Hitachi Plasma has no video, solid blue light

[beaven24]

I am repairing a Hitachi Plasma P50S601 and could use some help.
A relative was watching the TV and the bottom 1/3 of the screen turned yellow and then the whole screen went black with the Blue LED flashing. She had to unplug the set to restart the TV and it worked fine again before going black after a short period of time. This repeated itself a few times until now when turning it on, the screen is just black and the blue power LED stays constant and on. She doesn't know how many times the LED flashed providing a fault code.
I did my forum homework and read about the normal bulging capacitors on power supply and bad buffer boards with this model TV. The capacitors were bulging and measured 2800uF out of circuit when they were supposed to be 3300uF so I replaced them. I tested both SDR buffer boards by checking the continuity of the small caps at each IC and they were all fine. Unplugging one board at a time made no change either. The power supply Vs and Va voltages only read about 3.8V. Vcc is fine at 5.1. I'm thinking one of the boards is either pulling the power supply down or the power supply isn't getting the ok signal from one the other boards and not coming on. I've already tried a different power supply and no change. The TV responds fine to the remote control commands and the audio works as well. Any suggestions on which board to try next? YSUS or main board maybe? Both YSUS and XSUS boards don't have any grounding when checking Va, Vs, Vu or Vcc on them. Sorry so long but thought I'd get all the info out there. Thanks!

[Agent24]

Re: Hitachi Plasma has no video, solid blue light

Or the power supply is bad...?

[R_J]

Re: Hitachi Plasma has no video, solid blue light

Here is some trouble shooting information

Any Time Vs/Va voltages do not appear and a test is made, each time a new test is to be made,
• Press the Power Button and Turn the Plasma OFF.
• Wait until you hear a "Click".
• Unplug the CN68 connector.
• Re-Plug the CN68 connector. If this is not done, the Turn On command for Vs/Va at Pin 7 and 8 of
the CN68 connector will not happen.
You can unplug both upper & lower buffers, do the reset and then mointor the vs or va while turning on the tv, if the voltage comes up and stays up, I suspect one or both of the buffers, try each each buffer by it self reseting P.S. between tests, If the voltage comes up for a second and drops off I would suspect the ysus being bad and possibly one or both buffers.

A Yellowish-Green picture or highlights Can be caused by the logicboard

[beaven24]

Re: Hitachi Plasma has no video, solid blue light

Thanks for the guide and information. Using it, I've confirmed that all voltage readings are correct on the CN63, CN64, CN68, and CNPPS connectors except for the Va and Vs Power Supply voltages on CN64. I checked the turn on commands from CN68 pins 7 & 8 and the Vcego at pin 7 is correct and working but I'm getting no output from the logic board Vsago at pin 8. I've tried unplugging the CN68 connector to reset the logic board several times but it has no affect. I've even tried many combinations of unplugging certain boards and then resetting the logic board but still never get power on pin 8. I tried a jumper wire to force pin 8 on which does cause a change but the Vs and Va voltages on the power supply then fluctuate and never stay consistent. I have 2 power supplies and I don't think they would both be bad. I'm leaning towards replacing the logic board. Any thoughts?

[beaven24]

Re: Hitachi Plasma has no video, solid blue light

I replaced the logic board and now get the correct Vsago turn on voltage and also finally get a picture on the screen. However I am getting some black horizontal lines from a few IC's on the upper buffer board and some off color vertical bars in two spots. The Vs, Va, and Vcc voltages on the power supply are now constant but are way too high. I'm not able to adjust the voltages down anywhere close to the correct reading. I'm thinking the high voltages are causing the lines and bars but I'm not sure why the voltages are off so much. Both of my power supplies read high. Any thoughts where to go from here?

[beaven24]

Re: Hitachi Plasma has no video, solid blue light

The horizontal lines were corrected by reseating the ribbon cables on the upper buffer board. The discolored vertical lines were corrected by reseating the ribbon cables on the new logic board for the lower ABUS-B and ABUS-C boards. I now have a good picture however the power supply voltages are still way too high. All of the power supply connectors show the correct voltages when the TV is in standby mode however they go high when the TV is on. I did notice the grounding pins on all of the power supply connectors show a voltage across them when the TV is on. I have been unable to find a short anywhere to be the cause.

[Agent24]

Re: Hitachi Plasma has no video, solid blue light

Edit: Double post

[Agent24]

Re: Hitachi Plasma has no video, solid blue light

I now have a good picture however the power supply voltages are still way too high. All of the power supply connectors show the correct voltages when the TV is in standby mode however they go high when the TV is on.

What did you measure and what are they supposed to be?

I did notice the grounding pins on all of the power supply connectors show a voltage across them when the TV is on. I have been unable to find a short anywhere to be the cause.

Measuring from one ground wire to another? Where exactly are you measuring?

[R_J]

Re: Hitachi Plasma has no video, solid blue light

What brand meter are you using, I have an LG meter that does not like measuring voltages on ysus boards, I think it takes the a/c drive signal and adds it to the dc voltage, My fluke works just fine on the same tv. The meter could also be picking up the stray r.f. from the tv when its running.

