Dynex DX-LCD32 Power Board

[stevekasian]

Hi,

Posted a question in General section the other day about an IC here: https://www.badcaps.net/forum/showthread.php?t=13262

Now that I have my camera working again, I'm ready to troubleshoot this thing :-).

I am getting perfect power on the +5v and +15v rails, just no power on the 24v side. I replaced 4 components (the large cap was due to damage inflicted upon it while prying it from the hot glue sticking it down).

I have checked all components on the board that are not an SMD IC or other special device, and transistors. In other words, the black multi-pin items on the back of the board as well as a couple of little transistors and IC parts have not been properly evaluated (because I don't know how to check them properly). None of them show any short circuits.

All heat-sink mounted devices (MOSFETs, diodes, etc.) HAVE been thoroughly tested out of circuit and are in working order.

Another person posted on a forum in Mexico that he had the exact same components blown, and stated that he believed that the SMD IC in the image below would probably need to be replaced as well. But no follow up from him, so I don't know what ever happened with it. He did say the small IC906 (between the two heat sinks in Pic #1) was blown on his, but I only checked this one for shorts and found none. Not sure how to check it properly otherwise.

Any help and wisdom on this issue would be greatly appreciated. I am really stuck on this thing, but i don't want to give up and order another board because I already put $16 and hours of time into this one, and I would like to see it through and make a learning experience out of this. Lord knows I need the knowledge!

Thanks,
SK

[retiredcaps]

Re: Dynex DX-LCD32 Power Board

1) For the two diodes (circled in red) mounted on heat sink, what the the DC voltages on the middle pin?

2) For the two capacitors (circled in red), what are the DC voltage across the capacitors? Are the voltages stable?

[stevekasian]

Re: Dynex DX-LCD32 Power Board

-disregard-

[stevekasian]

Re: Dynex DX-LCD32 Power Board

Thanks, retiredcaps, for the help. Unfortunately I am unable to safely apply working voltage to the board and test it while live at this time. I'll need to obtain proper equipment to tackle the more difficult jobs I guess.

I started in December with little more than a soldering iron and some screw drivers. Now I've got a multimeter, heat sink compound and some other stuff (plus about 7 previously broken but now working monitors and a few of the same in TVs!). I'll just have to gradually acquire more and more equipment as time goes on to solve some of these.

Thanks again!
SK

[fleetwise]

Re: Dynex DX-LCD32 Power Board

1) For the two diodes (circled in red) mounted on heat sink, what the the DC voltages on the middle pin?

2) For the two capacitors (circled in red), what are the DC voltage across the capacitors? Are the voltages stable?

Hi I almost feel like I'm hijacking this thread but I have the exact same board with the exact same components replaced and the exact same result.
If I may give my results asked of the original poster:

#1 The center pins on the diodes read 0.25 volts DC
#2 The large cap shows 406 volts DC and the small cap reads 13.5 volts DC.

Should I try a new smps ic control as it has main_vcc voltage and B+ voltage?
The only schematic I have shows B+-390V and the data sheet for the TEA1532CT says 12 volts at the main_vcc pin so 13.5 volts may be a bit high,but I'm not educated enough to know if this would make a difference.

[retiredcaps]

Re: Dynex DX-LCD32 Power Board

The only schematic I have shows B+-390V and the data sheet for the TEA1532CT says 12 volts at the main_vcc pin so 13.5 volts may be a bit high,but I'm not educated enough to know if this would make a difference.

Check out

https://www.badcaps.net/forum/showth...hlight=TEA1532

for a good explanation of TEA1532.

[ibanez1357]

Re: Dynex DX-LCD32 Power Board

Check D913 and all the surrounding components.

R945 as well.

[fleetwise]

Re: Dynex DX-LCD32 Power Board

Check out

https://www.badcaps.net/forum/showth...hlight=TEA1532

for a good explanation of TEA1532.

Thanks, that answered all my questions. Replaced the tea1532ct and the 24 volt section came to life. Assembled it all and the panel came right up. Looks like a new tv again.
Thanks

[BlkSmth]

Re: Dynex DX-LCD32 Power Board

Can you guys share which components you replaced along with locations?
also, what was the subsitute for the TEA1532CT GreenChip II SMPS control IC Replacement?

Thanks much! , I would love to get mine in working order as well.

[PlainBill]

Re: Dynex DX-LCD32 Power Board

Can you guys share which components you replaced along with locations?
also, what was the subsitute for the TEA1532CT GreenChip II SMPS control IC Replacement?

Thanks much! , I would love to get mine in working order as well.

