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ReTrO
Joined: 08 Feb 2010
Posts: 28
Location: London, UK
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| Posted: Sun Dec 01, 2013 5:27 pm Post subject: |
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I have found half of C52 on the LVPSU board floating around so going to replace that too. 
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Richard
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ReTrO
Joined: 08 Feb 2010
Posts: 28
Location: London, UK
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| Posted: Sun Dec 01, 2013 6:20 pm Post subject: |
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Looks like a Z5U 0.1MFD/uF 500V cap. Seems hard to find which is odd. Found some one eBay in the US, so might be some time to get them here in the UK.
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Richard
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sun Dec 01, 2013 11:52 pm Post subject: |
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| ReTrO wrote: | | I have found half of C52 on the LVPSU board floating around so going to replace that too. |
it'd just not normal to find loose parts rattling around. Was this thing dropped from the ceiling or ?
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Mon Dec 02, 2013 1:30 am Post subject: |
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Yup
Those caps will explode occasionally, one went off in my face one time........
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ReTrO
Joined: 08 Feb 2010
Posts: 28
Location: London, UK
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| Posted: Mon Dec 02, 2013 10:15 am Post subject: |
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The projector was taken down carefully, it had stopped running while it was still up there and given the black burns on the cap and mosfet it's not too surprising they are floating about.
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Richard
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winny
Joined: 09 Oct 2013
Posts: 403
Location: Sweden
TV/Projector: BD808s, BG1209/2
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| Posted: Mon Dec 02, 2013 11:55 am Post subject: |
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| ReTrO wrote: | Right, LVPSU out, opened and dusted (it had 14 years of dust in it, looks like the projector was made in 1999 from all the date stamps, although some on the chassis say 1994).
I heard a rattling sound on removing the LVPSU and have found half a power transistor floating around, might be all/part of the cause. See photo attached.
Is it worth me simply replacing it and testing it again? |
Take out the transistor and set your multimeter to diode-test mode and measure in all six directions (pin 1 to pin 2, pin 1 to pin3 and pin 2 to pin 3 + flip the polarity and redo all) and report back the results from your multimeter before you put any new transistor in there and try again.
| ReTrO wrote: | | Looks like a Z5U 0.1MFD/uF 500V cap. Seems hard to find which is odd. Found some one eBay in the US, so might be some time to get them here in the UK. |
Go for higher voltage, like 600 V and it should be easier to find one. You can probably (but not guaranteed) choose a better dielectric than Z5U too if sourcing is a problem.
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ReTrO
Joined: 08 Feb 2010
Posts: 28
Location: London, UK
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| Posted: Mon Dec 02, 2013 2:23 pm Post subject: |
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| winny wrote: | | Take out the transistor and set your multimeter to diode-test mode and measure in all six directions (pin 1 to pin 2, pin 1 to pin3 and pin 2 to pin 3 + flip the polarity and redo all) and report back the results from your multimeter before you put any new transistor in there and try again. |
Thanks, just to confirm if this is the transistor pins or the pcb locations? As the transistor is only half left I'm not sure it'll measure much now.
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Richard
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barclay66
Joined: 27 Jun 2011
Posts: 1304
Location: Germany
TV/Projector: Marquee 9500 Ultra
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| Posted: Mon Dec 02, 2013 2:48 pm Post subject: |
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Hi,
I think he meant the transistor pins (1=Gate, 2=Drain, 3=Source). See the corresponding datasheet (http://www.vishay.com/docs/91233/91233.pdf).
I had a LVPS open this weekend. Q1, Q2 and Q3 are part of the PFC circuit and are connected in parallel for Drain and Source. The Gates are driven through 10 Ohm resistors (all of them originating from the driver circuit, U9).
It could be possible that the Q2 and Q3 have been damaged too (and/or their Gate resistors). In any case I would remove all three and mount three MOSFETS from the same batch. Replacing all three resistors wouldn't be a bad idea too.
When replacing C52 You should take a look at other parts connected to it. There's at least one diode that could have shorted...
Regards,
barclay66
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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winny
Joined: 09 Oct 2013
Posts: 403
Location: Sweden
TV/Projector: BD808s, BG1209/2
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| Posted: Mon Dec 02, 2013 5:47 pm Post subject: |
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| ReTrO wrote: |
Thanks, just to confirm if this is the transistor pins or the pcb locations? As the transistor is only half left I'm not sure it'll measure much now. |
Pcb locations.
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ReTrO
Joined: 08 Feb 2010
Posts: 28
Location: London, UK
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| Posted: Mon Dec 02, 2013 8:07 pm Post subject: |
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Cheers
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Richard
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ReTrO
Joined: 08 Feb 2010
Posts: 28
Location: London, UK
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| Posted: Sun Dec 08, 2013 11:01 pm Post subject: |
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Removed all 3 mosfets and tested the PCB, same resistance readings on all 3 while off (which I hope is a good thing).
1-2 @ 839 Ohm, 1-3 @ 1926 Ohm and 2-3 @ 0.463 MOhm.
All back together awaiting the new caps now.
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Richard
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winny
Joined: 09 Oct 2013
Posts: 403
Location: Sweden
TV/Projector: BD808s, BG1209/2
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| Posted: Sun Dec 08, 2013 11:08 pm Post subject: |
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You need to use the diode test mode of your multimeter. The results will be in volt, not ohm.
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| Melifluonze wrote: | | Digital is easy. This is torture, but far more interesting... |
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winny
Joined: 09 Oct 2013
Posts: 403
Location: Sweden
TV/Projector: BD808s, BG1209/2
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| Posted: Thu Dec 19, 2013 9:58 am Post subject: |
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Any updates?
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| Melifluonze wrote: | | Digital is easy. This is torture, but far more interesting... |
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ReTrO
Joined: 08 Feb 2010
Posts: 28
Location: London, UK
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| Posted: Thu Dec 19, 2013 7:14 pm Post subject: |
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I've not had a chance to do anything else recently due to buying a house.
Currently waiting for the capacitors to arrive too.
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Richard
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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