magnavox 37mf321d/37 powering on problems

[ENERGYSAVINGS]

Re: magnavox 37mf321d/37 powering on problems

I thought you had replaced the inverter board?
Besides, if you just unplug the inverter board, it will tell you if that is the issue or not, replacement is NOT necessary!
The inverter board is not necessary for the logic/ audio to turn on, it just provides the back-lighting.

[fixerofthings]

Re: magnavox 37mf321d/37 powering on problems

I thought you had replaced the inverter board?
Besides, if you just unplug the inverter board, it will tell you if that is the issue or not, replacement is NOT necessary!
The inverter board is not necessary for the logic/ audio to turn on, it just provides the back-lighting.

I did swap the inverter board before, but this was a package deal through ebay. I didn't have much choice but to take the package as it was with both boards. Worst case is I have yet another extra or can resell it if it does the same thing as the other spare and original I have. The price for the two boards together was far cheaper than what I've seen the scaler board go for by itself on ebay and other sites.

[ENERGYSAVINGS]

Re: magnavox 37mf321d/37 powering on problems

Fixer of things,
Don't get me wrong, I am not putting you down for taking the package deal, and getting the "new" inverter boards. Though it would be easy to read that into what I wrote, especially via E-mail.

My only point is that the inverter board if disconnected will just give you a very dark screen, but you would probably still be able to see that the panel was trying to create a picture without any back-light.

If the TV does not turn on with the inverter unplugged, it's not going to turn on period.

If you trust your power supply, then you most likely have a bad main board. I do want to emphasize the probably part. It could also be the T-Con, if the T-con is not on the main board.

With nothing but help and good intentions in mind,
-Craig

[fixerofthings]

Re: magnavox 37mf321d/37 powering on problems

Fixer of things,
Don't get me wrong, I am not putting you down for taking the package deal, and getting the "new" inverter boards. Though it would be easy to read that into what I wrote, especially via E-mail.

My only point is that the inverter board if disconnected will just give you a very dark screen, but you would probably still be able to see that the panel was trying to create a picture without any back-light.

If the TV does not turn on with the inverter unplugged, it's not going to turn on period.

If you trust your power supply, then you most likely have a bad main board. I do want to emphasize the probably part. It could also be the T-Con, if the T-con is not on the main board.

With nothing but help and good intentions in mind,
-Craig

The T-con board is a separate board from the main board. The new screen came with a new inverter board and a new T-con board, but the new T-con board was bad.....I would get sound, but the only picture I got at the time was 4 broad vertical colored stripes. I swapped in the old T-con board from the old damaged screen and things were fine for about a month until the current issue came up. The new T-con board that was bad still allowed the TV to turn on, so not so sure the issue is with the T-con board. I've done some searching out there and the T-con boards are fairly cheap if the main board doesn't fix the issue......

I'm starting to miss the old technology of CRT screen TVs and vacuum tubes instead of the new technology. This "new" LCD & LED technology isn't exactly the most reliable or long lasting compared to the old CRT technology.

Case in point.....I have an old CRT screen Sony that I purchased new back in 1991......it still works to this day like the day I first bought it.......fantastic! I use it in the workshop with a digital decoder box and over the airwaves antenna and it still looks pretty good for an old TV.

[ENERGYSAVINGS]

Re: magnavox 37mf321d/37 powering on problems

Fixer,
I agree with you 100%, at least it wasn't a guessing game when it came to repairing CRT televisions, I could always troubleshoot to component level, whether it be a transistor in the AGC circuit, or a bad horizontal output transistor for example.

These newer HD flat panels are MUCH less reliable. And onn top of that, it's practically a guessing game as to whats wrong with the set.

I worked at a TV ( and all other consumer electronic repair shop) just last year.
The owner who was also the most experienced person in the shop on the newer TV's just used what I call the "Poke and Hope " method to troubleshoot. If something came in that needed component level troubleshooting, it was given to me.

By the way, you provided the solution to the problem in your letter.

If the TV turned on with a different, though partially defective T-Con board, THAT IS THE PROBLEM! Not the main board.

If you could return that package or just re-sell it, I would!

My god dude. It turned on with a different T-con board. Why look elsewhere?
Get a T-Con board you can really trust, and you will have a working TV! I'd stake my reputation on it. After all, you proved it.

Please don't take this as me talking down to you, I'm just saying, you proved what I'm saying.

You can re-coup your losses by selling off what you know are good boards.

[ENERGYSAVINGS]

Re: magnavox 37mf321d/37 powering on problems

By the way,
I'm all jacked up on too much coffee right now, and had too little sleep last night.
So If I missed some part of your letter, or just got the order of events wrong I apologize for my strongly worded sentiments.

