
timestamp: September 20, 2016, 04:27:38 pm
content: What's that you are working on Feedback.loop

author: feedback.loop
author_rank: Frequent Contributor
timestamp: September 20, 2016, 06:38:22 pm
content: Quote from: Vgkid on September 20, 2016, 06:38:43 amWhat do you think an acceptable price range would be for a replacement module?I am trying to come up with a solution, which wouldn't be just my one-off project, but would be repeatable: not too expensive, easily obtainable components, minimal modifications to the meter.

author: dacman
author_rank: Frequent Contributor
timestamp: September 21, 2016, 09:51:10 pm
content: Replacement OEM displays were about $155.00 when they were available.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: September 23, 2016, 03:25:16 am
content: I don't understand the step #27 of the internal adjustment procedures:"Deselect HOLD and disconnect DVM. Select 1000V range and apply +10mV. Connect oscilloscope Lo to TP21, Hi ot TP5. Adjust R20 for noisy waveform at zero point."I don't understand what do they mean by "noisy waveform at zero point". Any ideas? Thanks.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: September 23, 2016, 04:11:00 am
content: On page 22 Fig 3.13 , it looks like they are asking you to adjust the zero point of the waveform to zero. You will have to look at the waveform and pick out zero from the five different possible levels and adjust from there.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: September 23, 2016, 05:20:51 am
content: Quote from: ManateeMafia on September 23, 2016, 04:11:00 amI am looking at the waveform, which I attached, and don't get what exactly they propose to adjust. I just skipped the step assuming it was good enough, and the meter seems to work fine, but I would love to understand exactly what is going on.

author: bitseeker
author_rank: Super Contributor
timestamp: September 23, 2016, 05:58:22 pm
content: Your screenshot looks like it has the waveform pretty well centered around zero. If you adjust R20, does the entire waveform move up and down? If so, then it seems to me that you have it right where it should be.

author: dacman
author_rank: Frequent Contributor
timestamp: September 23, 2016, 09:34:15 pm
content: Quote from: feedback.loop on September 23, 2016, 03:25:16 amMy guess is that the test point should be TP3 (near M15) vice TP5. The noise should appear just below zero. Also, in step 16, TP13 should be TL8. In step 17, TP13 should be TP19.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: November 08, 2016, 03:05:23 pm
content: Finally, I got around to the display replacement video. This is part one. Three different approaches were discussed. A working prototype was built.https://youtu.be/H9_Jwy-2vXU

author: bitseeker
author_rank: Super Contributor
timestamp: November 09, 2016, 03:54:58 am
content: Quote from: feedback.loop on November 08, 2016, 03:05:23 pmThat certainly was comprehensive. It was great to follow along with your analysis and then see the pros/cons of each approach. Looking forward to part 2!

author: feedback.loop
author_rank: Frequent Contributor
timestamp: February 20, 2017, 08:15:15 pm
content: Finally, after many delays and distractions I got around to the part 2 of this project. In this part a replacement display module and a controller board were built and installed. Since more pins were needed to drive five displays, ATMega164PA was used with the MightyCore library for Arduino IDE to support it. The result is not very good. The displays are not very bright, the brightness differs from display to display, and the viewing angle is quite limited. Suggestions for better displays for a reasonable price are welcome.https://youtu.be/mcHUmgmyhtoArduino MightyCore:https://github.com/mcudude/MightyCoreTFT ST7735 library:https://github.com/sumotoy/TFT_ST7735/tree/1.0p1Snap fasteners:https://www.mcmaster.com/#93040A112

author: dacman
author_rank: Frequent Contributor
timestamp: February 21, 2017, 01:14:02 am
content: Can you set the color to orange? (Since that is the filter color.) Also, thanks for the McMaster part for the latch. I can get the OEM ones but they are made of nylon, which is usually pliable, but the heat inside the units dries them out and causes them to become very brittle. Maybe the McMaster-Carr ones will last a little longer. Also, check the plastic "bolts" securing Q1 and Q2 to heat-sinks on the back.

author: bitseeker
author_rank: Super Contributor
timestamp: February 21, 2017, 01:34:18 am
content: Great job, feedback.loop. I've seen some not-too-expensive Panaplex (gas discharge) display modules, but don't see ones right now that are as low in cost.Following are some Beckman displays currently on eBay, just as an example. I've seen some 2-digit versions go for around $5 last year.http://www.ebay.com/itm/S2T5-Beckman-SP-353-Gas-Discharge-3-Digitsl-7-segment-Display-/232132776452http://www.ebay.com/itm/S2T5-Beckman-SP-356-Gas-Discharge-4-Digitsl-7-segment-Display-/361811468210One of each of the above would cover the seven digits required. However, the sign and special indicators would still need a solution (LEDs with template?). Also, according to the following page, the characters on these Beckmans are only 14mm high, which might not fill the 25mm available in the panel's window to your liking. But, it's just an example.http://www.datamath.org/Display/SP353.htm

author: CalMachine
author_rank: Frequent Contributor
timestamp: February 21, 2017, 02:06:44 am
content: Wow! I'm blown away at your craftsmanship and ability to make it look similar to the real thing. I was planning on doing something very similar to this to a Datron 4808 that has had the front display busted.

