shmups.system11.org

http://imgur.com/a/jPoZK
I made a "idiots guide to rgb modding various JVC pro monitors (TM-H1950CG, TM-H150CG and so on).

Thanks to Mikejmoffit, Voultar and Knuckleheadflow for a lot of the info that gave me the idea and information!

And if I effed up anything, do let me know.

Thanks for sharing the intro. I've added it to the OP.

I followed the JVC 27020 instructions and rather to connecting it to SCART I used VGA. I also went and found a diagram that recommended I put a 1k resistor between the the Sync pin and the H/VSYNC on the VGA (http://www.arcadeinfo.de/showthread.php ... -via-SCART).

When the VGA cable is not connected to anything the screen is blue, as soon as I connect the VGA to my laptop the screen goes black and nothing I do changes it. I am using the CRT EMU driver which works on my crappy arcade monitor so I am certain that is configured properly.

Not sure what to do next.

Assuming this set is one that's suitable. Check the cable and the connections. At a guess, either you're delivering sync but not 5V, or vice versa. If you think you're doing both, disconnect one, then vice versa, and see what happens. Each by itself should turn the screen black, i reckon. If the sync is failing, as in the screen stays blue, lower the value of the resistor in the horizontal sync line. You may need to try various combinations of resistors; different sets are different.

As usual when I post, VileTim will be along shortly to correct me



... so Tim, thanks for your advice on the Samsung set with the TDA8841 jungle chip that had the RGB-inputs shut off. Sadly the EEPROM was a Samsung-special KS24c04 with a protected one-time-only write buffer on the lower addresses. I think my $2 Aliexpress programmer ate it for breakfast - next time i'll tie the WP pin high before i start. Either way the set was no longer able to write to it once the code was corrupt, or to any other EEPROM, so i couldn't adjust anything and then re-read the chip. I had a bunch of fun though, and learned a lot. I've done some EDID programming with the gear since, and the tube is now being used with a different, RGB-hacked chassis in one of my cabs. Let me know if there's ever anything I can do for you. Or better yet, let me buy you dinner when i come up to Sydney later in the year!

I guess I shouldn't assume the proper tv and chip but the model and chip match the instructions I was trying to follow; JVC AV 27020. I have rgb from the chip going to rgb on the vga adapter. I pulled 5v to the chip with an inline switch but not to vga (not sure where that would even go) and the one sync wire from the chip.

With ground connected the screen is black. With ground disconnected the screen is garbled but if a change the background I can see that it is changing on the tv so it is getting some sort of signal. If I pair the 2 VGA sync cables togeather it just show more mess if I put to 1k resistors on the then pair then I just a different mess (read that on another post). No matter what I do though connecting ground always blacks it out.

I know I have the right setup on my machine and the resolution isn't set too high. None of my solder joints are tounching. I am. It sure where to go from here. I can post photos of anyone would think it will help.

Hi guys . I just did my 5th mod but I did have a weird issue, The picture was there but way overdriven. I could not find a service manual for this TV or even a chassis manual so I had to literally open the tv to look at the jungle chip and find the datasheet for it, jungle was a LA7612N. I went with the usual 75ohm termination on each of the color lines followed by the .1uf ceramic cap, the only other thing that I will do this week is add a 1Kohm pot on each of the color lines and find if I can bring the color lines to a suitable voltage for this jungle. Thanks for any advice ahead of time.

I attempted the RGB mod on a Toshiba 27AF61 today, end result was a black screen. It seems 5v being tied to pin 25 for fast blank is working properly, I may be wrong though. I cut the diode input side that connects to pin 25 and wired the 5v VCC from pin 51 to it. I cut the input side of the 0.1 uf caps feeding into the OSD RGB pins and injected my signal there. I also soldered to the s-video connector's luma pin for sync. Could anyone tell me what I may have done wrong? Here are some pictures of how I wired things up and the datasheet. Any input is greatly appreciated, I'm very new to this.

Hi nem, following with interest, have the exact same JVC TM-1700PN (https://cvp.com/pdf/jvc_tm1700pn.pdf)





Schematics I found online: https://www.elektrotanya.com/jvc_tm-1700pn-s_chassis_a17.pdf/download.html

Haven't tried anything yet, will post my disasters, and hopefully victory here.

