Proview 3200 no backlights

[budm]

Re: Proview 3200 no backlights

From the pictures, it looks like the 24v is generated by one transformer, the 12v is generated by another transformer to the right of the 24V transformer.
Can I see good clear pictures straight shot of the bottom side of the board so I can trace the connections? Also a straight shot of the top side.

[smason]

Re: Proview 3200 no backlights

From the pictures, it looks like the 24v is generated by one transformer, the 12v is generated by another transformer to the right of the 24V transformer.
Can I see good clear pictures straight shot of the bottom side of the board so I can trace the connections? Also a straight shot of the top side.

Will do tonight.
I did test the caps and the 2 power resistors in the 24v section that powers the inverter, they test fine.

[smason]

Re: Proview 3200 no backlights

From the pictures, it looks like the 24v is generated by one transformer, the 12v is generated by another transformer to the right of the 24V transformer.
Can I see good clear pictures straight shot of the bottom side of the board so I can trace the connections? Also a straight shot of the top side.

Best I can do for today:

[smason]

Re: Proview 3200 no backlights

OK I'm convinced now that it is indeed a power supply issue.

The supply will only come up with full 24v occasionally, and only when brought up with no load. Once it's up and stable it seems to be able to deliver a fair amount of current.
I even got it running, then plugged in the inverter and got all backlights on. once.

So, I'm not to well-versed on SM power supplies. I'm assuming if it can output several amps sometimes, it's not a regulator or FET issue, more likely a sense issue.
Are the sense resistors the 1W resistors on the component side? Or are some of the surface mount resisors on the solder side involved?

[budm]

Re: Proview 3200 no backlights

Yes it is the power supply problem, plus the blown fuse for the inverter board PWM IC.
I try to trace out the connections on the power supply board, but it is a little time consuming since I have to look at the top side, then the bottom side to figure out the circuits.
How much is the replacement power supply?
That big green resistor on the top side by the MOSFET on the heatsink that drive the 24V transformer is the Source current sensing resistor, there should be a small surface mounted resistor that is also connected to the Source pin that will be connected back the I sense pin the SMPS IC.

[smason]

Re: Proview 3200 no backlights

OK I'm convinced now that it is indeed a power supply issue.

Well I measured a bunch of the resistors/diodes that are connected to the 24v side, nothing obvious. I looked at the datasheet of one opf the pwm chips, and decided that without service information, and as much as I love a challenge, and to learn something, screw it, life's too short, and I don't have the time to dedicate to it. I ordered a supply off of Ebay for $40.00

We shall see.

[smason]

Re: Proview 3200 no backlights - Update it's alive!

screw it, life's too short, and I don't have the time to dedicate to it. I ordered a supply off of Ebay for $40.00

We shall see.

Finally got the supply. It shipped in 2 days to San Diego, a relative was going to bring it on a plane, but cancelled the trip. SO good old USPS took a 2 weeks and way too much money to get here.

I popped the supply in, and fired it up, backlights!
Re-assembled it (holy sh*t what a pain in the ass) and nope, not working.

Disassembled it, hmm inverter is unplugged. I had it assembled upside down so the cables were too short. Had it worked it would have been funny wondering why the hell the picture was upside down. re-re-assembled it, even more of a pain, and it's on test and working!

I feel bad for "board swapping" when it's probably a $0.49 part, but didn't have the time or the brain power to focus on it. The owner will be happy.

[retiredcaps]

Re: Proview 3200 no backlights - Update it's alive!

It shipped in 2 days to San Diego, a relative was going to bring it on a plane, but cancelled the trip. SO good old USPS took a 2 weeks and way too much money to get here.

Depending on the service, 2 weeks from the USA to Canada is excellent. I always try to get the cheapest shipping rate so I'm used to waiting 2 to 4 weeks.

At least you didn't get screwed by UPS/FedEx for brokerage charges of $35 or more.

[Paul678]

Re: Proview 3200 no backlights

Check that small black fuse that looks like a resistor by the inverter connector to the right, it should have 15 or 20 printed on the top. Common failure for this board.
It looks something like this:
http://s807.photobucket.com/albums/y...ps27a023ac.jpg
You can use 0.22, .33, or 0.47 Ohms 1/4 Watt through hole resistor, one of its leg is connected to the 24VDC input, it is used to supply the power to the PWM IC.

Hey, I know this is an old thread, but.....

THANK YOU, BUDM!!!!!!

This was the fix for my unit!!! I checked all the larger
white fuses, and they were all fine, but this little black
fuse was it! Luckily, I have plenty of spare boards to
steal parts from, as I know most of you do as well!!


THANK YOU, THANK YOU, THANK YOU!!!

DID I MENTION, THANK YOU???

[budm]

Re: Proview 3200 no backlights

I am glad it is just simple to repair, thanks for the feed back.

[zaperbaby]

Re: Proview 3200 no backlights

I have this tv and the power board was showing 3-5v pulse on the 12v line heating the board with a hair dryer it would power on normal

I found a tiny cold solder joint on one of the ic chips on the bottom of the power board pushing on it would get power up and running.

The solder looked perfect but it has been working perfect since I put some flux and re-soldered it.

just gos to show even perfect looking solder can be cracked.

anyway good luck hope this may help some one

[LITEZONER]

Re: Proview 3200 no backlights

i KNOW This is an old post, But hope I can still get some advice, My power supply puts out 12.1 volts across the 12V side but only 23.5 V across the 24V side. Is this okay or within limits? My Backlight comes on for 2 seconds and then goes off, I have repaired an open fuse at F1 on the inverter board, It showed 20 on the top 1A 76V, Before repairing this fused link, I did not get any backlight at all. I am suspecting the inverter board itself went bad somewhere, But as I understand it the fuse is suppose to protect it from things like that. where to go next.

Thank you in advance for your valued reply's and knowledge, I am very glad you all are here.

[vinceroger69]

Re: Proview 3200 no backlights

2 seconds to black can be a number of problems the first thing i would check are the transformers on the inverter board one might have a faulty winding is there a part number on them to find the resistance checks.

[LITEZONER]

Re: Proview 3200 no backlights

I have not seen a cap leak from the side like this, is this leaking or is it some kind of sticker residue?

[LITEZONER]

Re: Proview 3200 no backlights

Part number on Inverter is Board VIT70002.00, I320B1-24-V02-L3C1

[vinceroger69]

Re: Proview 3200 no backlights

well worth changing those two capacitors in my opinion the plastic covering looks like its got hot and shrunk on the left one two.

[LITEZONER]

Re: Proview 3200 no backlights

you were right on the money on those transformers, two of them were open. I had some old ones that had comparable resistance, and Bingo, we got in living color. Thank you

[vinceroger69]

Re: Proview 3200 no backlights

cool thats good i would also change those two capacitors though use panasonic fm/fr/fc if you can.Good job you had spare inverter transformers ive just picked up a boxed 22in toshiba set that uses one inverter transformer and that has a open secondary winding so just had to order one.