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Search: Posts Made By: R_J
Forum: Troubleshooting TVs and Video Sources Today, 08:30 PM
Replies: 25
Views: 1,686
Posted By R_J
Re: LG 42LE4500 PSU Replaced Backlight Failing Again

I suspect each strip is divided in two, so 26 led's X 3V 78volts, the power supply outputs 89V/0.96A, and the control circuit likely accounts for the extra 11v. I believe there are 8 led control...
Forum: Troubleshooting Computer Displays Today, 08:08 PM
Replies: 4
Views: 37
Posted By R_J
Re: Samsung 2493HM and damn BN44-00195A PSU

Mosfets have three leads, Source, Drain and... Gate. The gate is the control lead of the mosfet
Forum: Troubleshooting TVs and Video Sources Today, 07:58 PM
Replies: 10
Views: 74
Posted By R_J
Re: Sanyo RFWZV475F DVD Recorder/VCR Combo Turning off when loading tape

When replacing the caps in the power supply, make sure to replace the small electrolytics in the primary circuit, usually around 1~10f/50v, they can dry out and cause unstable problems. Post some...
Forum: Troubleshooting Power Supplies and Power Supply Design Today, 06:57 PM
Replies: 88
Views: 1,791
Posted By R_J
Re: mercury pc power supply only 5vsb supply.

It looks like the mosfets in the primary shorted and blew the gate resistors and diodes, and likely the two small electrolytics were bad as well.
Forum: Troubleshooting Computer Displays Today, 06:42 PM
Replies: 4
Views: 37
Posted By R_J
Re: Samsung 2493HM and damn BN44-00195A PSU

Remove the transformer and check it out of circuit, The readings will be near 0Ω. With the transformer removed check the diodes and resistors in the gate circuit.
Forum: Troubleshooting TVs and Video Sources Today, 06:20 PM
Replies: 10
Views: 74
Posted By R_J
Re: Sanyo RFWZV475F DVD Recorder/VCR Combo Turning off when loading tape

You must have done something to it because it was loading and playing (with the erratic capstan) before in the first video and now it is no longer loading the tape. Check that any mechanism to board...
Forum: General Electronics Technical Discussion Today, 02:25 PM
Replies: 1
Views: 47
Posted By R_J
Re: GTX1070 VRM keeps shorting out

The ic is likely a RT9611AGQW There could be gate drive resistos that are open but usually if the fet shorts (drain to gate) the ic will be damaged.
Forum: Troubleshooting Power Supplies and Power Supply Design Today, 09:54 AM
Replies: 17
Views: 494
Posted By R_J
Re: QW-MS3010D 30V 10A Variable PSU Blown MOSFET

Well the mosfets won't work if the resistors are open, so will it work after? If the resistors are good, then that's not the problem.
Forum: Troubleshooting TVs and Video Sources Yesterday, 09:16 PM
Replies: 35
Views: 607
Posted By R_J
Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

Well that line connects to the processor and if it does'nt change then the error could occur. Check the resistance of that line to ground.
Forum: Troubleshooting TVs and Video Sources Yesterday, 07:25 PM
Replies: 10
Views: 74
Posted By R_J
Re: Sanyo RFWZV475F DVD Recorder/VCR Combo Turning off when loading tape

In the first video was the sound coming fom the smps section? it sounds to me like the power supply was having an issue, I have heard that sound before, noisy smps. In the second video it could be...
Forum: Troubleshooting Power Supplies and Power Supply Design 06-04-2020, 09:54 PM
Replies: 17
Views: 494
Posted By R_J
Re: QW-MS3010D 30V 10A Variable PSU Blown MOSFET

R2 and R5 are likely 47Ω, they should be the same value. Check the voltage before Q2 (p75nf75), the output of the dual diode (STTH1602CT) or across C11,16 or 22
Forum: Troubleshooting TVs and Video Sources 06-04-2020, 09:30 PM
Replies: 35
Views: 607
Posted By R_J
Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

When the tv stays on for the 30~45 seconds, do you gat a picture? If the error code is correct, it is DET_5V error, since you have 5 volts, that supplies one end of R9740 and the other end connects...
Forum: Troubleshooting TVs and Video Sources 06-04-2020, 06:54 PM
Replies: 39
Views: 801
Posted By R_J
Re: Vizeo E500i AO dead with led on