Update: I believe I terminated the 75 ohm resistors incorrectly, I removed them and I get a clean picture on the words of the OSD. I also found that the tv was not blanking because I ran 5v through the diode rather than directly, and the input voltage needed to be below 2v. After figuring that out, I now have the screen fully blanking, but now it is just a black screen. Could this possibly be because the OSD RGB in on the TA1310 Jungle IC requires 1.25 VPP?

Looks like you terminated the rgb lines incorrectly on your scart plug.

http://imgur.com/a/8PmVY
Your circuit mathces the one on the right, you want it to be like the one on the left.

Edit: just now saw your follow up post
Why not connect to the unused rgb inputs (3-5), and pins 6 and 10 for activating rgb ? Unless you know those inputs to be disabled of course.
If you do try that, remember that the analogue rgb inputs expect 0.5V p-p, so you need a voltage divider to get correct levels. http://i.imgur.com/Ysx1o0k.jpg This would work in that regard.

I'm not sure if they are disabled or not, but I'll try it tonight and report back. Should I pull pins 6 and 10 out of circuit?

I tried this tonight, as well as any other combination of things. I still get no image from it when blanking. I saw that supcrackers attempted an rgb mod on a Toshiba model with the same IC, hopefully he can chime in as to whether he was successful.

[/quote]
I tried this tonight, as well as any other combination of things. I still get no image from it when blanking. I saw that supcrackers attempted an rgb mod on a Toshiba model with the same IC, hopefully he can chime in as to whether he was successful.[/quote]

What pin are you using for sync? From the picture it doesn't seem like sync is going to pin 38.

Excellent, then there's two of us.

For the record, my efforts resulted in failure. I might return to it at some point when I have more time.

Sorry I just saw your post. I tried unfortunetly when I was wiring everything up, my wife walked past the dissembled set on the ground. Her skirt snagged the pins on the neck. What followed was a crack and a long hiss. Sorry I wasn't any help, its my wife's fault.

You may need to isolate all the pins you're connecting to if they are connected to ground or to the OSD. I always point out that lifting pins is the hardest way of doing it. Best option is to find a component in series that you can remove, or a trace you can cut.

Pin 6 is blanking for 3-4-5, pin 10 is blanking for 7-8-9. It is possible that the spare RGB input does not work, so be prepared to try the OSD input instead.

Finished off my 5th crt RGB mod, this time on a 32" RCA F32685. Took 2 days cause at first the image was way over driven, so my boy |Ben Fong suggested some series resistors on the color lines. I decided to go for 1k pots to be more flexible in finding this tv's sweet spot. Thanks to Ben also for making a nice neat hole for the scart and switch. This one was a bit of a crap shoot because I could not find the service or chassis manual. So I did not know if it was mod ready until I opened it found the Jungle and looked up it's datasheet. Enjoy guys .

I just got an Apex AT2704S from the dumpster, and I'm seeing RGB in on the jungle IC, but no blanking pin.

Here is the service manual: http://www100.zippyshare.com/v/igsePqps/file.html
and the datasheet for the jungle IC: http://www100.zippyshare.com/v/WmQgyaDD/file.html

Also a different question. Is there a way to have PAL support on this TV with composite and S-Video? It already syncs up correctly, but the picture is black and white.

Everything is there in the datasheet.

You can jump on the bus and flip a bit on in a register:



Or, you can pull the blanking pin logic high manually:






As for out-of-the-box 50/60Hz support. That's entirely dependent on the IC:



If it's triggering on 50Hz, you probably just need to flip a bit to enable the color-burst for PAL encoded transmission, 4.43Mhz.

The first step is to identify the IC. Is it NTSC only or multi?

Then I would read the datasheet.

The IC is the TDA 8843 (rebranded), which does support PAL. I'll focus on RGB for now, and try my hand at PAL color later.

So if I understood correctly, I feed 0.4v to the blanking pin and 0.7Vpp RGB?

Will I need to get an external 4.43 MHz clock if the TV doesn't have one already?

