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 Post subject: Re: TV RGB mod thread
PostPosted: Sun Jul 15, 2018 3:17 pm 



Joined: 19 Sep 2017
Posts: 19
boogiemanspud wrote:
Image

Image

I recently modded a Sharp 32uc4. Did the standard 75 Ohm resistors to ground on R, G, B lines, and the .1uf capacitors right before the jungle chip. It works but the image appears too bright. What's the procedure for dimming it a bit? Would trim pots on the R, G, and B lines work? I can dim it through the menu but I'd like the RGB input level to more closely match the rest of the inputs on the tv.

Right now I'm running sync to the green port on the component inputs. I've not seen anything mentioned (I'm up to page 40 lol) but does the sync line need any kind of components, or is it just the sync line coming from your console?

Thanks for any advice!


Nice, seems like you're close enough. As Pikkon mentioned, trimpots will be fine to find the sweet spot, in my experience it will be 75R, 100R or 150R.
your sync is fine as is.


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 Post subject: Re: TV RGB mod thread
PostPosted: Sun Jul 15, 2018 4:43 pm 



Joined: 30 Jul 2017
Posts: 29
Been away from the thread since I successfully modded my 20" Toshiba 20AF41 about a year ago. Haven't had any real issues with it yet other than maybe there is something loose with the RGB/OSD toggle switch because it'll flicker if I wiggle the switch itself in the right way? Not sure as it's barely a problem.

I have kept an eye on craigslist though for the same model as I wanted to try and do it again but even cleaner. Also to just have another original set to compare to. Another 20AF41 did show up but it was some hours away and I didn't care that much. Surprisingly though, this 24" Toshiba 24AF42 showed up nearby recently:

Image

I actually wasn't aware an identical 24" version of this set existed. My 20" is big enough, plus it's the same size as I had back in the day so I have something of a connection with it, and I figured 24" would be too big for the stand and area I have it in but.. I told the person if there was no interest in it I'd give her $20. She eventually came around.

So yea, not exactly sure why I got it or what to do with it yet. Mostly curious if the insides are exactly the same. Did Knuckheadflow ever finalize a PCB? And I guess people were working on an OSD Mux thing as part of that. Something that you can just solder the wires and components to and streamline the process a bit? Have there been any new tricks or discoveries in the past year? Does anyone have suggestions or different options for the toggle switch? I used a standard 4PDT metal stick switch before but I'd be curious to find something different, like a rocker switch, maybe to even use on the front bezel.


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 Post subject: Re: TV RGB mod thread
PostPosted: Sun Jul 15, 2018 8:35 pm 


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Thanks guys, now I have to wait for the postman to bring my trim pots. Right now I'm using IC hook test leads while testing, I'm looking forward to actually buttoning this mod up and getting everything properly soldered.

EDIT: Oh boy, I just found a JVC J13805CL which is a 13" clear Institutional/Prison TV. This thing is really sweet. It's RF only, but I'm gonna try to look into this, it has closed caption and in the menu it also says analog CC. I'm pretty sure it has a CC board as there is a board in there off to the side. I'm having a terrible time finding a service manual but I'm going to try to look up the chip and hopefully be able to piece somethign together. I'll keep you guys updated on what I find.


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 16, 2018 5:01 am 



Joined: 19 Sep 2017
Posts: 19
boogiemanspud wrote:
EDIT: Oh boy, I just found a JVC J13805CL which is a 13" clear Institutional/Prison TV. This thing is really sweet. It's RF only, but I'm gonna try to look into this, it has closed caption and in the menu it also says analog CC.

Start by locating the jungle and inspecting its datasheet, if it has ext analogue RGB input, shouldn't be too hard to sort it ouut from there


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 16, 2018 6:20 am 



Joined: 30 Jul 2017
Posts: 29
Been going through previous pages and I see this RGB Mux schematic and calculator that MarkOZLAD and Syntax put together.. I kind of can't even begin to comprehend what is going on here because all this came about while I was gone. So doing this setup eliminates the need for a toggle switch?

