So I desoldered the DS1225 nvram carefully and fitted a 28 pin DIL socket.
Took the nvram and just to see if there was still any life in it I programmed it using a TL866ii programmer, using a .bin file from the EEVblog thread.
With the nvram replaced, the scope booted up without any errors. Now this was just a temporary test until I get a known good DS1225AD from Mouser, but at least it proves that the original cal data was bad ;) And the readout does not have the question marks anymore, hurray.
The remaining issue is the triggering. The symptoms are:
- scope triggers in auto lvl / auto mode with sweep speeds longer than 2mS. At 1mS it triggers most of the time, but not all, with faster timebase speed it gets more and more intermittent and at 500uS or so it stops triggering. This is with Y input at 200mV/cm and probe on the cal point (400mV p/p).
- the display is OK, everything reading as expected there.
Before I start going through sweep troubleshooting, has anyone seen a trigger issue like this?
Keith
