Electronics > Repair
Dead TDS3000B (3054B) , possibly processor?
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pcarew:
Hello all,
I have a TDS3054B that used to work, but had not been powered on for 3-4 years.
When I did power  it  on, it wouldn't boot, just white backlight and fan. No other activity.
Here's what I looked at so far:


* Power Supply and regulators - Good         All looks good. 15V from Power supply. Regulators generating +/- 5V and 3.3V

* Oscillators - Good         Both 48Mhz and 75Mhz oscillators working

* MAX708 Reset - Good         Generates reset at power on as expected

* MPC8660 Processor running  - Bad
There seems to be no life whatsoever on the main board from the processor. I've checked address lines in various places/chip pins and there is *no* activity

I'm suspecting either a dead MPC860 or maybe it needs re-balling.

Have others encountered this on a TDS scope before?
Before I start taking any drastic action with this board, does anyone have any other suggestions as to what to check?

Thanks
Paul.

StefanF:
I had also a blank screen with my 3014B.
There was still activity (Delay led turned on when pushing delay button,also react on autoset button.)
The culprit was the display itself.
I could manage to get the scope(display) running by powerwing the scope up for 30min, then turn it off and directly turn on again.

Stefan
sicco:
I made a BDM (PowerPC legacy background debugging port) adapter, and wrote pc code for a ftdi ft2232 usb adapter that uses this backdoor. On a good scope this allows you to peek and poke into the mc860, and beyond.
BDM port is on ~5 pins of the 100 pin expansion connector.
I think BDM works even when there’s no cpu clock.

Published elsewhere in eevblog. https://www.eevblog.com/forum/repair/tds3014-adventures-(seeking-75-75mhz-oscillator)/msg3704437/#msg3704437

There’s an extra serial maintenance port also on the 100pin connector, TTL level, that spits out how VxWorks is booting. Maybe that port still tells you something.

You may want to check a clock buffer chip, a SOT23 ic not too far away from the mc860.
pcarew:
Thank you Sicco, this is helpful.
pcarew:
I'm continuing to examine the TDS3054B motherboard and looking to identify the various ICs surrounding the MPC860.

Does anyone know what this 5 pin device is (circled in red in attached JPG)?
( The photo is taken from Dave's teardown video as I'm not in front of my one at the moment)

It's marked as 7Z2G but I'm failing (or google is failing) to find/id this device.


Thanks
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