Sanyo DP42848 No Sound/Picture not the inverters

[revfds]

Hi ALL!

I was given this TV by my father, it stopped working at his place of employment and since I've fixed some tvs/monitors in the past he said i could have it and maybe save it from a landfill or what not.

He told me the video went out, put the sound still worked. However, I plugged it into both my cable and PS3 and was not able to get any sound. I'm not sure how it was hooked up when it was working, and without the picture i can't be sure what input, etc. it's set on, but even cycling through the inputs didn't produce any sound.

I've tested the inverters (I think that's what they are, the two boards on either side of the TV in the back, covered by metal grates) and each point on the connecters tested at 12v.

Also, The TV DOES power on. The indicator light on the front lights up, and you can hear the gentle hum of power flow.

I've also looked at the capacitors and none of them seem to be visibly blown. Any suggestions on what to test next? I can post pics if requested, and I have a multimeter, though it doesn't test capacitors (On a side note, any suggestions for one that would, would be greatly appreciated. The ones I have looked at vary greatly in price and I haven't wanted to take the risk of purchase being an uninformed buyer.)

Like i said, the TV was free, so whatever I have to replace would, in the end, probably be a good deal for me.

Thanks in advance for any help!

[johnboy1313]

Re: Sanyo DP42848 No Sound/Picture not the inverters

Turn the TV on. Hold a flashlight directly up to the screen so that the lit end of the flashlight is touching the screen. If the picture is being driven, you should be able to see at least a small part of the picture around the perimeter of the flashlight. Try holding the flashlight directly in the center of the screen and press the menu button.

Does the backlight come on at all? Do you own a digital meter?

[budm]

Re: Sanyo DP42848 No Sound/Picture not the inverters

"I've tested the inverters (I think that's what they are, the two boards on either side of the TV in the back, covered by metal grates) and each point on the connecters tested at 12v" I doubt that the inverter board for 42" TV will be 12V, it has to be 24VDC.
Pictures of all the boards?

[revfds]

Re: Sanyo DP42848 No Sound/Picture not the inverters

johnboy1313: I tried that with my phones flashlight, but to be honest it's not very good. I'll get a brighter one and try it with the menu button like you suggested tonight.

"Do you own a digital meter? " You mean a digital multimeter? Yeah, i have a Radioshack brand 29-range Multimeter.

budm: It's possible I'm mistaken, as i tested it a few weeks ago, but as i recall they tested to the correct number that i had read online, whether it was 12v or 24 i can't be 100%. I'll do it again and get some pics up for you.

Thanks for the quick replies and suggestions!

[revfds]

Re: Sanyo DP42848 No Sound/Picture not the inverters

Okay, so using a flashlight I was able to read instructions to do an input search so I did that and got it to recognize my snes, and thus had sound. I'll edit my post with an image of the inverter board, and check the voltage again with the multi-meter.

[budm]

Re: Sanyo DP42848 No Sound/Picture not the inverters

If you search the forum you will get lots of posting on this model.
https://www.badcaps.net/forum/search...archid=3103094

[revfds]

Re: Sanyo DP42848 No Sound/Picture not the inverters

http://i.imgur.com/gPGZR16.jpg

There's a picture of the inverter.

I had searched the forums before, that's how i knew what voltage to look for. Reading again now it says 24v, so I'm assuming that what It checked as before, but like I said, I'm going to re-check tomorrow.

[johnboy1313]

Re: Sanyo DP42848 No Sound/Picture not the inverters

At first startup, does the backlight come on at all and then shut off after a couple seconds, or does it stay completely dark?

[revfds]

Re: Sanyo DP42848 No Sound/Picture not the inverters

No, at no point does the backlight come on.

[revfds]

Re: Sanyo DP42848 No Sound/Picture not the inverters

Ok, i tested the connectors to the inverter and they registered at 24v (23.87ish)

Checking the white fuse, the multimeter said it was short so I'm guessing that's the culprit?

would it be better to just replace both the inverter boards that trying to swap out this fuse?

[tom66]

Re: Sanyo DP42848 No Sound/Picture not the inverters

A fuse should read shorted.

[revfds]

Re: Sanyo DP42848 No Sound/Picture not the inverters

oh, well the one on the other inverter board registered as open, so I'm guessing that is bad?

[tom66]

Re: Sanyo DP42848 No Sound/Picture not the inverters

Yes. Was the board with bad fuse marked SLAVE (S) or MASTER (M)?

[revfds]

Re: Sanyo DP42848 No Sound/Picture not the inverters

Slave, it was the VIT71043.51

[tom66]

Re: Sanyo DP42848 No Sound/Picture not the inverters

Typically then you only need to replace the slave though you should at least get a brief backlight with a bad slave board.

[revfds]

Re: Sanyo DP42848 No Sound/Picture not the inverters

Okay, i replaced the slave board and still the same problem.

No picture but sound. What should I try next?

[johnboy1313]

Re: Sanyo DP42848 No Sound/Picture not the inverters

Have you got the service manual?

[tom66]

Re: Sanyo DP42848 No Sound/Picture not the inverters

Probably one of these
http://www.tgohome.com/ServiceManual...&Search=Submit

[revfds]

Re: Sanyo DP42848 No Sound/Picture not the inverters

I got it now. What should i look up?

[tom66]

Re: Sanyo DP42848 No Sound/Picture not the inverters

I would start by checking the BL ON/OFF signal going to the master inverter. It will be in the service manual if it is not marked on the power board. May be called BLON, ON/OFF, BL.