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Dead power supply power across the bridge 700 volts across the main capacitor indicating smps is filtering

Posted by will wonder on


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Sounds like you have a dead switching suppy. On these sets the best way to trouble shoot the power suppy is disconnect the horizontsl output and measure it Is it shorted yes replace the fly and the transistor and resolder several cold joints in the horizontal drive curcuit as well as in the main switching supply. If the HOT not shorted then your gonna need a service manual unless you shotgun the repair. Good Luck

Posted on Apr 19, 2006


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Str x6750

Check all the other components, at related SMPS circuit, for any loose solder terminals. Check and replace damaged component/s at it main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" or "Magazine" will make surf easy. Surf the site with patience. Pull up older posts.
It will be best to replace the power supply regulator board as card basis.

Smps colour

Okay; first off an SMPS is any number of power supplies used for electronics. So this is a very vague question. In a computer power supply to an IBM or PowerPC based motherboard (the later is now obsolete and no longer in use for most new computers) there is no one power supply "wire". Most video cards are powered via PCI port through the motherboard power supply connection.

Some very high power high end video cards and some SLI/Bridged cards require their own power source and this is usually a 12 volt rail much like the ones used for SATA power supply.

In a monitor, each make and model can be different depending on who supplied the power supply. The internal power cords can come in different colors. Though the standards are black white blue and green and red. Most displays don't use colored cords for connecting to the main board of the display. They use a 8 or 10 pin ribbon. Most of the colored wires are linking the main inducer to the LED back light.

If we're talking about the internal workings of an SMPS (Switch Mode Power Supply) there is no "display" wire. SMPS internal wiring is all about controlling and routing power to the different rails (that is the different power connectors). Never open an SMPS case, especially if it's plugged in. Switch-mode power supplies have capacitors that can provide a rather nasty charge, and several inducers that can hold a charge well after the power supply has been unplugged. Never service an SMPS on your own, always seek a professional when attempting to fix an SMPS. Though, for the most part, fixing a burnt out power supply is a waste of time, it'd be best just to buy a new one and recycle the dead one.

Computer smps not work properlly what problem

More than likely a bad voltage power rail, balanpv38.

Also more than likely caused by bad Electrolytic Capacitors inside the Switched-Mode Power Supply.

Radial Aluminum Electrolytic Capacitors.

Capacitors in the Output Stage, more than likely.

Capacitors are used as Filters, and Voltage Regulators. In the Input Stage of the SMPS they are used as voltage regulators. In the Output Stage they are used as filters.

Filter the rectified AC voltage, which is now DC. They make the DC voltage 'clean'. No ripples, clean DC voltage.


The two large blue sleeved Radial Aluminum Electrolytic Capacitors, you see marked with the letter B, can store Up To 100 Volts.
They are in the Input Stage.

IF, your fingers touch the terminals (2) on the bottom of the capacitor/s, YOU could receive the stored charge. Result is a Bad shock to FATAL.

IF, your fingers complete a circuit, that one or more capacitors are in, YOU could receive all of their stored charge. Result is a Bad shock to FATAL.

Capacitors need to be PROPERLY discharged before working on the unit.

This is hwy I cannot guide you in this endeavor. I will not guide you with the slightest possibility of you getting hurt.

Suggestion is to replace the Power Supply.

What can make a Power Supply go bad?

1) Low quality electronic components inside.

A) Low quality Radial Aluminum Electrolytic Capacitors
B) Low quality Power MOSFET/s
C) Low quality Rectifier Bridge
D) Low quality wiring due to the gauge of wiring used is too small.

2) Power Supply, (And inside of computer), is dirty inside.

An SMPS (Switched-Mode Power Supply), has two cooling components inside;

Heatsinks, and a small internal fan.

In the Wikipedia link of the open SMPS above, there are two Heatsink's used in this particular example;

One is in-between the letters B and C, and one is in-between the letters C and D.
Rectangular finned shapes connected by a vertical bar.

