Question about Televison & Video
Ok..... tv dead high pitch whine coming from the chopper transformer. There are output voltages of 135(B+), 10v and another 10v. Horizontal output transistor fine.
Voltages on lopt not present this a +25v, +15v, +180v, abl, afc, no scr aswell as high voltage but the is present at the input terminal of lopt.
Power led is on, however when bringing the tv out of standby these voltages above drop, the 135vdc drops to 95vdc.
Not sure if its the lopt or something else
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Posted on Jan 02, 2017
Check inside the receiver for a defective LM317 IC or a TIP42C transistor, but before that you should check for proper voltage from the power supply to that IC.
LM317/TIP42C control the switching of voltages that power up the LNB, you should be getting 14 volts for vertical channels and 18 volts for horizontal.
Posted on Mar 08, 2008
Disclaimer: The answer provided is entended for you to have some basic electronic knowledge and soldering skills.
Troubleshooting switching power supplies just sucks, but there are ways of finding the fautly componets. In my case, a visual inspection found 2 bad capitors, the tops bulging open and oosing goo. If you look at the tops of any other caps they should be flat. You can also note faulty caps by discoloration of the circiut board itself. I had one other faulty cap on my supply that, by visual inspection had been running hot. After replacing the defective caps (Nichicon 105c) I went with an ohm meter, and checked the smaller transistors for faults. Q1 a very common transistor was bad (2N3906) with a base emitter short. In conclusion, it's the cheap caps that are at fault, sometimes taking the silicon with them as they short out. The unit is now working.
As an added note, I understand that there is a Radio Shack branded version of the HD3150 as well.
Posted on Jun 12, 2010
Tips for a great answer:
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your problem is in flyback or high voltage section failure.
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