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Luuk neele
Joined: 04 Mar 2015
Posts: 186
Location: Wijk bij duurstede, the Netherlands.
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| Posted: Tue Mar 10, 2015 10:00 am Post subject: |
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it does, i read it on the forum here and decided to measure it. there goes a very small charge through to the battery.
now if i can only fix this damn smps...
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Mar 10, 2015 2:31 pm Post subject: |
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| Luuk neele wrote: | in standby the switch with +40 gives 56volts
the fuse with -20 gives -40 volts
on powerup the fuse with +40 gives 68volts
the fuse with -20 gives -42 volts |
You indicate here that in standby you are testing 56v and -40v on these 2 fuses. Are the corresponding leds also lit at this time?
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Luuk neele
Joined: 04 Mar 2015
Posts: 186
Location: Wijk bij duurstede, the Netherlands.
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| Posted: Tue Mar 10, 2015 2:36 pm Post subject: |
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none of the leds are lit when in standby, only the always on lights on the cpu card are on.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Mar 10, 2015 2:40 pm Post subject: |
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Edit: I think you answered this.
Last edited by macgyver655 on Tue Mar 10, 2015 2:45 pm; edited 3 times in total
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Luuk neele
Joined: 04 Mar 2015
Posts: 186
Location: Wijk bij duurstede, the Netherlands.
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| Posted: Tue Mar 10, 2015 2:41 pm Post subject: |
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no leds are on, the red led on the back should also be on, its not on. it neither goes on when i press power-on.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Mar 10, 2015 2:46 pm Post subject: |
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If "none" of the green leds on the power supply are lit in standby and you are testing voltage on all those fuses then something is wrong with your testing method.
Are you absolutely sure your meter is set to read "DC VOLTAGE" ? It is not on AC voltage or something else, is it?
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Luuk neele
Joined: 04 Mar 2015
Posts: 186
Location: Wijk bij duurstede, the Netherlands.
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| Posted: Tue Mar 10, 2015 3:08 pm Post subject: |
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the meter is set to DC in the 200 range, so it measures max 200v.
positive prong on fuse side, negative prong on metal case.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Mar 10, 2015 4:09 pm Post subject: |
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Do you have access to another meter?
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Luuk neele
Joined: 04 Mar 2015
Posts: 186
Location: Wijk bij duurstede, the Netherlands.
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| Posted: Tue Mar 10, 2015 4:14 pm Post subject: |
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i have, but i am using this meter correctly, ill get me another meter. but i doubt that's the problem.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Mar 10, 2015 4:21 pm Post subject: |
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Well let me ask you this. When you turn on the projector most of the green leds light up, except 2, correct?
Then when you turn it off, all the green leds go off, correct?
So if the green leds are not lit then how could you be reading that much voltage when the led is connected right at the output of the fuse?
If the voltage was actually there then the leds would be lit, correct?
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Luuk neele
Joined: 04 Mar 2015
Posts: 186
Location: Wijk bij duurstede, the Netherlands.
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| Posted: Tue Mar 10, 2015 4:26 pm Post subject: |
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that is true, ill measure to ground on the side of the fuse thats next to the led.
i think i accidentally measured only the hot side because i was tired yesterday 
the current flows left to right with right being the leds, i think i measured only the left sides of the fuses to ground, which would result in incorrect readings.
am i right?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Mar 10, 2015 4:31 pm Post subject: |
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no
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Luuk neele
Joined: 04 Mar 2015
Posts: 186
Location: Wijk bij duurstede, the Netherlands.
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| Posted: Tue Mar 10, 2015 4:34 pm Post subject: |
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to check if the fuse is open i could also just take it out and measure its resistance.
i could also measure across, if the meter reads 0 the fuse is good.
what should i do? i couldnt' find any anomalies in the psu
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Mar 10, 2015 5:40 pm Post subject: |
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Actually I wanted you to be checking for the correct voltage on both side of the fuse with the projector running. You say that 2 leds are not lit. If you have correct voltage on both sides of fuse then the led or buffer resistor is bad. If correct voltage on only 1 side then the fuse is no good. If no correct voltage at all then we have to test further to find out why.
But your test readings are just all over the place and are not realistic so I can not help you further until we find out why. So your meter would be the first suspect.
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Luuk neele
Joined: 04 Mar 2015
Posts: 186
Location: Wijk bij duurstede, the Netherlands.
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| Posted: Tue Mar 10, 2015 5:54 pm Post subject: |
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found it: both fuses were blown.
i took the smps out and measured resistance on all fuses, the +40 and the -20 have infinite resistance on their connector pair.
so something in that line has busted up, all other fuses give a proper result in continuity like they should.
happen to know what is directly in those lines? ill measure those for continuity
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Mar 10, 2015 6:06 pm Post subject: |
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Put the power supply and all boards back in, and measure for a short between the fuse and the chassis ground. If I remember correctly, the fuse is on the DC side of the power supply, and not the output of the transformer? Mac can confirm that. If not, you'll need to trace the outputs of the SMPS down to the motherboard connector, and measure for a short on each DC line to ground. If there's a dead short on a line, start pulling PC boards and see if the short goes away.
Ampros are known to have both tantalum and electrolytics short out. If so, you'll read a dead short from the DC line to ground. I've never had an RGB input board smoke, but have had caps on the quad decoder and V board short out. Transistors also fail on the H output board.
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Luuk neele
Joined: 04 Mar 2015
Posts: 186
Location: Wijk bij duurstede, the Netherlands.
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| Posted: Tue Mar 10, 2015 6:11 pm Post subject: |
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What about what I found out? I took ik out and all fuses read 0 in resistance like they should, the bad +40 and - 20 read infinite resistance so that leads me to believe that the failure is in the smps, is it not?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Mar 10, 2015 7:25 pm Post subject: |
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| Luuk neele wrote: | | What about what I found out? I took ik out and all fuses read 0 in resistance like they should, the bad +40 and - 20 read infinite resistance so that leads me to believe that the failure is in the smps, is it not? |
I really don't know what you found out. If those 2 fuses are blown again then you have a short somewhere. You have to test for short to ground like Curt suggested.
But I wanted to see if you did have proper voltage on 1 side of each of those blown fuses first just to verify the P/S was ok. But with your meter I am skeptical of assisting any further.
Because if I ask for a reading somewhere I am really not going to know whether to believe it or not.
Once you start getting correct and accurate readings let me know.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Mar 10, 2015 10:21 pm Post subject: |
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Generally the SMPS don't have failures, as in voltages that are off. The internal menu on the BArco 909 has the same issue, the readings can be 20% off, and the set still runs fine. I'd ignore the actual voltage readings, and see why the fuses are blowing. The fuses will be blowing due to a short external to the power supply, almost never because there's an issue in the supply itself.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Mar 10, 2015 10:42 pm Post subject: |
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| Curt Palme wrote: | | Generally the SMPS don't have failures, as in voltages that are off. The internal menu on the BArco 909 has the same issue, the readings can be 20% off, and the set still runs fine. I'd ignore the actual voltage readings, and see why the fuses are blowing. The fuses will be blowing due to a short external to the power supply, almost never because there's an issue in the supply itself. |
And how many of those Barcos read a high voltage when they are turned off? 
And then, since he has pushed smoke from the RGB board, vert board and focus board, all of which use the -20v supply, what if the P/S is actually putting out -40v or more on that rail. The actual output voltage is needed to be known to prevent more damage to more boards.
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