Sony KDL70R550A No Power


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Sony KDL70R550A No Power

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Meraux
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Aug 10, 2015, 8:39 PM

Post #1 of 22 (14564 views)
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Sony KDL70R550A No Power	Can't Post

Sony model KDL70R550A
Power board DPS-248BP
Lighting struck House knocked out TV while on. TV does not power on. Took cover off, no visual signs of damage. With power on took fluke voltage tester and passed over all parts on Power board. Lights up on all except the aluminum cover that is closest to the serial number and word Delta. Is power supply bad?

jts1957
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Aug 10, 2015, 9:19 PM

Post #2 of 22 (14563 views)
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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

Quote

With power on took fluke voltage tester and passed over all parts on Power board. Lights up on all except the aluminum cover that is closest to the serial number and word Delta.

What?!*~ Care to expand on this?

Confirm/Measure the DC voltages between the following pins of CN2 and chassis ground.
Pin 1 = 3.3V all time or standby?
Pin 8 = 12V tcon?
Pin 9 - 11 = 12V Regulated

Pin 3 = Power_On?
Pin 13 = BL_ON?

The last four would normally change drastically when set is On versus when set is Off. The first one should be present as long as TV set is plugged into mains.

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Location: Far, Far Away

(This post was edited by jts1957 on Aug 10, 2015, 10:20 PM)

Meraux
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Aug 10, 2015, 10:46 PM

Post #3 of 22 (14555 views)
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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

Thanks for the reply. I will try to do as you say tomorrow. I was referring to the aluminum heat sink. When I pass a voltage tester on top of all but 1 of them it lights up showing voltage. I guess it capacitors under them?

In Reply To

jts1957
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Aug 10, 2015, 11:00 PM

Post #4 of 22 (14552 views)
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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

You'll need a DVM digital volt meter, not a receptacle tester. And notice I mentioned chassis ground, which the heat sinks may or may not be at same potential.

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Location: Far, Far Away

(This post was edited by jts1957 on Aug 10, 2015, 11:01 PM)

Meraux
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Aug 12, 2015, 9:22 PM

Post #5 of 22 (14523 views)
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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

Can this test be done on the board while off of the TV by just plugging in the power cord? Does it have to be grounded in anyway?

jts1957
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Aug 12, 2015, 10:18 PM

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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

The back of TV IS removed. Black lead of DVM connected to chassis/frame (use a jumper wire with a alligator clip at each end). Set meter on DCV and select a range appropriate to voltage expected. Red lead of DVM is connected to the item/point being tested (Pin 1, then / Pin 8, then / Pin 9 OR Pin 10 OR Pin 11, then Pin 3 and finally Pin 13). Plug in TV and test.

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Location: Far, Far Away

(This post was edited by jts1957 on Aug 12, 2015, 10:41 PM)

Meraux
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Aug 12, 2015, 10:47 PM

Post #7 of 22 (14515 views)
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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

Thanks. I have the board out of the TV. My question is do I have to reinstall it to test or can I just put the power cable back on and plug it in. Do I have to have the other cables connected to the board for testing. If the board can be tested outside of the tv do I have to ground it?

jts1957
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Aug 13, 2015, 12:01 AM

Post #8 of 22 (14513 views)
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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

Since all the connectors can be removed and reconnected to the sockets on the power supply board with the power supply board mounted in its place in the set, let's try it that way - Board secured to chassis and ALL connectors connected as they were when you first removed the back cover of the set. With small pointy test leads on the DVM, Most points can be connected to by 'back-probing' at the connector (where the wire enters the connector). If you can safely probe the 'pin' at the rear of the part on the socket the is on TOP of the power supply board ... fine. At this point you will ONLY be probing the TOP side of power supply board - not the 'foil' side.

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Location: Far, Far Away

(This post was edited by jts1957 on Aug 13, 2015, 12:02 AM)

Meraux
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Aug 13, 2015, 3:57 PM

Post #9 of 22 (14488 views)
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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

I put the board back in the TV as you said. Here are the test results.

Pin 1= .3
Pin 8= 0
Pin 9= 0
Pin 3= 0
Pin 13=0

jts1957
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Aug 13, 2015, 5:43 PM

Post #10 of 22 (14484 views)
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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

Well, IF you took accurate readings, the board NOT producing 3.3 volts would mean that that board is definitely BAD.

Does that mean that replacing this board will fix the set? NO. It just means that to proceed further a known good board will have to be obtained and tried. At that point one of three things will occur:
1) New board will be blown (either arrives defective or fails once installed;
2) Pin #1 voltage will be present, but set will need further troubleshooting; or
3) Set will work normally.

