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I have a small switching power supply in a cable

I have a small switching power supply in a able box rg2000 and I have replaced defective capacitors which had high internal resistance. I got the supply up and running but found that when checking for ripple output when I put my scope ground on the chassis the power fuse blows. I find that the neutral has about 50 volts AC to AC to ground and the Hot (black wire) has about 60 Volts AC to an external ground. The metal Chassis should not be hot under normal conditions. Unit has a polarized 2 prong plug and house outlets all check proper for hot and neutral and ground as does my HP Scope. What do I check next? Thanks Art wa0njr

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Check around your diodes near the voltage regulation area for either a very bad diode or a direct short sometimes its near the resistor pack and very hard to see. But if it were me I would just change out the power supply and be done with it.

Posted on Sep 09, 2009

Testimonial: "Thanks for your input, repairing switchers is new challenge for me. I may be repairing a bunch of these for a small cable outlet."

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Bush tv model idlcd32tv05hd no pwer going to tv


Hello,

The issue you describe is consistent with a power supply board issue. This is the board where the AC goes to. This problem may have occurred as a result of irregular power supply, or excess power supply or power surge.

The TV is receiving current but cannot circulate or transfer the current to other necessary part of the TV because of the defective power supply board. You might be lucky it's just a blow fuse. Also a defective transformer can cause your TV not to power on.

All these can be checked on the power supply board.

But more often bad capacitors causes problem on the power supply board. I do not think the power board needs replacement, rather those defective capacitors is causing this issue. Open unit up and take a look at the power supply board.You will probably see one or more electrolytic filter capacitors that are bulged up in the top-not perfectly flat like the others.

The value of these capacitors will be different, most likely they will be somewhere around-820 to 2200uF/25 V( or /10V sometimes)

You can replace them with same values but I would recommend the voltage rating to be higher(like 35V for an original 25V) for reliability purposes.

What happens is,these bulged top capacitors will cause a low and unfiltered DC voltage=main board will malfunction(the relay will keep clicking until the caps are holding enough charge to bring the voltage up over a threshold point).

You can buy these capacitors at any Fry's or Radioshack store or you can order them online at vendors like "mcmelectronics.com"(look for electrolytic capacitors). After replacing these capacitor(capacitors) most likely the normal operation will be restored. Or you can by a refurbished complete power board to save you some stress.

Note: There may be also some other causes for this symptom ,like a defective T con board ,or main board,but the bulged top capacitors are the most common cause for this issue.

If you don't know about TV repairers, take the TV to the nearest repairman to fix the fault for you. Also, note that TV stores a lot of current, so wait a while before opening the TV back cover.

I hope this helps.

Regards.

Nov 27, 2011 | Bush Televison & Video

1 Answer

I have a Aquos LC-37GP1U new out of box. Have the blinking light issue. Power on for 2 seconds and then shut off. Replaced the power supply board as it was cracked. Still didn't help. Should I be...


Hi,


You have to check if the replacement power supply board is the same part no. as the original one, it is printed on the board itself.


I don't think that the fault came from defective electrolytic capacitor because like what you have said, the unit is new out of the box and you've already replaced the power supply board which is most of faulty electrolytic capacitor came from that board.


You've mentioned also that the original power supply board has cracked, I've suspected that the main board also has been damaged because the blinking led light error codes will be encountered if the power supply board or main board gone to malfunction. If you've confirm that the power supply board is the same part no. like the original one, then I would advice you to replaced the main board.


Please let me know if you need further assistance.


Have a great day!

Mjsazon

Nov 27, 2011 | Sharp Aquos LC-37GD6U 37 in. LCD HDTV

1 Answer

Sony trinitron kv36xbr400. no picture no sound. TV was fine this am. Returned to no pic. no sound. Cable guide does come up (visible) when turn on cable box. I have tried to reset by disconnecting from...


Hello,
turn of the TV, remove it from wall and try it in another outlet. Also, connect the TV to a DVD player. If there is still no sound and picture after connecting the TV to a DVD player, then it means the TV has developed a power problem.
The issue you describe is consistent with a power supply board issue. This is the board where the AC goes to. This problem may have occurred as a result of irregular power supply, or excess power supply or power surge.
The TV is receiving current but cannot circulate or transfer the current to other necessary part of the TV because of the defective power supply board. You might be lucky it's just a blow fuse. Also a defective transformer can cause your TV not to power on.
All these can be checked on the power supply board.
But more often bad capacitors causes problem on the power supply board. I do not think the power board needs replacement, rather those defective capacitors is causing this issue. Open unit up and take a look at the power supply board.You will probably see one or more electrolytic filter capacitors that are bulged up in the top-not perfectly flat like the others.
The value of these capacitors will be different, most likely they will be somewhere around-820 to 2200uF/25 V( or /10V sometimes)
You can replace them with same values but I would recommend the voltage rating to be higher(like 35V for an original 25V) for reliability purposes.
What happens is,these bulged top capacitors will cause a low and unfiltered DC voltage=main board will malfunction(the relay will keep clicking until the caps are holding enough charge to bring the voltage up over a threshold point).
You can buy these capacitors at any Fry's or Radioshack store or you can order them online at vendors like "mcmelectronics.com"(look for electrolytic capacitors). After replacing these capacitor(capacitors) most likely the normal operation will be restored. Or you can by a refurbished complete power board to save you some stress.
Note: There may be also some other causes for this symptom ,like a defective T con board ,or main board,but the bulged top capacitors are the most common cause for this issue.
If you don't know about TV repairers, take the TV to the nearest repairman to fix the fault for you. Also, note that TV stores a lot of current, so wait a while before opening the TV back cover.
I hope this helps.
Regards.

