Author Topic: Could it be these resistors, or should I suspect one of these tiny caps  (Read 1506 times)

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Offline guitchess

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I'm trying to fix this dumpster dive TV without guessing and replacing whole boards.  Someone else has tried that because the box that the set was found in contained an extra power supply board. 

Prelim details.
1.  When power is applied, nothing.  No flashing LEDs, sounds, smells, etc.
2.  When opened, there are no obvious signs of damage.  In fact, the set looks brand new. 

When I test voltage, the P board is supplying 4.3 volts on the standby pin when everything is connected.  According to the service manual, it should be around 5.8v.  When I disconnect the A board(main board in Panasonic terms), the P board output jumps to 6.5v.  Which led me to believe that something on the A board was drawing too much current. 

On the A board, voltage stays at the 4.3v all the way to IC5000, which leads to my main question(for now).  The two resistors in the partial schematic are shown to be 1% tolerance, and in circuit neither tests within spec(they are both more that 10% out). First, do you think is this situation that it would be necessary to remove them from circuit for an accurate read?  They are so tiny I doubt I will be able to reinsert them if they are not the issue, that is, if I don't loose track of them as soon as they're out of circuit.   Second, do you think that these resistors being lower than spec would cause the voltage to be lower than spec thereby not letting the set power on?   

The service manual that I am referencing came from here.
http://www.csweb.lar.panasonic.com/viewing/NA/TC-L32X5/SVC/MTV1202010CE_PRINTDB/NEW_TC-L32X5.pdf
 

Offline guitchess

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Re: Could it be these resistors, or should I suspect one of these tiny caps
« Reply #1 on: November 18, 2014, 01:14:00 pm »
FYI, the 22k tests in circuit as 19.4k and the 56k tests at 39.3k.
 

Offline wraper

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Re: Could it be these resistors, or should I suspect one of these tiny caps
« Reply #2 on: November 18, 2014, 02:38:27 pm »
They are unlikely to be faulty but shunted by surrounding components which gives you lower reading.
 

Offline EMUD

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Re: Could it be these resistors, or should I suspect one of these tiny caps
« Reply #3 on: November 19, 2014, 04:34:18 am »
Hi,
resistors normally raise their value when they are gone.

EMUD
 


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