You can now (with the set unplugged) put your DVM on a mid range (2K/20K decreasing to a lower range if necessary) ohm function and test each of the previous 5 points looking for shorts (any reading below 100 ohms, especially if you don't have to wait for the meter to stabilize).

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Location: Far, Far Away

(This post was edited by jts1957 on Aug 13, 2015, 5:45 PM)

Meraux
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Aug 13, 2015, 8:40 PM

Post #11 of 22 (14477 views)
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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

I tested ohms as you said.

Pin 1=300
All others=0

jts1957
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Aug 13, 2015, 9:30 PM

Post #12 of 22 (14476 views)
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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

The 'zeros' in "All others=0" is the SAME reading meter gets when you aren't taking a measurement (same range, leads apart/not touching)? Then it's indicating Over range.

IF the zeros are the SAME reading meter gets when you short/touch the meter probe tips together, Unplug the appropriate connector and find out if the zero is being caused by the power supply or the load.

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Location: Far, Far Away

Meraux
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Aug 13, 2015, 9:47 PM

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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

It would be same as not touching and apart or as you said over range

jts1957
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Aug 13, 2015, 10:27 PM

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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

Just for grins, If your DVM uses a '0' to indicate Over Range ... What do they use to indicate a short (Leads together on an ohm range)?

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Location: Far, Far Away

Meraux
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Aug 15, 2015, 5:22 PM

Post #15 of 22 (14460 views)
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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

It shows 0 when leads are touched together. I ordered a board. Will let you know what happens. Thanks for all your help.

jts1957
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Aug 15, 2015, 5:35 PM

Post #16 of 22 (14458 views)
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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

Zero with test lead tips touching AND zero with test leads apart both while on the same Ohms scale would tend to indicate a BAD meter.

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Location: Far, Far Away

Meraux
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Aug 18, 2015, 7:24 PM

Post #17 of 22 (14395 views)
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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

Same results with new board installed. No sign of power.

jts1957
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Aug 18, 2015, 7:33 PM

Post #18 of 22 (14394 views)
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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

Was this a NEW Power board obtained through Sony or a Sony authorized part distributor? OR
Was this a 'New-To-You' Power board obtained through an Internet parts puller/reseller (This includes amzone / fleabay and even occasionally SJ)?

Measure the DC voltage between the pin 1 of CN2 and chassis ground.
Pin 1 = 3.3V?

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Location: Far, Far Away

(This post was edited by jts1957 on Aug 18, 2015, 7:33 PM)

Meraux
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Aug 18, 2015, 11:49 PM

Post #19 of 22 (14382 views)
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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

New to me board. Same reading. Nothing changes when you hit power button.

jts1957
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Aug 19, 2015, 12:38 AM

Post #20 of 22 (14381 views)
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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

Let's go and confirm some things I took for granted in the beginning. First couple are rather rudimentary, I know.
Also at beginning you never explained your 'fluke'? I have a Fluke DVM, but suspect you are not talking DVM. Neon light two wire voltage tester maybe.

Let's try coming in from your power company, since working back from 3.3VSB with only photos is unlikely - AC is 110 - 240VAC so be careful with your meter probes.
1) The building HAS AC power?
2) Receptacle has power?
3) TV power cord is delivering aforementioned AC power to connector CN1? (Cord IS good?)
4) BD1 bridge is Receiving AC across center pins? BD1 is putting out DC voltage on end pins?

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Location: Far, Far Away

Meraux
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Aug 19, 2015, 7:28 PM

Post #21 of 22 (14335 views)
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Re: [jts1957] Sony KDL70R550A No Power [In reply to]	Can't Post

All good. Touching leads from meter to pins on board in from ac cord. 115 volts

jts1957
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Aug 19, 2015, 8:54 PM

Post #22 of 22 (14334 views)
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Re: [Meraux] Sony KDL70R550A No Power [In reply to]	Can't Post

Last time: What kind of Fluke you talkin' 'bout?

BD1 bridge is Receiving AC across center pins? 115 volts AC &
BD1 is putting out DC voltage on end pins? 115 volts (or other amount) AC? or DC?

Since I can't seem to locate any service literature on either the set or the power supply, will have to try researching some of major ICs and see if we get anywhere that way. On the foil side of board is a IC801 surface mount IC. I can't make out what is written on it. I think I see two or three rows of information. You may have to clean off with no harsher than rubbing alcohol and a q-tip and then look at with some kind of magnifier.

Since your Original board and the Replacement board you obtained are not outputting a standby 3.3 volt source, either BOTH boards are defective or I'm not yet seeing something.

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Location: Far, Far Away

(This post was edited by jts1957 on Aug 19, 2015, 9:16 PM)

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