Re: ViewSonic VX922 and VX724 Bad CapXon
I have just been checking those diodes (Diodes removed from board) and I am confused by the 100 ohms or less.
Using a meter that has a diode option. The open circuit setting (probes not touching) is 1466 mV (dropping with use)...
Both diodes connected to the meter the correct way round negative probe to silver band 462mV-482 mV
Both diodes connected the wrong way round positive probe to the silver band 1466-1460 mV open circuit.
With the ohms meter setting...
The wrong way positive...
Hunt
Member
Last Activity: 04-24-2018, 02:04 AM
Joined: 06-30-2009
Location: UK
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Re: ViewSonic VX922 and VX724 Bad CapXon
Thanks guys, I will now start to look for parts.
...
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Re: ViewSonic VX922 and VX724 Bad CapXon
I've stumbled on this; however I cannot see U101......Leave a comment:
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Re: VierwSonic VX922 and VX724 Bad CapXon
I see what you mean; yes, the U101 does indeed have 6 pins.
The board has FSP043-2PI01 printed on it.
P/N: 3BS010131 3GP Rev:1...Last edited by Hunt; 02-15-2018, 03:47 AM.Leave a comment:
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Re: VierwSonic VX922 and VX724 Bad CapXon
Stunningly fast response!
Here it is.
Do you think I have a chance of repairing this if I change those components?
P.S.
From looking at DSC00276.jpg of yours, the SMPS IC is a CET ? ,5, 4?, 2, M/ , Z last line C?, E , F, ? 4 N G...Last edited by Hunt; 02-14-2018, 03:23 PM.Leave a comment:
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Re: VierwSonic VX922 and VX724 Bad CapXon
9 years on and those caps that were bad and repaired are still going strong
Unfortunately the power supply has gone with a bang.
1. The single (rectifier) on the heat sink that is at right angles to the heat sink that usually has the bad caps has burnt out, U101.
Anyone know the part number for this?
2. 400v 100uf electrolytic positive wire has what looks like burnt electrolyte oozing out, C114.
3. Not related, I think to the current problem; however, seem sensible to replace 470uf 10v...Leave a comment:
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Re: Hp 1940 flicker
My HP 1940 lasted till now with only the odd flicker perhaps once a week. I just went blank and came back up ok.
Now though it has a constant flicker with the green light going on and off.
I have done a re-solder just in case it was a simple problem again but it has made no difference
so I think the monitor has had its day.
3 years extra life is very good thanks to this forum
Problem is they do not seem make the old format monitors now.
Of to see what is available secondhand...Leave a comment:
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Re: Hp 1940 flicker
I have fully reassembled the repaired monitor and have used it in a three-monitor system now for a week or more and I am very pleased with the results.
I have not added a fan. However, I have provided more cooling holes to the metal case and to the plastic back cover.
Pictures attached.
P.S. As I write this, I'm sure the monitor made a click. Any ideas what this could be?...Leave a comment:
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Re: Hp 1940 flicker
There is a comment somewhere that people have fitted fans to monitors.
Is there a suitable place on the monitor to pull 12v or even 9v (make less noise) DC to run a fan off?...Leave a comment:
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Re: Hp 1940 flicker
Well it has been nearly a week since I re-soldered all the underside joints in the area of the four transformers and near all the discoloured section of the board.
No flickering yet and I believe the use of the monitor is reprehensive of when it was faulty.
My only concern now is the comment above about... "Also check the two rectangular body gray caps for value and leakage otherwise you may blow up your transistors."
How do I test for the above?
I'm also wondering if drilling more holes in...Leave a comment:
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Re: Hp 1940 flicker
Those photos are stunningly clear; have you a good camera or are you using some special lighting?
The board looks very clean....Leave a comment:
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Re: Hp 1940 flicker
Hmmm... Children could be about but under supervision.
I was thinking that since all the metal was on the screen and that metal is earthed I should be ok. In addition, I was hoping if I can get this monitor, working it could be one of three. Thus if there is no plastic bezel the gap between screens would be smaller. Not having the cover would make the screen last longer as well.
The flicker is a definite black screen then full text screen like blinking.
I have not yet soldered any connections...Leave a comment:
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Re: Hp 1940 flicker
I spoke to soon
Now I am using the monitor more like I did before it has flickered. It is not a bad and if I leave it a moment the screen settles down and works ok.
I'm using the monitor without the case still; is that safe?Leave a comment:
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Re: Hp 1940 flicker
I have been testing this monitor for a couple of days now and it has not flickered and the text looks sharper better than ever.
Throughout this test, the plastic back and front bezel have not been fitted.
I wonder if the air slots in the plastic back have the same area as the metal chassis. Could poor ventilation be a problem?
In any event, currently just re-soldering the entire top side transformer connections as directed has done the job.
One caveat I must add is that the repair is...Last edited by Hunt; 02-21-2012, 04:51 AM.Leave a comment:
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Re: Hp 1940 flicker
Very good picture; we all now know the chip number....Leave a comment:
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Re: Hp 1940 flicker
I've assumed yes; all upper mini transformers (what are they and what do they do?) have had there connections resoldered.
Voltage accross C605 is...
Power to monitor with switch off 326V
Monitor switched on 320V
Monitor left on and screen blanked 328V
Now going to replace all metal work and attach to stand without plastic case to do longer test to see if flicker has gone....Leave a comment:
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Re: Hp 1940 flicker
Resolder all these top side (main component board side) solder joints yes?...Leave a comment:
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Re: Hp 1940 flicker
I am reluctant to do any re-soldering since I cannot see any section that looks cracked by heating up and cooling down or any signs of dry joints when observed with a jeweller's eyeglass.
Sorry just seen the bit about joints Circled in red!
The IC seems to have a logo of ST at the top left to the right of that there is a circle that contains a lower case e and a number 3
In the middle on the left there is a circle that contains characters F2 that are oriented (-90deg) bottom to top,...Last edited by Hunt; 02-18-2012, 03:41 AM.Leave a comment:
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Re: Hp 1940 flicker
You board looks the same as mine with the same hot areas....Leave a comment:
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Re: Hp 1940 flicker
I cannot see any bulging caps so I am now not sure how to progress
What should I do next?
Thanks.
P.S. I had to crop photos to get them to upload; hope they are ok....Leave a comment:
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