HP 1955 Monitor Repair Guide
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Re: HP 1955 Monitor Repair Guide
When test in Diode mode, the display will display forward voltage of the semiconductor junction, typical silicon will show about 600~700 range (which is 0.6~0.7V), so the one with 165 and 1065 are not right. I use Ohm mode to look for low resistance reading since bad semiconductor will no longer act like semiconductor any more when it is bad. I would test them out off he circuit to be accurate.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: HP 1955 Monitor Repair Guide
The the capacitor I removed was the original and I have seen reports about the original caps, that they do blow often. The original cap from memory is PowerStor and the replacement I am getting is a Panasonic and the price seems to indicate quality lol....I hope so. The corrosion appeared as silvery lumps on the capacitor pins.Last edited by nickBcap; 09-02-2013, 05:04 PM.Comment
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Re: HP 1955 Monitor Repair Guide
There are those grey PVC caps between the transistors, don't forget about that, they create distortions in the measurement.Less jewellery, more gold into electrotech industry!Half of the computer problems is caused by bad contacts
Exclusive caps, meters and more!Hardware Insights - power supply reviews and more!Comment
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Re: HP 1955 Monitor Repair Guide
The cap is part of the Royer Oscillator tuning circuit in con junction with the Inverter transformer, if it is bad it will cause the Oscillator to run at the wrong frequency as designed and it damage the C5707. So check the value of the cap and for leakage resistance.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: HP 1955 Monitor Repair Guide
Removed C5707 - all of them shows about 17,26 MOhms (charging or discharging)Last edited by sermulis; 09-02-2013, 07:19 PM.Comment
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Re: HP 1955 Monitor Repair Guide
The tuning cap is next to the two c5707, for example:
http://s807.photobucket.com/user/bud...tml?sort=3&o=1
Is the version of your board made by BenQ. the circuits may match your board.Attached FilesLast edited by budm; 09-02-2013, 09:24 PM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: HP 1955 Monitor Repair Guide
hmm..
is there any other options, before i start replacing (if i will) all components one by one.
from measuring tools i've got only multimeter.
i have no tool to test cap. visualy it looks OK - no leakage, corrosion or smth else.Comment
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Re: HP 1955 Monitor Repair Guide
By the way, that black FUSE PF701, what resistance do you get, from my experience repairing these board, that bad black fuse will show 3~10 Ohms of resistance instead of less than one Ohm.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Comment
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Re: HP 1955 Monitor Repair Guide
So if you check the voltage on either ends of that black fuse with ref. black lead to the chassis, what do you get?Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: HP 1955 Monitor Repair Guide
You have indicated on your post that the customer can shake the monitor to make it work but you cannot see any bad solder joints, from the pictures I can see small ring around the transformer's leg. When I work on these boards, I will also re-flow all the solder joints. See example of the ring develops around the component'e lead: http://s807.photobucket.com/user/bud...tml?sort=3&o=0Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: HP 1955 Monitor Repair Guide
You have indicated on your post that the customer can shake the monitor to make it work but you cannot see any bad solder joints, from the pictures I can see small ring around the transformer's leg. When I work on these boards, I will also re-flow all the solder joints. See example of the ring develops around the component'e lead: http://s807.photobucket.com/user/bud...tml?sort=3&o=0
checked connector to logic board - receiving 4.97, 3.20 and 1 VoltLast edited by sermulis; 09-03-2013, 07:16 AM.Comment
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Re: HP 1955 Monitor Repair Guide
OK, just to be sure, black probe on the chassis, red probe on either end of the fuse and it shows 0V, then the power supply for the inverter is not working, but since the 5V power supply for the main board is also generated by the same transformer, then I will expect you not to have 5V power supply working either. Please post good clear pictures of YOUR board, pictures of both side of the board.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: HP 1955 Monitor Repair Guide
OK, so more likely you do not have the 5vdc output to feed the main board either. So carefully check the DC voltage of that large main DC filter cap, it should have more than 300VDC on its two legs (the reading should be Line voltage x 1.414= xxxx DCV).
I can see ring (cracked solder) on one of the AC input connector. Similar to this: http://s807.photobucket.com/user/bud...tml?sort=3&o=2Last edited by budm; 09-03-2013, 06:23 PM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
-
Re: HP 1955 Monitor Repair Guide
OK, so more likely you do not have the 5vdc output to feed the main board either. So carefully check the DC voltage of that large main DC filter cap, it should have more than 300VDC on its two legs (the reading should be Line voltage x 1.414= xxxx DCV).
I can see ring (cracked solder) on one of the AC input connector. Similar to this: http://s807.photobucket.com/user/bud...tml?sort=3&o=2
resoldered bad joints on AC jack and large capacitor. Measured line voltage on large cap legs - got 300V (so 300 X 1.414 = 424V DCV) so it looks ok?Comment
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Re: HP 1955 Monitor Repair Guide
your line voltage is 220 x 1.414 = about 311V, so the board is getting the Main DC to feed the switching power supply circuits OK. Your board seems to match the diagram I posted on post 147. Did you down load that diagram? So with just power supply board by itself with the board power cord connected, check the DC voltage on the TWO LEGS OF Zener Diode ZD601, DO NOT TOUCH anything on the board with your hands!Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: HP 1955 Monitor Repair Guide
That the VCC for the IC601, it can easily be the filter cap in that power supply section that supplies the VCC for the IC.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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