Fixing Toshiba Regza 37" LCD TV

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

I googled and found out there is something call bypass inverter protection.

Has anyone done this before?

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

I got myself a replacement inverter board, 6632L-0522A (original one is 6632L-0541A) and replaced it. The picture runs fine for about an hour and then went black. I tried to restart the tv and now it's always black with the audio playing.

I emailed the seller and showed him this video, he replied that the inverter board he sold me have this protection mode which will be activated when it detect a problem. He told me to remove the protection by shorting the capacitor in circle in red.



I'm skeptical, any idea what should I do?

[martino]

Re: Fixing Toshiba Regza 37" LCD TV

Selldoor is telling you it's difficult to desolder those transistors,so yes,take a rolled up piece of paper or whatnot,so that you can aim the hot air from the hair dryer onto one component at the time,to try and find the one that's giving you trouble...
Desoldering you do with a solder gun,not a hair dryer.

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

Hi selldoor, sorry noob here so don't understand what you mean.

OK first thing to try might be to check the soldering on them and the transformer.

Do you mean check the soldering using the hair dryer? How do I do that?

They can be quite difficult to remove so if you can narrow it down to one by sheilding
and heating one at a time would be worthwhile.

What do you mean by remove? Using the hair dryer to remove the transistor and the transformer?

Narrow it down by shielding is to isolate which component is faulty? Can I roll up a piece of paper and point one end to each component with the hair dryer blowing the other end?

[Mogador12]

Re: Fixing Toshiba Regza 37" LCD TV

Hello there
I can dir What is the value of the zener diode that red and yellow and green thank you for your help


https://www.badcaps.net/forum/attach...1&d=1406742079

[selldoor]

Re: Fixing Toshiba Regza 37" LCD TV

OK first thing to try might be to check the soldering on them and the transformer.
They can be quite difficult to remove so if you can narrow it down to one by sheilding
and heating one at a time would be worthwhile.

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

Hi I managed to find a hair dryer and blew it on the inverter board, focusing particularly on the transistors (with regard to this post) and after 30 secs, the backlight went off.

There are 4 transistors, wordings on them are DJ36AH FDD 8447L, in this inverter board, am I correct to say one, particularly the one on the most right, or maybe more of these transistors are faulty?



Please advise what is my best option? Add heatsink onto the transistors, change transistors or change inverter board?

[stj]

Re: Fixing Toshiba Regza 37" LCD TV

yes, that's the idea

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

Its difficult to rule anything out as there is interaction between the boards.
You really need to do the hairdryer thing to pinpoint the problem.

Sorry can provide more details on how does the hair dryer thing will help to pinpoint the problem?

Is it to blow hot air on to the top of the different boards when the tv is on, one at a time and if the backlight goes off, the board that is currently blowing would be the cause of the problem?

[selldoor]

Re: Fixing Toshiba Regza 37" LCD TV

Its difficult to rule anything out as there is interaction between the boards.
You really need to do the hairdryer thing to pinpoint the problem.

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

Ok, I placed the back cover back and less then 30 mins the backlight goes off. I measured the input 24v voltage to the inverter board by placing the black probe on pin 6 of the connector and red probe on the F1 fuse side closer to the capacitor C2 and it's 23.9v.

So can we rule out the power supply and the main board are working fine and is this the case of the bad inverter board? Could it also be the problem with the t-con board?

[selldoor]

Re: Fixing Toshiba Regza 37" LCD TV

DO NOT touch any heatsinks whilst the set is powered up or for 15 minutes after.

What you can do it to apply extra heat to the boards using a hair drier to see
if the set goes off.

Problem could still be wiring to the bulbs in particular the top set as they normally get hotter than the rest. Also lying the board down may have moved the wires.

[martino]

Re: Fixing Toshiba Regza 37" LCD TV

I'd say it's because the cover is off now,the heat can escape a little easier....
Time to get the hair dryer out and heat up some boards?

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

Update, the tv is still running fine since power on.

I highly suspect it's due to overheating on one of the components, maybe capacitor (I still can't find any bulging capacitor) or one those of components on the power board with the heatsink, which is causing the backlight to go off when the back cover is attached.

Anyone can confirm my findings? Is it safe to touch the heatsink on the power supply board? If yes, any idea is it possible to attach a fan and draw 5v power from the power supply board?

I also found this youtube video.

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

Previously, while in standing mode and with the back cover on, the backlight will goes off after 30mins but it've been almost 2 hrs now and it's running fine.

The difference is now the tv is lying down with one side supported, no back cover and some screws have been removed on the main board to allow easy access to the inverter board connector.



What's happening?

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

Yes, correct. You should read a voltage close to 24V. Keeping the negative lead on pins 6-10, place the red probe on the fuse labeled F1, 12A/65V, on the side closest to the capacitor C2 and you should also read +24V. If not, double check the fuse with multimeter on Ohms scale (200) and the TV off. If reading close to zero Ohms > fuse ok, if reading 1. then the fuse is open (shortcircuit somwhere on the board).

Hi the problem come back again and I'm finally have time to do this test now.

I've measured the F1 fuse using the multimeter's continuity mode and there beeping sound so the fuse should be ok right? Anyway if this fuse is broke, it should have the problem from the start right?

I've also measured the 24v input to the inverter and it's 23.7v, will measure again when the backlight goes off.

Am I correct this is the test if the problem is caused by the power supply or the inverter board? When the backlight goes off, if the input voltage to the inverter is not ~24v then there's something wrong with the power supply board and if the ~24v is ok then there's something wrong with the inverter board?

Anything else that I should also measure while waiting for the backlight to go off?

[selldoor]

Re: Fixing Toshiba Regza 37" LCD TV

MAGIC

Maybe the moving about has moved a bulb wire slightly or when you switched it on. a spark caused solder to melt on a bad joint and resolder itself.

These are both reversible fixes so the test will come when you switch it off and on again.

If posting more pictures please use manage attachments rather than posting in line or offsite
when the images will disappear

[addytzu123]

Re: Fixing Toshiba Regza 37" LCD TV

First thing through my mind - bad solder joints. Since you have pinched/pulled/pressed the connectors while testing, maybe some contact may have been reestablished, either on inverter side or on the power board side.
Some real photos front/back would shed more light into the issue.

[ABuNeNe]

Re: Fixing Toshiba Regza 37" LCD TV

Something strange happened when I opened the back, turn on the TV and tried to wait for the picture to go black so I can measure the voltage but it did not happen. It should happen after running for about ~30mins but it've been running for more then an hour and it still working fine.

Any idea what happened?

[addytzu123]

Re: Fixing Toshiba Regza 37" LCD TV

Yes, correct. You should read a voltage close to 24V. Keeping the negative lead on pins 6-10, place the red probe on the fuse labeled F1, 12A/65V, on the side closest to the capacitor C2 and you should also read +24V. If not, double check the fuse with multimeter on Ohms scale (200) and the TV off. If reading close to zero Ohms > fuse ok, if reading 1. then the fuse is open (shortcircuit somwhere on the board).