On a K7000 Medium Res I'm working on, D19-22 all pass current in both directions in-circuit but test good out of circuit.
Is this normal or does it mean I have a short somewhere?
Is this normal or does it mean I have a short somewhere?
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have you tried running it with an end of D10 pulled out? this will disable the HV shutdown; entirely theoretically, if it runs with D10 out you most likely would have a bad voltage regulator. I have had some chassis I never finished fixing that even with new voltage regulators, the B+ would be pegged. which at that point I would guess there's some bad major resistors.
if you have D10 pulled and it still doesn't work however, you're looking at a bad HOT.
I have pulled D10 and it still doesn't work but HOT tests good in and out of circuit. Waiting on a new flyback and a replacement R101 to get here. I will also replace the HOT, VR and shutdown pot. I've replaced R89 already, which was way out of spec
yeah, all those valuable resistors I mention a lot are subjected to a lot of heat which is why a) they fail and b) the solder pads usually disintegrate. if you lose the right ones in the circuit there, you'll have what you're experiencing. in other instances it'll put you in a fuse blowing nightmare; I'm guessing this is caused by the concentration of power that has nowhere to go, so it gets stuck on the diode bridge side and pops the fuse.
R101 could be at fault, so you're stuck until that arrives. there's a goofy little transistor at Q10, and the transformer at T2. I don't really know how to test T2 except swap with a known good one maybe -- I've personally never found a bad one. lastly, there's IC2, which if I recall is the smaller of the 2 chips. that has some kind of power drive control; I think if you desolder pin 16 on it and go to measure a bad R101, it'll actually reach the full 6.8k ohm reading (from my travels)
lastly, there's C36. if that doesn't work then you won't have horizontal deflection either. I read in a thread earlier you can do a continuity test between the 2 halves and if it shows a short then it's bad. never tried this myself.
From personal experience, if C36 is out of whack it will start blowing fuses. In my K7000 I accidentally got C36 and C38 switched when doing a width cap adjustment and kept blowing the fuse on the chassis. Once I corrected my dumbass mistake, the HV shutdown ceased and the fuse quit blowing.
Since the OP here indicated that no fuse blew, I would believe that C36 is functional and within specs.
If you are still in HV shutdown after lifting on end of D10 and not blowing fuse then you have a horizontal deflection problem.
Have you measured the voltage at the metal tab of Q11 (HOT)? Also look for any lifted or broken pads on the legs of Q11. Any break in a trace or lifted pad will put you in shutdown.
I'll bet you will have 0 volts there. If so start looking for a break, lifted pad, or cold solder joint. I just fixed a K4900 that had a pad burnt loose from the trace where the collector lead on the HOT soldered to.
Also have you checked Q10. It is your horizontal drive transistor. If bad that will put you in shutdown also.
Ed