I got a used unknown condition old LCD monitor(Acer AL2021) which is from my friend!

Few days ago, I converted my Samsung SyncMaster 510N monitor to run on a battery to use on a battery converted CCTV system! After It worked; I made a stupid decision to skip the undervoltage protection circuit made by a TL431 VRef IC; And accidently touched the 5V wire to the 13V wire, blowing up the main PCB.

After some inspection; I found that it's voltage regulator ICs were blown! Then I replaced all of them with some LM117 and LM317 IC s to check weather it still works! But, unfortunately, only the Main IC was saved, which indicated by the buttons and the LED started to response! But; the SE7889 Display controller IC started to get hot!

Then; one of my friends gave me a LCD monitor; which he found from a computer repair guy said "they are irreparable devices", He said 'You keep it and if it's fixable, you can use it!'

He said me that the 'Acer' logo comes on and in a fraction of a second, it goes off!

So me and my friend opened it and found the main power board was tampered with some sort of a Chinese device(Huamei HM-619)!

So without further inspection; I brought it home and removed the unknown device and powered it with a battery(It is connected after the reverse voltage protection diode!) to test it! And then; the things in the videos started to happen! (Hope the videos will explain the situation better!)

Images of the Backside


Video1 - https://drive.google.com/file/d/1ZUeWMGr6UVN7ujP5PnQbk_33Ka1X1tho/view?usp=share_link
Video2 - https://drive.google.com/file/d/1-KlVw0Yj3MzzjHOKwKqrbwi1CRDzsSQB/view?usp=share_link

So I have 2 questions!
1) Is this a fixable problem? And is it worth to spend 50$ (Which is a lot in our currency) to buy a new one?
2) How can I fix the other monitor? Does anyone here have a spare board of a SyncMaster 510N monitor?

All the service manuals with schematics are attached!

Thanks.

 

Welcome to AAC.

The module you removed appears to be from a previous repair. From what I can gather it is a replacement for the switching element (MOSFET, etc.) in monitor, TV, etc. power supply.

It looks like someone had repaired the monitor but the module also died.

Here is the best information I can find, though the English is poor and it is hard to understand without context:

