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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Sun Feb 18, 2018 10:37 pm 



Joined: 14 Feb 2018
Posts: 6
leonk wrote:
^^^ image broken



Fixed the image link.


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Sun Feb 18, 2018 11:15 pm 


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Joined: 09 Aug 2017
Posts: 1458
Location: Australia
radaxian91 wrote:
Hey guys,


I've installed the borti RGB Bypass board into a 1CHIP PAL SNES but I can't get any output. The instructions say to take CSYNC from pin 151 but that didn't work. I've also tried taking CSYNC directly off the S-RGB chip pin 18 with no luck.

I've followed the instructions here but they don't seem to work... or I've missed something.

Removed so far -

R15, R16 and R17 from the SNES mainboard
R28 and D1

Excuse my long test wires...

[/img]


Even with no sync you should at least get a rolling Image on a crt. If using ossc or gscart then you wint as they need sync to process signal.

If you are using ossc or similar try composite video for sync. If you get a picture then its def your sync that's the issue

I notice between your install and the one below it the RGB lines are on opposite sides of the resistors. Maybe double check that.


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Sun Feb 18, 2018 11:19 pm 


This is a modified version of the GitHub repo, to make the overall usability more comfortable for the end-user while having a single design.

He has to close J3 for getting CSYNC passed to the MultiAV pin 3: https://www.videogameperfection.com/pro ... ypass-amp/
And by the way: S-CPUN pin 151 has an easy access at the bottom side ;)

Image


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Sun Feb 18, 2018 11:40 pm 



Joined: 07 Apr 2016
Posts: 1399
Do I need a low-pass filter for an RGB-modded SNES Mini going to a CRT?


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Feb 19, 2018 3:43 am 



Joined: 14 Feb 2018
Posts: 6
borti4938 wrote:
This is a modified version of the GitHub repo, to make the overall usability more comfortable for the end-user while having a single design.

He has to close J3 for getting CSYNC passed to the MultiAV pin 3: https://www.videogameperfection.com/pro ... ypass-amp/
And by the way: S-CPUN pin 151 has an easy access at the bottom side ;)


Thanks for that.

J2 and J3 were quite unclear from the instructions, but on that new link you sent I see what you mean.

So with J3 closed I now get sync, but still no image.

The RGB points are taken from the vias as in the photo.

FYI - Using this cable wired for TTL pass through sync - https://www.retrogamingcables.co.uk/nintendo/super-nintendo/packapunch-super-nintendo-entertainment-system-snes-n64-rgb-av-scart-cable-ntsc-gold-scart


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Feb 19, 2018 5:15 am 


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Joined: 02 Jan 2016
Posts: 139
radaxian91 wrote:
borti4938 wrote:
This is a modified version of the GitHub repo, to make the overall usability more comfortable for the end-user while having a single design.

He has to close J3 for getting CSYNC passed to the MultiAV pin 3: https://www.videogameperfection.com/pro ... ypass-amp/
And by the way: S-CPUN pin 151 has an easy access at the bottom side ;)


Thanks for that.

J2 and J3 were quite unclear from the instructions, but on that new link you sent I see what you mean.

So with J3 closed I now get sync, but still no image.

The RGB points are taken from the vias as in the photo.

FYI - Using this cable wired for TTL pass through sync - https://www.retrogamingcables.co.uk/nintendo/super-nintendo/packapunch-super-nintendo-entertainment-system-snes-n64-rgb-av-scart-cable-ntsc-gold-scart


What is your setup like? Are you going straight to a PVM or some kind of upscaler?
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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Feb 19, 2018 5:44 am 



Joined: 14 Feb 2018
Posts: 6
unmaker wrote:
What is your setup like? Are you going straight to a PVM or some kind of upscaler?



I've tested it via an RGB CRT and an OSSC.


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Feb 19, 2018 7:55 am 


If you get sync, there might be something different wrong. Does composite video still work?


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Feb 19, 2018 7:56 am 


GeneraLight wrote:
Do I need a low-pass filter for an RGB-modded SNES Mini going to a CRT?