author: bitseeker
author_rank: Super Contributor
timestamp: February 21, 2017, 05:35:11 pm
content: I totally forgot about LED filaments, which could be arranged to make numeric displays. Of course, you'd have to find ones that would fit the space or be very crafty to chop them down.Here's an example. It does approximate the look and feel of Panaplex.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 21, 2017, 07:20:12 pm
content: There are a few LED units with a suitable size. The normal ones are too thick, but SMD ones should be OK. LIke those:http://www.pollin.de/shop/dt/MjM4ODc4OTk-/Bauelemente_Bauteile/Aktive_Bauelemente/Displays/SMD_LED_Anzeige_KINGBRIGHT_KCSC3008_105_A.htmlOnly the special signs / units might still need a special display. It might be possible to adjust the contrast / intensity on those modules.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: February 21, 2017, 08:26:08 pm
content: Quote from: CalMachine on February 21, 2017, 02:06:44 amDo you have a particular display in mind?

author: nidlaX
author_rank: Frequent Contributor
timestamp: February 22, 2017, 01:56:08 am
content: Remember thisHP 6632B OLED display replacement project?Just a thought.

author: CalMachine
author_rank: Frequent Contributor
timestamp: February 22, 2017, 02:04:28 am
content: Quote from: feedback.loop on February 21, 2017, 08:26:08 pmNot in the slightest. That is one of my projects I have planned a little down the road. I want to work on a voltage reference first. But when I do get to it, I will definitely keep you in the loop

author: feedback.loop
author_rank: Frequent Contributor
timestamp: February 22, 2017, 02:10:22 am
content: Quote from: nidlaX on February 22, 2017, 01:56:08 amI don't see any details there. Do you have the model of the display used in that project?

author: nidlaX
author_rank: Frequent Contributor
timestamp: February 22, 2017, 02:12:54 am
content: Quote from: feedback.loop on February 22, 2017, 02:10:22 amThey used this 16x2 panel:http://www.ebay.com/itm/IIC-I2C-1602-16x2-OLED-Module-Display-For-Arduino-PIC-AVR-ARM-/161162845021But if you wanna go big, try this extra large 20x2 yellow OLED panel:http://www.mouser.com/ProductDetail/ELECTRONIC-ASSEMBLY/EA-W202-XDLGEDIT: Wow, this 96mm wide 20x2 panel also looks nice:http://www.ebay.com/itm/IIC-I2C-2002-20x2-OLED-Module-Display-With-Arduino-Example-/191835417963These larger graphic OLEDs also exist, but I don't know where you could get them:http://www.winstar.com.tw/products/oled-module/graphic-oled-display/256x64-oled.html

author: feedback.loop
author_rank: Frequent Contributor
timestamp: February 22, 2017, 03:50:41 am
content: Quote from: nidlaX on February 22, 2017, 02:12:54 amThe first and the second are not graphic. The third is graphic, but won't fit into the meter and seems to cost about $150.

author: nidlaX
author_rank: Frequent Contributor
timestamp: February 22, 2017, 03:59:28 am
content: Quote from: feedback.loop on February 22, 2017, 03:50:41 amShame that the third option is so expensive and won't fit.I take it the character displays aren't preferable? You could take your current approach and use small 1" OLED modules to emulate 1-2 digits from the Panaplex.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: February 22, 2017, 04:33:31 am
content: Quote from: nidlaX on February 22, 2017, 03:59:28 amI don't see how to draw 9 large digits plus symbols on a two-row character display.Regarding those .96" OLED on eBay, I did consider them, but they are either white or blue and won't span the window on the meter vertically (not by much though), so I preferred TFT. However, if I give up the color, or put a red or orange filter in front of the white ones, they might be a good option.

author: z01z
author_rank: Regular Contributor
timestamp: February 22, 2017, 08:20:45 am
content: There are bigger OLEDs available, like1",1.1"and1.3", though these are all in white.There's also avertical 0.96"display that might be a bit bigger than the horizontal one.I got the 1.3" one from them (with the matching connector) and though it needs some extra circuitry to drive it, they do work, the datasheet has the needed schematics.Another approach could be a custom panel with SMD orange LEDs laid out as the original segments, with a diffuse layer in front and a mask in between, that would separate the segments from one another, like that filament display posted here previously. This way you could emulate the middle dots as well, and with appropriately cut out masks, all the special symbols.One could even etch a mask from a thin one sided PCB, though I'm not sure how the green tinge of the PCB with the orange light would look, probably terrible. Just a random idea.

