Forum: Troubleshooting TVs and Video Sources
Yesterday, 03:51 PM
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Replies: 10
Views: 175
Re: Samsung PN58C550 58" Plasma PSU BN44-00331A
You might want to check the diodes in the power supply secondary like DS811 etc. check that they are not shorted, they will likely read low in diode test if they are schottky diodes.
Also check...
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Forum: Troubleshooting TVs and Video Sources
Yesterday, 03:26 PM
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Replies: 10
Views: 175
Re: Samsung PN58C550 58" Plasma PSU BN44-00331A
What do you mean "However VX804S I got nothing out of" what where you expecting to get out of it? If the are not shorted or cracked, they are very likely good and your problem is with the mosfets and...
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Forum: Troubleshooting TVs and Video Sources
07-02-2022, 01:08 PM
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Replies: 28
Views: 288
Re: Small RCA TV white screen
Transformers only work with AC they do not pass or convert DC (the diodes then convert the ac to dc)
The mosfet you replaced switches the raw 12volt input across the pimary of the transformer at...
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Forum: Troubleshooting TVs and Video Sources
07-01-2022, 08:33 PM
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Replies: 28
Views: 288
Re: Small RCA TV white screen
That will work, You should have mentioned you got the mosfet from Digikey earlier as there is also a 100ma transistor with the marking XF, which would not work.
So good to here you have it...
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Forum: Troubleshooting TVs and Video Sources
07-01-2022, 07:40 PM
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Replies: 28
Views: 288
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Forum: Troubleshooting TVs and Video Sources
07-01-2022, 06:32 PM
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Replies: 9
Views: 88
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Forum: Troubleshooting Audio Equipment
06-30-2022, 10:28 PM
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Replies: 3
Views: 600
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Forum: Troubleshooting TVs and Video Sources
06-30-2022, 09:12 PM
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Replies: 28
Views: 288
Re: Small RCA TV white screen
The circuit is not likely to work when you replace a FDN339AN mosfet with a RN1406 transistor (Marked XF)!
The smps ic operates at a min freq. of 50khz and up
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Forum: Troubleshooting Laptops, Tablets, and Mobile Devices
06-30-2022, 08:53 PM
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Replies: 78
Views: 50,600
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Forum: Troubleshooting TVs and Video Sources
06-30-2022, 06:36 PM
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Replies: 28
Views: 288
Re: Small RCA TV white screen
Why suspect the transformer? the transistor you installed is wrong, the source resistors should be 1.5Ω not 10Ω and circuit is not going to work with wrong parts installed, and could cause even more...
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Forum: Troubleshooting TVs and Video Sources
06-30-2022, 12:20 PM
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Replies: 12
Views: 133
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Forum: General Electronics Technical Discussion
06-30-2022, 10:55 AM
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Replies: 6
Views: 106
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Forum: Troubleshooting TVs and Video Sources
06-29-2022, 07:52 PM
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Replies: 28
Views: 288
Re: Small RCA TV white screen
If it was a sot23-3 marked 339, (in picture 5) it was a FDN339AN N-Channel mosfet. How did you find the correct values of the resistors, if they were burnt? What values did you use? They seem to be...
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Forum: Troubleshooting TVs and Video Sources
06-29-2022, 03:24 PM
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Replies: 28
Views: 288
Re: Small RCA TV white screen
The plug in picture four looks crooked, make sure it is seated properly. (the flat cable does not just pull out and get pushed back in, the latch must be released) What resistors did you replace that...
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Forum: Troubleshooting Audio Equipment
06-29-2022, 12:51 PM
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Replies: 11
Views: 112
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Forum: Troubleshooting Audio Equipment
06-29-2022, 12:43 PM
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Replies: 11
Views: 112
Re: Sony CFS-B11 Radio cassette boom box
The supply to IC301 should be 7.6 volts on pin 1, Pin 18 is a 4.8v output that is switched by the ic, This output controls the base of Q303 which supplies 4.1 volts to the tuner board, that's why...
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Forum: Troubleshooting TVs and Video Sources
06-29-2022, 11:59 AM
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Replies: 10
Views: 175
Re: Samsung PN58C550 58" Plasma PSU BN44-00331A
I suspect the bridge rectifiers are ok but you likely have a shorted modfet in either the main or pfc circuits.
There are also two MOV's VX801S and VX803S, what is the resistance across each and do...
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Forum: Troubleshooting TVs and Video Sources
06-29-2022, 11:07 AM
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Replies: 10
Views: 175
Re: Samsung PN58C550 58" Plasma PSU BN44-00331A
The relay will NOT be the cause of the short causing the fuse to blow. The relay is just a controlled switch. Check the two bridge rectifiers for shorted diodes, then check if there is a short across...
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Forum: Troubleshooting Audio Equipment
06-28-2022, 10:21 AM
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Replies: 9
Views: 181
Re: Intimidation Professional sub advice please
There likely is no protection circuit. I suspect the output mosfets could also be bad, I see what looks like a lead trimming or solder splash on the mosfet lead in the lower left of your picture.
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Forum: General Electronics Technical Discussion
06-25-2022, 04:11 PM
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Replies: 11
Views: 194
Re: Conversion of Anolog Voltmeter into Ammeter
You would need to remove the 3k in series and then use a shunt across the movement.
As the meter is now, 3 volts gives FSD, with a resistance of 3500Ω the current through the movement is about...
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Forum: Troubleshooting TVs and Video Sources
06-25-2022, 12:12 PM
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Replies: 7
Views: 205
Re: Bn44-00623B pfc mosfet very hot
How was QP802C shorted? was it shorted D~G ? if it was you may have damaged the gate drive components, likely a shorted diode. Also check if there is a zener diode off the IS pin of the drive ic that...
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Forum: Troubleshooting Audio Equipment
06-25-2022, 11:24 AM
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Replies: 9
Views: 181
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Forum: General Electronics Technical Discussion
06-25-2022, 10:23 AM
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Replies: 11
Views: 194
Re: Conversion of Anolog Voltmeter into Ammeter
That is battery tester and likely has an internal load resistor to load the battery to get a proper reading when testing 1.5v batteries. It likely won't move with .3v
With your current setup 12v, 8Ω...
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