Tek 2465B with blank screen
Previously done: DallasNV replaced with Fram.
Scope was working until one day the screen remained blank. I did a recap from a kit but the problem remains.
It powers up with all leds on, then steps thru leds: ch1,ch2,ch3,ch4,add,invert,vert,add ;stuck here
No text or trace appears on screen, except beam find shows some short traces.
Able to enter normal mode by pressing A/B trigger button.
Able to enter diagnostic monitor and manually run tests, but no display.
The nine J119 reference voltages look good, but I found the front panel/DAQ outputs to be low (+0.225v,-0.250v instead of +1.36v,-1.25v). I was unable to make the suggested DAQ Ref adjustment because the voltages only vary a little. Not sure I am performing the adjustment correctly. Replacing DAQ Ref pot R2010 and cleaning the area did not fix it. While disconnected, the Ref input circuit seemed ok.
Jumpering J504 for a fixed -1.25v reference artificially restored the +1.36v,-1.25v refs, so downstream circuits are probably ok. This also brought text back to the screen and allowed me to see the boot error as "Test 05 Code 24". The service manual says Test 05 checks "Line Trigger source, A Trigger generation, and Control DAQ". Troubleshooting flowcharts say to see the Options service manual about Code 24, but I see no mention of it there.
I'd like that code explained before I decide its the DAQ.