Tektronix TDS display discolouration - Page 1
Forum section: electronics / repair

author: ulix
author_rank: Regular Contributor
timestamp: January 20, 2025, 03:25:00 pm
content: Hello everyone,currently looking at some old Tektronix TDS scopes (700 series) and noticed that a lot of them do show discolourations of the display. For example the grid and parameters written on the right are in red/pink. Is this an indication of a failing tube or can this be atributed to other problems?Thanks a lot for your replys

author: m k
author_rank: Super Contributor
timestamp: January 23, 2025, 02:27:42 pm
content: IF it's not mentioned it can be a camera effect.https://www.eevblog.com/forum/repair/color-display-failure-tds500-tds700-series-c-or-d/

author: TERRA Operative
author_rank: Super Contributor
timestamp: January 23, 2025, 03:26:19 pm
content: Possibly a common-ish problem where the LCD shutter fails. Often it presents as discolouration in blobs as parts of some of the shutter fails to respond to the shutter signal.There is no fix besides either putting up with it, replacing the CRT assembly, or installing an LCD panel (You can find information on various LCD swaps around the forums).Can you provide a picture of the problem? Try to take a photo when the boot graphic displays, as it's an easy way to show the problem most prominently.

author: AndyC_772
author_rank: Super Contributor
timestamp: January 23, 2025, 04:37:39 pm
content: I'm surprised any of those old scopes are still running.I had a couple of them maybe 15 years ago and they were getting on a bit then. Bulky, noisy, and very power hungry - about 500W IIRC.They were fantastic bits of kit in their day and I'm not sure there's anything that's really replaced them for functionality at the price. If you really need 500 MHz on a hobby budget, and it doesn't matter too much if it dies with a bang one day, then go for it - but I'm glad I replaced mine with a Keysight MSOX3054A for a whole host of reasons. I got my desk back, for one thing.FYI the screen is a bizarre hybrid of a mono CRT with a colour LCD shutter in front of it, and it may just be hard to photograph without artefacts. True colour LCD conversion kits are available but cost as much as the scope itself.

author: TERRA Operative
author_rank: Super Contributor
timestamp: January 23, 2025, 05:26:17 pm
content: A slightly longer exposure time can capture a nice screenshot, if you can hold the camera steady.

author: StrayElectrons
author_rank: Contributor
timestamp: January 23, 2025, 06:17:43 pm
content: Pink light tint is dying CCFL lamps.Either panel or replace CCFL with new one or LED backlight mod.Tricky to do as you have to disassemble some of LCD panel to access the lamps or for LED mod.Cheers,

author: CaptDon
author_rank: Super Contributor
timestamp: January 23, 2025, 07:06:01 pm
content: The TDS 500, 600, 700 series are CRT with the shutter system. Pink to one side as mentioned could be only an artifact of camera shutter speed. The normal failure of the shutter usually comes from a physical shock to the front of the display and it usually takes the form of a discolored blob in one area. CCFL is used only in the newer series like TDS2000, TDS3000. Also be aware, the colors can be edited on the older 600 / 700 series. I have the trace colors on my TDS644B edited to match the new TEK scope colors, 1=Yellow, 2=Blue, 3=Magenta, 4=Green.