When I first got the AL1716 the back light flashed every few seconds and the power led flashed from green to yellow/orange.
Verified:
120v AC at bridge
160v DC at main capacitor
5v on 5v side, adding a good cap didn't improve
12v on 12v side, adding a good cap didn't improve
Short “5.ON/OFF” to “1.VCC5V” back light still flashes
4 electrolytic capacitors on display board check good
Display chip TSU16AK-LF gets very hot
No logo on display
No semiconductor shorts on either the power supply or the video board.
Shorting “5.ON/OFF” to “1.VCC5V” should eliminate the video board 79040130 or the power/PWM board 79040140 as faulty. If the back light still flashes then the PWM is faulty but the logo should be seen. If the backlight stops flashing then the video board is faulty and no logo is likely.
I short the screen on yet the back light still flashes and no logo is seen which means that both boards are faulty. This is not good considering that the AL1716b is not popular enough to have spare parts on eBay.
I left it several days then went testing again to see if there was something that I had missed. I noticed that the MOSPEC SRF1040C D805 diode array on the 5v output only has 0.181 voltage drop in circuit and 0.141 voltage drop out of circuit which seemed a bit low to me.
Knowing that SMPS diode arrays of the same polarity are mostly interchangeable I raid one of my busted power supplies from a Compaq EVO D510S and select a ST BWY51. The SRF1040C has an insulated mount and the BWY51 does not so I must bring along the insulator. With the BWY51 installed the outputs read 5.08v and 13.30v, the 12v line is over 1v higher than before. The video chip doesn't overheat as fast. Shorting the back light control line to 5v lights the back light without flashing. The video board dims the monitor at the times where it would have blanked the back light if I wasn't shorting the back light on.
Now the power supply and inverter work! It could have been a bad solder or a leaking diode.
The power button is able to turn the monitor off but it doesn't behave well when it goes back on. So the video board does something intelligent but doesn't work well enough to show an image. Pin 8 of U103 and U106 have 5v on them. SMD decoupling caps C140, C142, C144, and C138 have 3.3v on them. Then I notice a 3 pin chip U102 on the video board called AS1117L-33 with 5v and 3.3v on two legs. The data sheet shows that it's a 1 amp regulator available in voltages 1.8v, 2.5v, 3.3v, 5.0v, and adjustable. Then I see a similar chip U101 AS1117L-18 which should be a 1.8v part but is outputting 4.0v. SMD decoupling cap C134 has 4.0v. C106 and C148 have 4.0v which is the output of the 1.8v regulator. C148 and C101 has 5v which is the input to the 1.8v regulator. The 1.8v regulator internals must be shorted on to get max output.
Now that I know what the voltages are and where they come from I can easily figure out where all these voltages are used. With the monitor unpowered and the DMM on diode test I hook one probe to the output of a voltage regulator and run the other probe across all the chips and other important devices. 5v is used on U105, U106, U103, and not used on U104. 3.3v and 1.8v is used all over U104 but not any others.
With the power back on going along C137 to C125 I see 3.3v, 4.0v, and 5v so 4.0v is definitely going into the video chip from the defective 1.8v regulator. With the part out the video chip gets hot really fast. The exact part is not available on eBay but a LM1117 1.8v seems to be an exact match so I'll get that one. But that China part is so far away. If only there was a way to verify that the new regulator would fix the problem.
I need a regulated 1.8v and I know that some Pentium IV chips run around that voltage so I start testing motherboards. Turns out those old 1.7Ghz P4 run at 1.73 volts so I rig up some Cat 5 wire to get power from the motherboard setup to the monitor setup and continue testing. The video chip doesn't get hot when only 1.73v is supplied. Unfortunately we have two independent power supplies that go on at different times. After some testing trials and errors I power up the 1.73v motherboard supply then quickly power up the monitor supply:
The Acer logo shows!
The power supply failure might cause the video board failure. With both failed I get a complex green/yellow power L.E.D. and back lighting sequence which appears to change over time because the power cycling and the video errors are running together and can be affected by the buttons because the video chip is partially working.
A quick look at the Dell 1702FP LG L1800FPK board shows that it has a 1117S25 2.5v regulator, a BA033 3.3v regulator, and a KA78M05R (78M05, 7805) 5v regulator that pulls from the 12v source. Looks like all these video boards have one or more regulators that are susceptible to power supply failures and easy to fix.
The victory is short lived. I put a new 1.8v regulator in and the Acer logo shows clear. Unfortunately the VGA input is out of sync. Perhaps the 1.8v lines running too long at 4.0v burned out part of the display chip.
