Straight Circuit Tester

Straight Circuit Tester

Dell Monitor Repair (Likom L705xxx Model) With No Power Symptom

This DELL 17” Monitor (Made in Malaysia under LIKOM model L705XXX, product no: L7055LP) came in with no power symptom. Normally after opening up the cover I would look at the power supply (primary side) for any burnt and cracked components first. If there are darkened area and burnt components, I would tell myself that this Monitor needs a little more time to repair it. If it is not (component’s intact) I would usually begin to discharge the filter capacitor and start checking the fuse.

Okay, it is confirmed that all the primary side components looks good in this Monitor.

First, discharge the big fat filter capacitor with a resistor (I know that the voltage already drained off but it is a normal procedure for me because what if the start up resistor has an open circuit?) then check the fuse.

If the fuse is okay, experience will tell you that the bridge diodes are also working fine. Place your black probe of your analog meter set to x1 to the center pin (drain) of the power FET and red probe to the other pin one at a time (gate and source). If the pointer of the meter doesn’t kick then 80 % of the Power FET is okay. If you want to 100% confirm if it is good then you have to solder it out and test. If the pointer shows a reading then most probably the power FET has developed a short circuit. The result that I got from this Monitor was the pointer don’t flick.

Now is the time for me to use the dick smith flyback tester to check the smps primary winding. The result that I got was, the led bar don’t lit. Ah ha! That was a clue and this clue tells you that it is either the smps primary winding is shorted or one of the secondary diodes has given way. Of course you can check all the secondary diodes with your normal multimeter first (remember, every electronic repairers have their own procedure methods of troubleshooting) but I prefer this way as I want to confirm also if the smps primary winding is working or not.

Usually smps transformer is very robust thus I didn’t suspect it to pull down the flyback tester reading. I straight away check all the secondary diodes with my analog meter and found one diode shorted (part number U202G). Since I do not have this part number, I use a UF5404 ultra fast recovery diode as a replacement. In fact I use this UF5404 to all 14 to 17” Monitor as a replacement for all part number of secondary diodes. The spec of this diode was 400volt, 3 Amp with 50 nanosecond.

After the replacement of the diode, and placing the flyback tester probes again to the primary winding, the result shows full bar on the LED. Don’t be happy with the result yet because your job still hasn’t done.

Now I moved on to check HOT with the same procedure as checking the power FET. The HOT checked to be okay too. Next, I check the internal capacitance of the flyback transformer to see it is shorted or not or is the capacitance value run. For your information, internal capacitor in flyback transformer gave lots of problems in computer Monitor. I also scanned thru the B+ FET and found it to be good too.

Now is the time to switch on the Monitor, however this round I don’t connect any bulb because it was only a shorted diode in the secondary side. I would only connect a light bulb after repair when there is major short circuit in the primary side such as a blown bridge rectifier, shorted fet and smps primary winding and also burnt components in the board.

The DELL 17” Monitor worked beautifully and after long hours of burn-in test, I declared it okay and ready to send back to my loyal customer. Isn’t it fun to be able to repair a Monitor and at the end you get paid for something you like doing. I just love electronic repair!

About the Author

Check out the two links below. You will be pleasantly surprised to find out that LCD and Electronic Repairs are so Easy and Highly Profitable for even a novice. You can learn the repairing secrets easily.

Find out How to Repair Any LCD Monitor - It is a breeze!

Learn the Secrets of Testing Electronic Components.

Economy Circuit Tester $18.99 Economy Circuit Tester;

Circuit Tester Set by Performance Tool $8.99 3-piece set;Circuit tester;Continuity;High/low 6/12/18/24/36 volt tester Circuit Tester Set by Performance Tool

Tripplite / 3-LED PLUG-IN CIRCUIT TESTER / CT120 $28.94 Tripplite - 3-LED PLUG-IN CIRCUIT TESTER - CT120

Low Volt Circuit Tester $6.49 The Low Volt Circuit Tester tests for shorts, grounds, open circuits, broken wires, and bad connections in 6 & 12 volt systems. Use with power on.

