Tektronix TDS460A

[EddyInChicago]

Hi All,

I'm a new here and hope someone can help me out with a problem I'm having with my TDS460A scope.
When I power it on, all the LEDs come on the front panel and stay on. There is nothing on the CRT. It
seems locked or in some boot mode. Any advice on what I can do?

NOTE:  I have taken the scope apart (after this problem.....not before ever), and check for loose or broken
connections. Also, checked for leaky caps.  Thanks in advance.

Ed

[Testtech]

Check the two lithium batteries, I think if one or both are dead, it won't boot. And check the power supply voltages as well.

[EddyInChicago]

Here is a picture of two identical scopes I have.  The one on the bottom is a good working scope. The one on top is the scope that will not boot correctly (at all).
Notice the top board; it has an ".8" on the 7 segment LED. The one on the bottom has a "0".  Any ideas?

[madao]

8. on 7seg-display  always? It look not good.  Dead CPU Board...  dead firmware: short life on 7-seg display.
Then check  reset-ciruit and   clock. if all run fine- - it would  be to much difficult to repair

https://forum.tek.com/viewtopic.php?f=568&t=138100

Try it at frist with debug port.


Greetings
matt

[wn1fju]

For what it's worth, when I recapped my TDS520 scope, almost all of the SMT electrolytics on the display board showed signs of leakage (puddles, etc.) but
none of them on the processor board did.  Yet all the caps were bad, measuring only a few nanofarads.  I was also getting a hung boot condition with the
diagnostic LED showing ".8" on mine.  So take another look at the capacitors.

[madao]

TDS400A  (not  old TDS400)  haven't  bad SMD eletrolytics . But possible: PSU with bad caps. 
Reason:  TDS400A series is late modell (since 1996,  issues with SMD capacitor is solved)