How to use PSU

How to use PSU

Beside using PSU to replace adapter need, this adjustable voltage and current can use to quickly find any circuirity sortage and voltage injection due testing replace missing power and signal needs.

The SMPS meter is a meter that controls the consumption of the current flow whenever feeding a board with it. If the voltage is not applied to the board then the amperage will read 0000.
On the top of the unit you will find 2 displays; one located at the left and is labeled Current. This will be used to read the current consumption, and the another display is located on the right side. It is labeled Voltage and it can reads the voltage applied.
If the current meter shows 1000, this will mean that the consumption of the current has reached 1 ampere. While if it reads 0100 this means 0.1 amperes has been used and so on.
Limit the maximum amperage up to 5A. Lowering and raising the ampere meter can be done through the pots by turning them to the left or right. If left current will be lowered. But if turning it to the right we will raise the amperage.
Each SMPS has two pots; the pots located to the left side raise or lower the current/voltage slowly, while the pots located to the right side they raise or lower the current/voltage fast.
The Voltage Meter is the screen located to the right and it is being used to monitor the applied voltage. If 19V is displayed on the LCD, this mean that the voltage available at the positive JACK of the PSU has reached 19V. the maximum Voltage that can be reached with this unit 30 Volt.
The voltage can be changed accordingly to the needs, ranging from 1V up to 30V by rotating the voltage pot. How to raise and lower the voltage is the same way as lowering and raising amperage explained above.
Avoid changing the voltage while the jack is plugged on the motherboard to avoid use of excess voltage during the voltage value setting.
If the plug ground has not been used this will be not a big deal.
Attach Cable jacks on the positive and the negative pool at the PSU, you should make test first with a voltmeter to determine the positive from the negative cable. Once this done it should be not be reversed. But when by mistake the cables were reversed the PSU will remain protected.
PSU is equipped with 30 universal adapter jacks. So that the technician will simply replace the jack in accordance with the model of jack laptop needed.
Make sure that the applied voltage is in conformity with motherboard needs before use.
If at the time of use, the PSU goes off. Or the voltage that was set dropped drastically while the ampere meter high increases, this means that there is a short on the motherboard.
Connecting cable is used to inject voltage to point / track voltage loss. clamp can be used
as the probe so that the cable connection is longer.

Universal jack adapter

Shorted Motherboard could be happen in very beginning VALW section .it mean short already happen on DC jack adapter , DC regulated power supply besides using it to power up electronic circuit it can also be use to troubleshoot and find out a shorted component in a motherboard?

Assuming you have confirmed that the VCC supply lines shorted to ground through some faulty components, you can easily detect it with the use of a variable digital DC regulated power supply Using DC regulated power supply short circuit could identified by the PSU ampre meter after plug in jack adapter ,Current suddenly goes high and voltage drastically down or drop .

Voltage usage 19V and current start at Zero before plug in and Look at the both monitoring current (Red) and Voltage (Green) after jack pug in to monitoring short circuit on VALW section.

VALW section on Laptop motherboard have 3 block of section calls VIN or ADP+ ,VBAT or B+ and 3V_5V system (most common circuit design 3V_5V on VALW) but some of circuit design 3V_5V section on S_5 state or appear after switch .

To check with multimeter use set to X 1 Ohm and measure between the supply pin and the main board ground and then reverse the probes. A good board should not show two similar reading and if you get two similar ohms reading then this means that the line had shorted to ground through some faulty components.

Most potential cause of short on VALW section are capacitors ,They use as filter and 1 of pin embedded to the ground side .

To find shorted component using PSU by pushing the voltage on that sort circuit and shorted component will goes hot and easy to find .To avoid any damage use lower voltage than ADP+ needs. For example if ADP+ 19V use 10V to inject and current not higher than 1.5Amp.