No substitute should be necessary. The original part is available from Digi-Key for $1.47 each.

PlainBill

[fleetwise]

Re: Dynex DX-LCD32 Power Board

PlainBill is right. It is Digikey # 568-5344-1-ND for the TEA1532CT. I also found the mosfet shorted and 2 resisters burned open. I replaced the mosfet (STP10NK70FZP)at location Q902 with one rated for 800 volts. Digikey # 497-5972-5-ND. The resisters were at R933 and R976. I used 0.1 ohm 2 watt MO, Digikey# RSMF2JTR100CT-ND.

[BlkSmth]

Re: Dynex DX-LCD32 Power Board

PlainBill is right. It is Digikey # 568-5344-1-ND for the TEA1532CT. I also found the mosfet shorted and 2 resisters burned open. I replaced the mosfet (STP10NK70FZP)at location Q902 with one rated for 800 volts. Digikey # 497-5972-5-ND. The resisters were at R933 and R976. I used 0.1 ohm 2 watt MO, Digikey# RSMF2JTR100CT-ND.

Thanks for your time my friend. I appreciate the info
I've got 6+ of them R976 (0.1 OHM 1W FUSE RESISTOR) coming from malaysia (due in on the 9th of June 2011). These where out of production/no longer manufactured parts. Since I wanted a genuine FUSED Resistor with them values, it left me not much choice.... total shipped was 24.00 ...so if anyone in the future needs one (I live in northern michigan) simple paypal/stamp and mail ~ BlkSmth

[stevekasian]

Re: Dynex DX-LCD32 Power Board

Cool! I've just ordered the TEA1532CT from Digi-Key and will hopefully have a working TV by next week sometime :-D

Thanks so much, fleetwise, for "hijacking" this thread as you did - you will be responsible for saving my power board if it works! I'll post an update then and let y'all know.

I had a feeling if I sat on it long enough and kept checking back that something would come about. ;-)
SK

[BlkSmth]

Re: Dynex DX-LCD32 Power Board

Nice to see the thread alive Thanks all for your help! I've yet to get back to this board... There is another issue... D920 is blown and I need a replacement. I tried replacing just the R976 back then, pluggin it in and pOOOOF out D920 went along with the TEA1532(original one).... Anyone got a replacement part # suggestment? I do have the other parts and would love to get back to this project... It would also help get it out of my basement leaving room for other projects that have been planned :P

[stevekasian]

Re: Dynex DX-LCD32 Power Board

Unless D920 actually went "poof", or is otherwise visibly damaged, keep in mind that R958 is in series with D920, and will thus cause it to register as shorted on a meter in both directions.

Getting ready to R&R IC902 (TEA1532CT), as I just received it in the mail. (I LOVE Digi-Key - I ordered this thing Friday and it arrived today. That's literally like 2nd day air at a First Class postage rate! :-)

Will report back soon...

[BlkSmth]

Re: Dynex DX-LCD32 Power Board

Yeah man, it went poof alright! very visable so did the teac heheh....
I allready have mine to replace. However I wish to know how yours turns out. The D920 is lost.... got any suggestments for the replacement?

[stevekasian]

Re: Dynex DX-LCD32 Power Board

I now have a working Dynex DX-LCD32! Works flawlessly!

It was one bear of a task removing IC902, as it was pretty much bonded to the board in some way... so I just had to break the legs off and crush it with pliers and burn the rest of it off the board. I lost a couple PCB solder pads in the process of ripping the legs off with my soldering iron tip, but managed to bridge where needed on installation of the new part and ended up with a pretty clean job in the end.

Thanks again to fleetwise for firing this thread up again and making it known that the TEA1532CT is finally available for purchase! I'll take a $1.47 part and some bench time over a purchasing a $50.00+ used power board any day!

All in: < $18.00, several hours of time, and a healthy bit of education and experience in LCD power supply troubleshooting and repair. :-)

SK

[BlkSmth]

Re: Dynex DX-LCD32 Power Board

thats totally awesome brO! great job! if you ever get a chance to peek at d920 that would be great

[stevekasian]

Re: Dynex DX-LCD32 Power Board

I didn't know you needed a part number or rating for it. I have pictures but i don't think there was any writing on it - I'll check and post back.

[stevekasian]

Re: Dynex DX-LCD32 Power Board

Here you go BlkSmth... I was able to find 1 image in which I caught D920. It appears to be marked with an "A2". I adjusted the gamma a bit to highlight the markings.

Hope this helps...
SK

p.s. Yes, I know... I really made a mess of things @ IC902. lol

But I made it work! (last image)