Turboexpress LCD mod

SmokeMonster

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I think all of these screens are 5v-12v even if they don't state it. Everyone is running them on 5v without problems at least.
 

Genki

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That makes sense, if it runs 5v internally, it would work even if it was designed to run off car's 12v system. Ihave an LCD module coming in and my TE is coming back after getting recapped professionally (I didn't have the tool or experience to safely remove SMD caps and didn't want to ruin it)

The original LCD on TE took analog RGB and inverted sync (and negative 21v, probably LCD contrast?). If only small RGB display could be found today, it would be so much easier than hacking onto a chip to create ghetto composite signal. I plan to probe the LCD controller chip to see if it can take input beside composite, it is possible some chip can take separate video and RGB and just not used because most cheap backup camera only outputs composite to allow for cheaper wiring (1 shielded wire vs 3 or 4) and less hassle of getting correct wiring by people who don't understand electronics well.
 

duo_r

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Yup I'm using a 12v backup camera for a car and works just fine on 5V.
 

Genki

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I got the LCD in (a week late, it was held up half way to me for a week with no explanation) and I've already taken it apart. It employs AMT630 chip to handle video conversion to LCD. According to a random datasheet I could find, it takes Four Analog Inputs: 1xCVBS+1xS‐Video or 3xCVBS Input

No RGB input (darn) but S-Video is unexpected. With 3.5" LCD I doubt anyone can really tell if it's composite or S-Video anyway. I have no idea where 4 input came from since it only listed max 3 composite. Also this explains why we get stuck with "AV1" on screen at times.

I just need to get some time to actually start the mod. Any idea where I could get nice front screen cover suitable for 3.5" LCD? It'd be a shame if I scratched a mint cover trying to expand the opening.
 

duo_r

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You will need to purchase some plexiglass and file it down to fit.

I will also look into the bezel some are asking about. You can't mod the original bezel to fit the new screen
 

SmokeMonster

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Jan 25, 2014
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I got the LCD in (a week late, it was held up half way to me for a week with no explanation) and I've already taken it apart. It employs AMT630 chip to handle video conversion to LCD. According to a random datasheet I could find, it takes Four Analog Inputs: 1xCVBS+1xS‐Video or 3xCVBS Input

No RGB input (darn) but S-Video is unexpected. With 3.5" LCD I doubt anyone can really tell if it's composite or S-Video anyway. I have no idea where 4 input came from since it only listed max 3 composite. Also this explains why we get stuck with "AV1" on screen at times.
Great finds Genki. Actually, S-video input is really interesting. If we can't have RGB, that is a damn-fine alternative.
 

fluxcore

Another Striker
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Nov 4, 2013
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324
I got the LCD in (a week late, it was held up half way to me for a week with no explanation) and I've already taken it apart. It employs AMT630 chip to handle video conversion to LCD. According to a random datasheet I could find, it takes Four Analog Inputs: 1xCVBS+1xS‐Video or 3xCVBS Input

No RGB input (darn) but S-Video is unexpected. With 3.5" LCD I doubt anyone can really tell if it's composite or S-Video anyway. I have no idea where 4 input came from since it only listed max 3 composite. Also this explains why we get stuck with "AV1" on screen at times.

I just need to get some time to actually start the mod. Any idea where I could get nice front screen cover suitable for 3.5" LCD? It'd be a shame if I scratched a mint cover trying to expand the opening.

Nice. In the interests of clarity, can you post which LCD you bought?
 

Genki

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Nice. In the interests of clarity, can you post which LCD you bought?

http://www.ebay.com/itm/400906132184 This one. It was one of the 2 LCD suggested a while back on this thread. The plastic housing is held on by 4 clips, 2 on top and bottom. The LCD itself is glued on to the front cover and would need to be removed carefully to avoid breaking it. It also has audio support, I'd suggest wiring the audio in to ground to keep it silent.

I checked the schematic of LCD mod, it looks easy enough. The popular design has 4 pins from HuC6260 lifted off the pad and wired through resistor than a single transistor. To make it S-Video, you would need to wire only 3 to one transistor, and luma (pin 40) through a resistor then another transistor. I still need to figure out where to attach the amplified luma and chroma as the LCD board isn't marked for S-Video input.
 

Genki

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From this thread about LCD mod: http://pcengine.freeforums.org/express-gt-composite-t179.html

I took the original schematic from thesteve and made alteration for S-Video support. I have to test it though.
KEh9hor.gif
 

Genki

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Ok the docs I can find sucks. I can't find anything to tell me how to set default input so it may still boot up AV1 mode and needing button to change to S-Video mode.

Second, here's a shot of the LCD board: http://i.imgur.com/AESa2p7.jpg (large image) if I am reading the spec correctly, one of the 2 pins I need for S-Video is not connected to anything on PCB. The pins are very tiny even compared to TurboExpress chips. The resistors you see are about 4mm by 2mm and those are tiny. The pins on the chip is even smaller, one would need very fine point iron and not have the shakes (like excess caffine) to solder on one wire.

I am still going to try and check this to see how well it can switch to S-Video. I have a few S-Video devices that I'll use to test with before I try modding my TE. If I can get S-Video working without cooking the board, TE would be much easier. But if I need to do extra steps to get S-Video mode and can't get it to work by default, I'll fall back to composite.
 

