Forum: Troubleshooting TVs and Video Sources
Yesterday, 06:37 PM
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Replies: 107
Views: 10,324
Re: Sharp LC-60SQ15U TV DPS-167CP - No power
What do you have in place for D7950? Maybe disconnect whatever is in there and see if the vcc comes up.
The ic's startup cell IS providing the initial 9volts, (at low current) so there can't be...
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Forum: Troubleshooting TVs and Video Sources
Yesterday, 04:55 PM
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Replies: 5
Views: 77
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Forum: Troubleshooting TVs and Video Sources
Yesterday, 04:45 PM
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Replies: 107
Views: 10,324
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Forum: Troubleshooting TVs and Video Sources
Yesterday, 03:08 PM
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Replies: 107
Views: 10,324
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Forum: Troubleshooting Computer Displays
05-20-2022, 08:07 PM
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Replies: 21
Views: 2,610
Re: Benq BL3200PT with a cooked PSU.
Also check R651, it is a low value (likely under 1Ω). It is connected between the modfet source and the primary (hot) ground, if this resistor is open, the ic would have been damaged.
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Forum: Troubleshooting Computer Displays
05-20-2022, 08:01 PM
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Replies: 21
Views: 2,610
Re: Benq BL3200PT with a cooked PSU.
The components are connected between the ic's output and mosfet gate. You need a multimeter to check them to see if they are good or bad. as for the ic, it can't be tested but is likely bad.
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Forum: Troubleshooting Power Supplies and Power Supply Design
05-20-2022, 07:55 PM
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Replies: 8
Views: 117
Re: What is this part? (OG XBox Delta PSU)
Yes 102 would be a 1k pot, I suspect once you check it you will find it to be ok, Check between the two leads on the one side, then check between the single lead and each of the other leads, that...
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Forum: Troubleshooting Computer Displays
05-20-2022, 07:46 PM
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Replies: 21
Views: 2,610
Re: Benq BL3200PT with a cooked PSU.
Q651 is the main switching mosfet, if the pins were shorted, then the gate saw a very high voltage, so it likely destroyed the resistors and diodes in the gate circuit and also the driver ic located...
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Forum: Troubleshooting Power Supplies and Power Supply Design
05-20-2022, 07:02 PM
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Replies: 8
Views: 117
Re: What is this part? (OG XBox Delta PSU)
VR501 is the pot location, not it's value, check it with a meter or look for numbers printed on the pot. Are you sure it is bad, as I doubt it is burnt.
I see other pictures that have the same...
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Forum: Troubleshooting Computer Displays
05-20-2022, 05:11 PM
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Replies: 21
Views: 2,610
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 04:50 PM
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Replies: 107
Views: 10,324
Re: Sharp LC-60SQ15U TV DPS-167CP - No power
PC7904 is used to turn on Q7902 to supply vcc_on so it can be left out of circuit for now.
If you also remove pc7903 and D7908, pin 4 of ic7903 should be about 7volts, If it does not come up, try...
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 04:22 PM
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Replies: 107
Views: 10,324
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 04:16 PM
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Replies: 107
Views: 10,324
Re: Sharp LC-60SQ15U TV DPS-167CP - No power
Yes, check pins 1 & 4
The vcc voltage is initially supplied by the ic's internal startup cell which is bout 9volts, that part of the ic is working. When the power is first applied the internal...
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 03:50 PM
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Replies: 107
Views: 10,324
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 03:45 PM
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Replies: 107
Views: 10,324
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 03:33 PM
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Replies: 107
Views: 10,324
Re: Sharp LC-60SQ15U TV DPS-167CP - No power
WHY? because if that feedback winding is open circuit you will not get the boosted vcc voltage to make the ic work.
Look at the schematic, It's pins for this winding are 1&4, on your board they are...
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 03:14 PM
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Replies: 107
Views: 10,324
Re: Sharp LC-60SQ15U TV DPS-167CP - No power
Check the transformer winding between pins 4 and 5, it should be almost 0Ω, then check the resistors R7908,R7909,R7913, if they are good, check the diode D7904, also check the zener diode D7909
If...
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 03:05 PM
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Replies: 107
Views: 10,324
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 01:44 PM
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Replies: 107
Views: 10,324
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Forum: Troubleshooting TVs and Video Sources
05-20-2022, 10:46 AM
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Replies: 107
Views: 10,324
Re: Sharp LC-60SQ15U TV DPS-167CP - No power
If the optocoupler and the diode are good, then it only leaves the ic that is bad.
If you look at the datasheet page 11, you will see that without anything connected to the FB pin, that pin should...
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Forum: Troubleshooting TVs and Video Sources
05-19-2022, 05:29 PM
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Replies: 107
Views: 10,324
Re: Sharp LC-60SQ15U TV DPS-167CP - No power
I would check the resistance and compare with the other two or try exchanging it with pc7904 and see if you get your standby voltage.
You should be able to leave the zener diode out of circuit for...
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Forum: Troubleshooting TVs and Video Sources
05-19-2022, 04:40 PM
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Replies: 107
Views: 10,324
Re: Sharp LC-60SQ15U TV DPS-167CP - No power
I think something is causing the voltage to be too low. If you look at the datasheet for the ic (page 11) you will see FB/OLP pin is supplied by approximately 7 volts, this line is controlled...
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Forum: Troubleshooting Computer Displays
05-19-2022, 12:49 PM
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Replies: 6
Views: 200
Re: VisionQuest 24" monitor: works sometimes
I would start by replacing the small electrolytic next to the mosfet in the center of the power supply board, this cap can dry out over time and result in the power supply not starting
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Forum: Troubleshooting TVs and Video Sources
05-19-2022, 12:38 PM
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Replies: 107
Views: 10,324
Re: Sharp LC-60SQ15U TV DPS-167CP - No power
Check for a shorted D7988, or defective PC7903, something is killing the feedback voltage. I suspect the voltage needs to be above 1 volt and maybe around 3~5 volts, but needs to be lower than 8 volts
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