The other potential cause of short are N channel, when there is a leak on that mosfet ,lower n channel became leak and connect negative line to positive line .Do not lift lower N chanel if upper N channel leaking ADP+ sources will be get in to smps gate or enter to 3V or 5V section and could damage all component with is maximum voltage allowed only 6.3V

Vcc core Line also most potential N channel leak ,same as 3V_5V system Vcc core got 4 N channel too.(left and right side N channel) or I call them Upper and Lower N channel. Each Upper N channel on this line having source from ADP+ .As a switching transistor they only having out put as their Gate Value .If this and Upper channel leak than Lower N channel will leak also and connect negative line to positive line to stop ADP+ coming to Vcc core line .

Note : Short could be happen to VALW Source and VS_5,S_3,S0 VRAM,VCCP,VGFX.

Quite often whenever electronic equipment don’t function or work, we would immediately suspect a faulty switch mode power supply. But do you know that defective or shorted components in the motherboard or main board could cause the power supply to stop working too.

Switch mode power supply (SMPS) are designed so efficiently that whenever there is any short circuit occur in the main board , power supply would shut itself off and totally stop working. If you have no experience about troubleshooting switch mode power supply, you may think that the power supply have problem where in fact the main board is the real cause of no power problem.

Switch mode power supply have a current sense circuit  and if there is short circuit in the output  side (either in inductors output 3V and 5V section), the current drawn would be increase and this will lead the PWM IC to stop generating output to the power fet and thus the power supply would shut down. All this happen in a split of seconds and you do not have the chance to know if there are output voltages at the secondary side.

Same way as inject VALW ADP+ section but the Voltage not allowed to inject more higher than Section inject Value .

For example if short (feedback) Happen on inductor 3V section the maximum voltage injection not higher than 3V.

If short happen on 5V inductor ,we not allowed to inject higher than 5V. Remember to not inject more than 1.2Amp or PCB could be burned.

Why don’t I immediately turn the output voltage from the dc regulated power supply to 19V or 3V5 volts(depend of section short line identified If  do this and if the faulty components turned hot too fast, this will lead the faulty component to open circuit. If the faulty component open circuit, the current draw will drop and the only clue that you have to identify the culprit has been destroyed! If this thing happens then you may not have a higher rate to repair the board. Of course you still can by replacing one by one the SMD spider IC’s but this will surely eat up lots of repair time. 

Now connect the alligator clip from the positive output supply in the main board and the negative output to the main board ground, plug in the dc regulated power supply. Slowly vary the knob clockwise and see the voltage increase. At the same time the current draw can be seen from the current digital meter readout. From experienced, if there is a short circuit in the main board, whenever the voltage is increase, the current will rise dramatically and if no short circuit there would be less current draw.

if you observe that the current drawn also increase (rapidly) as proportion to the rise in voltage setting, you are now for sure that there is component shorted in the main board. What does this mean? It is a good news to us, because if the current drawn too much we can know the culprit by touching on the hottest components in the main board.  Using your finger you can touch on any components that are very hot. Touch on the IC’s, diodes, transistors, capacitors and etc. Once you located that only one component that is extremely hot to touch then that was the culprit! That’s the real cause of shorted circuit and replace it an other one.

Some time when inject the current on the suspect circuit doesn’t found any warm or hot component event current already increase at maximum setting  ,Big possibility cause of short is a Layer short. it mean negative terminal connected directly to positive terminal like showing picture bellow :

Cause of screws damage

Layer short cause of corrotion

Finding shorted on circuit

A short circuit is simply a low resistance connection between the two conductors supplying electrical power to any circuit. This results in excessive current flow in the power source through the 'short,' and may even cause the power source to be destroyed .in accordance with the laws of electronics, if the positive line connected to the negative supply rail (Ground) ,voltage definitely on the positive track will be changed to zero