Now that you have a different meter, check the DC voltage across C120 in standby, then force the power on with the 1k resistor to see if the voltage increases. This test will tell you if the pfc...
Forum: Troubleshooting TVs and Video Sources 05-29-2020, 06:14 PM
Replies: 72
Views: 8,113
Posted By R_J
Re: Toshiba 26AV600A

I don't believe the optocoupler is the problem
The datasheet says that pin 4 provides a 2v reference voltage which should show up on one end of R932, This voltage is from the ic itself so I suspect...
Forum: Troubleshooting TVs and Video Sources 05-29-2020, 05:54 PM
Replies: 10
Views: 183
Posted By R_J
Re: Samsung UA46C8000 Vertical lines

I would bet money someone cleaned the screen and liquid ran down and damaged the board that connects the lcd itself, Remove the front bezel and inspect that board, but it is likley not repairable
Forum: Troubleshooting TVs and Video Sources 05-29-2020, 05:48 PM
Replies: 1
Views: 87
Posted By R_J
Re: Vizio Main bord Question

Maybe the eeprom is not the problem?
Forum: Troubleshooting TVs and Video Sources 05-29-2020, 10:31 AM
Replies: 39
Views: 801
Posted By R_J
Re: Vizeo E500i AO dead with led on

What ac voltage are you talking about that is doubling? The ac from the line is rectified to 160VDC, Then when the power supply is turnd on, the PFC circuit starts and using high frequency switching,...
Forum: Troubleshooting TVs and Video Sources 05-28-2020, 09:27 PM
Replies: 72
Views: 8,113
Posted By R_J
Re: Toshiba 26AV600A

It would seem the ic is in standby, pin 5 needs to be above 50mv. Check the two resistors, R932 (3.9k) and R992 (100Ω) if they are ok, check that the optocoupler is not bad and that C991 is not...
Forum: Troubleshooting TVs and Video Sources 05-28-2020, 07:51 PM
Replies: 16
Views: 234
Posted By R_J
Re: TV Sharp LC 37D42U (DPS 178AP)

That was just an example, you could have a high load on one of the other supplies, You could try unpluging the inverter board and see if the tv turns on without backlight.
Forum: Troubleshooting Computer Displays 05-28-2020, 07:45 PM
Replies: 11
Views: 180
Posted By R_J
Re: Samsung 245BW BN44-0019A

It is likely easiest to unsolder the transformer secondaries from the board to check the smd components
Forum: Troubleshooting TVs and Video Sources 05-28-2020, 07:24 PM
Replies: 16
Views: 234
Posted By R_J
Re: TV Sharp LC 37D42U (DPS 178AP)

That looks like an over voltage/over current protection circuit, if any of the voltages are too high such as UR6V, then D7315 conducts and turns on the Q7304 SCR. The SCR turns ON shorting out ic7902...
Forum: Troubleshooting Computer Displays 05-28-2020, 07:12 PM
Replies: 11
Views: 180
Posted By R_J
Re: Samsung 245BW BN44-0019A

the 473 should read 47k but if you look at the circuit you will see they are basically in parallel with the transformer and the RM811/RM813 resistor. so it would seem, either the resistor or the...
Forum: Troubleshooting TVs and Video Sources 05-28-2020, 07:04 PM
Replies: 16
Views: 234
Posted By R_J
Re: TV Sharp LC 37D42U (DPS 178AP)

I was looking at the poor schematic, so it would be Q7902. Q7902 has 23v on the collector which is ok, to get the 15 volts on the emitter, the base needs to be turned on by the optocoupler IC7902,...
Forum: General Electronics Technical Discussion 05-28-2020, 06:43 PM
Replies: 28
Views: 3,879
Posted By R_J
Re: component identification

Glad to here its up and working again.
Forum: Troubleshooting Computer Displays 05-28-2020, 06:40 PM
Replies: 11
Views: 180
Posted By R_J
Re: Samsung 245BW BN44-0019A

Yes those are the components, the resistors look ok in your picture but check them anyway, also check the transformer to make sure the two secondary windings are not open.
The diodes are likely...
Showing results 1 to 25 of 500

 
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