Huamei　UniversaI　Power　Supply　Module　HM-619​

Published：2011/9/2 11:22:53　Hit：17858​

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Huamei UniversaI Power Supply Module HM-619​ 　　This module has noly three leading wires and can be connected to the original machine's circuit in the simplest way. the protective functions it has include the protections against over-voltage, over-current, short-circuit,and erroneous connection of leading wires, it can be installed so conveniently and quickly that use of just two wires (the black and red wires) of this module can achieve this purpose for most machines. Extrenely strong loading capacity and more stable and reliable ysage can bring great convenience to daily maintenance and application of this prosuct. lt not only can be uses to maintain and substitute various color TV's switch power supply circuit,but also is applicable for various large-size color TVs. Moreover, lt can be used in the switch power supplies of VCD.DVD.satellite receiver, etc. Now the case of color TV is used to describe its usage. 　　1. Dismantle the switching tube or thick-film block of original power supply, and fix this module solidly on the original radiating rib; 　　2.Connect the red wire to the original switching tube's welding point at pole C(field effect transistor is at pole D)or to the corresponding power tube's welding point at pole C inside the thick-film block; 　　3.Connect the black wire to the original switching tube's welding point at pole E(field effect transistor is at pole S) or to the corresponding power tube's welding point at pole E (black wires in parallel power supply circuits can bedirectly connected to hot ground not isolated from municipal power grid). 　　4.Cut off the line load and connect to it a 100Wbulb and turn on the machine.Then regulate the module's self-con-tained potential device to make the output voltage meet the required value.Output voltages of other windings can meet the requirements automatically.(When leav-ing factory,the module has already had its-output voltage regulated to the lowest value.For application on sifferent products,the lowest output voltage are different,for exanple, the lowest output for TV's ranges from 20V to 70V and the lowest output for video players is about 4V).During debugging,the voltage and poten-tial device must be regulated by plastic-handled small screwdriver; 　　5.The green wire is for remote-controlled switch-of. Conduction to hot qround can switch off the output. The machine that adopts light-coupled switch-off is connected to light-coupled pole C, light-coupled pole E is connected to hot ground, and other connection wires are all cut off from light-coupled pole C. If there are voltage-stabilizing components on the sides of light couoing, the components should be dismantled; however the control components for switch-off should be retained.(For those machines that have two light couplings, C and E of the two light couplings should be parallelized for operatio); for the series power supplies that use standby tubes, the green wire should be connected to pole C of standby tube and other components connected to pole C should all be cut off; 　　6. The green wire is also used for precise voltage regulation.The problem of inages changing with sounds that might happen after module is loaded can be solved by restoring the original machine's voltage-stabilizing components and by regulating and controlling the green wire through light coupling. In this way, the purpose of precise voltage regulation can be achieved.For utilizing the original machine's voltage-stabilizing cirvuit,output voltage of this module must be regulated up by about 20 V through dummy load;then the original machine's voltage-voltage can be lowered to the required value due to being subject to the original voltage-stabilizing control, and therefore, the effect of voltage stabilizing of the module can be the same as that of the original machine.Failure to lower or abnormal lowering of the output voltages or the machines that are connected to the original machine's voltage-stabilizing circuit can indicate problems of the original voltage-stabilizing circuit. 　　7.If disturbances and noises occur after installation, please remove other components than are connected to pole C of the original switching tube, and attach the absorption circuit that is composed of resistance R1(33Ω-100Ω/5W) and capacitance C1 (470P-1000P-2000P/1KV-2KV). For whistling sounds occurring to series power supply, please dismantle the capacitance parallelized with the original fly-wheel diode;if the whistling sounds continue, please ddismantle all the apacitances that are connected to the switching tube's pole C; 　　8.For the phenomena of failure to start up abnormal voltage, and automatic protection, please check whether the primary and secondary commutation diodes, filter capacitor, and corresponding loads are in shout circuit.If green wire exists,it should be cut off first to ascertain whether the failure to start up is caused by actions lf the remote-controlled switch-off circuit or by damage to this circuit.For series power suppply, whether the fly-wheel diode is in shout circuit or open circuit should also be ascertained; 　　9.The absorption circuit in figure 3 is relatively applicable for voltagereduced machines,and among them,the resistance R is 33K-51K/3W-5W, the capacitance C is 1000P-2200P/630V-2KV, and D is the quick diode. 　　 Additionally, it should be narrated here that for partial machine types, their switch transformers are not compatible with module and this might result in the failure of ortput voltage to meet the original machines tequirements and too loud noises to use this module. Nevertheless,this module can be used in other products. For modules that have been used before,the voltage must be regulated to the lowest output state before intallation lest excessively high voltatge might damage the components when the module is used in other products. The range of this module's output voltage is wide and it is normal when voltage is not regulatted to the required values,the output voltage is not stable or whistling sounds happen.​ Shijiazhuang Gaoxin District Huamei Electronic Component Factory​

This video might be helpful, but I can’t tell because I don’t know what languages you speak, nor for that matter even what language the video is in. I include it here just in case it has some value.

You can buy these modules quite cheaply, so replacing it with a working one might be a solution.

 

Welcome to AAC.

The module you removed appears to be from a previous repair. From what I can gather it is a replacement for the switching element (MOSFET, etc.) in monitor, TV, etc. power supply.

It looks like someone had repaired the monitor but the module also died.

Here is the best information I can find, though the English is poor and it is hard to understand without context:



This video might be helpful, but I can’t tell because I don’t know what languages you speak, nor for that matter even what language the video is in. I include it here just in case it has some value.

You can buy these modules quite cheaply, so replacing it with a working one might be a solution.

Thank you for your help!
But I feel like the power supply isn't the case! I feel like the main PCB has some sort of error!

I tried using different power supplies! But the problem is the same! The screen comes on for a fraction of a second(about 0.1 second as I found) and Can you help me to figure out what should be the problem?

Thanks!

 

On many occasions, when a system appears to start and then immediately stop functioning, it s because some input is not getting the correct signal required to continue. That could include something as simple as an open CMOS input, or it might be looking for an input after displaying the startup screen (the Acer logo). But it may also be from an over-voltage condition at some power input. So there are a number of fixable causes that might be the problem.
In addition to that, there are some power supply configurations that drop out quickly because a capacitor has failed. That problem is cured by replacing the failed capacitor.

 

Is the problem with the actual display panel or the backlight for the display panel ? With that information you can look at the part of the circuit that is responsible for the part that is not working.

Les Jones.