[PSU Pic. request] Tektronix TDS 220 repair

[sbeube02]

Hi Grumpydoc, your French is quite perfect 

I have replaced the ADG321D ASIC with one new from aliexpress.
I have no more noise on channel 1 but I still have the message "CH1 and CH2 aquisition failled" on startup.
Probe comp is still 3 kHz? I have tried to reverse engineer the PCB, and the probe comp signal is comming from the other ASIC ADG422.
I think my problem are caused by an early stopped calibration process.
I need to find the right equipement to perform the factory calibration.

[Tiny]

I have just measured the signal on the Probe Comp on my TDS220 ~5.2V, 3kHz. My unit gives fails the "Acquisition" part of the power-on self-check - still trying to narrow this one down.

[JFJ]

- still trying to narrow this one down.

Apart from directing you to the rudimentary checks given on page 6-40 of the service manual, members would need to know which type of main board your oscilloscope has, in order to make further suggestions.

There were two types of main board used in TDS220/210 oscilloscopes. The older design had the firmware in an AT27C040 OTP EPROM (mounted in a 32-pin PLCC IC socket). The later design used an AM29DL800B flash memory BGA chip - mounted directly onto the main board (the chip is marked: D800BB90V).