Electronics > Beginners
tektronix tds1012b led backlight retrofit
gimp-e:
Hi guys,
This is my first post. i aquired a tektronix tds1012b oscilliscope from an electronix recycler. The scope works, but after about 20-30 minutes, the screen goes black. After some research, it seems the CCFL backlight bulb goes out, and replacement bulbs aren't available. So, I'm in the middle of an LED retrofit for the backlighting as detailed on this site:
https://nt7s.com/2016/05/tds1012-led-backlight-retrofit/
In order to do this, I need a schematic of the tds1012b. Does anyone happen to know where I might get one? (I especially need the power supply section...)
thanks in advance.
Cheers!
tautech:
Welcome to the forum.
Depending on the voltage your LED backlight needs it shouldn't be hard to find the voltages you need on the PCB although current requirements need be considered before you hook onto just anywhere.
Check the service manual for the PSU header voltage assignments.
You can get the manuals here:
http://w140.com/tekwiki/wiki/Main_Page
Have a look at this one that Shahriar did:
https://youtu.be/smrMoIpvYTk
gimp-e:
Thanks for the reply! I already had both the user manual and service manual, but neither has a schematic. In the retrofit article that I'm trying to replicate, the author says he soldered to a 6V rail on the J9 connector of the PCB (which I will look at tonight), but I don't show that L9 connector anywhere in either manual. The service manual shows the main ribbon cable (J101), but no info on voltages, which is why I'm trying to find a schematic. Since I'm a newbie, I'm a little nervous to just go poking around blind with a multimeter inside this thing while it's on, since the goal is to repair and use it, not fry it.
tautech:
Is you look carefully at the pics of the Tek PSU I'm quite sure the rail voltages are listed in the PCB silkscreen next to the cable header. Unplug it and continuity test to the mainboard to find the 6V rail so to find a suitable pick off point for the LED backlight driver.
If you're still worried that it's not the right point, mark it with a sharpie and connect it together again, power it then measure it with a DMM.
You shouldn't need a schematic only open eyes and a clear head. ;)
Tell us how you get on. :)
gimp-e:
Thanks for the reply. I'm looking at it tonight after work, so hopefully I can find a place to solder the wires for the boost/buck converter. I want to do some more testing on that circuit before I wire it in, just to get the amp draw from the circuit as low as possible so I don't (hopefully) overload the circuitry in the scope.
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