The Heatsink absorbs heat from whatever object it is placed against.
The rectangular shaped fins absorb the heat, then radiate it away.
The small internal fan's air flow helps carry heat away from the fins.

If in-between the fins, and around the fins, is clogged with 'Gunk', the cooling capacity drops Tremendously.
('Gunk' = Dirt, dust, lint, hair, etc)

Heat = Wasted Energy
The Power Supply cannot keep up with the call for power, and components inside the Power Supply fail.


Wavy horizontal lines across the screen

It sounds that the main power supply section to your TV has the fault. The horizontal thik lines that appears crawling down across the screen should be of video 'HUM'. Have you replaced the main filter capacitor at the power supply section? If not, replace it along with the main rectifier. The AC power is rectifed by a bridge and applied ot this main filter capcitor. It will have a capacitance value between 120 to 350MFD 450VDC. Check this section. Measure the rectifed DC voltage acorss this main filter capacitor. It should be around 350VDC, if your home power supply line is 220VAC. If it is 110AC, this DC voltage will be around 165VDC; and it should be. If rectified DC voltage found lower than the input AC voltage, replace the rectifier bridge. In some sets, this bridge section have four diodes. Some other circuits, a bridge rectifier stalk may be used.

I have sony model no kv-bm14m40 it blinks two times.The voltage on the CRT base which was supposed to be 200 is 235.what do I have to do to solve this problem. I appreciate any help JJ

Two blinks - B+ over current protection (OCP), unit goes to the standby mode then displays the 2 blink fault. Could be a short in the power supply of any of the circuits
The switched output voltage from the power supply is mor than normal. The normal secondary main supply voltage to this set must be around 135VDC. It is now been exceeded that limit, and the overvoltagg; current protection circuits in the set detects this situation and gives you tow blinks as its indication.
Normally, this fault is common to most of the Sony Trinitron sets. The main cuse for this fault is loose solderings at the SMPS power switching section. Just resolder most of the supected solder terminals by applying a little more solder, without making any solder bridge short in between the adjecent solder points. If needy, replace the secondary voltage filter capacitor [the electrolytic capacitor fitted across the 135VDC to ground. This must help you. OK.

I have waveing in my tv

Picture waving can be due to many reasons. The first reason is ariel connection. Check it first for tight and not loose contacted. Second one is due to the main filter capacitor connected across the main rectified power supply DC. If the capacitor goes value reduced or opened, waves may occur. If this is the reason, picture will show blooming effect also. Check the mair rectifier bridge also. [email protected]

Can you reset a pc power supply

Is your question referring to resetting a Power Supply, as you would per se a surge protector?

In most cases No.
Most Power Supply's do not use a Circuit Breaker, nor a Fuse.
(May have to take that statement back, on some of the new Power Supply's though)

Once the Power Supply has gone bad, (Weak Voltage power rail, usually), it's time to buy a new one.

I find that Electrolytic Capacitors have failed, in most failed Power Supply's. However, that is just my general observation over the past 20 years.

Low quality Electrolytic Capacitors are used.
(Radial Aluminum Electrolytic Capacitor's)

These capacitors are used as Filters for the Power Supply. They filter the incoming AC electricity, and the outgoing DC electricity the Power Supply has converted.
(Input Stage, and Output Stage)

To wit:

The Power Supply used in a personal computer is an SMPS.
Switched-Mode Power Supply,


Here on the above Wikipedia page for SMPS, you will see a photo to the top right, of a typical SMPS.
You can click on the photo to enlarge.
(You can enlarge twice)

You are looking at a top view of a typical SMPS, that has the cover removed.
The large Electrolytic Capacitors, indicated by the letter B, are for the Input Stage.
The smaller Electrolytic Capacitors, indicated by the letter E, are for the Output Stage.

NEVER open a Power Supply, (SMPS), and try to work on it.

Even when a capacitor is removed from power, (Power Supply unplugged from power), the capacitors hold a charge for a LONG time.
Weeks, Months, sometimes over a year!

