Re: Fixed a ViewSonic N3260w
Success. I tried a 78L15 regulator, but for some reason it loaded down the B+ standby supply too much and the power supply wouldn't switch on.
I installed a 2N4401 and a 15V zener, and everything is running perfect. I might look at installing a small fan on the chassis close to the AC power socket; this will blow air directly through the power supply heat sinks and hopefully help it to run cooler.
Thanks for all the advice.
byacey
Member
Last Activity: 05-04-2020, 09:39 PM
Joined: 10-29-2013
Location: Alberta
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Re: Fixed a ViewSonic N3260w
I looked again, definitely just a reflection.Leave a comment:
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Re: Fixed a ViewSonic N3260w
Double Post.Leave a comment:
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Re: Fixed a ViewSonic N3260w
I checked the National 78L15 datasheet, and it appears it only needs a 2.5V differential to maintain regulation. Maximum current is 150ma, but I doubt the SM transistor is passing that kind of current.Leave a comment:
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Re: Fixed a ViewSonic N3260w
I may have some of the low drop out regs in the bin; I'll have to check. If not, I've got 2N4401 transistors and 1W zeners.
I just the thought the reg would be a more elegant solution.Leave a comment:
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Re: Fixed a ViewSonic N3260w
I did check ZD4, as I mentioned I measured 14.2V across it. As well the transistor is shot, because the base-emitter voltage is way beyond 0.6V.
I didn't bother removing it to test outside of the circuit. I'm confident with the voltage readings that the transistor is finished....Last edited by byacey; 10-30-2013, 11:25 PM.Leave a comment:
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Re: Fixed a ViewSonic N3260w
C16 is OK, it must be a reflection you are seeing.
I'll take some bottom pics after I get it running and clean up the flux.
I'll replace the remaining primary side caps, but for now they appear and test OK.
Any recommendations on an ESR meter? I should probably get one if I'm going to be working on these finicky supplies.Leave a comment:
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Re: Fixed a ViewSonic N3260w
Vcc on the PFC chip (IC3) is 11.2V, fluctuating slightly with the pulses.
I measure 36mV across R17 for about 3 seconds, and then it drops to about 24mV for a split second, and then climbs back up to 36mV repeatedly.
J13 which supplies Vs on pin 12, IC1, has 11.0V, pretty steady.
Gate of Q3 is pulsing from .1V to 2.3V
J14 (pin 1, IC3) has 1.3 to 1.7V, pulsing.
In reading about the PFC, IC1, It requires about 12.3V for the VCC voltage to operate normally. Because this is sitting at 11.2V,...Leave a comment:
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Re: Fixed a ViewSonic N3260w
Here's some pics of the board:
[URL="http://smg.photobucket.com/user/byacey/media/FSP212-3F01b_zpsdf74e62a.jpg.html"]http://smg.photobucket.com/user/byacey/media/FSP212-3F01b_zpsdf74e62a.jpg.html[/URL]
[URL="http://smg.photobucket.com/user/byacey/media/FSP212-3F01a_zps2383f239.jpg.html"]http://smg.photobucket.com/user/byacey/media/FSP212-3F01a_zps2383f239.jpg.html[/URL]
[URL="http://smg.photobucket.com/user/byacey/media/FSP212-3F01c_zps92d2f60f.jpg.html"]http://smg.photobucket.com/user/byacey/media/FSP212-3F01c_zps92d2f60f.jpg.html[/URL]...Last edited by byacey; 10-30-2013, 09:59 PM.Leave a comment:
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Re: Fixed a ViewSonic N3260w
No go on the mains filter cap; didn't make any difference. I also tested C16, the blue cap that drives the xfrmr, and it measures .0226uf, as it should be.
Additionally, I swapped out the 1000uF/35V filter caps that I mentioned before with some low ESR ones I picked up today, but no difference.
Looks like I'm going to have to get out the scope and see what IC3 is doing.Leave a comment:
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Re: Fixed a ViewSonic N3260w
R67 is a 0.51 ohm , and R36 is a 75K; well within tolerance.
I found a 200uF/450V cap in my bins; I'll try and parallel this across the input filter C1 and see if this makes a difference.Leave a comment:
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Re: Fixed a ViewSonic N3260w
I don't have an analog meter at home, I can pick one up later at the shop and re-measure the fluctuating voltages. All measurements taken with a Fluke 87.
Standby +5V is good, measures 5.07V and rock steady. R36 measures 74K in circuit, and R67 measures 0.5 ohm in circuit.
The rectified mains voltage across C1 is 165V @ standby. When switched on, it bounces around between 202V and 293V due to the supply pulsing.
Similar situation with the 12V supply, bounces between 8.9V and 11.1V.
The 5V supply is...Last edited by byacey; 10-30-2013, 12:22 PM.Leave a comment:
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Re: Fixed a ViewSonic N3260w
Sorry to resurrect an old thread, but I have a FSP212-3F01 that turns on, and I get a picture, but I can see the power supply is pulsing dropping out and re-starting over and over causing the picture to flicker. I've replaced all the secondary caps. I tried replacing the primary side caps, although I just had ordinary electrolytics, not the low esr. When I replaced these the back light was flickering, but no video, so I put the old caps back one at a time, and testing the supply after replacing each cap..
After replacing the 2.2uf, the video...Leave a comment:
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