LeCroy LT264M repair, does not power on. Update: powers on but broken trigger

[Jontm]

Measuring the voltage out of the MC10EL33 i get a voltage swing of more than 3 V, as shown in the attached picture. The voltage at 12R78 is down to just 200 mV with a DC of about 4 V. Trying to measure the 12Q3, it measures a bit odd. Multimeter in diode test I measure a voltage drop as low as 0.15 V on one of the transistors between base and emitter. On the others, they are in the 0.8 V range. I am suspecting that 12Q3 or 12Q4 might be bad. I think I might desolder them to test them properly and change both if they still measure bad when they are off the board.

[Jontm]

Base to emitter on 12Q4B measures in at O.L.
All the other transistors measures fine on 12Q4A and both on 12Q3. I have high hopes for this causing the issue.
Ordering a couple of these and changing them.
Will report back late next week if this solves the issue with the strange trigger control voltages.

[Jontm]

I do not get it. I have now changed out 12Q4, 12Q3, 12IC5 (MC10EL33). I have desoldered and tested 12Q5 and 12D2. All voltage rails measure ok (12 V, -12 V, 5 V, -5 V and -2.3 V)
The circuit does still not work. Scope at 12R71 and 12R72 shows a strong (1.7 V 125 MHz) clock signal with a negative offset of about 1.3 V. The signal is completely gone at 12R78. I do not understand. I mean i have changed out or checked all active devices. The resistors are also measuring ok, at least as far as it is possible to measure in circuit.
Measure point at the base of 12Q4B (pin 4) show -7 V as it is indicated in the schematic that it should be. I guess the next step would be to desolder all the passive components and replace them as well. At least the ones that are difficult to measure in circuit. Had hoped that i did not have to do this


Edit:
I measure 0 V on pin 2 and 6 of 12Q3. That surely cannot be correct ? Pin 1 and 3 measure 5 V. On pin 4 and 5 i measure the around -1.3 V signal with a strong 1V+ 125 MHz superimposed.
I also find it strange that i measure 12 V on pin 1 of 12Q4, i mean these are 11 V devices !? I could ofcource try to change out 12Q3, but i have already done it twice. However i might still try as sure does not look like it is working as it should...

[Jontm]

Haha. Third time the charm i guess. Finally got the 125 MHz ECL to CMOS circuit working after a quick run with the iron to go over all the solder joints one more time

Bad news is that the trigger cal does still fail... At least there is a output signal on the AD9850 now during the "ODP/EVT/HYST auto adjust". About 200 mV, 32 MHz signal. The adjustments still seem to fail however for some strange reason. At least it is a step forward, the ECL to CMOS circuit was broken and the AD9850 did not output anything before. Even though it seems like it did not have any impact on the cal result for some reason.

Edit: Haha, if fixing the clock signal to the AD9850 seems to actually made things worse. Now offset01 cal and offset05 cal fails in addition to digitizer cal fail. Scope still seems to work though. I guess, there is more than one thing not working correctly and fixing one of them does not necessarily fix the others. I guess i should just continue trying to find other circuits not working as intended. Stating to get a bit feed up with this repair.