Daewoo TV startup problem

Shorted somewhere?

Thanks Homer,

The HOT checks out as shorted when in situ, I then removed it and it still shows only an ohm or so across B-C, B-E and C-E in both directions, I take it this means it's dead?

Are there any specific components I should look at that may have failed and caused the HOT to go or anything that may have failed due to the HOT failing?

Before I removed the HOT I checked to see if there was ~132v between the C and E and there was no voltage present between any of the three pins, is this just a symptom of the HOT failure - power supply not coming up / regulating?

I've found three fusable resistors that all check out ok, a 60w bulb in series with the mains lead glowed bright with the HOT in place and still glows bright with the HOT removed. Does this mean that there is still a short somewhere and where should I look?

Any and all help appreciated.

Ian

I'd say so but I haven't done this stuff for 30 years.

the power supply is trying to come up but since the hot is shorted it is shutting down due to overcurrent protection does the b+ (voltage at the collector of the hot) come up to around 130v with the hot removed?

does the bulb dim after a while - this could just be the degauss circuit it takes a while to switch off with a series bulb

check the high voltage rating capacitors around the area of the hot and flyback for incorrect capacitance opens or shorts (out of circuit) also check for arcing at the flyback or around the connections to the yoke - these things can blow the hot or sometimes it just gets tired!

no probs

Yes B+ at the collector is okay with HOT removed.

The bulb dims after a few minutes with the HOT removed, but did not dim with it in. I'm only using a 60w bulb at the moment, from what I've read I should be testing with a ~150w bulb for a 28" CRT with the HOT replaced, is this right?

I've ordered a replacement HOT, which should be here Tue/Wed, and I'll start checking the components around the HOT in the meantime. Is it safe to assume that the LOPT is okay as there were no blown fuses.

Thank you for the reply,