Genki

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I hang my head in shame. I couldn't get it to work. I've tried and got either scrambled video or only B&W video. I did some probing, and found 2 of the 3 analog inputs are tied together, connected via a capacitor to ground. I guess that needs to be changed to enable different input but the spec I could find is about as useless as red light in Grand Theft Auto games.

So back to good ol' composite hack. Taking a break, trying to solder on 4 resistors to tiny pins took a lot of time and patience. The LCD panel still work despite the failed S-Video hack.
 

duo_r

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I will have to check but I think there is more missing in the S-video circuit that what you have there. Have you tried adding S-video to a PC Engine / TG16 yet?

I would try that first get familiar with how to add that then give this a shot. The Turbo Express is usually missing more components compared to the console versions so there might be a couple more components you need to add.
 

Genki

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I will have to check but I think there is more missing in the S-video circuit that what you have there. Have you tried adding S-video to a PC Engine / TG16 yet?

I would try that first get familiar with how to add that then give this a shot. The Turbo Express is usually missing more components compared to the console versions so there might be a couple more components you need to add.

I had not modded my TE when I was trying to get S-Video input working. I was using S-Video out of my SNES which I know was working fine with my regular TV. Since SNES image came up either black and white or scrambled no matter which analog inputs I tried, it had to be something on the board that sets the video mode. I went ahead to do composite on my TE and did the mod. I also got a second LCD so I could keep trying, using the VGA to composite/S-Video converter that I found at Goodwill recently for a few dollars (works)

EDIT: just took apart the new LCD I just got. Same seller but the board inside is different! Still using same AMT630 but the layout and all are different so I have work cut out checking to see if components connected to analog inputs are same or not.

EDIT2: I think the second LCD is garbage. It worked fine when I tested off my laptop via VGA to composite and composite from SNES but when I tested it on my modded TE, the picture rolled. I think I may go postal on those cheap Chinese trash that can be just so slightly unreliable it seems to work on normal spec but fails on hacks.
 
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BladeDancer314

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The turbo express is picky, I've had tons of LCD screens were the picture rolls, I've never found a fix.

The Steve said the LCD is incompatible, get a diff. one
 

Genki

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And I am finally done!!! This LCD: http://www.ebay.com/itm/181529434603 worked with my Express and it doesn't have buttons installed so I didn't need to remove it to make it fit. I don't have a final lens, I just trimmed the original lens that came with the LCD panel as it's already convenient sized window with border. Just carefully traced from the original Express lens, applied double-sided tapes to the back, cleaned of anything then installed the temporary cover. It looks very nice.

It does have the annoying AV1 on power on for a few seconds.

I'll post pictures later.

EDIT: pictures!
Whole thing. I didn't do well on trimming the original lens cover so there's uneven spots but it'll keep the prints off the LCD itself.
Without flash on my camera
 
Last edited:

Black_Tiger

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And I am finally done!!! This LCD: http://www.ebay.com/itm/181529434603 worked with my Express and it doesn't have buttons installed so I didn't need to remove it to make it fit. I don't have a final lens, I just trimmed the original lens that came with the LCD panel as it's already convenient sized window with border. Just carefully traced from the original Express lens, applied double-sided tapes to the back, cleaned of anything then installed the temporary cover. It looks very nice.

It does have the annoying AV1 on power on for a few seconds.

I'll post pictures later.

EDIT: pictures!
Whole thing. I didn't do well on trimming the original lens cover so there's uneven spots but it'll keep the prints off the LCD itself.
Without flash on my camera

Looks very nice. :)

Did you set it up so that the screen has an on/off switch on the exterior of the Express? I bought one with every possible mod and the screen switch is there so that it doesn't drain the built-in rechargeable battery pack when the TurboGrafx-16 portion is turned off.
 

Genki

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Looks very nice. :)

Did you set it up so that the screen has an on/off switch on the exterior of the Express? I bought one with every possible mod and the screen switch is there so that it doesn't drain the built-in rechargeable battery pack when the TurboGrafx-16 portion is turned off.

It does depend on where you tapped for LCD power. Mine's after the power switch that powers the whole TE so when it's off, the LCD s off.
 

BladeDancer314

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Dec 8, 2013
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You gotta take your time with the screen cover.

It's probably my most disliked part of the LCD mod.
 

Electric Grave

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So, what's with the pic with all those units, are you gonna sell them or are they sold already? What's the scoop?
 

Genki

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Jun 15, 2015
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Anyone have a template for replacement LCD lens? I never finished my mod and it still has the ugly chopped up LCD screen cover and I wanted to replace that with a nice plexi sheet but somehow I've lost the original TE lens.
 

duo_r

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The replacement should be slightly bigger that is how I did mine so you don't have to exactly match the size, you just need to cover up the space behind. Just trace the shape and make to slightly bigger and make sure you dremel it to fit flush.
 
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For some reason I can't click on pictures or view profiles, it says I don't have permission.

I have a TE and all needed parts to upgrade to the 3.5" screen, but I have a few questions. If any of you are still around that would be willing to help, would you please email me at jameskenney1@comcast.net or if someone could message bladedancer314 and ask him to message me that would be amazing.

Thank you!
 

Neodogg

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For some reason I can't click on pictures or view profiles, it says I don't have permission.

I have a TE and all needed parts to upgrade to the 3.5" screen, but I have a few questions. If any of you are still around that would be willing to help, would you please email me at jameskenney1@comcast.net or if someone could message bladedancer314 and ask him to message me that would be amazing.

Thank you!


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