I got the board out of the TV and went over it, verifying and matching up various connections using the schematics I drew up for the previous TV. Just some of the RGB pin numbers are different and that's it.

Not entirely sure how to use the calculator..
- Am I just inputting my values in the two beige cells and the light blue is the result? I believe the TB1253N Jungle IC takes 0.7v but I can only find the datasheet for the TB1253AN.
- 1n4148 is a diode package? Or is that a specific part number the diode to be used here? Anyone have a part number I can reference for specs?
- What are these external RGB resistors? I don't have any resistors between the external RGB and Jungle IC except for the 75 ohm terminations.
- The 5v I pulled off the regulator and was wired into the switch I think? Is that the blanking signal?
- From the footage and pics, it looks like the external RGB is still displayed on top of the OSD RGB? Is there a reason for that or is are my eyes playing tricks on me.

I've got 4.7 kOhm resistors on the Micon OSD Out into switch. The original Jungle IC RGB IN 0.1uF caps get replaced with 1.5uF caps. That one wire off the 5v regulator, and the sync wire to the component input. And that's all I had to do with the TV board I think.

Ugh, this is so frustrating. Its been a year, I took a bunch of notes and some pictures of what I did before at the time, but I'm missing certain key explanations of my own work and a pic of the bottom of the circuit board I put together. Probably just figured it out and didn't bother to record what I did. And now that there is the new Mux trick, I'm having to learn all over again rather than just hooking it up the same way I did before. Be awesome if there was something I could read on how it works in laymans terms and not so much equations and math.

I'm confused :cry:

Toshiba 24AF42 Service Manual


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 16, 2018 2:33 pm 



Joined: 19 Sep 2017
Posts: 19
Seikenfreak wrote:
I'm confused :cry:


I have made a video documenting a RGB mod I did using MarkOZ and Syntax' circuit. MarkOZ helped me out with that mod and it turned out great.
This might help clarify a few things you're confused about.

https://www.youtube.com/watch?v=0bPb2xCp6zc&t=1s


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 16, 2018 6:49 pm 



Joined: 30 Jul 2017
Posts: 29
Thanks for the video link, although it didn't help me too much. The one thing I may have understood is that, because we're merging both of the signals, it affects the overall brightness of the picture, and so resistors have to be used inline of the RGB wires to compensate? Or is that just the TV you were working on in particular?

- I'm continuing to read through older posts and it seems MarkOZLAD said that the diodes are not actually needed? I can't find the post now, of course, but he was somewhat vague about exactly which diodes he was talking about. Is that all wires, or just RGB on one side? Does it include the blanking wires?

- So even with the RGB muxing, a toggle switch is still needed to cycle the single 5v blanking wire between RGB and the composite/component input?

As someone who isn't a genius with electronics, that calculator seems like it would be easier to use if everything was just blank, yet each cell had instructions on what information needed to go in that cell. Same for the schematic illustration. It's confusing because I don't know what information there is only for that particular TV, if it's part of an equation for all TVs, or is stuff I need to replace with values from my own TV for this Muxing schematic (besides the marked "Blanking" ones.) Since he mentioned making schematics using Excel (no idea how that's possible, unless it takes forever), could you go one step farther for visual presentation and actually place the blank value cells and results in line of the schematic?

I find the more I look at that schematic calculator, the more confused I get, in contrast to the schematic djcalle made in his video there where I at least feel like I can compare that to my own setup and it's similar. I'm eager to get rolling on this TV, I've got some ideas on how to put together a nice I/O section, but it sounds like I need to order stuff and I'd like to know if I should buy these new diodes, pots, a variety of resistors etc to figure this out. I already have resistors and caps that I used for the previous Toshiba.

Thanks for the help.


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 16, 2018 10:26 pm 


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It's a super simple calculator and picture. If your having so much trouble with it you should get someone else to have a look.

Wanna do it in excel and make the picture prettier? Knock yourself out.


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 16, 2018 10:36 pm 


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Seikenfreak wrote:
Been going through previous pages and I see this RGB Mux schematic and calculator that MarkOZLAD and Syntax put together.. I kind of can't even begin to comprehend what is going on here because all this came about while I was gone. So doing this setup eliminates the need for a toggle switch?

