Is this 55" Hitachi a good buy? (lines on screen)

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Post an ad saying you're looking for TVs like that which have cracked panels. Or sell it and break even. I would normally sell it to someone who is a TV tech and could buy parts directly from Hitachi, or thinks they might have luck at repairing the PSU.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Does anyone know the return policy for these online vendors that sell boards? I hate to be the guy that buys boards for testing but I might end up trying when I get some spare cash.

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

If you buy from eBay, you usually have a 7-14 day returns policy, but shipping costs both ways aren't included.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Ok, I brought my trusty meter home. It seems there is no VS voltage coming from the psu. I think it should be 90v. Three of the heat sinks are actually ingraved "5v" "11v" and "90v" and I assume they are for testing. The 5 and 11 test good, nothing on 90. Am I to assume the psu is malifunctioning or could there be a legitimate reason it's not putting out 90v?

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Can you measure the 90V with both sustains unplugged?

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I hooked up only the connections necessary to power on and hear the sound (main and logic). I still get no 90v. Also, there are some voltages that are missing or weird that go to the main board. I will be able to test them in a few hours when I get home and I will tell you what it is.

I think that a faulty board may be signaling PSU to not output 90v. But this doesn't explain the other missing voltages...

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I'm almost suspecting your power supply is faulty...

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Does anyone know what Vsego, Vsago, Vrs, or Vra stand for or what the value should be? According to the service manual (page 58b if you have it) these are all voltages that return from the panel back to the PSU. In actuality the harness connects the PSU and the logic board.

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

They are used to encourage pixel emission or to erase the display. Generally if they're bad you'll still get a picture it'll just be dim or filled with sparkling pixels. Don't know what those each are for Hitachi plasmas.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Hmm, ok. Well according to the service manuals block diagram, these 4 voltages are the only ones that go TO the power board everything else goes AWAY. So if there was something signaling the PSU to not generate Vs and Va, it would be in one of these 4 wires, right? Let me see if I can post the diagram.

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Vsego and Vsago might enable Vse and Vsa; but the other two... I'd GUESS they are the plasma specific voltages, but wouldn't be sure... it would be really strange for the sustain to turn on the Vs.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Both ego and ago are 0v, but I still have a feeling it's the power board that is causing the no picture. I guess I can order another one and see if it gives Vs with the y and x boards unhooked.

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Is there a VS-ON or PDP-GO pin on the power supply going to the main board(s)?

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Is there a VS-ON or PDP-GO pin on the power supply going to the main board(s)?

From ps to main board I have standby 3.3 and 5, power off, and ACClock. From main back to ps there is PoWER 1, PoWER 2, and PoWER 3. Then another harness has 5.6, 10, and 12 v. Going from ps to main.

I don't see any VS-on or PDP-go

I tried to get the connection diagram into an image that is legible but its not working. Here is the manual, diagram is page 58. http://www.givemefile.net/smanuals/p...ile/36647.html

Strange. There is a pin on the main board labeled Lcd_go, but its not connected.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Today I received a new power board, and it gives the same results. There must be something that is preventing the logic board from sending the ON command to the pboard... Is there anything that would go POP on a logic board? All the voltages are so low that I wouldn't think so.

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I remember some NEC plasmas have a lock-out where they won't turn on after a failure, they need to be reset. To reset them you held MENU for 10 seconds whilst trying to power on. Maybe there is a similar procedure for Hitachi.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I'm not sure that is the problem because the tv will come "ON" with sound, just no display. I will look around though. You think the front LED flashing 7 times wile it turns on signifies anything or just normal procedure? Also, is anyone familiar with the "knight rider" LED code hitachi uses? I don't understand the code that is flashing and the service manual doesn't help...

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I'm not sure that is the problem because the tv will come "ON" with sound, just no display. I will look around though. You think the front LED flashing 7 times wile it turns on signifies anything or just normal procedure? Also, is anyone familiar with the "knight rider" LED code hitachi uses? I don't understand the code that is flashing and the service manual doesn't help...

I think N times blink with normal standby LED or power LED is the TV just powering up, I have encountered many TVs that do that. I have no familiarity with Hitachi plasmas, though repairing one is on my wish list...

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I am still determined to conquer this beast. I noticed that I do get proper VS and VA voltage when the tv first comes on, but only for 1 second and then it quickly returns to 0. I can unplug either buffer and I get the same result. If I unplug the y or x sus board I never get VS or VA. Does this mean anything to you? I have ordered a ysus and logic board. Hoping one will fix it.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I installed a new Ysus board today (without the buffers) and tested my Vs and Va voltage. Both were present and steady! I then hooked up just the top buffer to see if I could get the top 1/2 of the picture working. Unfortunately it caused my Vs and Va voltage to disappear AGAIN! Unhooking the buffer does not fix it either, so I just toasted this Ysus board it seems...

So I have either bad buffers, or a bad Xsus right? Any tips on deciding which one?