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Nathan
Nathan, Installer
Category: TV
Satisfied Customers: 20505
Experience:  Custom home theater installer, authorized dealer top brands.
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I have a maxent 42 inch plasma that has sound and no

Customer Question

I have a maxent 42 inch plasma that has sound and no picture.
Submitted: 1 year ago.
Category: TV
Customer: replied 1 year ago.
Maxent MX-42HPM20 plasma (LG parts). When I turn it on, the power light goes on, but the screen stays black (not dimly lit, and not on sometimes then fades out). The power supply board's heat sinks warm up, and so does the ysus board's, but it doesn't seem like the zsus board heat sink warms up.
Customer: replied 1 year ago.
Also, the tv does make a "click" sound when I turn it on.
Expert:  Nathan replied 1 year ago.

Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.

Sorry to hear you’re having trouble.

Did you test the 2 fuses on the z-sus?

Customer: replied 1 year ago.
No, I don't have a multimeter at home
Customer: replied 1 year ago.
The fuses are the opaque white type so I can't visible determine if they have blown either
Expert:  Nathan replied 1 year ago.

Correct, they are ceramic type fuses and require a meter to test.

If you don't have one, just replace them anyway. Fuses are cheap, you can pick up a set at radio shack or even an auto parts store. It'll be a 250v fuse. Take these ones with you and they'll get you a new set to change in for a few $.

Or get them online if needed: http://amzn.to/1h49Q0m

Customer: replied 1 year ago.
If the tv wasn't working because there was only a problem with the zsus board (such as its fuses being blown) wouldn't the tv light up at least partially?
Expert:  Nathan replied 1 year ago.

No, not necessarily.

Typically you wouldn't always get sound with the zsus out, but when those heatsinks aren't warming up there is clearly a problem there and the fuses are the first place to start. Since you don't have a meter you either have to get one or replace the fuses. You're not going to be able to isolate or diagnose anything properly when one board is known not to be fully functional.

Customer: replied 1 year ago.
I do get complete sound currently (even with the picture out). Once I replace those fuses, assuming they have blown, what difference should I see other than the zsus heat sink warming? If it was just the fuses, should I expect the screen to work again?
Expert:  Nathan replied 1 year ago.

Well this is mostly a diagnostic process.

Either everything will work and you're back to normal

OR those fuses will blow again, indicating a fault on the z (pretty common) and that board would need to be replaced.

The real difficulty comes in here because this is just such an old model that finding 10 year old boards is next to impossible, making repairs difficult and cost prohibitive.

Customer: replied 1 year ago.
I'm still confused: If the zsus board goes and everything else is ok, shouldn't the tv screen light up slightly, or light up and then fade out? Since nothing lights up at all, doesn't that indicate that either the ysus board or something else is wrong?
Expert:  Nathan replied 1 year ago.

You won't always get the screen to light up, all of these boards work together. You can try disconnecting the z and see if anything changes.

Yes, it is still possible the y is bad, but until you have a known working z board, it is difficult to pinpoint anything with confidence.

Have you tried disconnecting the buffer boards individually to see if you get anything with just one of them up?

Customer: replied 1 year ago.
If I disconnect the zsus and everything else is working properly, what difference will I notice? Will the screen light partially?I haven't disconnected the buffer boards as they are at the bottom and covered by multiple other components (as shown in attached photo), correct?
Expert:  Nathan replied 1 year ago.

Yes, the buffers are the 2 at the bottom.

You may notice nothing with the Z disconnected, if the fuses are already bad, it may not change anything. You can try disconnecting the Y only though just to confirm if you lose sound there.

The idea with the buffers is that you'd possibly get half a picture with one out.

Customer: replied 1 year ago.
I completely disconnected the z board, and saw no difference. Will check the y board
Expert:  Nathan replied 1 year ago.

Thanks.

You should have 2 fuses on the Y board also, since you don't have a spare or meter, you could try swapping the Y and Z fuses to see if anything different happens.

Customer: replied 1 year ago.
I disconnected the y board and didn't see anything different. Also, I tried disconnecting each of the buffer boards individually, but saw no difference. Will try swapping fuses next
Expert:  Nathan replied 1 year ago.

Thanks

Customer: replied 1 year ago.
I swapped fuses and saw no difference
Customer: replied 1 year ago.
When I disconnected the buffer boards I disconnected the 2 tape connections on both boards and didn't see any change to the screen
Expert:  Nathan replied 1 year ago.

Thanks for checking. Unfortunately at this point I have limited service documentation available, and your ability to do any definitive diagnostic electrical testing is limited, so we really cannot proceed any further from here.

If I had to take a guess, I'd expect you've got a bad Y board, however based on the age of the tv there are no longer any parts available, no matter which board it is.

If you wanted to send your Y board in for repairs, you can do so here: http://bit.ly/1NCzeat

Personally, I wouldn't consider it worth any further investment for an offbrand 10 year old 720p tv. Even if you fix this, the tv is well past its expected service life and would not be expected to have the other components last much longer anyway. If it were me, I'd be much more inclined to invest my money in a new tv, when you can get a brand new LED tv with twice the resolution, updated features, and a fresh warranty, in the $300 range.

Depending how you'd like to proceed though, I can recommend replacement options, or I can opt out and see if another expert here would be willing to work with you further on this. We are really at the limit of what can be done without you being able to detailed testing with a meter though.

Best regards, ***** ***** for the news,

Nathan

Customer: replied 1 year ago.
If I could get a multimeter, what would I test?
Expert:  Nathan replied 1 year ago.

All of the outputs of the power supply, to begin with. I'm not able to go through that level of diagnostic detail with you though. For one it is far outside the scope/value of the initial question here, and I just don't have the service manual handy to guide you through with specific test points. You can test the output voltage pins marked on the power supply though.

Customer: replied 1 year ago.
Thanks-how would you go about connecting me with someone else who could continue the conversation?
Expert:  Nathan replied 1 year ago.

I would opt out of the question. This opens it up to other tv experts on the site to step in and assist.

I am an independent technician and I've spent my personal time, unpaid, in a good faith effort to assist with the question for which you solicited my services. I am only paid for my efforts when customers such as yourself leave positive feedback for my work. Again I apologize there is not a better outcome here, though this is really beyond either of our control. I do hope you’ll consider leaving a positive rating for me, rather than “shoot the messenger”, so that I may get credit for my time spent in good faith to answer your question accurately, up to this point.

To be honest though, even if I do opt out, I would not expect another expert to be willing to step in at this stage. The overall question value is very low, and not really a fair evaluation of "low detail". We are all independent techs and upon conclusion get only a small fraction of your fee. If you had taken this in to a local repair shop you'd be paying a $100 minimum diagnostic fee just to have them look at it and give you the same information. Detailed step by step diagnostics are well beyond the scope of a low detail question.

Best regards,

Nathan

Customer: replied 1 year ago.
Besides telling me to replace the fuses (which I now know from a multimeter test are fine) and telling me replacing any of these parts rather than buying a new tv is a waste of money, you haven't really given me any help on how to figure out what is wrong with my tv.
Expert:  Nathan replied 1 year ago.

I'll opt out and give another expert a chance to step in.

Note: They'll see everything up to this point.

Do not reply back or rate at this point, either will send you back to me and hinder anyone else from possibly replying.

Best of luck to you.

Nathan