RCA F27732SB TV Blows Fuse

Sounds like you pretty well nailed it. Check the chopper transistor and rectifier diodes on the input first, and keep in mind that if one of those checks bad, other parts in the area may be bad as well.

I have tested the 4 rectifier diodes and they all seem to be opened (VOLTAGE DROP IN BOTH DIRECTIONS). Do you thing that these shorted diodes could have shorted the IC regulator and the chopper transistor? Thanks

replace the diodes, remove the chopper transistor AND the PTC, and power the set up with 100w bulb in series int he mains line. be wary if it glows brightly. if it is dim or fades, you will know your rectifier is probably ok now.

-B

Are the diodes shorted or are they open? Did you test them out of circuit?

I believe the diodes are shorted as the voltage drop appears in both directions. I tested them in the circuit. Do I get false readings if they are in the circuit? Thanks.

Do I get false readings if

Very often - depends on the other components in the circuit. Only way to know for sure is to test them out of circuit.

Mark Z.

In or out of circuit, bridges, if not short usually good, also take a look at the output transistor next to the flyback on a heatsink, and cold solders on the horiz. drive transformer. also older rca's have a lot of bizarre problems due to their "on board" tuner, if you do manage to get it on just go over the tuner to avoid future problems. Shane.

Thanks I will retest the diodes and I will try to replace them. I will also test the chopper transistor along with HOT. Also I have found 1 other diode shorted right near the chopper transformer. Hmmmmm

Consider yourself lucky it's not one of the older RCA sets that used two SCR's to derive flyback scan.

Hi I will try to test some HV components to determine how bad the short really is and I will post again.

Hi again, I was wondering, what could have caused all 4 rectifier diodes to short?

What else have you found wrong? Is the set working now?

Hi I am still working on the set. I have not gotten around to check it out. At the moment I have removed all 4 rectifiers. I will test the HOT and chopper today.

could be several things - mains surge, bad ptc, bad chopper, shorted mains capacitor... being common reasons in my experience. usually, however, a fusible resistor opens first in the case of problems further into the power supply .

-b