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Search: Posts Made By: R_J
Forum: Troubleshooting TVs and Video Sources 10-18-2020, 05:52 PM
Replies: 2
Views: 49
Posted By R_J
Re: AOC led monitor

What voltage do you have ACROSS the main filter, C907? check R924, it should read 0.47Ω.
What photocoupler are you talking about? U902? if that is it, what ground were you using? hot ground or...
Forum: General Electronics Technical Discussion 10-18-2020, 11:05 AM
Replies: 12
Views: 130
Posted By R_J
Re: SMPS Resistor confirmation

I would suggest getting the repair kit as recommended by redwire, it may be cheaper and you will have all the correct replacement parts. Then it might be wise to use a 60~100 watt incandescent lamp...
Forum: General Electronics Technical Discussion 10-17-2020, 06:20 PM
Replies: 12
Views: 130
Posted By R_J
Re: SMPS Resistor confirmation

Using a 1Ω for R611 will change how the circuit operates, the voltage across the resistor will be almost double and that might upset the base voltage on Q602. Q602 sure looks bad from the picture....
Forum: General Electronics Technical Discussion 10-17-2020, 01:06 PM
Replies: 12
Views: 130
Posted By R_J
Re: SMPS Resistor confirmation

On the mosfet with the tape, did you insulate the mounting screw, or just not use one? The zener is not that critical as it is just used to clamp any high frequency spikes across R611 when the mosfet...
Forum: General Electronics Technical Discussion 10-17-2020, 10:36 AM
Replies: 12
Views: 130
Posted By R_J
Re: SMPS Resistor confirmation

The transformer is not the problem, removing it will prove nothing. if the mosfet is not shorted, then I suspect there is a short on the secondary. I see someone replaced D650 and I suspect they used...
Forum: Troubleshooting Computer Displays 10-17-2020, 10:11 AM
Replies: 20
Views: 970
Posted By R_J
Re: Samsung Syncmaster 245b BN44-00195A

ICP801S (TDA4863) VCC is on PIN8. It gets that voltage from the M_VCC line. QB802 is the regulator/switch for this voltage. The source of the voltage is from TB801S,pin5, this is rectified by DB803...
Forum: General Electronics Technical Discussion 10-17-2020, 09:33 AM
Replies: 12
Views: 130
Posted By R_J
Re: SMPS Resistor confirmation

gold & silver multipliers are common, the value is correct, but I suspect there is more wrong. Where is the resistor located? is it in the source lead of a mosfet? If it is the source resistor, a 1Ω...
Forum: Troubleshooting TVs and Video Sources 10-16-2020, 09:23 PM
Replies: 8
Views: 218
Posted By R_J
Re: Samsung UA60H7000AW Power Supply

Yes that cap checks ok, they usually go open when bad. Check that none of the diodes (DM851,2,3 & 4) are not shorted, But I suspect the ic, If it was working at all it should provide burst pulses to...
Forum: General Electronics Technical Discussion 10-15-2020, 04:43 PM
Replies: 9
Views: 141
Posted By R_J
Re: Is the thermistor NTC? PTC? just by looking?

The ones you have pictured do look like ptc's used in old crt degaussing circuits.
Forum: Troubleshooting Computer Displays 10-15-2020, 04:38 PM
Replies: 13
Views: 232
Posted By R_J
Re: HP D8911 CRT losing red from VGA

Then the problem is likely between the plug P801 and the ic801, If it was just the red, it could be C801 going open, or bad connections on the board
Forum: Troubleshooting Computer Displays 10-15-2020, 04:23 PM
Replies: 13
Views: 232
Posted By R_J
Re: HP D8911 CRT losing red from VGA

How does the on screen display (menu) look? is it also missing red etc. ?
Forum: General Electronics Technical Discussion 10-15-2020, 03:41 PM
Replies: 9
Views: 141
Posted By R_J
Re: Is the thermistor NTC? PTC? just by looking?

