LG 60PZ550 Plasma - No Sound, No Picture

[southbound]

Re: LG 60PZ550 Plasma - No Sound, No Picture

Swapped the Z-sus board and still no change in the TV behavior. Checking the vzb test points on this one and all I see is a rise to ~0.2vdc then a slow bleed off. The original gave me a rise to 6vdc then slow drain down. Any thoughts?

I obviously cannot 100% rule out this 'new' board is also bad. It was described as 'working, pulled from a TV with a cracked panel'. If we suppose that this one (or my original) is possibly 'good', are there any other causes for the vzb voltage loss? I am not opposed to ordering another Z-sus board from a different supplier, if we feel confident that the problem is limited to that board.

[tom66]

Re: LG 60PZ550 Plasma - No Sound, No Picture

OK, there is a connector on the Z-sus going to the control board. Is there a legend printed near this connector?

[southbound]

Re: LG 60PZ550 Plasma - No Sound, No Picture

Yes. Picture of the legend attached.

[tom66]

Re: LG 60PZ550 Plasma - No Sound, No Picture

OK, can you measure the ZBIAS, VZB1 and VZB2 pins with everything installed. The black probe goes on the chassis, red probe on the test point.

[southbound]

Re: LG 60PZ550 Plasma - No Sound, No Picture

I'm not seeing much. To chassis ground: ZBIAS is 1.885v, VZB1 & VZB2 both show nothing (.002v).

Additionally, I checked pins 1 & 2 which the legend has as 18v and neither showed anything. I am assuming pin #1 is to the left, but I checked both ends. I can swap back in the original board at any time for comparison if you'd like. Thanks again.

[tom66]

Re: LG 60PZ550 Plasma - No Sound, No Picture

Hmm, 18V not present might cause this problem.
Can you find a similar point on the Y-sus and see if the 18V is also missing?

[southbound]

Re: LG 60PZ550 Plasma - No Sound, No Picture

I couldn't find another 18v point anywhere else on another board. I did check for 15v (pins 28, 29, & 30) on the Y-sus ribbon coming from the controller bd and got nothing.

The 5v pins do read okay, FWIW.

[tom66]

Re: LG 60PZ550 Plasma - No Sound, No Picture

OK, at the top of the Y-sus there should be a connector where Vs and Va come in. Is there a 15V (or 18V) point on there as well?

[southbound]

Re: LG 60PZ550 Plasma - No Sound, No Picture

No 15v or 18v labeled there.

Looking over the Ysus, Zsus & PS boards and I cannot see any other connector shown to carry the 15v or 17v (other than the ribbon cables discussed earlier that connect to the Controller Bd).

If the 15v / 17v is generated on the PSU, I'm not finding how it's delivered out. I'll attach two close-up shots of the PSU board: One of a stamp mentioning 17v located near the connector for the PDP(?) (the board with all the hdmi ports), the second pic of another stamp on the PSU board mentioning 17v. Not sure if these will mean anything.

[tom66]

Re: LG 60PZ550 Plasma - No Sound, No Picture

Huh. I checked the Y-sus using pics from Shopjimmy, and it appears that it generates the 15V, as I can't see any way the control board gets the power to the Y-sus and Z-sus.

There are some fuses on the Y-sus, please test as highlighted. Use your ohm range on your multimeter, set to 200 ohms. Measure across the fuses. A good fuse tests below 3.0 ohms.

[southbound]

Re: LG 60PZ550 Plasma - No Sound, No Picture

Hmm. Okay, the fuse located beneath the long heatsinks looks bad (FS104, 2A/120v) - charges up to ~50k ohms then slowly bleeds down. The rest all look good. I hadn't checked these earlier, overlooking them thinking they were resistors.

Do you recommend just changing the fuse at this point or troubleshooting for a cause?

[tom66]

Re: LG 60PZ550 Plasma - No Sound, No Picture

It might just be a replacement job if it has blown with no apparent cause. Y-sus board installed, set powered up. Meter black on chassis red on each end of blown fuse, DC volts, what do you measure?

[southbound]

Re: LG 60PZ550 Plasma - No Sound, No Picture

On the one side, I get a constant cycling voltage of ~9.8v to 10.8v. Other side 0, as expected. Hmm, the supply side should be steady, no?

Also, for my knowledge: when it comes to the point where we'd like to see the result of replacing a component fuse (like we are dealing with here), is there anything wrong with making a temporary test setup with a standard fuse (ie Bussmann AGC with same rating) hooked up with alligator clips?

[tom66]

Re: LG 60PZ550 Plasma - No Sound, No Picture

No problem with using an external fuse like that, but it does look like something is bad on your Y-sus causing the 15V to drop, so I'd not expect much to happen.

[southbound]

Re: LG 60PZ550 Plasma - No Sound, No Picture

In the meantime, I will look into getting another Y-sus board. Updates to follow.

Thank you for your help.

[JeffandPeggy]

Re: LG 60PZ550 Plasma - No Sound, No Picture

I have a LG Plasma 60pz550 and yesterday we noticed that, around the perimeter (Not quite reaching the middle) There's this Greenish, rainbow type effect and it, kind of, flickers a little when the camera shots change. It's really noticeable on a black and white TV show. I say rainbow because it may have a little red to it, but it mostly looks greenish. Is this something I can get fixed or is the TV done? Any info would be, greatly, appreciated.

[JeffandPeggy]

Re: LG 60PZ550 Plasma - No Sound, No Picture

I need to post a question about a LG Plasma 60PZ550 picture problem, but I'm not allowed to create a thread. Can anyone help me please? I don't have time to use this forum for a month before I can ask a question.

[tom66]

Re: LG 60PZ550 Plasma - No Sound, No Picture

You can create a new thread after your first post, initial PM from TopCat (automated) tells you this.

[JeffandPeggy]

Re: LG 60PZ550 Plasma - No Sound, No Picture

Tried to post thread and got this/

JeffandPeggy, you do not have permission to access this page. This could be due to one of several reasons:

Your user account may not have sufficient privileges to access this page. Are you trying to edit someone else's post, access administrative features or some other privileged system?
If you are trying to post, the administrator may have disabled your account, or it may be awaiting activation.

Thanks anyway

[nasium]

Re: LG 60PZ550 Plasma - No Sound, No Picture

Southbound, did you ever get this resolved? I have the same tv with the same fuse blown? I ran the same tests as Tom suggested and tested the Zsus board for 18v and got 5.2v. I tested the Ysus board for 15v and got .32v. Control board checks out. I installed a known good Ysus board and the same Fs104 fuse blew. I have sound but no picture.