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 Post subject: Re: TV RGB mod thread
PostPosted: Tue May 02, 2017 1:35 pm 



Joined: 07 Aug 2006
Posts: 391
Location: Sydney, Australia
jwo825,

Be careful with old television sets that don't have any A/V inputs. Many of them have a live chassis. That means the ground of the TV set is not isolated from the mains power input. You can get an electric shock just from touching the set's ground while it's switched on. It's not a problem for normal operation because there's no exposed metal on these sets except for the RF connection, which is isolated. Live chassis power designs stopped being popular once AV inputs became standard as the cost of extra A/V isolation circuitry was greater than the cost of making a safe, isolated power supply.


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue May 02, 2017 2:13 pm 



Joined: 29 Nov 2016
Posts: 36
viletim wrote:
jwo825,

Be careful with old television sets that don't have any A/V inputs. Many of them have a live chassis. That means the ground of the TV set is not isolated from the mains power input. You can get an electric shock just from touching the set's ground while it's switched on. It's not a problem for normal operation because there's no exposed metal on these sets except for the RF connection, which is isolated. Live chassis power designs stopped being popular once AV inputs became standard as the cost of extra A/V isolation circuitry was greater than the cost of making a safe, isolated power supply.


Thanks. Fortunately, I grew up in the CRT era and know all about the potential for electric shock. I made myself a discharge tool and made sure to discharge it and double check with the volt meter before going in there.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed May 03, 2017 3:05 am 


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Joined: 26 Jul 2016
Posts: 93
I think I'm done with the board. It's pretty simple, I just did what the datasheets told me to do. But this being my first, there's probably a bunch of layout don'ts and I could probably keep tweaking it for who knows how long, but I think this will do for now. Those that know EE/PCB design, I'm open to any tips. I tried to make it look nice at least. It's small too; 45mm x 60mm, 1.77" x 2.36".

Image

Image

I was originally going to etch it myself, but I think I might get it done professionally. So I figured I'd ask if anyone here would be interested in getting in on that. I've got a day job, so I'm not looking to start a business here and everyone is free to make their own copy (guess I'll have to upload the files somewhere eventually).
I think it'd be under $10 a board. Additional parts are 12 (or 9) resistors, 6 capacitors, 3 ICs and an on-off switch. This comes to an additional $5-10, depending on where you buy it.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed May 03, 2017 7:42 pm 



Joined: 20 Jan 2016
Posts: 72
suprcrackers wrote:
tjsynkral wrote:
In my experience with SNES, the very first models with the separate sound unit and S-ENC video chip put out very soft and drab RGB (as well as S) and barely worth upgrading that model from S to RGB. However, if you modify that model SNES with component output, the sharpness is fantastic and you get perfect square pixels. The only downside is the color temperature is noticeably different from RGB and other video outputs, so you'll be adjusting the color settings on your TV when you switch.

The SNES Jr provides great RGB with the RetroRGB board (I added S and CSYNC as well). It's not quite as sharp as the component mod for the S-ENC model but it's much better than the original and you don't have the calibration issues.

Side note, I don't have experience with the later SNES Phat 1-chip models.



So are you saying a component modded 1st gen SNES has a superior picture to a 1chip RGB modded SNES that uses a 7374? Or are you basing your findings of the old 7314s or off the standard stock RGB output with resistors to reduce the brightness?

I'm asking because on my 1chip I just took 750ohm resistors to ground and called it a day. I thought the picture looked pretty good compared to my old first gens RGB, but I have always wondered how a 7374 based solution would look in there. I really liked the results in had with my PC Engine using the 7374. Interested in doing a component mod to my first gen SNES too. Thanks.


I just said that I have no experience with the 1chip :D (Are you including the Jr. in your definition of 1chip? They're not the same thing.)
I think it's highly down to personal preference whether S-ENC or SNES Jr. RGB is better. They're both excellent, but I tend to favor the Jr. because I prefer hooking up with SCART and I don't need to re-adjust the color settings on my TV.

I still think the pixel edges are sharper with the component modded S-ENC SNES.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed May 03, 2017 7:52 pm 



Joined: 20 Jan 2016
Posts: 72
KnuckleheadFlow wrote:
I think I'm done with the board. It's pretty simple, I just did what the datasheets told me to do. But this being my first, there's probably a bunch of layout don'ts and I could probably keep tweaking it for who knows how long, but I think this will do for now. Those that know EE/PCB design, I'm open to any tips. I tried to make it look nice at least. It's small too; 45mm x 60mm, 1.77" x 2.36".

I was originally going to etch it myself, but I think I might get it done professionally. So I figured I'd ask if anyone here would be interested in getting in on that. I've got a day job, so I'm not looking to start a business here and everyone is free to make their own copy (guess I'll have to upload the files somewhere eventually).
I think it'd be under $10 a board. Additional parts are 12 (or 9) resistors, 6 capacitors, 3 ICs and an on-off switch. This comes to an additional $5-10, depending on where you buy it.


