Sanyo DP58D33 sound but no picture

[budm]

Re: Sanyo DP58D33 sound but no picture

Example of capacitors (brown rectangular shape) on the tab bonding boards.

[ace88bull]

Re: Sanyo DP58D33 sound but no picture

I did more research into TAB failures and what they are. I'll look closely at the failed one that's attached to the panel, see if it's pulling loose or defective in some other obvious way.

Anyway to test it with a multi-meter? Or is it mainly visual/putting pressure on it with the screen on?

[budwich]

Re: Sanyo DP58D33 sound but no picture

there is no tests for the tabs themselves. As budm suggests look / test the smd components with a meter. You can compare your results with the "other side" as a lot of the circuitry is "mirrored" on both sides.

The test of the tcon cable disconnection only tells you that from the tcon towards the panel, there is a problem. The bonded tab failure is one type of failure with which there is a "save" mode to get the set back. However, there are other failures in the path... related the tabs on the bottom (which is NOT saveable) and smd components (which can be carefully repaired in most cases).... so you do need to do some more and post picture if unsure as some "bad choices" will not end well.

[budm]

Re: Sanyo DP58D33 sound but no picture

Check the RESISTANCE of those caps by setting the meter to Ohm Mode.

[ace88bull]

Re: Sanyo DP58D33 sound but no picture

Alrighty, I'll pull the bezel and have a closer look at that stuff as well as take some pictures.

[ace88bull]

Re: Sanyo DP58D33 sound but no picture

No obvious damage that I can see.

Resistance on the bad side shows 10 to 11ohms with either meter lead on either side of the sdm. And it's the same for every capacitor on that side.

On the good side the capacitors are lead dependent. One side showing no resistance and the other way shows readings in the milliohm range.

[budwich]

Re: Sanyo DP58D33 sound but no picture

I am not sure I understand "On the good side the capacitors are lead dependent. One side showing no resistance and the other way shows readings in the milliohm range."

What does "no resistance" mean.... "0" ... or infinite which means "very high resistance".

As mentioned, IF the smds that you are looking at are similarly labeled (Cxxx) and in about the same place, they should react / measure the same.

perhaps disconnect the tcon to panel cable again and repeat the test (hope you are doing resistance measurements without power on) just to check results / confirm results... just in case.

Right now I would say perhaps one of those caps is basically shorted. You might have to study the edge board a bit and follow the track with your eyes and meter to see where things lead. Further, with the bad side tcon removed, you can potentially and carefully, find some voltage points at the edge board where the TCON is delivering potentially 15-18dc to drive the panel... I think. Once you determine that you might be able to trace that same point on the other side.... of course, there won't voltage there but it will help understand the circuit better. Basically, IF there is a problem (short in the board) where by the voltage sent to the panel is "loaded / reduced", that is monitored and the controller shuts things down to prevent further damage and other things (fire). Anyways, I think you are headed in the right direction.

[budwich]

Re: Sanyo DP58D33 sound but no picture

the pictures that you have posted are only of the bottom tabs. what about the side?

[ace88bull]

Re: Sanyo DP58D33 sound but no picture

Sorry, I’ll try to clarify. I misread my probe to probe test. On the bad side, using the red and black probes I can test either side of the caps with them and get 10-11ohms. On the other side with the probes testing one way I’d get O.L or I guess infinite resistance and with the probes reversed they’d get either around 7 M ohms or ~100 M ohms.

I did the test without the T Con board connected and no power connected.

Could you explain what you meant by “the side” for pictures?

[budwich]

Re: Sanyo DP58D33 sound but no picture

there are likely tabs on the each side of the panel... similar to the bottom.

Anyways, it is highly likely you have an smd failure as you can see... they are perhaps shorted on one side versus the other which shows a high impedance.

[ace88bull]

Re: Sanyo DP58D33 sound but no picture

Well dang. Couldn’t be something simple could it...lol.
Possible to replace those smd’s? Worth messing with?

[budm]

Re: Sanyo DP58D33 sound but no picture

You found the problem, now it just a matter of removing them and compare its capacitance with the one in the working side, if anything at all this will be good learning experience for SMD soldering works.

[budwich]

Re: Sanyo DP58D33 sound but no picture

well I wouldn't "jump" just yet. First, I find it unusual that you say "all" measure 10 to 11 ohms. What is "all" as in which ones are you referring to. Further, it is more likely that perhaps one is bad and depending on the circuit lay out, it is "paralleled" to others in some form such that your measurement is showing the same result for "all".... but is might actually be more likely that none of them are bad and it is something in the circuit further down from the capacitors that is "shorted" that is reflecting in your measurement "points". Again you need to look / picture the side of the panel to confirm how it is designed with any tabs.

Ultimately, if indeed the smds that you have "found" are bad, potentially they can be carefully replaced as budm suggests if you are reasonably good at soldering. But I do would do more checks as suggested first.

[ace88bull]

Re: Sanyo DP58D33 sound but no picture

Here are what I think are the tabs on the side of the panel.