EEVblog 1515 - Dumpster Tektronix TDS540D 500MHz Oscilloscope LCD Replacement - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: November 15, 2022, 05:27:18 am
content: Part 2 in the dumpster Tektronix 4CH 500MHz TDS540S oscilloscope.Replacing the CRT with an LCD had a few issues...Ebay listing here:https://www.ebay.com.au/itm/225251897379

author: darkspr1te
author_rank: Frequent Contributor
timestamp: November 15, 2022, 07:01:10 am
content: When i saw the disruption in the initial image i knew it was the dot clock setting, iiyama monitors used to have that option burried in the menus and god forbid you change it to a setting incompatible with the vertical refresh your vga card is outputting right now as you would end up with a corrupted image or heavily overscanned image including the menu which relied in the incoming clock signal to match displayed timing , if you were lucky and had matrox or ati cards they would auto switch or you could change via a command line program which ment sometimes making a boot disc for dos with autoexec.bat running your command to switch vert freq of the vga signal.ah the memories.darkspr1te

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 15, 2022, 07:04:27 am
content: Nice bodge!Question re. the HDD option in there, is there any software on that HDD by chance? I have some of the TDS software packages but I'm always on the lookout for more.

author: sean0118
author_rank: Frequent Contributor
timestamp: November 16, 2022, 09:41:03 am
content: I still have Tektronix TDS754A parts available (in Sydney) which maybe be useful for this... front panel knobs look the same at least...https://www.eevblog.com/forum/buysellwanted/fs-tektronix-tds754a-parts-only-(sydney-aus)/msg4254691/#msg4254691

author: bob808
author_rank: Frequent Contributor
timestamp: November 16, 2022, 11:14:35 am
content: You should have checked the 12Vin circuit of the LCD board. It might have step up/down regulators on board which would be ok with 15Vin. Even a linear regulator wouldn't dissipate much extra heat with another 3V on top. The only issue would be the input caps if they're 16V rated, too close for comfort.

author: nctnico
author_rank: Super Contributor
timestamp: November 16, 2022, 11:43:00 am
content: You should remove the glass from the bezel. That is quite dark and not necessary with an LCD screen fitted.

author: Andie
author_rank: Contributor
timestamp: November 16, 2022, 06:28:07 pm
content: Regarding the fan related surprise: Once I replaced the fan on a HP54100A scope, which apparently checks for the ripples in the fan current, presumably caused by commutation. The HP didn't work with modern fans until I injected some ripple from a small mains transformer into the fan current.

author: thm_w
author_rank: Super Contributor
timestamp: November 16, 2022, 10:23:56 pm
content: Quote from: Andie on November 16, 2022, 06:28:07 pmJust sounds like a poor solution to a simple problem.Either use fan with RPM output (if they had them then), or put a NTC temperature sensor on the board for 5c.

author: EEVblog
author_rank: Unknown
timestamp: November 17, 2022, 02:14:35 am
content: Quote from: TERRA Operative on November 15, 2022, 07:04:27 amDon't know. It's now packed up ready for shipment.

author: james_s
author_rank: Super Contributor
timestamp: November 17, 2022, 02:33:51 am
content: Quote from: TERRA Operative on November 15, 2022, 07:04:27 amWhat software was offered? I have the HDD in my TDS784C, I thought it was just for storing captured waveforms and such.

author: Bud
author_rank: Super Contributor
timestamp: November 17, 2022, 05:02:29 am
content: Quote from: thm_w on November 16, 2022, 10:23:56 pmI have a couple computer fans salvaged from several years back, they have a thermistor built-in, the fan starts ramping up when air temperature hits 37C.