It seems like a lot of wasted space to me - you could fit 2 boards in the same space if you made it more compact. You could also redesign it to eliminate the 3 links.
Why resistors on the output? I would want the RGB outputs to go through 0.1 or 0.01 caps and nothing else.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed May 03, 2017 7:54 pm 



Joined: 20 Jan 2016
Posts: 72
Pikkon wrote:
Here's my component modded super fami running on my trinitron.

Image


It looks pretty nice, how did you wire yours? I ask because the way I wired mine up doesn't match any of the diagrams on the internet and I'm curious if you went with the internet plans or did your own thing.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed May 03, 2017 8:27 pm 



Joined: 14 Apr 2017
Posts: 4
Any people with osd mods could test this image please?, I wonder what ranges are you getting :

Image


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed May 03, 2017 8:29 pm 


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Joined: 10 Jan 2014
Posts: 405
Location: USA
tjsynkral wrote:
(Are you including the Jr. in your definition of 1chip? They're not the same thing.).


Yes, for all intents and purposes they are the same. The 1CHIP SNES and SNES Mini differ only any board routing and PCB size.
_________________
For console modding, please send all inquiries to sales@voultar.com
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 Post subject: Re: TV RGB mod thread
PostPosted: Wed May 03, 2017 10:00 pm 


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Joined: 26 Jul 2016
Posts: 93
tjsynkral wrote:
It seems like a lot of wasted space to me - you could fit 2 boards in the same space if you made it more compact. You could also redesign it to eliminate the 3 links.
Why resistors on the output? I would want the RGB outputs to go through 0.1 or 0.01 caps and nothing else.


I'm not sure what you mean by 3 links.
The resistors on the output are there as specified by the LT1675 data sheet. It's an amplifier too with the output twice the input voltage and the data sheet mentions it needs to be terminated, with no caps added on the pins.

I laid it out with hand soldering in mind so I used relatively big 1206 components mostly and left the option to use headers on the input and output. I also wanted to have three resistors in line on the input for 0.5 Vpp TVs; for 0.7 they can be jumpered. I suppose I could have squeezed everything closer together at the cost of making assembly more annoying, but I don't think by half. Besides, I think it's already pretty compact frankly. It is after all only about the size of my two thumbs.


Last edited by KnuckleheadFlow on Wed May 03, 2017 11:03 pm, edited 1 time in total.

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 Post subject: Re: TV RGB mod thread
PostPosted: Wed May 03, 2017 10:08 pm 


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Joined: 15 Apr 2016
Posts: 47
Knuckleheadflow, I would be down for ordering a couple of those boards to try out.


Last edited by suprcrackers on Thu May 04, 2017 12:40 am, edited 1 time in total.

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 Post subject: Re: TV RGB mod thread
PostPosted: Thu May 04, 2017 12:36 am 


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Joined: 26 May 2015
Posts: 4
tjsynkral wrote:
Pikkon wrote:
Here's my component modded super fami running on my trinitron.

Image


It looks pretty nice, how did you wire yours? I ask because the way I wired mine up doesn't match any of the diagrams on the internet and I'm curious if you went with the internet plans or did your own thing.



Thanks,the board is a SNS-GPM-CPU-01 or 02.

All I did was add a 100uf cap to the Pr and Bp and for green I took it from pin 7 of the multi out and added a 100ohm,did a pal snes the same as well.

And I have done the SHVC-CPU-01 and I used this and it came out good.
https://gbatemp.net/attachments/comp-jpg.44482/


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 Post subject: Re: TV RGB mod thread
PostPosted: Thu May 04, 2017 4:34 pm 


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Joined: 26 Jul 2016
Posts: 93
tjsynkral, dude! You were so right. There was tons of wasted space.
I decided to throw out my ideas of how it should be spaced out and wanted to see how close I can make everything without any other considerations. About halfway through I realized it won't be that much harder to hand solder and that I like this layout way better. The board is now 42.5mm * 25mm, 1 2/3" * 1". That's less than 40% of the original area!

Image

Image


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 Post subject: Re: TV RGB mod thread
PostPosted: Fri May 05, 2017 2:06 am 


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Joined: 24 Jul 2016
Posts: 69
KnuckleheadFlow wrote:
tjsynkral wrote:
I also wanted to have three resistors in line on the input for 0.5 Vpp TVs

Out of interest, because I'm about to mod a 0.5Vpp input set, what should the value of those resistors be for a 0.7Vpp source?

The board is looking pretty nice!


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 Post subject: Re: TV RGB mod thread
PostPosted: Fri May 05, 2017 4:46 am 


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Joined: 26 Jul 2016
Posts: 93
Thanks, I can't wait to actually have one.
When a TV has 0.7 Vpp OSD, that's the same as most RGB video sources and no voltage divider is needed; so 0 ohms.
Image

That's what I meant by jumpered. You could just put a wire across the pads, but if you're ordering other resistors already and they're 100 for $1.00...