Probably not


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Feb 19, 2018 8:13 am 


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Joined: 18 Feb 2015
Posts: 2334
Location: DFW area, Texas
radaxian91 wrote:


That's the link to the NTSC version. I assume you know the sync pin on NTSC cables would end up going to a power pin in your PAL console, correct? Also is your console a 1CHIP revision? I'm sure you already covered these bases, but I just wanted to be sure on both counts. Edit: I see that you say it is a 1CHIP console, so that's covered then.
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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Feb 19, 2018 8:44 am 


He has removed R28 and D1 from his PAL 1Chip mainboard. This frees pin3 from 12V and makes it useable for CSYNC.

But in general you are absolutely right! People in PAL regions have to be aware of that and have to mark there cables carefully if they have CSYNC cables lying around. Falsely plugged in a unmodified PAL console and powered on ... ouch ... :?
This is also the reason why all my cables are 'Pseudo' sync-on-luma cables. Pseudo, because my consoles are modified to output csync on the luma pin.


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Feb 19, 2018 9:15 am 


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Joined: 18 Feb 2015
Posts: 2334
Location: DFW area, Texas
borti4938 wrote:
He has removed R28 and D1 from his PAL 1Chip mainboard. This frees pin3 from 12V and makes it useable for CSYNC.

But in general you are absolutely right! People in PAL regions have to be aware of that and have to mark there cables carefully if they have CSYNC cables lying around. Falsely plugged in a unmodified PAL console and powered on ... ouch ... :?
This is also the reason why all my cables are 'Pseudo' sync-on-luma cables. Pseudo, because my consoles are modified to output csync on the luma pin.


Okay cool, yeah I was just concerned and wanted to make sure he didn't actually fry something in his console. It is strange that he's not getting a signal from R, G, or B. With all 3 lines not working, there must be something fundamentally wrong with his mod and not just a loose connection.

Anyway, that's a good idea to use the safer luma pin for re-routing csync. Semi-related: I found out the other day that the Neo Geo RGB cables I got from retro access were using composite for sync access. While that works fine most cases, My OCD got the better of me, and I opened the cable up and swapped the csync wire to the csync pin. Works great, and it seems to be a bit easier to dial in perfect sampling phase on the OSSC.
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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Feb 19, 2018 10:19 am 



Joined: 22 Dec 2010
Posts: 227
Now that you have jumper J3 closed try connecting Csync to the via that borti suggested or pin 7 of the S-RGB chip or even S-CPUN pin 151 as you did previously. Pin 18 on the S-RGB chip may not be sufficient in some cases with this mod. I have measured pin 18 on two "S-RGB A" chips and and it was 4.6Vpp which might just about be enough at about 281mVpp once it has been through the amp circuit if you're lucky but the one "S-RGB" chip that I measured was about 4.1Vpp on pin 18 which is a bit low at about 250mVpp once it has been through the amp circuit.


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Tue Feb 20, 2018 2:36 am 



Joined: 14 Feb 2018
Posts: 6
borti4938 wrote:
He has removed R28 and D1 from his PAL 1Chip mainboard. This frees pin3 from 12V and makes it useable for CSYNC.

But in general you are absolutely right! People in PAL regions have to be aware of that and have to mark there cables carefully if they have CSYNC cables lying around. Falsely plugged in a unmodified PAL console and powered on ... ouch ... :?
This is also the reason why all my cables are 'Pseudo' sync-on-luma cables. Pseudo, because my consoles are modified to output csync on the luma pin.



Yes R28 and D1 were removed at the start.

The console now only produces a grey screen with composite after installing this board. It was working beforehand.


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Thu Mar 01, 2018 2:41 pm 



Joined: 01 Mar 2018
Posts: 8
Kind of OT but does anyone have these in stock? Everyone I've checked is out.


