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Jujeet
Joined: 25 Mar 2007
Posts: 22
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 Posted: Sun Jan 25, 2009 8:27 am Post subject: |
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I am still hesistant to replace IC805 . I input a external dc voltage 13.5 to pin1 of the regulator, output reads 12.1volt.IC806 input is being IC805
output,IC806 pin 2 reads 8.9volt, IC807 pin 2 reads 4.99volt. My power supply current meter reads 1.2amp. I dont see any loading of the supply.
Is the +15volt rail not sourcing enough current?
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jts1957
Joined: 24 Nov 2008
Posts: 2476
Location: Far, Far Away
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| Posted: Sun Jan 25, 2009 9:21 am Post subject: Re: Panasonic TC-29V50R |
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Presuming 15 volts is present at L822 ONLY when one side is of L822 is lifted (& drops to 8.46 volts when L822 is connected) ... I see ONLY three paths/possibilities looking at the schematic:
(There has to be a defect with at least one of the following)
1) IC805 &/or C827 or
2) Through R2316 to base of Q2303 and D2303/C2335/C2339 or
3) some sort of leakage at P83 Pin # 1 (or elsewhere on the trace itself). |
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LJ
Joined: 09 Dec 2008
Posts: 47
Location: Earth
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| Posted: Sun Jan 25, 2009 7:02 pm Post subject: Re: Panasonic TC-29V50R |
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| jts1957 wrote: | Presuming 15 volts is present at L822 ONLY when one side is of L822 is lifted (& drops to 8.46 volts when L822 is connected) ... I see ONLY three paths/possibilities looking at the schematic:
(There has to be a defect with at least one of the following)
1) IC805 &/or C827 or
2) Through R2316 to base of Q2303 and D2303/C2335/C2339 or
3) some sort of leakage at P83 Pin # 1 (or elsewhere on the trace itself). |
Or maybe C816.
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Jujeet
Joined: 25 Mar 2007
Posts: 22
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| Posted: Mon Jan 26, 2009 10:36 am Post subject: |
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I have change C827 but still same problem.I went to disconnect L820 ,measured the rectified voltage, reads 10.2volt ( without C816 )and actually changed C816 to 3300uf 25volt,its reads 14.5volt across C816 enough to power 7812 regulator.Look like I have to change IC805 finally,currently I have runout of 7812 regulators
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jts1957
Joined: 24 Nov 2008
Posts: 2476
Location: Far, Far Away
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| Posted: Mon Jan 26, 2009 10:51 am Post subject: |
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| Do you have 14.5 volts across C816 WITH everything else connected? |
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Jujeet
Joined: 25 Mar 2007
Posts: 22
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| Posted: Mon Jan 26, 2009 11:04 am Post subject: |
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| I have 14.5volt at C816 with IC805 pin3 floating. |
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LJ
Joined: 09 Dec 2008
Posts: 47
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jts1957
Joined: 24 Nov 2008
Posts: 2476
Location: Far, Far Away
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| Posted: Mon Jan 26, 2009 11:16 pm Post subject: |
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IC805 is 12 volt regulator.
In a prior post you said you put a 13.5 (external) to pin1 and output (pin #3) reads 12.1 volts.
Now you're saying with pin 3 disconnected you have input voltage (14.5 at C816) to this regulator.
I'm confused. Was pin #3 floating when you put in external voltage in your prior post? |
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Jujeet
Joined: 25 Mar 2007
Posts: 22
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| Posted: Wed Jan 28, 2009 2:19 pm Post subject: |
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Sorry for the typo error.
Should reads as "I have 14.5 volt at C816 with IC805 pin 2 floating"
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jts1957
Joined: 24 Nov 2008
Posts: 2476
Location: Far, Far Away
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| Posted: Wed Jan 28, 2009 8:31 pm Post subject: |
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IC805: Pin #1 = Input ... Pin # 2 = Ground ... Pin # 3 = Output
If you have 14.5 volts at input with either pin # 2 or pin # 3 floating AND 8.46 volts with EVERYTHING connected ... IC805 MUST be defective!
(Unless there's something else you're not telling us) |
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