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#31
Re: FREE VB Display Repairs
Posted on: 2013/5/29 4:50
PVB Elite
Joined 2011/3/10
USA
900 Posts
Top10 PosterLong Time User (8 Years) 30+ Game Ratings
i picked up a tool to magnetize my driver. i also picked up some gratan pan phil #4x1/2" plated sheet metal screws. after installing the newly repaired ribbon cables, i carefully cleaned the mirrors with a q-tip and some compressed air. i then reassembled my vb and started to notice things i never saw before. like the background of the bound high title screen and the lines on the "mario tennis" title. which, naturally, made me think it was related to the cables. LOL. this past year of glitch has made me ultra paranoid and observant.

i did have to open up my vb twice and pull out the cables a fraction of a mm, as dogp suggested.

dogp: i can't thank you enough. my vb can't thank you enough.

cheers!
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#32
Re: FREE VB Display Repairs
Posted on: 2013/5/30 22:53
VUE(xpert)
Joined 2005/9/17
USA
312 Posts
Long Time User (14 Years)
Quote:

DogP wrote:
Quote:

MineStorm wrote:
Pat, what's the fix for a constantly shrinking / expanding image in one display ?

I've never come across one that did that, but it'd have to be something in the control loop of the mirrors. There's an opto that detects the mirror vibrating back and forth... the system counts the pulses and either speeds up or slows down the mirrors to make it oscillate at exactly 50Hz.

IMO, the opto is the most likely culprit... either it's just dirty, or could be failing. There could also be a problem with the wiring, or the circuit that drives it, but since the other eye is working fine, I'd say that's less likely. I guess it's also possibly caused by a mechanical failure.

If you have a scope, you could look at the opto pulses and make sure that they're actually happening, and at a constant rate... otherwise I'd first check that the wiring is all connected well, and try blowing out the opto area. I don't think the system will run open loop if there's no signal at all from the opto (I seem to remember the display going black when I've stopped the mirrors)... though I'd have to try again to confirm.

DogP


So, interesting that this should come up.

I put together the first of my two repaired VBs last night and started playing GPinball. First off, the fix worked *perfectly* -- the game works 100% and looks great. The Lens of that VB is a bit busted, so there's a little smear, but I got back to enjoying my games and it was a lot of fun. :) Thanks again, DogP!

At one point, I started focusing on the starfield in the background and I saw the whole image start to expand just a little bit and snap back to the right size. It kept doing this. I didn't think to see if it was on one eye versus the other, though; will check tonight.

DogP: Can you show on a picture exactly where to look on a VB for any trouble? I don't have a scope at home, but I work with a fully-stocked electronics workshop with a number of guys that could help me out. But I have no idea where to look on the device...
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#33
Re: FREE VB Display Repairs
Posted on: 2013/5/31 5:54
PVB Elite
Joined 2012/7/9
USA
833 Posts
Top10 PosterLong Time User (7 Years) 20+ Game Ratings
I resent the package with tracking and sent you the PayPal amount.
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#34
Re: FREE VB Display Repairs
Posted on: 2013/5/31 6:10
PVB Elite
Joined 2011/3/10
USA
900 Posts
Top10 PosterLong Time User (8 Years) 30+ Game Ratings
What is the best way to clean the mirrors? I'm getting black lines that I assume are dust on the mirrors. They are noticeable on solid red backgrounds. I'm seeing more in the left eye, so that would be the right mirror?

I tried to gently rub them down with a Q-tip but it didn't seem to work very well. Compressed air didn't seem to help much, the particles I see on there are stuck. I'm also afraid to really shoot them with the compressed air for fear I may break something.

I did clean out the red lenses so I am assuming these lines are dust particles on the mirrors.
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#35
Re: FREE VB Display Repairs
Posted on: 2013/5/31 8:38
PVB Elite
Joined 2003/7/25
USA
1507 Posts
PVBCC 1stCoderContributor#3 PosterHOTY09 EntryLong Time User (15 Years) App CoderPVBCC 2010 EntryPVBCC 2013 Entry
Quote:

jrronimo wrote:
DogP: Can you show on a picture exactly where to look on a VB for any trouble? I don't have a scope at home, but I work with a fully-stocked electronics workshop with a number of guys that could help me out. But I have no idea where to look on the device...

Since I've never troubleshot this problem, it's hard to say exactly what to look at... but here's some technical info and pics of what I'd look at.

The first pic is just the stuff to look for. On the left is the servo PCB, the right is the display assembly. The second pic shows a closeup of the board. You can see the opto with the flag (attached to the mirror) that breaks the beam as the mirror moves.

