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 Post subject: Re: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Sun Mar 07, 2021 6:45 pm 



Joined: 10 Aug 2020
Posts: 7
r757chan wrote:
Hmm, this makes me tempted to just convert RGB to component for the CRT and just forget the RGB mod unfortunately. Is there anywhere on the board you can get voltage from based on what input you set the TV to? If so this could probably be used to trigger a relay or something and still keep everything remote controlled.


Why not just have your source activate blanking? You can usually find a couple volts at the SCART output of most game consoles, which you could simply feed into your blanking line. This way your blanking is automatically activated when your console is powered on, and deactivated when the console is powered off.


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 Post subject: Re: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Sun Mar 07, 2021 7:04 pm 



Joined: 04 Mar 2021
Posts: 5
I'm using a Crosspoint so my plan was to use bnc cables.


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 Post subject: Re: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Fri Mar 12, 2021 4:18 pm 



Joined: 11 Aug 2017
Posts: 51
The IC I was thinking of was the MAX7461.

The output line is pulled low on no sync, high when there is sync. Hook it to your composite sync line, and the output to your blanking pin. The result is that if composite sync is present, RGB input is displayed. No composite sync, you get YPbPr. I suppose you could get dance and use two of them, detect sync on the Y line on YPbPr, and then use logic to determine which to display if both are present.

Image
http://cloud.tapatalk.com/s/604b93a9454ea/MAX7461.pdf


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 Post subject: Re: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Sat Mar 13, 2021 12:23 am 



Joined: 04 Mar 2021
Posts: 5
Thank you, this is promising. Just to make sure I understand what I'm reading since I'm only a little familiar with electrical diagrams and verbiage.

Pin1:
I'd add a wire with a 0.1 uF capacitor in series from my sync line to pin 1. The description says to AC-couple the input with the capacitor and that DC-coupling won't work, which I don't understand. The diagram also shows putting a 75 ohm resistor from the sync line to ground. From what I understand the RGB lines will already need to have 75 ohm resistors to ground, but I haven't seen them as necessary on the sync line. Should I wire one in as the diagram indicates? It might be worth pointing out at this point that sync from the Crosspoint will be TTL and my understanding is that I need to wire a 470 ohm resistor in series to get it down to the correct level. I was thinking I might add this 470 ohm resistor as switchable so I can switch between accepting the higher or lower level sync, in case I want to plug a console directly in to the TV.

Pins 2 and 3:
Wire them both to chassis ground. Presumably they can be bridged together?

Pin 4:
Wire this in before the blanking pin on the JC. Diodes seem like a good idea to prevent the 5v from flowing the wrong ways at this junction. I'm not wording what I'm thinking of very well, sorry. The diagram also shows a 1k resistor to the 5v source. Would this be necessary for this application?

Pin 5:
Wire the 5v source here. I should wire a 0.1uF capacitor between this and ground, I think?


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 Post subject: Re: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Sat Mar 13, 2021 3:02 pm 



Joined: 11 Aug 2017
Posts: 51
Looks to me like you are reading it correctly.

As to AC-coupled vs DC-coupled, you have hit the limits of my understanding, but given that we are working on the low-voltage side of the board, I assume we we are working with dc-coupled.


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 Post subject: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Sat Mar 13, 2021 3:18 pm 



Joined: 11 Aug 2017
Posts: 51
https://www.noiseengineering.us/blog/20 ... -where-why

TL;DR - the diagram as-written is AC-coupled. In other words, the cap and resistor present on pin 1 AC-couple it. There is nothing further to do. Since the sync signal isn’t so different from an audio signal described in the article, we need to treat it the same way.


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 Post subject: Re: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Sat Mar 13, 2021 3:31 pm 



Joined: 11 Aug 2017
Posts: 51
Considering the effort it might take to make a simple PCB that takes the guesswork out of this. Have a handful of pads to solder to - OSD RGB, RGBS input, RGBS jungle then all one should need to do is pull RGB out-of-circuit at the OSD chip and the jungle and solder some wires to those pins, along with the sync input of their choosing. The result should be pretty clean. Not that what we have here is difficult by any means, but that would remove most of the effort and give you a one-stop way to handle it all.

The last time I did this though, I used eagle software on a Mac through a windows VM. Wasn’t a great experience. Need to see if I can come up with something better.


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 Post subject: Re: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Tue Mar 30, 2021 6:08 pm 



Joined: 30 Mar 2021
Posts: 1
I'm looking to see if anyone can help me RGB mod a JVC AV-27BM5. It uses the TA8725AN jungle IC but it outputs R-Y G-Y and B-Y instead of RGB, and the circuit layout seems to be alot different from other mods I've seen online. I plan to run this crt from a VGA graphics card (Ati radeon 5000 with 15kHz driver) but I am having trouble figuring this out. Any help would be greatly appreciated.


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 Post subject: Re: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Wed Apr 07, 2021 8:30 pm 



Joined: 11 Oct 2018
Posts: 11
Cinder wrote:
Hello friends. I am very happy with the beautiful image provided by the sony trinitron crt. I have made several rgb mods and the image is beautiful. But I have a problem with a sony crt tv model kv-21fv12 / 5 with BA5 chassis. The problem is that vertical stripes or bars appear as ghostly on TV. The rgb mod was a success but I would like to know if these stripes are solved with a replacement of electrolytic capacitors. If so, will it be only those in the horizontal section? or recommend changing all of the crt.
https://postimg.cc/rzkB7JXc
https://ibb.co/JkXByMC
https://ibb.co/dBMNYv2
https://ibb.co/Xt1tK01


Have you found a solution for the ghosting/shades at the leftmost edge of the screen? Its mostly noticeable on plain clear colours..
I cant complain at all for the overall quality of the image, but i hope to make it better.

Photo doesnt show the artifact quite well, but it's there..
Image

Image

And here its a pic of the overall quality of the image from the Amiga500 on this set..
Spoiler: show
Image


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 Post subject: Re: Sony BA-5D/BA-5 Chassis TV RGB Mod with OSD Mix
PostPosted: Wed May 12, 2021 9:46 pm 



Joined: 04 Mar 2021
Posts: 5
numbski wrote:
https://www.noiseengineering.us/blog/2017/5/12/ac-vs-dc-coupling-what-where-why

TL;DR - the diagram as-written is AC-coupled. In other words, the cap and resistor present on pin 1 AC-couple it. There is nothing further to do. Since the sync signal isn’t so different from an audio signal described in the article, we need to treat it the same way.


I finally got a few of these MAX7461 in the mail and I couldn't get them to work. My RGB is working just fine with blanking wired into a switch, but when I tried to use a MAX7461 it just left blanking on constantly. I'm assuming I wired something wrong but I couldn't figure out what. Also they were way smaller than I was expecting and very difficult to solder to.

Just as an experiment I removed the 1k resistor between Vcc and LOS and blanking was always off. If anyone has any thoughts on how I should have wired it I would greatly appreciate it.


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