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Sat Mar 10, 2018 10:26 am 


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Joined: 22 Aug 2005
Posts: 50
Location: San Jose, CA U.S.A.
I have an interest in connecting a few of my consoles to an arcade monitor, most likely a Wells Gardner 25" K7000 or a Nanao MS8. With the K7000, it seems it can accept the AC coupled video output from the consoles but the MS8 cannot. As of now, I am using Arcade Forge's Sync Strike to harvest RGB, VGnd, and CSync from my retro-access sourced SCART cables then connecting that to a JAMMA fingerboard, then connecting to my JAMMA cab. I want this to work on my Nanao MS8-based cab as well. DC coupled video is required and I am holding out for viletim's next revision of SCART2Jamma whenever that becomes available. Would like to put something together to hold me over until then.

What I would like to know is if the THS73xx, particularly the THS374, series chips output a DC coupled signal that will work properly for an arcade monitor. If so, how do I enable DC coupled output considering that output from the consoles is AC coupled? Thus far, all I know of is Bob's guide here and here. Does simply following Bob's guide achieve this?


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Mon Mar 12, 2018 11:40 am 


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Joined: 22 Aug 2005
Posts: 50
Location: San Jose, CA U.S.A.
Spent some time reading the data sheet over the weekend. Seems Bob's guide captures what I am asking but in more curt terms. So if I am not mistaken, the only thing required for DC coupled output is 75 ohm termination on the output. Page 24 on the data sheet says:

Code:
Note that the THS7374 can drive the line with dc coupling regardless of the input mode of operation. The only requirement is to make sure the video line has proper termination in series with the output-typically 75 ohms.


So basically, if I am not mistaken, follow Bob's guide and I should be fine. Also, if this is true then, doesn't seem that this Sony BVM/PVM monitors are all that much different than arcade monitor when it comes to RGB 15khz input? Learning this stuff is pretty cool.


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Thu Dec 13, 2018 5:38 pm 



Joined: 13 Dec 2018
Posts: 8
Mods, is it possible that images could be uploaded to the forum itself, as attachments, so that photos in this less year old thread would still be present? I have encountered a few of these so far as a new member, and, I really am not trying to be a PITA about it, but, it does result in some lost knowledge in the threads. Several other forums I frequent no longer allow image linking at all, and insist on direct uploads of images (properly size limited to no more than 1024x768, or sometimes 800x600 to limit bandwith usage) to protect against broken or removed image links from third party image hosting sites.
Many thanks for considering it.
-o


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Wed Aug 21, 2019 7:12 pm 



Joined: 09 Oct 2016
Posts: 4
I have installed SNES RGB Bypass Board Vers. 4.1a with S-Video in my SNES mini and am noticing the brightness to be really high. Every component is soldered on the pcb and I have it wired for csync.

Is this expected?


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Wed Aug 21, 2019 7:37 pm 


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Joined: 21 May 2013
Posts: 312
Blonu wrote:
I have installed SNES RGB Bypass Board Vers. 4.1a with S-Video in my SNES mini and am noticing the brightness to be really high. Every component is soldered on the pcb and I have it wired for csync.

Is this expected?

What value resistors are installed for R11, R21, R31 on the bypass board? According to bort4938's readme:-
-for the 'regular' 1Chip model: use 750 Ohm resistors
-for the SNES Mini/Jr.: use 1.2k Ohm resistors


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Wed Aug 21, 2019 8:05 pm 



Joined: 09 Oct 2016
Posts: 4
Here is a picture of the assembled pcb.

https://imgur.com/gx0heiN

I think i assembled the parts as per the BOM. Do the registers look incorrect? I assembled as per the BOM and i think they are https://www.digikey.com/product-detail/ ... -ND/729799


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 Post subject: Re: THS7374 vs THS7314 + 1 chip brightness fixing
PostPosted: Wed Aug 21, 2019 8:44 pm 


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Joined: 21 May 2013
Posts: 312
Blonu wrote:
Here is a picture of the assembled pcb.

https://imgur.com/gx0heiN

I think i assembled the parts as per the BOM. Do the registers look incorrect? I assembled as per the BOM and i think they are https://www.digikey.com/product-detail/ ... -ND/729799

Looks like R11, R21, R31 are correct for SNES Mini, but I cant work out what value resistors have been used for R12, R22, R32?


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