I got the board out of the TV and went over it, verifying and matching up various connections using the schematics I drew up for the previous TV. Just some of the RGB pin numbers are different and that's it.

Not entirely sure how to use the calculator..
- Am I just inputting my values in the two beige cells and the light blue is the result? I believe the TB1253N Jungle IC takes 0.7v but I can only find the datasheet for the TB1253AN.
- 1n4148 is a diode package? Or is that a specific part number the diode to be used here? Anyone have a part number I can reference for specs?
- What are these external RGB resistors? I don't have any resistors between the external RGB and Jungle IC except for the 75 ohm terminations.
- The 5v I pulled off the regulator and was wired into the switch I think? Is that the blanking signal?
- From the footage and pics, it looks like the external RGB is still displayed on top of the OSD RGB? Is there a reason for that or is are my eyes playing tricks on me.

I've got 4.7 kOhm resistors on the Micon OSD Out into switch. The original Jungle IC RGB IN 0.1uF caps get replaced with 1.5uF caps. That one wire off the 5v regulator, and the sync wire to the component input. And that's all I had to do with the TV board I think.

Ugh, this is so frustrating. Its been a year, I took a bunch of notes and some pictures of what I did before at the time, but I'm missing certain key explanations of my own work and a pic of the bottom of the circuit board I put together. Probably just figured it out and didn't bother to record what I did. And now that there is the new Mux trick, I'm having to learn all over again rather than just hooking it up the same way I did before. Be awesome if there was something I could read on how it works in laymans terms and not so much equations and math.

I'm confused :cry:

Toshiba 24AF42 Service Manual

Seikenfreak wrote:
Thanks for the video link, although it didn't help me too much. The one thing I may have understood is that, because we're merging both of the signals, it affects the overall brightness of the picture, and so resistors have to be used inline of the RGB wires to compensate? Or is that just the TV you were working on in particular?

- I'm continuing to read through older posts and it seems MarkOZLAD said that the diodes are not actually needed? I can't find the post now, of course, but he was somewhat vague about exactly which diodes he was talking about. Is that all wires, or just RGB on one side? Does it include the blanking wires?

- So even with the RGB muxing, a toggle switch is still needed to cycle the single 5v blanking wire between RGB and the composite/component input?

As someone who isn't a genius with electronics, that calculator seems like it would be easier to use if everything was just blank, yet each cell had instructions on what information needed to go in that cell. Same for the schematic illustration. It's confusing because I don't know what information there is only for that particular TV, if it's part of an equation for all TVs, or is stuff I need to replace with values from my own TV for this Muxing schematic (besides the marked "Blanking" ones.) Since he mentioned making schematics using Excel (no idea how that's possible, unless it takes forever), could you go one step farther for visual presentation and actually place the blank value cells and results in line of the schematic?

I find the more I look at that schematic calculator, the more confused I get, in contrast to the schematic djcalle made in his video there where I at least feel like I can compare that to my own setup and it's similar. I'm eager to get rolling on this TV, I've got some ideas on how to put together a nice I/O section, but it sounds like I need to order stuff and I'd like to know if I should buy these new diodes, pots, a variety of resistors etc to figure this out. I already have resistors and caps that I used for the previous Toshiba.

Thanks for the help.



1N4148 is the part number for the diode. Just google it, everywhere sells them.

A switch is not needed because pin 16 of the scart is supplying your external blanking, instead of the TV's internal 5v regulator. If the console plugged into the scart isn't powered on, it doesn't blank the screen for external RGB, allowing the original composite/s-video/component to show.

The mux circuit is taking the place of the voltage divider between the RGB out of the Micon IC and the RGB in of the Jungle IC, it sidesteps the TV's own handling of these signals so you have to knock the 5v source voltage down to 0.7v for the jungle. To do this you want to adjust the R1 and R2 values, which are the OSD RGB inlines of the mux circuit and the EXT RGB inlines + 75 ohm termination respectively.