author: Le_Bassiste
author_rank: Frequent Contributor
timestamp: February 22, 2017, 01:59:52 pm
content: Quote from: feedback.loop on February 22, 2017, 03:50:41 ami got mine fromwww.texim-europe.comfor approx. EUR 40 per piece.quality is not too shabby, so i gave it a test drive with one of my K2001. they "fit like a glove" into the display frame of the DMM, with no modifications to the frame at all:

author: nidlaX
author_rank: Frequent Contributor
timestamp: February 22, 2017, 02:02:06 pm
content: QuoteOh my, I need to find a US dealer for these...

author: Le_Bassiste
author_rank: Frequent Contributor
timestamp: February 22, 2017, 02:08:40 pm
content: rest assured, it is by no means as crisp and bright as the original VFD.

author: texaspyro
author_rank: Super Contributor
timestamp: July 08, 2017, 07:22:26 pm
content: I was thinking about doing a replacement front panel board for the HP-53132A counter... the only way to get a new display for these counters is to send HP $1600+ for a new board... they won't sell the display separately. Crystalfontz sells a 192x32 graphic LCD for a reasonable price. They also have smaller displays.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: March 29, 2019, 05:52:40 am
content: Reviving this topic.I was asked to share the code (yes, after 2 years!), so here it is. But it is not the same code I showed in the video. At some point I decided to play with this project a little more. I shifted some more complexity to hardware to make things more reliable and repeatable across different meters. No particular reason, just wanted to clean things up a bit.I cleaned up the interrupt signal by using 74LS74 flip-flop: phase2 clock to pin 3 (CLK) and the address selector to pin 2 (DATA), pins 1 and 4 are pulled up. The output from the flip-flop (pin 5) is used to interrupt the MCU and also to latch both address and data. I added one more 74LS374 to latch the address as well (only 4 lines are used). With this configuration the rising edge from the flip-flop happens when both the address and the data are stable, and the glitch is avoided entirely. Now there is no rush at all to read the address and the data in software. This drastically simplified the software. The interrupt routine was a crazy mess in assembly and very time sensitive. Now it is 3 lines in C, no naked interrupt trickery is needed. Enjoy.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 29, 2019, 02:32:22 pm
content: Thank you very much

author: Johnny10
author_rank: Frequent Contributor
timestamp: March 29, 2019, 05:36:17 pm
content: So you changed the hardware and software for the Display LEDs you used a few years back?What did Le_Bassiste reply have to do with the Datron project?I do like that display of his also.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: March 29, 2019, 05:53:20 pm
content: Quote from: Johnny10 on March 29, 2019, 05:36:17 pmI am not sure I understand your point.I was asked in a private message to share the code. I thought that reviving the topic to share with everybody would be a good idea.I did make some changes since I published the videos, so I described the changes.The displays I used are cheap TFT displays (not LEDs). I don't quite like them: not very bright and viewing angle is limited.The comments by Le_Bassiste have to do with some other project using an OLED display.

author: Johnny10
author_rank: Frequent Contributor
timestamp: March 29, 2019, 09:13:43 pm
content: OK,Sorry I got lost in that thread.Thought maybe you were saying you reworked your displays something similar to Le-Bassiste.Thanks for clarifying.I have a few broken Datron 4000 displays also.

author: branadic
author_rank: Super Contributor
timestamp: March 29, 2019, 09:48:17 pm
content: In this case you want to follow this thread:https://www.eevblog.com/forum/repair/datron-4000a-getting-at-test-points/msg2289120/#msg2289120-branadic-

author: feedback.loop
author_rank: Frequent Contributor
timestamp: June 14, 2020, 07:05:09 pm
content: I finally decided to try another approach for display replacement in this good old Datron 1071 meter. Design decisions are discussed in detail, and the code for ATmega164PA is shown. The new display is very bright with a very wide viewing angle, but it could use a better diffusing overlay.

author: branadic
author_rank: Super Contributor
timestamp: June 14, 2020, 08:33:40 pm
content: Well doneYou can use a white paper (80g) between spacer and printed foil / photo film as a diffusor. This worked at least for me and this is what I've shown in my pictures. Sorry if I forgot to mention this.Very early prototype using white spacer had printed paper instead of the printed photo film, fixed with Kapton tape to the board, which worked to, but I skipped that approach later.-branadic-

author: seebeck
author_rank: Contributor
timestamp: June 15, 2020, 04:16:49 am
content: I saw a FLUKE 343A DC voltage calibrator, the spec is 0.003%...

author: feedback.loop
author_rank: Frequent Contributor
timestamp: July 20, 2020, 01:51:10 am
content: A sheet of paper was added between the spacer and the overlay film, a few more things were tried as well. It seems that a thicker spacer should help, but I don't have the means to make one at the moment.

author: The Soulman
author_rank: Super Contributor
timestamp: July 20, 2020, 08:19:10 am
content: Quote from: feedback.loop on July 20, 2020, 01:51:10 amUse the transparent plastic of a cd case as a spacer?Looks good already btw.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 20, 2020, 07:48:03 pm
content: What happens, if you put a window like from the Aglient 34401A in front of your LED display?It should defuse and focus at the same time.