Tektronix TDS210 repair - oscillator help needed

[TERRA Operative]

RE: blade....

Thought I could help here but apparently the TDS220 I have access to is older and the board is different...   

I powered this one up and it was working before I opened it up for the pictures.  Don't match yours unfortunately.

As an aside, if you were wanting to update your firmware, you can program a new PROM chip with v1.19 from this link and just plug it straight in there in place of 163-0792-02
https://w140.com/tekwiki/wiki/TDS220

[blade]

Thanks for all the help. I check my OE# pin and it has 10.8K resistance to ground and 3.5k to VCC(3.3). Very different than your results. In diode mode I measure 0.56V to GND and 0.71V to VCC(3.3V). The multimeter negative terminal is tapping the OE# pin in diode mode. Based on these values I think I'm measuring the flash internal resistance and some diode junction (clamping diodes most likely)

So, I probed the back of the board for continuity test and quick enough found a 100Ohm resistor in series connected to the OE# and a via on the other end going under the ADG422 ASIC. I probed the new found via with the ASIC pins and no contact. This could be the broken via. I put a picture where this resistor is located and the new via i tested. Can you safely verify the continuity to the ASIC? If not I will have to remove the ADG422 and take a look underneath.

PS: thank you PwrElectronics for your effort, even though your board is different. These new mainboards with BGA flash have V2.x firmware  and I believe is the last update by Tektronix.  The flash chip is an EEPROM with JEDEC CFI interface. Program and calibration data are on a single chip. I ordered some  24pin 0.5mm flex connectors and cable from Aliexpress. I plan to read the chip memory and dump it here. A few people were asking for it years ago, but no one seemed to have it.

PPS: I mentioned in my previous post that CE# is tied to ground. This is wrong. CE# is connected to pin 29 on ADG422. I powered on the scope and used a frequency counter to see what the flash is doing. There is a 1.3Mhz signal on the CE# pin and all data pins have 300~700Khz on them. So the chip is working. Someone with the same board as PwrElectronics had the same issue as mine, and the problem was that his flash got corrupted and the scope could not write incremented power cycle counter to flash. In my case the OE# pin has to go HIGH to write to flash. Instead it is always at 20mV.

[TERRA Operative]

Ok, I get 4.6K when probing between that BGA pin and ground while not using the continuity beeper on my multimeter. Red herring...

Also, probing the two points you show in your latest pic gives me continuity, and 100R resistor. Flipping over the PCB has the via to just outside the chip, and the trace visible to the pin, as per the attached image.

[blade]

That would be pin 23 on AGD422. I can confirm I also have connectivity from ASIC to OE# via 100R resistor. My continuity checker might have missed it in the first place, thanks for pointing it out. The flash chip connectivity is OK. I also probed DRAM chip. I figured that since there is activity on the flash, the boot process might have moved further. Pin 16 (/RAS) is held HIGH. According to the function table in the datasheet, that corresponds to DRAM being in Standby mode.

At this point, it can be assumed that the flash chip is corrupted and it is in a continuous read loop(maybe scope was shut off in the middle of a write process and got corrupted, who knows). There is not much, I can do at this point, but wait for the parts to arrive and build a simple JEDEC CFI logic analyzer to probe what happens in the data bus. that will probably take a few weeks. The U430A footprint will be my tapping point to the chip. To read the flash, I will probably have to remove R305 to suppress clock signals to ASIC and halt it so to avoid any digital interference.

[TERRA Operative]

Let me know if you need more probing done, I can open up my scope again.