The diodes on the OSD lines are to prevent any funky business causing interference between OSD and EXT RGB, these are the ones that aren't strictly necessary. The only difference this should make to your maths and the calculator is changing source voltage from 5v (Micon output) to 4.3v (due to diode voltage drop of 0.7v).

To find out what specific values you need, look at the RGB lines between the micon and the jungle on your set. The inlines on OSD RGB should be the same as the ones on your set. The inlines on EXT RGB should be 75 ohms less than the termination resistors in the tv. If you decide to use diodes on the OSD lines to prevent funky business, only then do you need the calculator, and it's as simple as dropping the source voltage and then adjusting the resistors to match the output voltage to the non-diode version.
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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 1:01 am 



Joined: 18 May 2017
Posts: 400
Firstly, the Toshiba 24AF42 is definitely suitable for OSD mux.

To understand the OSD mux principles, please first understand voltage division. In the OSD mux we are replacing the ground resistors that are in the set from factory (in your case R139, R140 and R141) with resistors on the the External RGB lines.

Another thing to understand is that the resistors on the External RGB lines will not drop the voltage on the external RGB.

I don't really feel like spoon feeding you but as this is my hobby I looked up your set.

To mod it I would remove R139, R140 and R141. We won't bother with diodes.

A quick check of the OSD Mux calculator...set diode drop to zero, OSD RGB Inline Resistor to 4700 (R121, R122, R123). Playing around with the External RGB Inline Resistor field, if I use 750 I get 0.71754V output. Close enough.

I notice on the PCB picture in the service manual that the OSD RGB circuits go through a set of jumpers. This would be a good place to solder your external RGB lines.

From your scart port, connect the RGB lines to ground via 75R, then connect them to the jumpers via 750R resistors.

Couldn't be easier.

Because you have those big jumpers, you could easily remove the jumpers and install diodes there, in that case you would use 910R on your RGB lines.

For blanking, if you want to use a switch option, Hook up a wire from your 5V regulator, IC503 Pin 3, to the switch and the from the switch to the leg of W805 that is closest to IC101.

Oh, and djcalle put resistors in front of his 75R in order to lower the external RGB signal strength and decrease the brightness.


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 1:58 am 


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MarkOZLAD wrote:
In the OSD mux we are replacing the ground resistors [on the OSD RGB lines]


I would swear by all that is holy that neither you nor syntax mentioned this when you posted the calculator, lol. Understanding this, the damn thing makes a lot more sense to me (i hope). We're removing the resistors to ground that are on the OSD RGB lines, and not replacing them as the 75R terminations on our newly-added external RGB lines do the job.

This is a relief to me :)


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 2:10 am 



Joined: 18 May 2017
Posts: 400
buttersoft wrote:
MarkOZLAD wrote:
In the OSD mux we are replacing the ground resistors [on the OSD RGB lines]


I would swear by all that is holy that neither you nor syntax mentioned this when you posted the calculator, lol. Understanding this, the damn thing makes a lot more sense to me (i hope). We're removing the resistors to ground that are on the OSD RGB lines, and not replacing them as the 75R terminations on our newly-added external RGB lines do the job.

This is a relief to me :)


The External RGB Inline Resistor + the normal 75R become the new ground resistor for the OSD RGB lines that is....

This is exactly what I was going to explain to you if you called!

Ignoring a possible termination resistor in the console, for the Toshiba it would be 5V * (750 + 75) / (4700 + 750 + 75) = 0.746666 V p-p

Factoring the termination resistor in the external console it's....

5V * (750 + (75*75)/(75+75)) / (4700 + 750 + (75*75)/(75+75)) = 5V * (750 + 37.5) / (4700 + 750 + 37.5) = 0.7175V p-p

I tend towards going just over the 0.7


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 2:13 am 



Joined: 18 May 2017
Posts: 400
I might do some algebra and come up with the formula for determining the Ext RGB resistor for a given OSD inline....

Ok, without diodes....

