Tektronix DSA602A No Screen No Work Diagnostics Succesfully Complete: SOLVED

[Johnny10]

OK, so I really shouldn't be starting a new project just yet but I couldn't resist.

I bought a DSA602A for parts to have on hand, fans, boards, CRT, etc.
When I picked unit up I found it was newer and in much better condition than my DSA602 that I use every day.

Turning it on I got a Dmx Pipeline 4 error and after pressing screen to exit diagnostics mode the unit locks up and screen goes blank.

Did some research and consensus was poor wave soldering on heavy backplanes.
So I heated the #1 and #24 pins on each Ram chip of Pipeline 4.
Error corrected.
Restart machine and after diagnostics sequence screen goes blank and locks up.
Both Fine button LEDs are lit alongside Vertical and Horizontal knobs.

So I restart and force machine to halt during diagnostics, by the way, I have clear crisp display during diagnostics including working touchscreen and ability to run all tests manually.
Unit passes every test.

When exiting diagnostics and in the blank state the calibrator functions, fans run.
However, the Touchscreen Panel light is set to off and the Fine control lights are lit on both knobs.
All other LEDs are normal
Do not have control of front panel buttons or plug-ins.

Any Ideas or experience with this?

I am following service manual but not much help when tests pass.
I am leaning towards a problem in the display controller board A16
This boards function is consistent with display of traces and grids

[Johnny10]

After fixing the memory error by resoldering pipeline #4.
Unit would stall after completion of self test.

Solution
More reading, more reading, service manual, then Tektronix website.

Question:
Someone in our group turned the DSA off while it was running the complete self test. Now each time we turn the instrument on it never finishes the self test and the instrument cannot be used.

Answer:
In the users manual under the heading of Initialization, page two of that discussion tell you how to erase the nonvolatile RAM. Hold down the WAVEFORM and TRIGGER menu buttons as you turn on the power. When the LEDs next to the menu lights stop blinking, release the buttons. When the instrument completes self test, a message"should be displayed that says "Teksecure Erase Memory Status: erased." All volatile RAM will be erased, including waveform and settings memory. The instrument will be set to a factory default condition.


After applying reset unit ran complete diagnostics and initialized oscilloscope and plugins (took about 10 minutes).

Hey Hey  Merry Christmas!!