[johnboy1313]

Re: magnavox 37mf321d/37 powering on problems

By the way, you provided the solution to the problem in your letter.

If the TV turned on with a different, though partially defective T-Con board, THAT IS THE PROBLEM! Not the main board.

If you could return that package or just re-sell it, I would!

My god dude. It turned on with a different T-con board. Why look elsewhere?

I think he meant when he first installed the new panel, the TV turned on.

[ENERGYSAVINGS]

Re: magnavox 37mf321d/37 powering on problems

Figures, it was too easy.

F.O.T.

Could you give a short chronological synopsis of what was done again? And the results?

But if you KNOW the main board isn't the issue, And you KNOW the P.S. isn't the issue, And unplugging the inverter doesn't make the TV turn on with audio at least, and the Remote Receiver board has been replaced.....
That kind of leaves the T-Con board standing alone doesn't it? Have you unplugged the panel, to check for audio only as well? If nothing else, there HAS to be a voltage from the power supply that comes on to power the inverter board(s), and other things as well, when the power button is hit. If that's not happening, and all else is good, the T-con is probably locking the bus, keeping the set from powering up.
Would you agree with that statement?

[fixerofthings]

Re: magnavox 37mf321d/37 powering on problems

I think he meant when he first installed the new panel, the TV turned on.

Yes, this is what I said.

The LCD panel was an NOS replacement which came with a T-con board and an Inverter board. I originally installed it as is, but found that the T-con board that came with the NOS panel had an issue, so I replaced it with the "known good one" that was on the set's original LCD panel. I was replacing the original panel due to some kind of physical damage that occurred to the screen during a prior move.

So, the current T-con board is the original T-con board and WAS working, but it may be possible that it has failed.

[fixerofthings]

Re: magnavox 37mf321d/37 powering on problems

Fixer,
I agree with you 100%, at least it wasn't a guessing game when it came to repairing CRT televisions, I could always troubleshoot to component level, whether it be a transistor in the AGC circuit, or a bad horizontal output transistor for example.

These newer HD flat panels are MUCH less reliable. And onn top of that, it's practically a guessing game as to whats wrong with the set.

I worked at a TV ( and all other consumer electronic repair shop) just last year.
The owner who was also the most experienced person in the shop on the newer TV's just used what I call the "Poke and Hope " method to troubleshoot. If something came in that needed component level troubleshooting, it was given to me.

The faulty board will get scrapped/recycled of course......no way I'd ever sell a dead/defective board to someone, even for parts!

By the way, you provided the solution to the problem in your letter.

If the TV turned on with a different, though partially defective T-Con board, THAT IS THE PROBLEM! Not the main board.

If you could return that package or just re-sell it, I would!

My god dude. It turned on with a different T-con board. Why look elsewhere?
Get a T-Con board you can really trust, and you will have a working TV! I'd stake my reputation on it. After all, you proved it.

Please don't take this as me talking down to you, I'm just saying, you proved what I'm saying.

You can re-coup your losses by selling off what you know are good boards.

My plan is, once I determine which board is the faulty one, the others will get re-sold to recoup my investment. The PSU board I got was for a fraction of what they seem to be going for, so no worries on recouping that. Also, the package deal price for the Inverter and Main boards was less than the price of what people are getting for the main boards themselves! So, any way I look at it, this will be a win-win situation once the tv is working again.

Once I determine which board is the faulty one, it will get recycled/scrapped. I won't take the chance on re-selling it even as non-working, for parts. I don't need that potential aggravation! LOL!

[fixerofthings]

Re: magnavox 37mf321d/37 powering on problems

Figures, it was too easy.

F.O.T.

Could you give a short chronological synopsis of what was done again? And the results?

But if you KNOW the main board isn't the issue, And you KNOW the P.S. isn't the issue, And unplugging the inverter doesn't make the TV turn on with audio at least, and the Remote Receiver board has been replaced.....
That kind of leaves the T-Con board standing alone doesn't it? Have you unplugged the panel, to check for audio only as well? If nothing else, there HAS to be a voltage from the power supply that comes on to power the inverter board(s), and other things as well, when the power button is hit. If that's not happening, and all else is good, the T-con is probably locking the bus, keeping the set from powering up.
Would you agree with that statement?

I haven't ruled out the main board yet. Waiting for the replacement to come in. I have ruled out the PSU and the Inverter board and the IR board. But as I said, the replacement main board was a package deal for both a main board and an inverter board, so I'll double check the inverter board with that one as well.