Then the correct answer is you can not tell the difference.
Forum: Troubleshooting TVs and Video Sources 10-15-2020, 11:02 AM
Replies: 6
Views: 147
Posted By R_J
Re: Weird Screen Failure Samsung UN55KU6300F

It may take some time to get rid of the spot, Not much of an option other than replacing the lcd.
Forum: Troubleshooting Power Supplies and Power Supply Design 10-15-2020, 10:14 AM
Replies: 3
Views: 125
Posted By R_J
Re: Panasonic SA-AKX16 CD STEREO SYSTEM (DEAD)

It looks like the power supply is working ok and not the problem.
Pin 12 is the power on signal from the microprocessor, The fact you have +3.25 (+3.3v) on pin 6 is good, that SYS3.3V feeds the...
Forum: Troubleshooting TVs and Video Sources 10-14-2020, 05:06 PM
Replies: 5
Views: 103
Posted By R_J
Re: Toshiba 32SL738G - No sound

It could have been dirty contacts in the headphone detect switch in the jack itself, simply plugging in the headphones cleaned the switch contacts, for now.
Forum: Troubleshooting TVs and Video Sources 10-14-2020, 09:57 AM
Replies: 6
Views: 147
Posted By R_J
Re: Weird Screen Failure Samsung UN55KU6300F

The fault is with the lcd panel itself, there are video's showing a way to remove this by using a q-tip and working the black circle to the edge of the panel. Here is one video :...
Forum: Troubleshooting Audio Equipment 10-14-2020, 09:48 AM
Replies: 16
Views: 274
Posted By R_J
Re: Sony STR-DE697 - Bad Transformer. Replacement? Unknown Value!

Like khron said, disconnect CNP903 going to the digital board, If C950 is bad as in open, you should still get some standby voltage, check that there is not a short across C950.
Forum: General Electronics Technical Discussion 10-13-2020, 09:05 PM
Replies: 9
Views: 141
Posted By R_J
Re: Is the thermistor NTC? PTC? just by looking?

Check the resistance with your meter, then apply some heat and see which way the resistance changes. If they are inrush thermistors they are likely ntc, if they are for, example in a crt degausing...
Forum: Troubleshooting TVs and Video Sources 10-13-2020, 08:27 PM
Replies: 11
Views: 207
Posted By R_J
Re: Sony xbr-65x900e wont power on after storm

Did you check the fuses on the JK board ? What is the number on Q9001 ? Q9001 will be a mosfet and will likely be controlled by the POWER_ON (CN9000, pin6)
I suspect you should have voltage on pins...
Forum: Troubleshooting Audio Equipment 10-13-2020, 07:45 PM
Replies: 16
Views: 274
Posted By R_J
Re: Sony STR-DE697 - Bad Transformer. Replacement? Unknown Value!

Yes you did it right, the a/c voltage may read a bit higher without any load, once installed it should be ok and the dc voltage should be close to the 9v required.
Forum: Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals 10-13-2020, 10:50 AM
Replies: 5
Views: 167
Posted By R_J
Re: Old 286 motherboard cries for help

I see the corrosion on the board and it has likely damaged the feedthroughs connecting the different layers, check that they are ok and not open
Forum: Troubleshooting TVs and Video Sources 10-13-2020, 10:41 AM
Replies: 18
Views: 430
Posted By R_J
Re: Samsung HPR5072- No Power- No Standby

The fault is likely U101, that circuit is fairly simple so there is not much that can go wrong. You could try replacing C104 & C170 and see if that helps. Check that R145 is not open and that ZD102...
Forum: Troubleshooting TVs and Video Sources 10-12-2020, 09:28 PM
Replies: 60
Views: 820
Posted By R_J
Re: TCL 65S517 No Backlight, Picture and Sound OK

ok, it was just the picture. you can check the VBUS voltage between hot ground (L602) and VBUS+ (L601) But I suspect it is ok.

Then have a good look at C620 (or check it if you have a cap tester)...
Forum: Troubleshooting TVs and Video Sources 10-12-2020, 08:31 PM
Replies: 60
Views: 820
Posted By R_J
Re: TCL 65S517 No Backlight, Picture and Sound OK

I think I spotted your problem... R649 (22Ω?) is blown/missing, it should be the same as R652. I suspect QW4 could be damaged as well

So you have good vcc and the enable is also ok, Check the VBUS...
Forum: Troubleshooting TVs and Video Sources 10-12-2020, 07:38 PM
Replies: 60
Views: 820
Posted By R_J
Re: TCL 65S517 No Backlight, Picture and Sound OK

If you follow the trace from pin 15, it connects to J5 & J43, that is ground. I would check pin3 for VCC and pin4 for enable (BL_on)
Check the voltage between hot ground (L602) and VBUS+ (L601)
Showing results 1 to 25 of 500

 
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