[beaven24]

Re: Hitachi Plasma has no video, solid blue light

The problem seemed to be my meter and the use of it. I was using a craftsman model 82140. When I grounded the common lead of the meter to the TV frame, the voltages at the power supply test pins where nearly twice what they should be. However when I put the common lead of the meter on one of the power supply's ground pins at a connector, then the voltages were normal. I also checked the voltages using an older meter, Ideal model 61-720 and the voltages were correct no matter where I grounded the common lead.

The TV is fixed, thanks Agent24 and R_J for the help!

[kca]

Re: Hitachi Plasma (P50H401) has no video, solid blue light - YSUS good or bad?

Wondering if either R_J or Agent24 (or anyone with experience re: Hitachi plasmas) is there to help me with a question about my Hitachi P50H401. Here is a synopsis of my current situation, taken from two prior posts:

I've been working on a Hitachi P50H401 for a couple of weeks now, learning from this site and other forums as well as I have progressed. I'd really like to get some quality, detailed advice before I plug back in new SDR boards to help ensure that I won't lose them when power is applied.

Here is my current scenario:

1) The two 3300uf caps were swollen, so I replaced them both.
2) The two SDR boards (U and D) were both clearly damaged.
3) I disconnected both SDR's and connected a video source. It now goes from red to solid blue on the front panel and stays that way. The sound is perfectly fine, but there is (of course) no picture as the SDR's are unconnected to the YSUS board.
4) I can change channels (as evidenced by the sound of various channels changing) with the DirecTV remote and can change the volume with the Hitachi remote.

I have checked, double, and triple-checked all of the voltages involved.
PSU is fine. All voltages are in order.
PSU to XSUS is fine (via connector CN23)
XSUS to YSUS is fine (via connector CN22)
YSUS from XSUS is fine (via connector CN32)


My focus is now on the YSUS Board (and, in particular, the two connectors that lead out from the left side to the SDR's):

THIS is the current crux of the matter. I tested all 25 pins on the lower left connector that comes out of the YSUS board (and ultimately leads into the SDR-D), and ALSO the 25 pins on the YSUS upper left connector (that leads, ultimately, to the SDR-U).

I assumed that I would find exact voltage matches because both of these connectors are labeled exactly the same on the circuit board itself. That turned out to be the case, the voltages do match, EXCEPT for pin #8 and pin #21 (counting up from the bottom) on the LOWER LEFT CONNECTOR ONLY. Those two read 0.00

All of the upper left connector pins had readable voltages, including its pin #8 (-24.5v) and pin #21 (-51.8v).


Note: On both the lower and upper, pin #8 is labeled as DA2 on the circuit board, and pin #21 is labeled as DA1.


All of this leads to a rather simple question I hope can be answered. Does the fact that I get the two 0.00 readings on the lower left connector mean that this particular YSUS board is entirely defective and must be replaced?

{Or, can I repair it in some way? Or, as is my hope, these two 0.00 readings will NOT prevent the SDR-D board, or the tv in general, from working properly when I connect it?}

It seems very odd to me that the upper left YSUS connector has readings at pins #8 and #21 and the lower left YSUS one does not.

Please feel free to reply in as detailed and as exacting manner as you'd like. I am into this pretty deep, as you can see, and I want to get it right before risking $120+ on the SDR U and D's.

---------------

Follow-up to Post #1 above:

Help needed. Still trying to determine if my YSUS is defective or not.

Here are the full voltage readings from taken from both the Upper and Lower connectors (25 pins on each) that come off the left side of the YSUS and head into the SDR's themselves.

Question is:
Are these voltages indicative of a properly functioning YSUS board in this Hitachi P50H401 I am working on, or do the two 0.00 readings that are highlighted below proof of a short that will damage one or both SDR's?

The only positive values in the list are marked in green.


PIN ---(UPPER)---NAME---(LOWER)

25------(52.2)------H1-------(52.2)
24-----(-51.8)------S1------(-51.8)
23-----(-51.8)------S1------(-51.8)
22-----(-51.8)------S1------(-51.8)
21-----(-51.8)-----DA1------(0.00)
20-----(-48.8)----OC2-1----(-46.8)
19-----(-46.8)----FVCC3----(-46.8)
18-----(-51.8)-----CLK1----(-51.8)
17-----(-51.8)------S1------(-51.8)
16-----(-51.8)------S1------(-51.8)
15-----(-52.2)------S1------(-52.2)
14------(52.2)------H1-------(52.2)
13-----(0.00)----No label----(0.00) {these 0.00's are as expected}
12------(79.0)------H2-------(79.0)
11-----(-24.5)------S2------(-24.5)
10-----(-24.5)------S2------(-24.5)
9------(-24.5)------S2------(-24.5)
8------(-24.5)-----DA2------(0.00)
7------(-21.5)----OC2-2----(-21.8)
6------(-19.5)----FVCC4----(-24.5)
5------(-23.9)-----CLK2-----(-28.0)
4------(-24.5)------S2------(-24.5)
3------(-24.5)------S2------(-24.5)
2------(-24.5)------S2------(-24.5)
1-------(79.2)------H2-------(79.2)


Thanks in advance for your replies.

[Agent24]

Re: Hitachi Plasma has no video, solid blue light

Sorry, I am nowhere near a plasma TV expert! I'm sure you will get help from someone else though.