Laptop motherboard Voltage requirements to life are ADP + _5V and 3V. the fast way to identifying ADP+ present in all measuring point needs is measuring on the SMPS IC input sources (VIN) and discrete Upper N channel mosfet  source , if this voltage present no need to check ADP Fet and Bat_ fet on VIN and BAT +VALAW section anymore . They should be already present. Then measure the PL (inductors) for 3V and 5V for 3_5V system if they not present first step to check whether there is a feed back on 3V and 5V section lines by testing continuity to ground. If there is a feedback 3V and 5V system will not present although LDO and auxiliary power already present. Remove the Inductor (PL) with have a feedback , if pin 1 reply buzzer (diode continuity test)definite short coming from SMPS or discrete upper/lower N channel, n-channel leak test method by testing continuity (buzzer) pin 8 and pin 1 if there is continuity it’s means mosfet leaking and need to replace .Check on schematic that lower upper string of n channel is connected to ground (lower) pins 1,2,3 if the upper n-channel leak it will also lower become leak and connected to ground to withstand voltage n-channel source into the path of 3V and 5V .do not lift lower n channel if this case happen, otherwise adp+ will passing through to 5V3V section and damage all capacitors with maximum 6.3V allowed .
Leaks will also enter through the gate n channel to track the H1 / H2 and can damage the SMPS ic itself or the surrounding capacitor. Make sure all positive paths are not being connected to ground. If Feedback coming from pin 2 inductors short are coming from +3V_5V output lines.
In order General of Power supply system on laptop motherboard some of difference board ,3_5V system with auxiliary power cant detect by 3_5V inductors. This power both or one of them coming after switch on (VS) ,easy way to identified the system working whit is finding auxiliary power supply to powered Embedded control ic and Bios chip ic . 
After All above mention power present than unit could switch on than power goes drop causing VS feedback the easy way to find out any feed back are by indentified any inductors for VS supply .Same way with finding short circuit on VALW section or cut of VS jumper point (JP) if available and testing ground continuity there ,note any maximum voltage allowed before voltage inject on voltage rail to find short on VS lines. Injecting over voltage and current could harmful and damage the circuit board .

Apple Macbook air A 1237 (820-2179) totaly death ,14.5 V already have in TPS 51120 pin 22(Vin) but no Vreg3 and Vreg5 output present .before claim TPS 51120 damage i check Vreg3 and Vreg5 LDO output by dioda tes buzzer 0001 ohm,tes continuity to the ground also 0001 omh positively there is a feed back on Vreg 5 line .pull tps 51120 out than inject 5V using PSU to finding shorted componen on that line to save time and found Caps C 7604 become hot and replace with good one than put TPS 51120 again on place and Vreg3 present for 3.3V and Vreg5 present 5V.current monitoring on PSU goes up to 0.8a .it's mean board is switch on it self I put adapter of concerning hit sink fan not install yet to avoid chip and processor damage. after that ,test it again well fan running without switching .

Acer 4738 Quanta ZQ9 Totally death .Current usage 0008 amp .Open Quanta ZQ9 schematic on Page 37 to measure adp+ circuit need .This acer using 19V adp+ Voltage .Checking PQ13 N channel source pin 5,6,7,8 19V present. PQ 14 N channel source same way to check PQ 13 .This both upper n channel are power source for 3V and 5V_ALW need. RT 8206 (dc pwr sply) controlling trigger gate driver trough pin 4 gate PQ13 and PQ14 and supply 3V_and 5V motherboard power need requirement to live..There is no trigger for both of 3V_5V system it mean there are no power for VSB(voltage switch button) ,Bios ic,EC ,SB .this motherboard even can't switch .
Analyses goes to RT 8206B as a gate trigger .checking main power input for RT8206B trough VIN pin 5 (19V present) checking ONLDO input pin 4 (9V present) it mean all power input available for this IC. checking LDO output Zero .in normal condition if VIN and ONLDO presented LDO should get output for 5V.this voltage become VL signal enable to activated 5V_EN and 3V_EN .without this gate trigger for 3V_5V system will not present .suspected this IC damage take off from circuit board before replace with a new one checking LDO output for feedback...test continuity 0000 ohm to the ground..using PSU set 5V started pushing current 1amp and found caps PC70 become warm and checking continuity positive this PC70 cause a feedback and hold LDO output .replace caps and put back RT8206B .Testing both gate N channel 3V and 5V trigger available .checking PL13 5V_ALW present ,checking PL 14 3V_ALW present .