Help!

[mpobanion]

Hi,
I replaced two 1000uF 200volt Capacitors that were below the +130 supply. The voltage drop across the Cap's + to - is about 163volts but the measurement from a ground point to + side of Cap's is only 116v. I ‘am learning about this all and not an expert.
Does anyone know, if there is no High Voltage going to Cathode Ray Tube's in a rear Projection TV's, would the LOFT or fly back transformer be at fault always and could bad convergence Integrated Circuit's stop any picture HV from getting to CRT's?

PlainBill, could you possibly help since you have knowledge about TV's

Thanks

[PlainBill]

Re: Help!

Hi,
I replaced two 1000uF 200volt Capacitors that were below the +130 supply. The voltage drop across the Cap's + to - is about 163volts but the measurement from a ground point to + side of Cap's is only 116v. I ‘am learning about this all and not an expert.
Does anyone know, if there is no High Voltage going to Cathode Ray Tube's in a rear Projection TV's, would the LOFT or fly back transformer be at fault always and could bad convergence Integrated Circuit's stop any picture HV from getting to CRT's?

PlainBill, could you possibly help since you have knowledge about TV's

Thanks

163 volts is about what I would expect from a bridge rectifier with 120VAC input. The discrepancy between the voltage across the caps and the voltage to ground is most likely because you have a live ground at this point in the circuit. It's been a long time since I worked on a rear projection TV, but IIRC, CRT designs have used a SMPS to produce the desired voltages. I see no reason why a RPTV wouldn't do the same.

As far as the convergence ICs preventing high voltage from getting to the CRTs; I would say that is highly unlikely. A fault in the convergence circuit MIGHT cause shutdown of the deflection, but I would look to other things first.

As always, a good (or even poor) schematic, or even a model number would help immensely. And many people here have a much greater knowledge of TVs. At this point in my life it would take a great deal of coercion before I would stoop (physically) to working on one. Well, maybe if a very beautiful woman asked....

PlainBill