Verified:
120v AC at bridge
160v DC at main capacitor
5v on 5v side, adding a good cap didn't improve
12v on 12v side, adding a good cap didn't improve
Short “5.ON/OFF” to “1.VCC5V” back light still flashes
4 electrolytic capacitors on display board check good
Display chip TSU16AK-LF gets very hot
No logo on display
No semiconductor shorts on either the power supply or the video board.
Shorting “5.ON/OFF” to “1.VCC5V” should eliminate the video board 79040130 or the power/PWM board 79040140 as faulty. If the back light still flashes then the PWM is faulty but the logo should be seen. If the backlight stops flashing then the video board is faulty and no logo is likely.
I short the screen on yet the back light still flashes and no logo is seen which means that both boards are faulty. This is not good considering that the AL1716b is not popular enough to have spare parts on eBay.
I left it several days then went testing again to see if there was something that I had missed. I noticed that the MOSPEC SRF1040C D805 diode array on the 5v output only has 0.181 voltage drop in circuit and 0.141 voltage drop out of circuit which seemed a bit low to me.
Knowing that SMPS diode arrays of the same polarity are mostly interchangeable I raid one of my busted power supplies from a Compaq EVO D510S and select a ST BWY51. The SRF1040C has an insulated mount and the BWY51 does not so I must bring along the insulator. With the BWY51 installed the outputs read 5.08v and 13.30v, the 12v line is over 1v higher than before. The video chip doesn't overheat as fast. Shorting the back light control line to 5v lights the back light without flashing. The video board dims the monitor at the times where it would have blanked the back light if I wasn't shorting the back light on.
Now the power supply and inverter work! It could have been a bad solder or a leaking diode.
The power button is able to turn the monitor off but it doesn't behave well when it goes back on. So the video board does something intelligent but doesn't work well enough to show an image. Pin 8 of U103 and U106 have 5v on them. SMD decoupling caps C140, C142, C144, and C138 have 3.3v on them. Then I notice a 3 pin chip U102 on the video board called AS1117L-33 with 5v and 3.3v on two legs. The data sheet shows that it's a 1 amp regulator available in voltages 1.8v, 2.5v, 3.3v, 5.0v, and adjustable. Then I see a similar chip U101 AS1117L-18 which should be a 1.8v part but is outputting 4.0v. SMD decoupling cap C134 has 4.0v. C106 and C148 have 4.0v which is the output of the 1.8v regulator. C148 and C101 has 5v which is the input to the 1.8v regulator. The 1.8v regulator internals must be shorted on to get max output.
Now that I know what the voltages are and where they come from I can easily figure out where all these voltages are used. With the monitor unpowered and the DMM on diode test I hook one probe to the output of a voltage regulator and run the other probe across all the chips and other important devices. 5v is used on U105, U106, U103, and not used on U104. 3.3v and 1.8v is used all over U104 but not any others.
With the power back on going along C137 to C125 I see 3.3v, 4.0v, and 5v so 4.0v is definitely going into the video chip from the defective 1.8v regulator. With the part out the video chip gets hot really fast. The exact part is not available on eBay but a LM1117 1.8v seems to be an exact match so I'll get that one. But that China part is so far away. If only there was a way to verify that the new regulator would fix the problem.
I need a regulated 1.8v and I know that some Pentium IV chips run around that voltage so I start testing motherboards. Turns out those old 1.7Ghz P4 run at 1.73 volts so I rig up some Cat 5 wire to get power from the motherboard setup to the monitor setup and continue testing. The video chip doesn't get hot when only 1.73v is supplied. Unfortunately we have two independent power supplies that go on at different times. After some testing trials and errors I power up the 1.73v motherboard supply then quickly power up the monitor supply:
The Acer logo shows!
The power supply failure might cause the video board failure. With both failed I get a complex green/yellow power L.E.D. and back lighting sequence which appears to change over time because the power cycling and the video errors are running together and can be affected by the buttons because the video chip is partially working.
A quick look at the Dell 1702FP LG L1800FPK board shows that it has a 1117S25 2.5v regulator, a BA033 3.3v regulator, and a KA78M05R (78M05, 7805) 5v regulator that pulls from the 12v source. Looks like all these video boards have one or more regulators that are susceptible to power supply failures and easy to fix.
The victory is short lived. I put a new 1.8v regulator in and the Acer logo shows clear. Unfortunately the VGA input is out of sync. Perhaps the 1.8v lines running too long at 4.0v burned out part of the display chip.
Attached Files
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But today, I’m making an exception here. Why? No idea. Perhaps only because the repair details are still “fresh” in my head… which is ironic, given this is a 16 year old monitor that hardly anyone will care about today. It is new to me, though. 
I picked it up last November from someone on my local Craigslist. It wasn’t very close to where I live, but was close to a family friend that I had to go visit anyways. So after watching the posting on Craigslist for a few weeks and seeing it getting...
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