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Old 04-18-2008, 01:33 AM   #1
vince88
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Exclamation MAG Innovision LT716S Model 700P, seven bulged Xunda's

I just opened a MAG Innovision LT716S that does not power up. The power board is another typical case of 'bad caps' bulged and 'oozing on top', as shown in the pictures. These caps are all on the secondary side of the power supply: seven Xunda capacitors, including six 470micF/25V/105deg and one 220micF/25V/105deg. Failures of the components have taken out the two fuses on the primary [in-line with the mains VAC wires] and secondary sides.
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Last edited by vince88; 04-18-2008 at 01:41 AM.. Reason: Spelling
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Old 04-18-2008, 07:43 PM   #2
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Default Re: MAG Inoovision LT716S Model 700P

First, check all pins on the bridge rectifier and MOSFETs on the primary side for any internal shorts with a multimeter.
If OK, replace all electrolytic capacitors with Nippon Chemi-Con KY Series, with the 400V/450V unit being replaced with a Nippon Chemi-Con KMG Series unit.
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Old 06-17-2008, 11:52 PM   #3
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Wink Re: MAG Inoovision LT716S Model 700P

I had time today to look again at the power board [1] the primary & secondary fuses tested OK when I used a sharp probe to get through the oxide [2] primary rectifier and both secondary Schottky dual-diodes [one dual common-cathode for the +5VDC and one dual for the +12VDC] tested OK with a multimeter on 'diode test' settings. I then recapped with capacitors bought at HSC in Sunnyvale: six 470mF/25VDC/105deg and one 330mF/25VDC, see enclosed photo. Note on the photo that the output pins of the power board are clearly marked +5VDC, +12VDC, GND, BRI, LPON.
The LCD now is fully functional.
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Old 06-10-2009, 12:18 PM   #4
timothypeacy
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Default Re: MAG Inoovision LT716S Model 700P

I had the same problem with a MAG LT716s, I replaced the capacitors, The seven mentioned above and now the monitor works but, it only stays on for 30 seconds or so. I'm not sure what is wrong now but, I'll let you know when I figure it out.
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Old 06-11-2009, 12:35 AM   #5
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Question Re: MAG Inoovision LT716S Model 700P

Quote:
Originally Posted by timothypeacy
I had the same problem with a MAG LT716s, I replaced the capacitors, The seven mentioned above and now the monitor works but, it only stays on for 30 seconds or so. I'm not sure what is wrong now but, I'll let you know when I figure it out.
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Please give some more info on what you did:
  • What caps did you remove (brand/series)?
  • What caps did you install (again, brand/series)?
  • It shuts down only the backlight or all the unit shuts down?
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Old 07-05-2009, 05:52 PM   #6
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Default Re: MAG Inoovision LT716S Model 700P

Interesting, had a similar problem with a PrOview 700P (same thing?) with a very similar power supply unit. It powered up initially for ~10 seconds, and thereafter would only flash the power light (it was struggling to stay "on.")

The seven Xunda's were popped, fuses and everything else looked good, so recapped and reassembled, works great.
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Old 07-05-2009, 06:05 PM   #7
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Default Re: MAG Inoovision LT716S Model 700P

Quote:
Originally Posted by Badcappy
Interesting, had a similar problem with a PrOview 700P (same thing?) with a very similar power supply unit. It powered up initially for ~10 seconds, and thereafter would only flash the power light (it was struggling to stay "on.")

The seven Xunda's were popped, fuses and everything else looked good, so recapped and reassembled, works great.
Proview 700P, KDS 700P, MAG 700P, all the same ugly beast as long as they are "whatever" 700P
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Old 01-27-2011, 01:28 AM   #8
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Default Re: MAG Inoovision LT716S Model 700P

First of all...
Hello.

timothypeacy said:
I had the same problem with a MAG LT716s, I replaced the capacitors, The seven mentioned above and now the monitor works but, it only stays on for 30 seconds or so. I'm not sure what is wrong now but, I'll let you know when I figure it out.

Me too!
My MAG LT716s was in my closet for almost ummmh... im not sure... a long time... in this new year cleanup i found it and i felt nostalgic then
i recapped the damn power supply and it worked!...
For a few minutes at least, now i turn it on and the light in the lcd goes away inmedeately... well in 1 second.
i can see the image but no backlight at all... i was wondering... should i threw it away? kick the capacitors out of the #$%&# thing ? or sacrifice a virgin in the name of the gods of the valhalla to make it work?

PD: thanks for the help in advance and sorry for my bad english.
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Old 01-27-2011, 03:00 AM   #9
Rtech
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Default Re: MAG Inoovision LT716S Model 700P

Its not just those caps that fail,but also C10 and C11, next to each of the Inverter transformers.Measuring ESR in circuit,shows they look ok,BUT as they are across the transformers,this confuses the issue,and they usually fail on ESR testing when out of circuit.
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