Hopefully first own digital oscilloscope! $150 blank screen TDS3012B to repair

[Synesthesiac]

Hey guys!

With some recent contract work ideas and custom projects, I decided to splurge on some at home test equipment. The electronics reuse store luckily had a broken Tektronix 3012B that stated the functions of the oscope worked, just needed a screen repair due to a blank screen. Sure enough it powers up, the relays click, test outputs are correct, and messing with the scales clicks the relays but the display stays a full white. It's actually the exact issue that was listed and forgotten in this thread: https://www.eevblog.com/forum/repair/tds3012b-repair-tentative-help-needed/. Edit: Looks like its similar this one too where it could be the display itself! https://www.eevblog.com/forum/repair/tek-tds3014b-defect/

So I decided to post here before continuing with tearing this thing apart to see if anyone has experienced this issue before? I'm thinking either a screen replacement (possibly costly), main board replacement (yikes, I'll buy a VGA output module before that!), or a possible component replacement based on my findings. With everything else powering up, I'm (possibly incorrectly) assuming that it wouldn't be the PSU. And luckily I do have another analog oscope on hand to analyze the VGA or other signals that should be going to the display.

Any tips for a young player before he gets his hands dirty?

[Synesthesiac]

After ensuring the power rails were correct and not too rippled, I went ahead and bought another $45 NL6448BC20-08E screen and it worked! The only issue I have now is that the horizontal scale knob keeps resetting back to 10s/div once I turn past about 4ms/div but I'm unsure if that's more to do with it failing to set to another level, the encoder itself, or the software just needs a refresher. Either way, I have a good digital oscilloscope for $200!

Also if I do update the firmware, will that get rid of the FFT and Adv Trigger modules that are pre-installed on the scope? I don't have the actual plug-in addon sticks, but the modules seem installed and I don't want to lose em. I'd rather just deal with troublesome knob then

[JesseLackey]

Hi, first congrats on taking a risk and making it work!  for $45 a new screen is really great.  I recently bought a MSO 4104 at an auction where the scope powers up but then overheats and fans were not working; two SMT fuses replaced, and ... voila.  It was also missing the pan/zoom knobs, which was an obnoxious $70 including $25 shipping from tektronix, but this whole endeavor was the deal of a lifetime probably.  I'm not sure I'd have been as brave as you to get something with a dead screen. 

About the modules.
There was a seller on ebay who was selling "empty modules", for the MSO/DSO 4000 series anyway, something like 4 of them for $150 and with such you should be able to transfer them out of the scope and then back in again.
But - I'd guess it is unlikely that a firmware update would erase such modules, b/c tektronix would have so many people furious if they did do that with no warning.
FWIW, the MSO4104 has a later version of the FW than I was able to find on tektronix's website of all docs for the series.  Curious.

Have fun!
J

[tautech]

It was also missing the pan/zoom knobs, which was an obnoxious $70 including $25 shipping from tektronix, but this whole endeavor was the deal of a lifetime probably.

Try Sphere for Tek parts:
https://www.sphere.bc.ca/test/tek-parts/tek-knobs.html