Tektronix TDS3000 (TDS3052B, TDS3034B) Boot Process

[benj38]

Did anybody ever succeed in repairing a Tek TDS3000B series scope that is stuck on the splash screen with known good NVRAM and PSU?

I have both a TDS3052B and TDS3034B with the same problem: both get stuck on the splash screen, no floppy sounds, no relay sounds, no front-panel lights.

I have fixed my share of these scopes, but never had this problem, nor did I see in any of the threads in this forum any report of fixing a scope with these symptoms (though the problem was discussed more than once).

I would make the following notes:

• By replacing parts with a working TDS3064B I know for certain that the NVRAM is not the issue, nor is the PSU or the battery board.
• All supply rails (+5V, -5V, +3.3V) generated on the main board also test fine by comparison to the working TDS3064B.
• Both clock chips on the main board are fine.

I have seen mentions of possible bad RAM, Flash ROM, or CPU needing re-balling, but no mention of anybody actually verifying any of these suspicions.

[coromonadalix]

check if the crystal (s) oscillators are ok,  not sure but some did mention, one who get defective ?  a 25Mhz  if not mistaken ?

[benj38]

check if the crystal (s) oscillators are ok,  not sure but some did mention, one who get defective ?  a 25Mhz  if not mistaken ?

They are fine. That is what I meant by item 3 in the notes in my original post.

[lern01]

Is there a problem with the firmware? Just like the TDS1000 & TDS2000 B C series card with three green lights.In addition, it is recommended to use a good oscilloscope to connect the oscilloscope's built-in calibration source output port to monitor the frequency changes during the oscilloscope startup process. What is the frequency when it is stuck on the startup screen?

[benj38]

I am not sure if there are enough similarities with the TDS1000 & TDS2000 B C series scopes to be of much use, but I may be wrong.
In any case, the calibrator output, on both faulty scopes I have, outputs no signal at any time.

[lern01]

I am not sure if there are enough similarities with the TDS1000 & TDS2000 B C series scopes to be of much use, but I may be wrong.
In any case, the calibrator output, on both faulty scopes I have, outputs no signal at any time.

If the calibrator has no output, it is recommended to find the calibrator fault first. It may be that the chip that generates the calibration waveform is not working. The normal machine startup is the boot screen, the calibrator first outputs a 1KHz square wave, and then enters the system. I hope this can help you.

[benj38]

If the calibrator has no output, it is recommended to find the calibrator fault first. It may be that the chip that generates the calibration waveform is not working. The normal machine startup is the boot screen, the calibrator first outputs a 1KHz square wave, and then enters the system.

This is not the case with the TDS3000 and TDS3000B series scopes.
In these scopes the calibrator output does not appear on power on. It appears only a few seconds after the splash screen shows, and a fraction of a second before one hears the first relay click. My faulty scopes freeze on the splash screen before the relays click, and since there is no calibrator output we can only conclude that the freeze occurs even a bit earlier.

In short, there is no reason to suspect any problem with the calibrator output generation. It is the boot process that freezes early that is to blame.