EDIT: I'm also seeing at S.3.9 something about OSD blanking to feed minimum 4v. Anything I should do about that?

EDIT2: Table 67 (also on the datasheet) tells me to tie pin 26 HIGH to enable RGB. Does this TV natively support RGB, and should I even worry about that or just override the OSD regardless?

Interested to hear how you get on. I had a set with a TDA8841, a few pages back in this thread. Exact same datasheet. Feeding the blanking voltage would blank the set, but no RGB would show. Viletim suggested the IE1 bit controlled the RGB inputs being on or off, not the fast blanking per se. (Datasheet P15.) Is your set muxing the OSD into the RGB inputs or RGB outputs of the 8843? If the former, you're set with blanking voltage and RGB. If the latter, you may have to get into the EEPROM and alter the IE1 bit - find my posts further back, and the one on the last page and see what i did wrong there

Still amazed at the tenacity in this thread.

I doubt it will come to this, but, if I wanted to go retro gaming again and wanted one of these TVs, are these posted in FS ever? I think my days of modding are over. Then again, I've not hooked up a game console before the Wii in years. Fucking adulthood...

Hey man don't give up. You can do this. I understand your point on adulthood. I got married 14 years ago in which we got pregnant almost immediately. Gaming started becoming an apple in front of the horse type of thing. It was always over the horizon. The point at which I figured I would have time to game gradually shifted from 22 > 25 > 30 > 40 > retirement > nursing home. Strangely the modding never left me.

Well, I still do some modding... it's just outlandish clothes and not electronics now.

So... some problems. OSD is all black as expected since I cut the OSD RGB lines, and when I flip the switch for OSD blanking, the entire screen goes black. All good so far. When I try feeding in RGB to the jungle IC instead of the OSD, nothing happens. It's just a black screen. Sync is working fine since I am seeing no interlacing and a very faint image (or a full image if I'm using Luma as sync) when the blanking is off. When I turn the blanking on, I continue to get a sync signal, but the screen is entirely black.

On the bright side, I accidentally discovered how to use YPbPr component on this TV, so that's nice, but I still want RGB.

I have tried feeding RGB through a 0.1 uf ceramic cap, and directly, both times tying them to ground with 75 ohm resistors.

Take a look 4 posts above yours

I'm not sure that's the answer, as I failed to achieve setting the IE1 bit, but given it's obviously not working now that's the next step. If you screw up like I did you'll kill the EEPROM though, which will kill the set without a clean replacement, so tie the WP pin high and make a copy first! Make sure to read back over my posts in this thread though, for a complete picture.

That set must have a Micro, and an EEPROM which may feed both it and the Jungle IC. Very importantly - where does the Micro dump the OSD - into the RGB inputs or RGB outputs of the Jungle IC on that set? (If it was outputs you really didn't need to cut the lines. If inputs, I don't see why what you're doing isn't working.)

OSD goes into the RGB inputs.

Rgr. Just wanted to make sure you weren't having the same problem I was. But then again, maybe you are. Like i said, it really should just work for you. I tried every combination of sync/blanking/OSD/RGBinputs, and couldn't get anything to show, even over the OSD. You KNOW your inputs are turned on, the OSD feeds into them - I'm assuming you've traced that, not just taken the datasheet at its word? If so, something else must be going on with the TDA884X series. I'd love to know what.

SUCCESS! I removed the 75 Ohm resistors, and it (almost) started working. Blanking just made the screen black, so I just fed 5v (with a switch) directly to the OSD's blanking output pin, and it worked.

Picture seems too bright, so I'm going to try new 75 Ohm resistors and see how that goes. I am still using 0.1uf caps for RGB lines.

EDIT: 75 Ohm resistors to ground makes it black again. Strange.

EDIT2: Removed the resistors again and just turned the brightness down. Picture looks perfect now.

EDIT3: Pictures:
https://imgur.com/a/Vmt06

Turns out this TV accepts TTL CSync just fine, although I still want to find out how to properly attenuate my SNES Mini.

So what did you do differently? I thought you were feeding 5V to the blanking pin all along?