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 17, 2022, 06:45:44 am
content: Quote from: james_s on November 17, 2022, 02:33:51 amHere's a list of what I know of off hand, there may be a few more but I'd have to dig around to see.Jitter Analysis - TDSJIT1V2Disk Drive Analysis - TDSDDM1Power Analysis - TDSPWR1Enhanced Printing Functions - TDSPRT1Communications Pulse Measurements - TDSCPM1Eye Pattern Measurements - TDSEYE1Communications Eye Diagram Measurements - TDSCEM1Processor Specifications Measurements - TDSPSM1I have Comms Eye Diagram Measurements, Eye Pattern Measurements, Jitter Analysis and Enhanced Printing Functions.I really want to get my hands on the Power Analysis so I can put my current probe to good use.

author: james_s
author_rank: Super Contributor
timestamp: November 17, 2022, 07:54:40 am
content: Quote from: TERRA Operative on November 17, 2022, 06:45:44 amJitter Analysis and Enhanced Printing could be useful, I doubt the comms eye diagram stuff is good for much anymore. I agree the power analysis sounds interesting. I wonder what Disk Drive Analysis does? That could be useful for retro stuff.

author: David Hess
author_rank: Super Contributor
timestamp: November 20, 2022, 10:26:52 pm
content: The VGA horizontal and vertical synchronization signals are also 75 ohms, so there should be 5 75 ohm terminations if those are used. They are actually useful as a fast edge test signal with transition times of 100s of picoseconds.VGA also supports synchronize on green and if you examine the green output, it usually contains the horizontal and vertical synchronization signals just like composite video. I suspect the problem was just selecting the correct synchronization source.Quote from: Andie on November 16, 2022, 06:28:07 pmAreca RAID controllers do the same thing. They use a 2 wire fan, and measure the ripple current to determine the RPM or if the fan is even operating.

author: strick
author_rank: Contributor
timestamp: January 10, 2023, 07:47:02 pm
content: Terra,I have a 580D and a 580C, both with hard drives...Would you be willing to share the applications you mentioned in your post? Also, I would assume they have to be activated. Did TEK do it for you or did you find a way around that?thanks,Strick

author: TERRA Operative
author_rank: Super Contributor
timestamp: January 11, 2023, 05:54:29 pm
content: Quote from: strick on January 10, 2023, 07:47:02 pmPM me your email and I'll send you what I have. I'm not sure what will work on 500 series scopes as I don't have one to test, but you'll soon find out.There's no special activation, just load the particular software on (I removed the HDD from the scope and replaced it with a CF card and adapter, so I copied the software over to the CF card from my PC using a USB card reader).Once you boot the scope, you can load the software package you want to use from the scope menu system.You can activate options via GPIB though, like this:Send the GPIB commands over GPIB after switching the protection switch to unlock and sending the text 'PASSWORD PITBULL' (without the quotation marks) via GPIB.Code:Option Name NVRAM Addr Hex Addr GPIB Command Description1M 4M acquisition length 0400081F 0000081F WORDCONSTANT:ATPUT 327686, 1 Extends standard acquisition length from 50,000 points per channel to 130,000 samples on three or four channels, 250,000 samples on two channels, and 500,000 samples on one channel.05 Video Trigger 0400081D 0000081D WORDCONSTANT:ATPUT 327687, 1 Oscilloscope comes with tools that allow investigation of a range of NTSC, PAL, SECAM, and high definition TV signals.13 RS-232C and Centronics interfaces 04000823 00000823 WORDCONSTANT:ATPUT 327688, 1 Add RS-232-C and Centronics interface ports.2F Advanced DSP math 04000827 00000827 WORDCONSTANT:ATPUT 327689, 1 Add advanced DSP math features such as FFT, integration, and differentiation.1F Floppy disk drive 04000825 00000825 WORDCONSTANT:ATPUT 327690, 1 Add 3.5 inch, 1.44 MByte floppy disc drive.2C Communication Signal Analyzer 0400082B 0000082B WORDCONSTANT:ATPUT 327692, 1 Oscilloscope comes configured for communications signal triggering and mask testing.3C P6701B with system calibration 0400082D 0000082D WORDCONSTANT:ATPUT 327693, 1 Oscilloscope comes with a P6701B and calibrated short-wavelength optical reference receiver on channel 1.4C P6703B with system calibration 0400082F 0000082F WORDCONSTANT:ATPUT 327694, 1 Oscilloscope comes with a P6703B and calibrated long-wavelength optical reference receiver on channel 1.2M 8M acquisition length 04000831 00000831 WORDCONSTANT:ATPUT 327695, 1 TDS 520D, 724D: To 2M samples on two channels and 4M on one channel. TDS 540D, 580D, 714L, 754D, 784D, 794D: To 2M samples on three or four channels, 4M on two channels, and 8M samples on one channel (Option includes a hard disk and is only available for the models listed above.)Note, some options need hardware to be installed (05, 13, 1F, 3C, 4C, 2M). Option will simply not appear if the hardware is not present.

