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View Full Version : TV to arcade monitor hacking (56K warning)



li_gangyi
23rd March 2009, 12:01 AM
Ok, I've actually done this a couple of months ago, never got around to posting the info up.

Disclaimer: If you kill yourself, injure someone, damage something, win a Darwin award because of my post, I shall not be liable.

I found a horse racing thingy cabinet at a local dumpster. Disassembled it and found the tube had a broken neck, this is a 14" Toshiba tube.

http://img207.imageshack.us/img207/1192/brokencrtneck.th.jpg (http://img207.imageshack.us/my.php?image=brokencrtneck.jpg)

The chassis in was some kinda 23yr old Eygo unit, kudos to Jomac for identifying and pointing me towards a schematic. Some wire-cutter happy guy went around and cut all the wires between the game boord and chassis, as well as from the chassis to the neck board.

http://img13.imageshack.us/img13/6852/23yroldmonitorchassis.th.jpg (http://img13.imageshack.us/my.php?image=23yroldmonitorchassis.jpg)

Had no idea if the board was actually working or not, I hooked up the board (power supply) and probed the sync pin with my oscilloscope.

http://img21.imageshack.us/img21/5805/compositesync.th.jpg (http://img21.imageshack.us/my.php?image=compositesync.jpg)

So at least now I know it's outputting a sync signal.

I was contemplating doing a tube swap, this would mean I have to get a TV with a suitable tube (same kinda neck diameter and pinout), as well as messing with the deflection coil if whatever on the tube is not suitable.

Went to a used TV dealer kinda place and got myself this.

http://img12.imageshack.us/img12/6360/denvictim14philips.th.jpg (http://img12.imageshack.us/my.php?image=denvictim14philips.jpg)

Phillips model 14GXsomething, don't remember the exact model now, it's in the Phillips Anubis S family. Next was to open the damn thing up.

http://img208.imageshack.us/img208/2262/dehvictimopen.th.jpg (http://img208.imageshack.us/my.php?image=dehvictimopen.jpg)

Alright, Toshiba tube also, but alas the neck diameter was wrong, should've checked that before I got the unit. I then decided to hack and turn the TV chassis to accept RGB signals.

The chassis uses a TDA8362 jungle IC, under a metal shield, a quick google search found me the datasheet and the required pinouts. RGB inputs were on pin 22, 23 and 24 respectively, there were coupling capacitors in place already, I just attached wires to a point before the capacitors. There was also another pin labeled RGBin, on pin 21, this is for blanking and RGB insertion (stuff like the OSD and all are usually RGB in-ned). Reading the datasheet tells me I need 0.9V on this pin during 'data insertion' conditions.

At this point I had my setup like this...

http://img4.imageshack.us/img4/16/seriouslyneedarealworkb.th.jpg (http://img4.imageshack.us/my.php?image=seriouslyneedarealworkb.jpg)

My room is pretty small, so most of the time I have to work on the floor, my table's perpetually messy with my PC games and stuff.

Turned the TV on and started probing around if there was a 0.9V source I can use to permanently enable the RGB inputs. After a couple of minutes I found one, soldered a small jumper wire from that to the RGBin pin (TDA8362 pin 21).

http://img297.imageshack.us/img297/692/rgbin.th.jpg (http://img297.imageshack.us/my.php?image=rgbin.jpg)

I then made a crude long wire from the game board, hooked the sync signal to the AV in, hooked one of the colors to one of the inputs (don't remember which to which, but I just wanted a picture). Aha, I have picture.

http://img6.imageshack.us/img6/440/1stsignofsucess.th.jpg (http://img6.imageshack.us/my.php?image=1stsignofsucess.jpg)

Now I proceeded to gut the TV, transfer the tube and all over to the cabinet, use some standoffs to mount the TV chassis properly inside, hook the wires and colors up properly.

http://img4.imageshack.us/img4/516/cabinternals.th.jpg (http://img4.imageshack.us/my.php?image=cabinternals.jpg)

The picture was far from perfect though, it was too bloody bright and the horizontal was too far off to be adjusted in.

http://img5.imageshack.us/img5/5457/horsez.th.jpg (http://img5.imageshack.us/my.php?image=horsez.jpg)

I then realized I haven't terminated the RGB signals. Installing 3 75Ohm resistors from the signal in to gnd fixed that. I still had the horizontal problem, as well as "AV1" permanently showing in the top corner (didn't see this before as it was too bright).

The AV1 problem I 'fixed' by snipping off a couple of wire-links that are part of the path main microntroller OSD signals take (to the jungle IC).

To fix the horizontal issue, I referred back to the schematic and datasheet, to see how the horizontal pot is wired.

http://img5.imageshack.us/img5/601/horizontalmodification.th.jpg (http://img5.imageshack.us/my.php?image=horizontalmodification.jpg)

Some kinda RC network thingy, dug an 'in the ballpark' resistor from my junk bin and stuck her in.

http://img8.imageshack.us/img8/8305/horizontalmod.th.jpg (http://img8.imageshack.us/my.php?image=horizontalmod.jpg)

Now the picture can be brought back in using the horizontal pot, and about everything is perfect. I don't have vertical hold and RGB gain settings to play with (vertical deflection and all is handled by ICs in this more 'modern' TV), I suppose I could add a potentiometer to individual RGB signals, but I'm satisfied with the color quality.

Focus and all are still present (flyback has these accessible), I suppose you could remove the sound and tuner sections, because these are unused. Luckily for me the TV retains it's AV1 channel setting if it's turned on after turning off, so I don't have to use a remote control or whatnot to switch it on.

Up till now I still have no idea what the title of the game is called. Except for the fact it's made by Tazmi (now Tatsumi).

I hope this helps the next guy who wants to try it, of course it'll be a little different on a different brand of TV etc. Even if you don't manage to get it, please don't throw the tube into the dumpster. Buy a suitable chassis (Jomac has a great chassis I hear, he is a real helpful guy btw), and use the tube.

Phew, this was a long post.

David_AVD
23rd March 2009, 07:58 AM
Well done. Some hard core hacking there. :023:

tnpshow
6th May 2009, 03:06 PM
I just saw this post now - nice work! I'd like to give this a try myself when I get a spare minute.

Any chance of a schematic showing the mods you did to the original to hook it all up?

li_gangyi
8th May 2009, 11:20 PM
Don't have that at the moment, but if I have enough free time later on or there's enough interest I might spend some time drawing them out. (I'm serving in the Army at the moment so I only get weekends off)

tnpshow
13th May 2009, 03:42 PM
If you get the time, please do. I think many would be interested in this mod.

Thanks!

Hewitson
14th May 2009, 01:45 PM
All he did was look up the datasheet for the jungle IC, solder 4 wires to it and terminate them with 75 ohm resistors.

Not trying to bag the mod, I think its great, but its hardly rocket science.

David_AVD
14th May 2009, 04:09 PM
.