Circuit Tester $299.59 Check energy sources to eliminate accidents & injuries Suretest circuit analyzers test AFCI's and GFCI's for proper operation, shared neutrals and wiring configuration. Illuminates for accurate results and has an ergonomic design for comfortable use. Neon lamps prevent false readings.

Lisle Electrical Circuit Tester $12.95 The ''Handy Hooker'' Circuit Tester is made with a hooded probe that protects your fingers and automatically centers the wire. Small size allows easy use in even the tightest places. Quickly test low voltage up to 28 volts. Alligator clip ground tester.

K Tool International Mini Circuit Tester. Each $10.23 Manufacturer: K Tool International. Each. Customers also search for: Discount Mini Circuit Tester, Buy Mini Circuit Tester, Wholesale Mini Circuit Tester, 769622727657, ToolWeb, Circuit Testers

Circuit Tester 6-12 Volts Electrical Tester Pen $5.99 Descriptions: Insert the connector into the Circuit Tester main body; Ground the jaw and use the tip of the Electrical Tester to detect, by piercing to the end of the flexible wire or the wire itself; If electrified, the located in the central main body of the Circuit Tester will light;Simulated alligator clip and grounding wire connected to handle;With Pen Shape, Light in handle that glows when circuit connection is made;The Electrical Tester can Help you find broken and live wires;use the Circuit Tester to tests fuses, light sockets and locates short circuits;the Electric Tester is ideal for auto, trucks, motor cycles, boats, and small engines;Weight: 31.5g

Lisle Low Circuit Tester $7.99 The Lisle Low Circuit Tester allows you to quickly check both AC and DC currents up to 28 volts with the power on. Helps locate shorts or breaks in wiring. Comes complete with an insulating grounding clip.

High & Low Voltage Circuit Tester $8.49 The High & Low Voltage Circuit Tester tests high voltage in spark plugs, plug wires, and distributor caps. Test 6 and 12 volt systems for shorts, grounds and open circuits with power on. Tester bulbs are replacable.

OTC Heavy Duty Straight Cord Circuit Tester. Each $20.59 Manufacturer: OTC. Each. Features and Benefits: 5' heavy duty cord Checks 6 and 12 volt systems Ergonomic, slim designed clear handle Bright red, slim style replaceable bulb Positive contact-molded strain relief Heavy duty, stainless steel probe with ins

OTC OTC3634 Heavy Duty Straight Cord Circuit Tester $35.7 Features and Benefits:. 5 heavy duty cord. Checks 6 and 12 volt systems. Ergonomic slim designed clear handle. Bright red slim style replaceable bulb. Positive contactmolded strain relief. Heavy duty stainless steel probe with insulated shaft. Heavy duty clip with positive soldered connection. Designed for testing electrical circuits and locating shorts grounds and open circuits.. nbsp;

Lisle Heavy Duty Circuit Tester $14.95 The Lisle Heavy Duty Circuit Tester quickly tests low voltages up to 28 volts. The probe, handle, cord and clamp are reinforced.

Lowvoltage circuit tester Pack of 25 $48.94 6 and 12v low voltage circuit tester. Comes in blister card package. Dimensions:. Length: 11. Height: 11. Width: 11

Lowvoltage circuit tester Pack of 50 $75.63 6 and 12v low voltage circuit tester. Comes in blister card package. Dimensions:. Length: 13. Height: 13. Width: 13

Lowvoltage circuit tester Pack of 75 $94.31 6 and 12v low voltage circuit tester. Comes in blister card package. Dimensions:. Length: 15. Height: 15. Width: 15

Lisle Bulb for LIS28400 Circuit Tester. Each $6.06 Manufacturer: Lisle. Each. Replacement Bulb for LIS28400 Circuit Tester Lifetime warranty does not cover abuse Customers also search for: Discount Bulb for LIS28400 Circuit Tester, Buy Bulb for LIS28400 Circuit Tester, Wholesale Bulb for LIS28400 Circuit

