Reasons why horizontal sync on LCD is erratic

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Discussion Overview

The discussion revolves around troubleshooting an erratic horizontal sync issue on an LCD screen from a found DVD player headunit. Participants explore potential causes and solutions related to electronic components, particularly focusing on capacitors and connections, while also considering the physical condition of the device.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes the condition of the device and the initial repairs made, noting that the horizontal sync is random and affected by the positioning of the screen driver board.
  • Another participant suggests that the issue may actually be related to vertical sync and recommends testing components in that area, particularly smaller electrolytic capacitors that could also be faulty.
  • A participant theorizes that the original failure of the capacitors may have led to the device being discarded, citing the presence of a CD in the drive as evidence of prior functionality.
  • One participant shares their success in cleaning the ribbon cable and IC contacts, which improved the device's performance, although they note further issues with the DVD drive mechanism.
  • Another participant emphasizes that while ICs may fail catastrophically, issues like the one described are often due to electrolytic capacitors or PCB tracks, suggesting a thorough cleaning and replacement of capacitors as a potential solution.
  • A participant reflects on the challenges of fixing the unit due to financial constraints and shares their efforts to source replacement parts for the shattered touch glass.

Areas of Agreement / Disagreement

Participants express varying opinions on the root cause of the sync issue, with some focusing on the horizontal sync while others suggest it may be related to vertical sync. There is no consensus on the exact solution, and multiple approaches are discussed.

Contextual Notes

Participants mention various assumptions about the state of the device and the potential impact of previous damage, such as exposure to weather and the condition of internal components. The discussion includes uncertainty regarding the effectiveness of proposed repairs and the sourcing of replacement parts.

Who May Find This Useful

Individuals interested in electronics repair, particularly those dealing with LCD screens and similar devices, may find the troubleshooting approaches and shared experiences relevant.

tundrawolf
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Hello,I recently found, yes found a DVD player headunit for a car in the desert. The touch portion of the screen, which was glass, was shattered, but the screen itself was intact. (More or less, save some scratches and the erosion of the matte finish in some areas)

I have gone through the unit, and found two power coupling capacitors to have burst. I cleaned out what I assume to be a years worth of dust and cobwebs from inside the unit. I used an automotive strength cleaner (As I frequently do with electronics) and a plastic bristle brush to clean off the garbage from the two main boards, and the other smaller boards. I replaced the burst capacitors with higher voltage rated units and have found that the unit actually powers on.

However, the horizontal sync is random.

It seems if I tap the screen driver board, or align it a different way, it has an effect on the randomness or "H hold".

I truly appreciate any ideas on this.

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Thank you!
Dave
 
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Your picture actually shows a vertical sync problem.

If you could identify the vertical sync section (maybe by the markings on the board), you could test components randomly in that area.

If it had burst electrolytics in it, it may have had reverse voltage applied to it. So, other smaller electrolytics could be faulty, too. They would be a good first choice anyway.
 
My fault, horizontal sync.

I have a theory, and that is that the caps blew, rendering it nonfunctional, at which point they discarded it. My only supporting evidence is the fact that there was a CD in the cd drive. I though that it was possible that when the power died the cd was essentially stuck inside.

I have done some research on the ICs, and I believe the one for display is called the ESS Vibratto ES6168FA, but I could be wrong.

The position of the display board in relation to the ribbon cable definitely has an effect, and when I get the position right, the display will stop refreshing, and slowly turn white.
 
I got it. I took the ribbon out from the other connection, cleaned it with brake cleaner, and used a wire brush to clean the contacts. I also used a small utility knife to go in between the leads in the ICs and a spray of brake cleaner, too. It did the trick.

Now, to clean out the dvd player drive. It is really a mess, dented in a little and something is binding somewhere.

It's too bad they shattered the touch glass.

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ICs tend to fail catastrophically but electros and printed circuit board tracks give the sort of problem you are seeing. Your device doesn't have much wrong with it.

I'd go over the printed circuit with a small stiff brush and whatever cleaner you have available. Then rinse and let it dry before applying power. Try flexing the board slightly to see if this affects the sync problem.

Then start replacing electrilytic capacitors. These are fairly cheap and they do deteriorate with age.
This is a gamble and you might manage a cure or you might throw the whole thing in the bin.

I guess it isn't worth getting it fixed commercially?
 
To be honest, I was taking my street cruiser offroad and exploring a new section of desert when I came across the ubiquitous "dump" of garbage, usually electronic, in the desert. What caught my eye was the headunit. I thought there was no way, so I looked closer, had the lcd been cracked I'd have left it, but it was intact.

Honestly, if I cannot fix this unit myself I really don't have the money to have it fixed.

I have emailed a company who sells it, and the manufacturer to see if I can get a replacement for the touch screen glass. It does have remote capability, so if I got a hold of the remote, then I might be able to control it that way.

The LCD screen itself has some pretty deep scratches, and the matte antiglare finish has corroded away in some spots.

I have the CD drive mechanism 30% apart, which was so dusty and sandy it didn't budge, but now it's pretty free after a dose of brake cleaner, and slick 50 lube.

It was like this, if the caps didn't fix it I'd toss it, because honestly, it was just rained on and snowed on several times in the past few days alone. I replaced two caps and traced the +, and it gave me a three tone beep, I was pretty stoked, and when I saw the screen come on I was really stoked. At the very least it can be a monitor, it has a slew of inputs and outs in the back of it.

Anyone know where I can get a 6.5" diagonal piece of touch glass? All I know is that the ribbon cable for the touch glass is a 4 conductor. Hopefully I can source a replacement from the manufacturer (In hong kong, but who knows) or an outlet who sells the unit.
Dave
 

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