maxent p420542hm8 flickers when warm,solution and question

[martino]

Hello all...

Had this TV for awhile,but could never pin point where the problem came from..
When cold it works awesome but as it warms up (approx 30 min) it slowly developed "flickering" on the screen,starting on bottom 1/3 of screen and slowly getting worse as times passes till you can't take it anymore and turn it off...once cold,it worked fine till warm......rinse and repeat,lol..

So after blasting all boards with a hair dryer I could pin point it to a BGA chip on the control board,touching it with the soldering iron made the screen flicker extreme,one shot of freeze spray and picture was perfect again..
See pic for chip pointed out by pen...

Short of reballing that chip,I like to reflow the chip....
Could use some advise on what would be the best method to do this..
I read about putting the board in the oven at 420f for 5 minutes works but would like your input/experience with this...

[freakaftr8]

Re: maxent p420542hm8 flickers when warm,solution and question

I personally never had success putting a board in an oven. However I have had success fluxing around the perimeter of the ic and using a hot air tool with a hot surface under the suspect IC. .

[tw2005]

Re: maxent p420542hm8 flickers when warm,solution and question

Hello all...

Had this TV for awhile,but could never pin point where the problem came from..
When cold it works awesome but as it warms up (approx 30 min) it slowly developed "flickering" on the screen,starting on bottom 1/3 of screen and slowly getting worse as times passes till you can't take it anymore and turn it off...once cold,it worked fine till warm......rinse and repeat,lol..

So after blasting all boards with a hair dryer I could pin point it to a BGA chip on the control board,touching it with the soldering iron made the screen flicker extreme,one shot of freeze spray and picture was perfect again..
See pic for chip pointed out by pen...

Short of reballing that chip,I like to reflow the chip....
Could use some advise on what would be the best method to do this..
I read about putting the board in the oven at 420f for 5 minutes works but would like your input/experience with this...

Pity you did not get the whole board in the picture, TNPA3654AC?
From what I'm seeing Rev AC is looking like a Panasonic generic D board for it's Customer panel TVs Maxent, Toshiba, Sylvania ?
(EDIT: It actually looks like all TNPA3654 boards are generics with differences)

Sounds like a fun challenge but why not consider these. Some boards you can't read those firmware labels TVRN680-1 & TVRN 583-1

I don't know about canadian exchange rates or post but another option unless you prefer component level repair.

Fairly expensive chip too. ALTERA EP1C6F256C7 look like min qty at mouser 90 at $40 ea or from a US Panasonic parts stockist C1ZBZ0002599 I'm seeing $60-70.

$16.50

$16.95


$19 but check this, picture shows a board with 2 ribbon connectors missing. Either they've used the wrong photo or listed wrong or they have several revisions for sale and you have to tell them which one you need??

$23.95

$25

$29.95

$29.99

$32.50

$34.50 SJ

[tom66]

Re: maxent p420542hm8 flickers when warm,solution and question

Huh. I have exactly the same board & issue on my 37" Panasonic HD panel. I never tried the FPGA. I bought a used board and the issue was the same, but I don't know if it was defective.

The reason I did not suspect the FPGA was primarily because my test patterns were also bad, but maybe the FPGA generates them in some way? I thought the FPGA was only involved in the LVDS and OSD overlay, but I might be wrong...

tw2005, the FPGA like a microcontroller is a custom logic IC. It has a program that Panasonic write for it built in. It's a lot like a massive array (around 6,000) of logic gates which can be configured into arbitrary patterns to do custom logic.

[tw2005]

Re: maxent p420542hm8 flickers when warm,solution and question

I was wondering if they were programmed because in the 42PA50 which uses the same IC it has a TVRN459 marked under the part number which you see for the EEPROM and FLASH to identify the firmware loaded.

Any of those boards providing it's the same rev and those firmware labels match I reckon they'll work as they were only in Non-panasonic models and I have seen a listing that states the Maxent, Toshiba etc.

Thanks for clearing up that ALTERA chip, i could not quite find the info to tell me whether it was programmable or not. I was suspicious, but unsure about it.

[tom66]

Re: maxent p420542hm8 flickers when warm,solution and question

I think the non-Panasonic ones might omit some of the initialisation and blink codes that the Panasonic one has.
On the D board, there are outputs for the power LED (it has the standby MCU too), but also inputs for SOS on DG board etc. That might not work well with non Panasonic bits so maybe that has different program.

[apetay]

Re: maxent p420542hm8 flickers when warm,solution and question

I have a MX-42X3 that's been sitting in wait for a year. I traced the symptoms on screen and voltages to a faulty "logic board" or whatever else you want to call it. I finally tracked down a replacement D board, or T-con board if you prefer (although I believe that nomenclature is reserved for LCD?). It's in the price range I can afford, and it came from an in-transit smashed screen model, so it's likely still good. TNPA3654AC. It is an exact match, so I'm hoping there will be no need to update the firmware. Any suggestions would be greatly appreciated.

[apetay]

Re: maxent p420542hm8 flickers when warm,solution and question

So, I've been through the entire rebuild from the bottom up including switching to a known good plasma screen. I still get start-up flicker, menus available for a second or two, and then just black screen. I guess I was wrong about it being the D controller.

Must be the damn A board. Should I cook it in the oven, or shoot at it with the heat gun?

[tom66]

Re: maxent p420542hm8 flickers when warm,solution and question

I have a similar fault with a Panasonic TH-37PV500B and while I reckon it is the D board I have not managed to pinpoint it. It's still in the pile of future repairs...

[apetay]

Re: maxent p420542hm8 flickers when warm,solution and question

I chose flux and heat gun, but to no avail.

[Muhammad zeeshan]

Re: maxent p420542hm8 flickers when warm,solution and question

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