The third pic is the back of the board. There's an IR LED, and two phototransistors in that plastic housing. The pins that I'd look at are pins 4 and 5. Those are the outputs of the phototransistors. What happens is the LED shines light, and the signal from the phototransistors changes when the flag moves back and forth blocking the light. The servo PCB looks at that signal to make fine adjustments to the mirror drive. I removed the screws to show the slot... it's possible that the board needs to be adjusted to get the proper signal... though I'd be careful, since you could definitely make it worse. But to adjust it, just loosen the screws and slide the board forward or backward.

The last pic is a pic of what pins 4 and 5 look like on the scope. Notice that it's a 100 Hz square wave (the displays oscillate at 50 Hz, which passes through 0 twice per cycle). You should see nice square waves like that... if you see skinny rounded bumps instead, then the board probably needs to be adjusted (as I talked about above), and if the signal is really weak, then you probably either need to clean the opto, or replace it (either the LED or phototransistor is getting weak). In my case, you can see the one signal is about ~500mVpp, and the other is ~750mVpp.

Of course it's not easy to probe those pins... I probed them at the connector that goes between the opto board to the servo board... they're pins 3 and 4 (though that's still a bit buried, so I used a small wire clipped to my scope probe).

I'd also verify that all the cables between the boards are securely connected. If only one eye is having a problem, I'd guess that the servo PCB is fine.

Oh, and I remembered correctly... the displays are disabled when one of the mirrors stops.

DogP

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#36
Re: FREE VB Display Repairs
Posted on: 2013/5/31 9:00
PVB Elite
Joined 2003/7/25
USA
1507 Posts
PVBCC 1stCoderContributor#3 PosterHOTY09 EntryLong Time User (15 Years) App CoderPVBCC 2010 EntryPVBCC 2013 Entry
Quote:

Dreammary wrote:
I resent the package with tracking and sent you the PayPal amount.

Cool... I wonder why they got returned to you the first time, but hopefully they make it here this time.

Quote:

Lester Knight wrote:
What is the best way to clean the mirrors? I'm getting black lines that I assume are dust on the mirrors. They are noticeable on solid red backgrounds. I'm seeing more in the left eye, so that would be the right mirror?

That's actually a pretty common problem. I've never thoroughly investigated it, but I'm pretty sure it's actually the clear plastic window on the LED display itself, not the mirror. Try swapping your left and right displays and see if the problem changes (probably won't look identical on the other side, since the angles will be different... but it should change).

If it does follow the LED display, then I'd use one of those microfiber cloths that you use for glasses/sunglasses to (gently) clean the window. If it stays the same, then I'd try wiping both sides of the optics on the display assembly (the lens next to the mirror).

And definitely let us know what you find out... that's one of those things that I keep meaning to look into if I ever get around to it.

And BTW, the left eye uses the left mirror and left LED display (and the same goes for the right).

DogP
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#37
Re: FREE VB Display Repairs
Posted on: 2013/5/31 10:53
PVB Elite
Joined 2011/3/10
USA
900 Posts
Top10 PosterLong Time User (8 Years) 30+ Game Ratings
I'll give that a try. In case it isn't the LED can you point out to me the optics on the display assembly?

Thanks!
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#38
Re: FREE VB Display Repairs
Posted on: 2013/5/31 11:11
PVB Elite
Joined 2003/7/25
USA
1507 Posts
PVBCC 1stCoderContributor#3 PosterHOTY09 EntryLong Time User (15 Years) App CoderPVBCC 2010 EntryPVBCC 2013 Entry
Quote:

Lester Knight wrote:
I'll give that a try. In case it isn't the LED can you point out to me the optics on the display assembly?

Thanks!


It's the big lens between the mirror and the LED display... you can sorta see it in the second picture behind the mirror. And if you remove the LED display and look in the hole... that's the other side.

DogP
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#39
Re: FREE VB Display Repairs
Posted on: 2013/6/2 4:01
PVB Elite
Joined 2012/7/9
USA
833 Posts
Top10 PosterLong Time User (7 Years) 20+ Game Ratings
Well according to tracking, it arrived. I sure hope that it's really at your house this time.
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#40
Re: FREE VB Display Repairs
Posted on: 2013/6/3 5:40
VUE(xpert)
Joined 2005/9/17
USA
312 Posts
Long Time User (14 Years)
@DogP: Thanks for taking the time to write that all out. I'll see if I can get some time with one of the guys this week or next (if they're not too busy) to sort this out.


Here's a different problem I'm running into: After putting my second VB back together, one of the displays seems to be "shifted" vertically in relation to the other one. While both displays are functioning perfectly, looking into the unit feels like it is actually damaging my eyesight, haha.

Quote:

DogP wrote:
And BTW, the left eye uses the left mirror and left LED display (and the same goes for the right).


Do you mean that the displays are actually side-dependent? I thought the displays were the same part for both sides. If they're side-dependent, then maybe I put the wrong sides on and that's causing this weird shifted (and painful!) view...?

Either way, does anyone have any tips on aligning the displays vertically? Has anyone else run into something like this?
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