As I said in the original post, the tv will not turn on using the remote control, nor does the green indicator light at the power button come on anymore. Also when trying to power it on using the power button on the front of the unit, the backlighting comes on briefly, flashes 2-3 times and the tv never turns on. It doesn't even get the chance to get to hear any sound.

I believe you are correct about something jamming up the BUSS in the tv, but not 100% sure what it is yet. It's not the ribbon cables, as I've triple checked all of those. It's not the PSU, as I substituted a "guaranteed" reconditioned one and also checked its spec vs. my original repaired one. (They spec out the same voltages at the same pinouts) It does not appear to be the Inverter board as both boards i have do the same thing (unless by some coincidence they are both fault, and it was not the IR board since I replaced the original with a NEW one right from Phillips/Magnavox. Only things left are 1) a possible faulty Inverter board still (could both of the ones I already have be bad? possibly, but not likely) 2)the T-con board could possibly have failed, or 3) it could be the main board.

I won't know for sure what the actual fault was until I have all the boards in hand next week and try them one at a time. I know fixing this thing by trial -and-error is not the proper way to diag it, but even the factory manual says check this, then that, if bad replace. Not repair, just replace whichever board as an assembly. So even Phillips/Magnavox has a replace as a sub-assembly mentality these days, yet they carry some individual electronic components for these boards on their parts page......strange! Don't diag the fault on the particular board, just replace it, but we'll offer you some parts for those boards anyway, even though we won't show you how to do that in our service manual for your tv......

BTW, Phillips/Magnavox never offered T-con boards or Inverter boards as replacement parts for this tv. They only offered the LCD panel and the boards were serviced WITH those panels......and they used 2 different LCD panels in the same model tv, as I found out when I was looking for a replacement panel! I lucked out whereas this one has the Chungwa panel that fits many other brands of tv's so the T-con boards and Inverter boards are cheap and easy to find, and seem to be fairly reliable compared to the LG/Phillips manufactured ones that seem to be more common to this PARTICULAR model tv.

I'm rambling now......sorry.

[ENERGYSAVINGS]

Re: magnavox 37mf321d/37 powering on problems

You? ranting? After my caffeine induced diatribe, I wouldn't call that ranting!https://www.badcaps.net/forum/images/icons/icon10.gif

Sounds like you have it under control. The only thing I haven't heard you try is disconnecting the inverter board to rule that out from overloading the PS.
Granted, two inverter boards is less likely, but still remains a possibility.....
It's worth a shot, and won't hurt anything. Just one more piece of info to go off of.

https://www.badcaps.net/forum/images/smilies/cheers.gif Right back at ya!

[ENERGYSAVINGS]

Re: magnavox 37mf321d/37 powering on problems

Oh, by the way, I for one who tries to troubleshoot everything down to component level, draws the line at things like the Main Board or the T-Con. Those are just too propietary and offer too little info (for the most part) to try to T-shoot.
I for one do not hold board swapping on these TV's against anyone. Power supply boards, yeah, especially if you have a schematic, a O-scope, etc. But these are not the old CRT TV's that were not all proprietary digital logic.

I really despise the fact that troubleshooting is pretty much out the window on so many problems on these new sets.

[fixerofthings]

Re: magnavox 37mf321d/37 powering on problems

Ok...I got all the boards in today. Replaced them one by one. No change, until.........I replaced the main/scaler board. Now it works as it should. So the issue THIS time was the main board. No idea what happened to it or why it failed, but the replacement board seems to work better than the original used to.

So with that said, I have listed the T-con board, the Inverter board, the PSU board, and the IR board that I purchased on ebay to try and recoup some $$ that I invested into this thing. Hopefully it lasts a lot longer this time around.

[ENERGYSAVINGS]

Re: magnavox 37mf321d/37 powering on problems

"If you trust your power supply, then you most likely have a bad main board"

Congrats on getting it to run. Out of curiosity, how is it running "better"?

At least you can recoup most of your out going money. And you saved the very substantial cost of a shop doing it.

And you get the satisfaction of doing it yourself.
In my book that adds up to well worth doing it yourself.https://www.badcaps.net/forum/images/icons/icon14.gif

[fixerofthings]

Re: magnavox 37mf321d/37 powering on problems

Out of curiosity, how is it running "better"?

It used to have an audible hiss coming through the speakers when the TV was on, now that hiss is non-existent. Also, when switching between the various AV ports and the HDMI port, and back to the tuner, it seems to take less time to do so than with the old board. Clearly there was something wrong with the original board that was jamming it up a bit before it completely locked itself up and rendered the TV useless.

[ENERGYSAVINGS]

Re: magnavox 37mf321d/37 powering on problems

Cool, and your right, those were signs of impending failure.

Glad your ordeal is over with.