Sharp LC-42D62U Inverter board

[FlipTV]

Hello everyone.

This is my 1st repair project.

I bought this display broken. You can see the video with a flashlight, but there is no backlight on the screen.

After inspecting the inverter boards, i noticed that the slave was burned on the board.

My question is, is it recommend to replace both Master and Slave boards at the same time?

What should I be testing on the inverter board with my MM to find the cause of the failure?

[tom66]

Re: Sharp LC-42D62U Inverter board

It's only necessary to replace/repair slave or master, not both.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Thank you for the reply.

The shopjimmy support staff informed me its recommended to replace both boards at the same time, saying that if the master board is weak it will damage the slave.

I'm assuming this was just an upsell attempt?

[tom66]

Re: Sharp LC-42D62U Inverter board

There is no way a bad master can damage the slave or vice versa, so yeah, it appears they were trying to sell you more than you need.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Thank you for the insight.

I'll post the results of my 1st repair project when its complete.

[tom66]

Re: Sharp LC-42D62U Inverter board

If you could post pictures too, that would be nice

[FlipTV]

Re: Sharp LC-42D62U Inverter board

I'll be sure to do that one i get home. I'm in the office right now multitasking lol.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

So i received my slave inverter board and replaced it. It's the same issue, I can see the image with a flash light but there is no back light. What can I test to see if the master inverter is at fault or if it could be the lamp itself.

Total noob here, sorry for the simple troubleshooting questions.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Here is a pic of the original slave inverter board which had a burnt mark. It's what made me think this was the issue.

[budm]

Re: Sharp LC-42D62U Inverter board

So are you getting 24V to the inverter boards?

[budm]

Re: Sharp LC-42D62U Inverter board

Can you take good close up around the white connector of the inverter boards?
There is a small black fuse 1.5A 76V (it has '30' on top) on the master inverter board, more likely to be open, famous failure in these CMO inverter boards.
By the way, that burnt mark is from high voltage arcing, which mean there is bad connection on that lamp connector, inspect the connector real well.

[cashkennedy]

Re: Sharp LC-42D62U Inverter board

Not sure how experienced you are / if you understood budm's first question, but he wants to know if the inverters are getting 24v while the set is fully on (like when you can use a flash light to see the picture)

To check that you will want your multimeter on 200v DC voltage setting (or some dc voltage higher then 24v) DC voltage is marked with a solid line over a dashed line. press the one probe of the multimeter to VBL pin on the conector from the power supply to the inverter, and the other probe to GND and tell us what voltage that reads.

As budm said, the burnt mark on that inverter is probably not a big issue / but just from a bad conector there.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Both boards get 24 volts when the set is on and I get those reading when pressing the probe on the test points on the board next to the transistors.

When I test the fuse that was mentioned with my multimeter, it gives a reading of 1.25.

Since this is a fuse, should this read OL on the multimeter and also beep instead of giving a reading?

Also how do I test the connector that goes to the lamp?

Thanks in advanced for you help with this. It is appreciated.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Here is a close up of the fuse

[budm]

Re: Sharp LC-42D62U Inverter board

1.25 Ohms, 1.25K OHMS, 1.25 M OHMS??. Your meter should at least beep.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

I am using a Fluke 12 DMM.

I am testing the fuse with the tv off and using continuity mode.

14.42k ohms
Or when I button with a solid white and yellow line I get
1.110

I get no beeps.

Attached is a pic of my MM

[truep]

Re: Sharp LC-42D62U Inverter board

Do you get a beep when you touch the leads together?If so, and you don't get a beep when you test across the fuse, The fuse is bad or you are not getting good contact. Be sure to press on the leads to insure good contact.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

I am definitely getting a good contact when testing the leads on the fuse. Do you think this could be the cause of the back light issue?

A bad fuse on the master inverter board?

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Should a fuse beep when testing it showing open line?

[tom66]

Re: Sharp LC-42D62U Inverter board

If the meter shows "OL" (Open Loop or Overload (resistance high)) while beeping, it is defective.