Re: Akai LCT3285TA Power Supply Issues Unstable 24V
Check resistance across that L6562D Vcc, power off.
Check resistance across that L6562D Vcc, power off.
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Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search. -
Re: Akai LCT3285TA Power Supply Issues Unstable 24V
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
OK, we need to trace out the VCC pin back to a switched transistor that get its B+ form the AUX winding of the 5VSTBY transformer.
Can I get 1/4 section pictures of the bottom side of the board so I can slearly see the traces?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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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
See post #20Comment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
Bud those pics good enough?Comment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
Here's another closeup of that ICAttached FilesComment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
OK I started tracing from VCC pin and it follows thru two 10 ohm resistors and then to D10. D10 tests good, but both 10 ohm resistors are open/very high ohms (in circuit). Do you think this is problem?Attached FilesComment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
Seems to go to that 2N4401 transistor right above that was originally shorted and replaced. Would that be the transistor we're looking for?Attached FilesComment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
Tracing voltage from transistor goes from 14.5V down to 8.5V through first 10 ohm resistor then to 0v through 2nd 10 ohm resistor. Should voltage be dropping at all through the resistors?Comment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
Well resistors drop voltage according to V = IR
But two equal resistors with the same current should drop same voltage.
First drop = 6V
Second drop = 8V
So there is a disparity between the voltages, the only possibility being that the resistors are not the same. However, if th drop across the first one is truly 6V, it has I = V/R = 600mA! flowing through it, dissipating 3.6W (probably no more than 1/3W rated 1206)... which is not going to work well it would be clearly burning. So we can say that is not likely and it is more likely there is some other problem with the resistors maybe they are open or there is a measurement error.
I would look at the L65xx IC being bad, unless some of those resistors are open.Last edited by tom66; 08-10-2013, 04:51 PM.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
I replaced the 2 bad 10 ohm resistors and now have 14V to VCC pin. 24V is stable at 23.8V now, but still only have 161V across cap in standby, and 155V when turned on.
I did replace the L6562D before already aswell.Last edited by kevinm34232; 08-10-2013, 06:05 PM.Comment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
Thought Id try to trace BACK from the 450V cap, it goes to an IC2, cant read the # on the chip tho. The other IC was IC1.Attached FilesComment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
Cap locationAttached FilesComment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
More InfoAttached FilesComment
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Re: Akai LCT3285TA Power Supply Issues Unstable 24V
Eyes are hurting now but IC2 is a OB2268CP
https://cdn.badcaps-static.com/pdfs/...2d6a23c015.pdf
Current Mode PWM ControllerComment
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