author: strick
author_rank: Contributor
timestamp: January 11, 2023, 05:56:52 pm
content: Thank you Terra! I'll send you a PM with my email address.Strick

author: strick
author_rank: Contributor
timestamp: February 06, 2023, 08:40:03 pm
content: I can verify that the TDS580D with a hard drive and 2M does run the TDS784D software. This included Comms Eye Diagram Measurements, Eye Pattern Measurements, Jitter Analysis and Enhanced Printing Functions.I found that I had to install a PCMCIA to CompactFlash adapter in order to put the CompactFlash in my laptop. The regular PCMCIA hard drives are double slotted and wouldn't fit in the laptop. I was able to copy TDSCEM1 (Comms Eye) via a floppy to the regular hard drive on the 580D and it worked, but the rest were too large and had multiple levels. These just failed to properly write to the hard drive.Strick

author: Trax
author_rank: Regular Contributor
timestamp: February 21, 2023, 07:10:02 pm
content: I just got an old TDS 784D, it has a bad display, you can somewhat see something but only a bit of the waveforms, the text is not readable.Is this failure more of the CRT known to be reparable, or do I need to swap it for an LCD like in the video?EDIT: i noticed that when i switch the display to hard-copy preview it kind of gets inverted and then everything is readable just on a white background.Can it be that I just need to tweak some pot to fix that properly?@Terra would your files work for my model as well and if so could you please share.

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 22, 2023, 12:47:55 am
content: Can you provide a photo?

author: Trax
author_rank: Regular Contributor
timestamp: February 22, 2023, 07:36:32 am
content: Here you go:https://ibb.co/5vmXcnnThe "Hardcopy Preview" comes out with messed up colors on the crammer but for the human eye its just fine, and looks completely white with color lines and black grid and text, etc...must be due to the faster shutter speed auto exposure sets in combination with how the CRT creates color its not your typical shadow mask mut somethign called NuColor, anyhow...The Normal and Bold images look on cammera considerably better then to the human eye, due to toe longer exposure you can see the UI elements on the photo quite easy, but to the human eye thay are almost unreadable in booth modes.

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 22, 2023, 08:00:48 am
content: Yeah, to get good photos you need to slow the shutter speed or similar to capture the whole 'colour cycle' as it flips between red, green and blue with the LCD shutter. Cameras are often faster than the CRT assembly in these units.Looking at those images, it looks like you may need to start troubleshooting with a run through the CRT contrast/brightness calibration.Check out the service manual at tekwiki, give it a tweak and let us know how you go.https://w140.com/tekwiki/wiki/TDS784Also, do a full factory reset on the unit too, just to make sure there's no funky setting somewhere that is messing things up.<shift>, <Display/Utility> then you should see 'Tek Secure Erase Memory' highlighted on the bottom of the screen. press the lowest soft-button to the right of the screen to select 'OK Erase Setup & Ref Memory' to reset the machine.If you don't see that by default after entering the Utility menu, press the left most soft-button along the bottom of the CRT to scroll through the options until you get to the 'Config' option.Now select 'Tek Secure Erase Memory' and press the 'OK Erase Setup & Ref Memory' as mentioned above to reset the machine.