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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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RCA F27732SB TV Blows Fuse
Hi everyone,
I have recently encountered a problem with my RCA 27" TV. The TV blows the fuse every time it is plugged in. I am unable to do voltage tests as there is NO power. I believe the problem is within the first few components (filter capacitor, diodes, chopper transistor, etc). I have not really taken a very good look at the set, but would like some sort of direction before I go ahead and start. Can someone direct me to the right direction of which are the most likely failed components? Thank you P.S. THE CHASSIS IS: CTC169CK5 |
#2
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RCA F27732SB TV Blows Fuse
wrote in message ... Hi everyone, I have recently encountered a problem with my RCA 27" TV. The TV blows the fuse every time it is plugged in. I am unable to do voltage tests as there is NO power. I believe the problem is within the first few components (filter capacitor, diodes, chopper transistor, etc). I have not really taken a very good look at the set, but would like some sort of direction before I go ahead and start. Can someone direct me to the right direction of which are the most likely failed components? Thank you P.S. THE CHASSIS IS: CTC169CK5 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. |
#3
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RCA F27732SB TV Blows Fuse
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 |
#4
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RCA F27732SB TV Blows Fuse
On Feb 12, 10:58 pm, wrote:
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 |
#5
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RCA F27732SB TV Blows Fuse
wrote in message ... 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 Are the diodes shorted or are they open? Did you test them out of circuit? |
#6
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RCA F27732SB TV Blows Fuse
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. |
#7
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RCA F27732SB TV Blows Fuse
wrote in message ... Do I get false readings if they are in the circuit? 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. |
#8
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RCA F27732SB TV Blows Fuse
On Feb 13, 12:24*pm, Meat Plow wrote:
On Tue, 12 Feb 2008 21:24:24 -0800, media3d wrote: 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. Unsolder one leg of each device and retest using your meter's diode check function. Often, in circuit tests can deceive. 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. |
#9
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RCA F27732SB TV Blows Fuse
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 |
#10
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RCA F27732SB TV Blows Fuse
Hi
I will try to test some HV components to determine how bad the short really is and I will post again. |
#11
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RCA F27732SB TV Blows Fuse
Hi again,
I was wondering, what could have caused all 4 rectifier diodes to short? |
#12
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RCA F27732SB TV Blows Fuse
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. |
#13
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RCA F27732SB TV Blows Fuse
On Feb 17, 2:00 am, wrote:
Hi again, I was wondering, what could have caused all 4 rectifier diodes to short? 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 |
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