If your fingers touch the terminals on the bottom of a capacitor, (Radial Aluminum Electrolytic Capacitor), the charge could be released to YOU!

If your fingers complete a circuit that one, or more capacitors are in, the charge could be released to YOU!

The released charge can be a BAD shock to FATAL!

There are also MOSFET's, and Rectifier Bridge's that can go bad in an SMPS.

There is a Proper way to discharge a capacitor. I will not detail it here because of the safety issue to you.
The best method is to replace the Power Supply.

Tell me the computer manufacturer name, and Model Number, and I will look up what Power Supply it uses, if the info is available.
(90 percent of the time it is)

For any questions please post in a Comment.


I also think it has something to do with the SMPS.

MOST computer failure can be attributed to Power Supply failure.
MOST computers out there are dirty inside, as well as the Power Supply.

Also, your diagnosis of the green light going out indicates PSU failure.
(Power Supply Unit)

The two cooling components for an SMPS are it's Fan, and any Heatsink's used inside.

Generally a metal plate that has tall, thin fins protruding from it.

The metal plate absorbs heat from whatever object it is placed against, and the fins absorb heat from the metal plate.

The fins then radiate the heat away.
If a cooling fan is used in conjunction with the Heatsink, the air movement helps to dissipate the heat, that has been absorbed by the fins.

Internal view of an average SMPS,


Upper right photo. (You can enlarge the photo by Left-clicking on it. You can enlarge it twice)

Once the cooling components of the SMPS are clogged with 'Gunk', the cooling capacity drops tremendously.

Heat = Wasted Energy

The SMPS tries to keep up with the call for power, but eventually cannot, and hardware components inside the SMPS fail.

NEVER open a SMPS, and try to repair it, unless you are a qualified tech. A qualified tech, knows the proper procedure to drain the power from the capacitors, before working on the unit.

(Frankly it's not worth the effort. The procedure is to just replace the SMPS)

Inside the SMPS are Electrolytic Capacitors.
They are used as Filters.
They filter the incoming AC electricity, (Input Stage), and the outgoing DC electricity made by the SMPS. (Output Stage)

An Electrolytic Capacitor slowly builds up a charge, and then releases it all at once.

You may compare it to a large swimming pool being filled up by a garden hose, then one wall of the pool is taken down all at once.

Electrolytic Capacitors hold a charge for Weeks, Months, or even over a year, in some instances, after being removed from power.

(In this instance it would be unplugging the PSU from power)

IF, your finger/s touch the terminals on the bottom of a Radial Aluminum Electrolytic Capacitor, the charge could be released to You!

IF, your fingers complete a circuit, that one or more of those capacitors are in, the charge could be released to You!

Shock can be Bad to Fatal!

(See those two large Electrolytic Capacitors, in the SMPS link photo I provided?
Upper left corner of the SMPS photo. They have blue plastic sleeves around them. They are indicated by the letter B.

These are Electrolytic Capacitors used in the Input Stage. If they are good, they have enough power stored to put X's in your eyes)

Ready to test this puppy (SMPS), or replace it? Just post in a Comment. (Believe upper right of your page)

(The SMPS in your computer puts out three main Voltages.
A) 3.3 Volts (DC)
B) 5 Volts (DC)
C) 12 Volts (DC)

Two C cell flashlight batteries produce 3 Volts (DC)

The test is done with a multimeter, or a power supply tester.
One example of a power supply tester,

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=5250576&CatId=5471 )

Buy a new Harddrive for it? Why?
If you do, be prepared to buy another genuine copy of Windows.

Information on the Compaq Presario SR1530F desktop computer;

HP Support>Compaq SR5301F desktop computer>Product Specifications main menu,



Dead md-350wps

first remove all the dust from smps then check power cord output by multimeter whether right or not ok then open and you will find one fuse there check it without supply if open then replace it if not then check whether a.c. supply reaches or not if present then check the thermister resistance it should be low also check the dry solder if present then remove it please check dc supply at primary filter (big cylendrical capacitor) if not present then 4 bridge rectifier diodes may faulty replace it
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