E: And just to show how small it really is:
Image


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 Post subject: Re: TV RGB mod thread
PostPosted: Fri May 05, 2017 5:14 am 


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Joined: 24 Jul 2016
Posts: 69
KnuckleheadFlow wrote:
When a TV has 0.7 Vpp OSD, that's the same as most RGB video sources and no voltage divider is needed; so 0 ohms.

That's not what I wrote :)

I have a 0.7Vpp source, but the jungle IC takes the OSD at 0.5Vpp. I imagine a simple 2/5 ratio divider would do the trick. Assuming I just throw in a regular 75R termination to ground, that would make the missing resistor 30R...?


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 Post subject: Re: TV RGB mod thread
PostPosted: Fri May 05, 2017 5:18 am 


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Joined: 26 Jul 2016
Posts: 93
buttersoft wrote:
KnuckleheadFlow wrote:
When a TV has 0.7 Vpp OSD, that's the same as most RGB video sources and no voltage divider is needed; so 0 ohms.

That's not what I wrote :)

I have a 0.7Vpp source, but the jungle IC takes the OSD at 0.5Vpp. I imagine a simple 2/5 ratio divider would do the trick. Assuming I just throw in a regular 75R termination to ground, that would make the missing resistor 30R...?


Oops, misread that. Yes, 30 ohms for 0.5 V.


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 Post subject: Re: TV RGB mod thread
PostPosted: Fri May 05, 2017 5:27 am 


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Joined: 24 Jul 2016
Posts: 69
Cheers for confirming :)


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed May 10, 2017 12:42 pm 


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Joined: 24 Jul 2016
Posts: 69
So i'm having a problem with the chassis from a Teac CT-M5122H. The RGB is connected through IC101 pins 14-16, with pin 13 as blanking. It works fine, i haven't yet adjusted the levels, but the interference in the picture is really, really bad. I've tried disconnecting the OSD at R635-R638, reconnecting it, and a few other things. The picture is crawling with grey, almost horizontal lines that bow a bit in the middle. Removing R655-R658 seems to make the problem worse.

Service manual, with schematic on last page - https://track5.mixtape.moe/rnatkf.pdf

Any ideas?

(Note that the service manual contains a mistake - pin 16 of IC101 is not connected to the blanking line near R655-R658)

EDIT: I really need to try taking the input caps right out of circuit so nothing from the filter caps near the missing ICs 801 & 802 can interfere...? I'll try it and report back.

...Nope. Made the noise problem far, far worse. I'm going to have to think about this one, but any help would be much appreciated :)


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 Post subject: Re: TV RGB mod thread
PostPosted: Thu May 11, 2017 7:01 pm 



Joined: 14 Apr 2017
Posts: 4
Are you guys making sure your consoles are producing a standard video signal?, Tim mentioned it is critical:

http://members.optusnet.com.au/eviltim/ ... m#megamstr


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 Post subject: Re: TV RGB mod thread
PostPosted: Fri May 19, 2017 12:56 am 



Joined: 18 May 2017
Posts: 6
Hey guys,

I have posted a new thread for my LG CA-20F80 that I have investigated RGB Scart modding. It turns out for certain LG chassis models you only need to replace the Composite jacks with a Scart jack for a simple mod that costs about 4 US Dollars and requires just some easy soldering and a change to the service menu.

http://shmups.system11.org/viewtopic.php?t=60010

I hope this is of interest,

Cheers,

MarkOZLAD


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 Post subject: Re: TV RGB mod thread
PostPosted: Sat May 20, 2017 1:06 pm 


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Joined: 24 Jul 2016
Posts: 69
viletim wrote:
The TDA8841 is a 56 pin DIP isn't it? Page 5 for pinout. R, G, B, into pins 23, 24, 25. 'Fast blanking' (RGB enable) into pin 26 (0.9 to 3.0 V). Page 15 of the datasheet mentions that fast blanking for RGB-1 is controlled by the IE1 bit in some internal register. If it's not set to 1 (active) then the blanking input isn't going to work. If this is the case then you'll need pull out the serial EEPROM connected to the micro and dump it. Compare the EEPROM dump to the register map on page 17. See if you can work out which byte contails the IE1 bit. If you're stuck try adjusting the colour saturation and reading it again.


I found a second, identical set, but am still having trouble. The register map doesn't correspond to the location the set is actually storing information on the EEPROM. I can adjust the colour saturation from 32 (50%) to B2 (50% with a leading 1), but nothing changes. And if I then change the saturation, to 51%, the byte resets the leading 1 to a 0, leaving a value of 33. I don't think the IE1 bit is where it's meant to be. I'd really love to be able to get into the service menu, but the remote batteries leaked and the traces are like grilled cheese. The cited service codes uses buttons this remote doesn't have, anyway.

Grrr. It's a nice tube again, but i can't think what to do next. I do get like a half-tone (is that right?) picture with the blanking pin set to 0.8V or so, i may not have tried that low a voltage before, but the picture is ghosted, dim, way off-colour and filled with noise - the same as the other set i was trying that's also EEPROM controlled (3 posts above this one). You can actually see the luma image in the background a little, I think. Only i can't find a half-tone mode setting as i don't have the remote :(


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