Sylvania LC320SLX No Power-Dead
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Please upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740 -
Re: Sylvania LC320SLX No Power-Dead
what your seeing @ that measurement @ this time of 165 volts DC is complete source voltage derived from your bridge rectifier network,once Q601 and its associated circuit start its operations you should see that 165 volt reduce down close to the 135 voltRon Driver,BSEE,CET,ISCET,NESDAComment
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Please upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740Comment
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Re: Sylvania LC320SLX No Power-Dead
Ok going to replace the bad resistor and see what happens well let you know what happens..Comment
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Re: Sylvania LC320SLX No Power-Dead
if no diodes are shorted ,then using pin 8 of T601 as ground read dc voltage @ Drain of Q601 should have 134 vols DC when set plug in if you do have the 134 v there then check for 5.3v on gate of Q601 those two voltages must be present to kick start Q601 into oscillation to get the power supply runningComment
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Re: Sylvania LC320SLX No Power-Dead
I know this is first thing to check but I removed main filter cap which is a 470uF200wv, it measures 414uF, ESR 0.07. Is it bad?
I've checked all resistors and diodes on the "hot" side of the board now all seem good.Comment
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Re: Sylvania LC320SLX No Power-Dead
did you use the same dvm you measure voltage with to measure the Capacitor? again how accurate is it? The 470uf most likely is rated @ +/-10% so if your reading 414uf i would replace the cap,the voltages on Q601 should be suffient to startup set if nothing else bad.I think you said in a prior post that Q601 gate had 0.00 volts due to a open R614 you replaced and now you have 2voltsRon Driver,BSEE,CET,ISCET,NESDAComment
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Re: Sylvania LC320SLX No Power-Dead
I have a Peak Atlas cap meter that I used to test it. That A33 voltage we were talking about I have 7.7v now, is that supposed to be 33v or 3.3v? Right on Q601 but I think I had 0v when the fuse blew so I'm not sure if I had voltage there before that.Comment
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Re: Sylvania LC320SLX No Power-Dead
no i don't think the C605 cap is keeping set from coming on,remember now since your on the secondary side of T601 for measurement make sure your using ground from secondary side like i post early i think it's pin 15Last edited by RON_CET; 07-22-2012, 10:05 AM.Ron Driver,BSEE,CET,ISCET,NESDAComment
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Re: Sylvania LC320SLX No Power-Dead
you can check Q602 for b-e short or e-c short also voltage from Q602 with using pin8 of T601 for ground as for t601 possible issue thats very low possibility now back over on secondary side @D638 source for al33v being thats low @7volt with set unplugged make sure you have no low resistance short from cathode which is band side of diode to pin 15 of T601Ron Driver,BSEE,CET,ISCET,NESDAComment
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Re: Sylvania LC320SLX No Power-Dead
OK so here's what happens, with my meter on 200k I put black probe to pin 15 of T601 and red probe to band side of D638 and the readings on the meter just keep going up until hits 200 then 0L.
FYI I have 3.3v on pin2 of IC631.
As for Q602 I have 2.0v on collector pin 2, 0.2v on emitter pin 1.Last edited by kevinm34232; 07-22-2012, 04:51 PM.Comment
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Re: Sylvania LC320SLX No Power-Dead
D638 indicate no shorts now,using pin 15 ground of T601 go back to D638 cathode (band side) and reread your voltage there also since you have the 3.3volts on ic631 that now tells me things on primary side of T601 is working so when can forget now Q601,Q602 and associate circuitRon Driver,BSEE,CET,ISCET,NESDAComment
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Re: Sylvania LC320SLX No Power-Dead
Hey Ron can look at page 37 of SM Block Diagram pin 2 of IC601 is 7.7v same as D638 also see a feedback circuit, any relevance?Comment
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Re: Sylvania LC320SLX No Power-Dead
Same voltage reading using pin 15 and/or chassis and cathode/band side 7.7v.Comment
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Re: Sylvania LC320SLX No Power-Dead
ok something sucking up our voltage on cathode D638 we need to start eliminating things on that 33volt line thats killing our 33v
located R661 lift one side then read voltage again @ D638 see if come upLast edited by RON_CET; 07-22-2012, 05:45 PM.Ron Driver,BSEE,CET,ISCET,NESDAComment
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Re: Sylvania LC320SLX No Power-Dead
Since the T601 transformer is used to generate more than one output voltages (multi output windings), are other output voltages OK beside the 33V supply?Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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