Jul 10, 2011 | Sony Televison & Video

1 Answer

Wont switch on either by remote nor the switch at the side even though the red power light is on this is a bush 32 inch flat screen tv


Hi,

The issue you describe is consistent with a power supply board issue. This is the board where the AC goes to. This problem may have occurred as a result of irregular power supply, or excess power supply or power surge.

The TV is receiving current but cannot circulate or transfer the current to other necessary part of the TV because of the defective power supply board. You might be lucky it's just a blow fuse. Also a defective transformer can cause your TV not to power on.

All these can be checked on the power supply board.

But more often bad capacitors causes problem on the power supply board. I do not think the power board needs replacement, rather those defective capacitors is causing this issue. Open unit up and take a look at the power supply board.You will probably see one or more electrolytic filter capacitors that are bulged up in the top-not perfectly flat like the others.

The value of these capacitors will be different, most likely they will be somewhere around-820 to 2200uF/25 V( or /10V sometimes)

You can replace them with same values but I would recommend the voltage rating to be higher(like 35V for an original 25V) for reliability purposes.

What happens is,these bulged top capacitors will cause a low and unfiltered DC voltage=main board will malfunction(the relay will keep clicking until the caps are holding enough charge to bring the voltage up over a threshold point).

You can buy these capacitors at any Fry's or Radioshack store or you can order them online at vendors like "mcmelectronics.com"(look for electrolytic capacitors). After replacing these capacitor(capacitors) most likely the normal operation will be restored. Or you can by a refurbished complete power board to save you some stress.

Note: There may be also some other causes for this symptom ,like a defective T con board ,or main board,but the bulged top capacitors are the most common cause for this issue.

If you don't know about TV repairers, take the TV to the nearest repairman to fix the fault for you. Also, note that TV stores a lot of current, so wait a while before opening the TV back cover.

I hope this helps.

Regards.

Apr 21, 2011 | Televison & Video

1 Answer

Powe will not turn on the timer is blinking green


the problem on ur tv is the control box ( hd tumer ) , the way to fix this problem is by replasing the 7 capacitors on the power supply on this box which is locate next to the tv chasis look like a cable box inside the tv , when ur take this box out open and u woulse a small power supply u most replace this 7 capacitor 1000uf 10-16volts and also solder the connector , that sould fix this problem i already fix 20 tv with the some problem

Dec 07, 2010 | Mitsubishi WS-55859 55" Rear Projection...

2 Answers

Takes to long for it to turn on. Think the switch is going bad.


I believe your problem is going to be defective filter capacitors in power supply. Classic symptom of taking longer and longer to come on. Will get progressively worse over time then wont come on at all. No need to replace the whole power supply board. Most knowledgeable repair shops will replace the swollen capacitors or you can try yourself if you are familiar with electronics.

The defective capacitors will usually swell up out the top making them easy to spot

Oct 17, 2010 | Samsung LA40A450 40 in. LCD TV

2 Answers

My LG Plasma 42PC3D turns on and off repeatedly. I turn on my FIOS set top box first and than the TV and it turns on and off repeatedly (front bottom display goes red and green, red and green repeatedly)....


Your plasma TV has a power supply 6709900019A. These power supplies failed due to defective capacitors. See the picture below and check the capacitors mark with the red lines. There are 10 capacitors that should be replaced even if they do not show signs of bulging/swelling on top.
The value of the capacitors is 3300uF/10V but you can use 25 volts as long as they fit in the space provided by design.


4c29d64.jpg

Sep 24, 2010 | LG 42PC3D 42 in. Plasma Television

2 Answers

TV Turns itself off with power light flashing


It is broken capacitors. Olevia used cheap quality capacitors for this model. Open up the back cover and examine the capacitors on the board closely. You will find a lot of capacitors oozing capacitors.

May 11, 2010 | Olevia 237T 37 in. LCD TV

2 Answers

Samsung Plasma Display HPN5039


Vladislav was able to fix his TV by replacing some defective capacitors in the power supply.
The locations of the defective capacitors are C523 and C524. The value is 0.22uF 400VDC or can use 600VDC as well.

You can also buy the entire power supply assembly by clicking here.
Good Luck.

May 07, 2008 | Samsung HPN5039 50 in. Plasma HDTV

1 Answer

Pc no start.........


You might have a bad power supply. If you have a voltmeter, check the voltage of the standby power supply. This voltage is present even if the system is off, plugged in. It powers a small portion of the logic circuit. It should measure within a couple of tenths of exactly +5 volts. If it is low, or high, this will prevent turn-on. The purple wire of the 24 pin connector is what carries this to the motherboard. The color coding layout is found at http://pinouts.ru/Power/atx_v2_pinout.shtml If by chance this voltage is OK, then check the full on voltages also. Repair of the defective supply is probably by replacement of one or more small electrolytic capacitors in the appropriate circuit, especially if you are technically savvy. Capacitors are available through several suppliers; Digi-Key supplyies Panasonic FC series which are suitable for switching power supplies. Or, you may just replace the whole unit.

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