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TV/VCR/Stereo Troubleshooting/Followup Question on Mitsubishi model Ck3536-r power up problem

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Question
QUESTION: Would the power relays on the S-power board still click closed if the ste12006 hybrid voltage regulator was bad? I have ac voltage going into this SPower board but I don't hear the power relays clicking when the set is first plugged into a wall outlet. I've recently replaced a bad 220 ohm 1/4w resistor that goes to pin 2 of the str12006 and replaced two bad diodes on this board. I have also tested all the electrolytic caps and replaced all the bad ones. I'm assuming that the ac power that feeds into this board should fire the relays even before powering the set on. Am I correct in my assumption?

ANSWER: It's such an old model; there are not hardly any support pages available or even parts to supply repairs.

I suggest you check for cold or cracked solder joints all around the power supply area including the voltage regulator.  Check the interconnections with the S board and main chassis as well.  You may need to replace the diode/rectifiers which produce the dc outputs necessary to run the system.  Are you getting substantial dc voltages at the electrolytic caps in the power supply?  If so, you may just have bad connections and cold solder joints lurking around the area.  

Yes, it takes dc voltages to run the tv circuits.

Happy hunting.



---------- FOLLOW-UP ----------

QUESTION: I don't have any dc output current coming off the SPower board to the main chassis board.  I don't believe the capacitors are charging up at all on the S Power board. If I can ask a previous question another way, will the dc power relays only click on and complete the current flow if the IC Hybrid voltage regulator is functioning properly or should the wall plug-in ac power board connection to the SPower board cause the three power relays to close their contacts and start the dc generation process when the tv is first plugged into an electrical outlet? Thank you for your assistance and comments as I attempt to bring thos dead horse tv back to life. I do have a schematic of the tv's power supply circuit but am not knowledgable as to how the set's startup routine is executed. For example, if the flyback transformer on the main chassis board is shorted will the power relays still click on the SPower board?

Answer
I can't answer your question about the relays because I have no schematic diagram and I don't know if the relays are after the rectifier diodes or at the output of the power supply.  But this I can tell you the dc from the power supply is necessary to run the main electronic system, including the flyback.

A shorted flyback can, indeed, cause the set to go into protection mode.  You can disconnect temporarily the line that feeds the flyback and see if it will start.  The relays are for protection and are actuated by too much current being drawn which is normally caused by a shorted circuit somewhere - and the flyback is always a suspect because it draws lots of current.

Sorry for your trouble; wish I could help you more.  Best wishes. For Sure.

Have a good week.  

TV/VCR/Stereo Troubleshooting

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Consumer Electronics of all kinds. Audio, esoteric audio systems and components, video, tv. Digital equipment for consumer use. Ham radio and automotive electronics. Note: I give advice on tv repair based on general consumer electronics engineering experience but I am not engaged in actual repair of sets. MAKE SURE YOU GIVE THE MAKE AND MODEL NUMBER AND AGE OF THE SET. BE SURE TO CHECK YOUR EMAIL FOR THE RETURN ANSWER DURING THE NEXT 24 HOURS AS I TRY TO REPLY TO ALL QUESTIONS WITHIN THE SAME DAY IF NOT THE SAME HOUR.

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