Tripp Lite - CT120 Circuit Tester $12.99 1.28 oz 3" Height x 1.50" Width x 0.50" Depth CT120 Circuit TesterNEMA 5-15PCT120 circuit testerOperating instructions Housing Type / Color: Black plastic Lighted Display: 3 indicator lights (2 yellow / 1 red) Tripp Lite's instant-read CT120 circuit tester detects wiring stability in standard 120 volt AC wall sockets. Simply plug the circuit tester into a receptacle and view the lighted 3 lamp status display for verification of correct wiring, open ground, open neutral, open hot, hot-ground reversal and hot-neutral reversal fault conditions. Sticker on the tester offers lighting combinations for each wiring condition. Ultra-portable design and easy to read lighted display makes the CT120 an excellent addition to any laptop carrying case, tool belt or workbench. Low cost design saves the expense of hiring an electrician to determine wiring stability. CT120 CT120 Circuit Tester Circuit Tester Lifetime Tripp Lite www.tripplite.com

Thexton THX121 Wirehawk Circuit Tester $31.84 121 Wirehawk Circuit Tester Features and Benefits: Fast handy For 12V/24V circuits Wirehawk requires just one hand to test circuits in hardtoreach areas. Works two ways: Captures and pierces wire with unique hook design or can be used as an icepick type tester. Hook feature makes Wirehawk simple to use and easy on fingers. If circuit is live bulb in handle lights up. Made of rugged plastic.Has 16 gauge 44inch ground wire with 50 amp clamp. Test up to 15 volts.

Power-On Circuit Tester $155.95 Tests function and operation of electrical motors, solenoids, relays, lights and more by supplying power or ground. For use on 12V and 24V systems. High impedance tester is safe (in test mode) for computer circuits. LEDs provide visual indication of continuity. Red or green LED shows polarity at probe.By Thexton.

TL-06 SMD Precise-Circuit and Micro-Electronics Tester Probe $7.8 TL-06 SMD Precise-Circuit and Micro-Electronics Tester Probe

Thexton Power On Circuit Tester. Each $143.02 Manufacturer: Thexton. Each. Features Benefits: For 12VDC or 24VDC systems LED visual indicator Red or green LED shows polarity at probe This is a simple and easy to use circuit tester. It supplies power or ground to test operation of electrical motors

Thexton THX137 Power On Circuit Tester $185.33 Features and Benefits: For 12VDC or 24VDC systems LED visual indicator Red or green LED shows polarity at probeThis is a simple and easy to use circuit tester. It supplies power or ground to test operation of electrical motors solenoids and more by supplying power or ground. Also is safe for computer circuits (in test mode).

Heavy Duty Circuit Tester - 6/12V $8.95 The best quality electrical circuit tester available for checking 6 and 12 volt systems. Made to last longer than anyone's lifetime! Use it to troubleshoot electrical circuits like any other circuit tester, but it is especially valuable because it will fit and work in confined crowded areas like under hoods and dashboards of modern cars and trucks. ? 6' ground wire remains flexible in cold temperatures ? Checks 6 and 12 volt systems ? Special overbite alligator clip designed to stay put! ? Sharp, nickel plated piercing probe By Tool Aid.

Ultimate Circuit Tester Kit $41.95 Heavy duty tester signals with a light and buzzer. The test kit test low voltage up to 28 volts. Also performs these functions: Find electrical shorts, checks polarity, detects battery drain, checks circuits from a distance. Heavy-duty coil cord extends over 8 feet. Detachable, spring-loaded hook pulls center of the wire into the probe every time. Attach alligator clip to the probe when a clip-on connection is needed.By Lisle.

Lisle Heavy Duty Circuit Tester / Jumper. Each $22.35 Manufacturer: Lisle. Each. Features Benefits: Two tools in one - works as a circuit tester and jumper wire The probe, handle, cord and clamp are reinforced for durability Comes with a strain relief spring on the cord Heavy duty circuit tester for checki

Lisle LS32900 Heavy Duty Circuit Tester / Jumper $32.03 Two tools in one works as a circuit tester and jumper wire. The probe handle cord and clamp are reinforced for durability. Comes with a strain relief spring on the cord. Heavy duty circuit tester for checking low voltage up to 28 volts. Tester becomes a jumper for powering electrical components or as a ground. A 2in1 tester that tests circuits up to 28 volts and works as a jumper wire for power or ground.

Lisle LIS32900 Heavy Duty Circuit Tester / Jumper $37.7 Features Benefits: Two tools in one works as a circuit tester and jumper wire The probe handle cord and clamp are reinforced for durability Comes with a strain relief spring on the cord Heavy duty circuit tester for checking low voltage up to 28 volts Tester becomes a jumper for powering electrical components or as a groundA 2in1 tester that tests circuits up to 28 volts and works ad a jumper wire for power or ground.

K Tool International 6 OR12V Heavy Duty Circuit Tester. Each $14.36 Manufacturer: K Tool International. Each. Customers also search for: Discount 6 OR12V Heavy Duty Circuit Tester, Buy 6 OR12V Heavy Duty Circuit Tester, Wholesale 6 OR12V Heavy Duty Circuit Tester, 769622727800, ToolWeb, Circuit Testers

Gb Electrical Gb Electrical Circuit Tester GRT-3500 $5.18 Circuit tester Receptacle tester and circuit analyzer Detects faulty wiring in any standard 110/125V AC grounded receptacle Tests 6 circuit conditions; open neutral, open ground, open hot, hot/ground reverse, hot/neutral reverse, and correct Easy-to-read signal indicators Plug in and watch the yellow and red lights identify the wiring condition Yellow UL listed 1 year limited warranty 1 per card Brand #: GB Electrical GRT-3500 UPC: 032076068431 Keywords: circuit analyzer circ tester electrical electric meter

Circuit Tester 6-12 Volt Electrical Systems $5.99 Descriptions: Drop forged high carbon steel, hardened and tempered;Simulated alligator clip and grounding wire connected to handle;With Pen Shape, Light in handle that glows when circuit connection is made;The Electrical Tester can Help you find broken and live wires;use the Circuit Tester to tests fuses, light sockets and locates short circuits;the Electric Tester is ideal for auto, trucks, motor cycles, boats, and small engines;Weight: 41.5g

H.D. Circuit Tester With 6-1/2'' Probe $19.95 Circuit Tester features and extra long wire that stretches up to 12 feet for use, then automatically retracts. Quickly and easily check electrical system circuits and accessories on 6 and 12 volt systems. ? Supersharp probe ? Heavy duty ground clip with insulator ? Wire is supported by strain relief spring at probe handle ? Bulb is easily replaced (Bulb: Tool Aid No. 27203 or G.E. 1889 or equivalent) By Tool Aid.

Wirehawk? Circuit Tester For 12/24V Circuits $25.95 Wirehawk? requirs just one hand to test circuits in hard to reach areas. Works two ways: Captures and pierces wire with unique hook design or can be used as ice-pick type tester. If circuit is live, bulb in handle lights up. Has 16 gauge, 44 inch ground wire with 50 amp alligator ground clamp. Use for circuits, connections, fuses and 2-cycle engine timing.By Thexton.

Gb Electrical Gb Electrical Gfci Circuit Tester HGT6120 $15.83 Gfci circuit tester Stop shock GFCI circuit tester with ground analizer Available Only at Dixon, Woodburn Brand #: GB Electrical HGT6120 UPC: 035632064687 Keywords: tester grnd fault circuit gfi receptacle circ analyzer electrical electrcl meter gfci stop shock

K-D Low-Voltage Circuit Tester $8.95 Circuit tester for 6 and 12V electrical systems is ideal for the home mechanic. It quickly checks headlight, taillight and turn signal circuits, faulty sockets, connections, fuses and broken wires. Tester comes in a tough, durable shock-resistant case. Includes 12V bulb and 36'' cable. Uses bulb #1893.

Heavy Duty Circuit Tester And Jumper By Lisle $21.95 The Heavy-duty circuit tester and Tester can be used to check low voltage up to 28 volts, and by depressing the red button the becomes a jumper for powering electrical components or a ground. The probe, handle, cord and clamp are reinforced for durability. Comes with a strain relief spring on the cord.