External RGB Inline Resistor = (0.7 * OSD Inline Resistor - 161.25) / 4.3

For this Toshiba which has 4700R inline

(0.7 * 4700 - 161.25) / 4.3 = 727.6R (next standard resistor size up is 750R)


If you include diodes

External RGB Inline Resistor = (0.7 * OSD Inline Resistor - 135) / 3.6

(0.7 * 4700 - 135) / 3.6 = 876.3889R (next standard resistor size up is 910R)

This has been added as a sheet on the OSD RGB Mux Spreadsheet.


Last edited by MarkOZLAD on Tue Jul 17, 2018 5:46 am, edited 3 times in total.

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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 3:52 am 



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First, thank you for the helpful replies MarkOZLAD and BobWoggle. Both of you laid it out in a more concise way.

I've been sitting here going over what BobWoggle said and putting together a diagram to help me visualize it. Now I see your post Mark and you've introduced some other information I wasn't aware of:

- I didn't realize termination resistors (R139, R140 and R141 in my case) existed/were being replaced on the RGB signals. I hadn't seen anyone mention that so I just thought it was only on Blanking based on the Sanyo reference schematic. Plus, I didn't have to do that on the previous TV with the switch setup. So there's one piece of the puzzle I was missing.

- So the OSD RGB diodes aren't necessary, but are they recommended as a precaution? Maybe certain devices might cause an issue at some point. If so, then it seems smart to put them in place. Thanks Bob for pointing out that 1n4148 is the specific diode part number. I already had a set in my shopping cart before Amazon died and I lost my whole list.

- What's also messing with me is that the factory Blank run from Micon (Pin 33) to Jungle (Pin 19) doesn't appear to have a voltage divider? It just has the D107 diode and a single 1.8k (R615) termination resistor. So the Sanyo schematic is referencing an addtional inline resistor and I don't see one in my setup. And I can't find a datasheet for this Orion OEC7074A Micon to see what the output voltage is there. I suppose I could probe it if I had to. I of course could just still not understand how voltage divider is functioning.

- If the 5v off the console will handle the switching, then it seems like I won't add a switch myself. Unless there are issues or specific circumstances people have come across? Assuming I don't use a switch, that would mean I inject the SCART Blanking signal after the the termination resistor (R615, 1.8k)? Messing with the calculator, I could do a 1300 (R1), 510 (R2), with diode to get 0.708v into the Jungle IC.

I understand those of you who are more familiar with this stuff can get impatient with simple questions, but you have to understand this thread is nearly 60 pages of random people declaring random things, quotes referencing posts from forever ago, newer information that contradicts earlier stuff, different TVs having different requirements etc etc. It's a sea of garbled mess. It may seem straight forward to someone who has been here the whole time reading each post as they come in slowly, but not necessarily for someone reading a years worth of experimentation in a day.

Thanks again for the answers. This got me a lot closer to understanding how this functions.


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 5:41 am 



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Looking at the blanking - I cannot find a datasheet for TB1253N but I have found the one for TB1254N. For the TB1254N, depending on the I2C switch for the Ysm mode, the RGB blanking will occur at either 0.7V or 3.3V. There doesn't appear to be a maximum so 5V should be fine.

It seems likely that this set would be in mode 1 where anything over 0.7V will blank it but I can't be sure. You may have to play with it to find out. If it does only require 0.7V I would connect Scart pin 16 after the diode D107.

It is indeed an interesting blanking circuit, it seems the micom can choose to blank the jungle using it's blanking pin and/or blank when the blue is active. If the schematic is correct the Micom is sending 3.8V to the jungle blanking pin. The micom will be outputting 5V and the ISS133 diode has a 1.2V forward voltage


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 6:22 am 



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MarkOZLAD wrote:
Looking at the blanking I cannot find a datasheet for TB1253N but I have found the one for TB1254N. For the TB1254N, depending on the I2C switch for the Ysm mode, the RGB blanking will occur at either 0.7V or 3.3V. There doesn't appear to be a maximum so 5V should be fine.

It seems likely that this set would be in mode 1 where anything over 0.7V will blank it but I can't be sure. You may have to play with it to find out. If it does only require 0.7V I would connect Scart pin 16 after the diode D107.

It is indeed an interesting blanking circuit, it seems the micom can choose to blank the jungle using it's blanking pin and/or blank when the blue is active. If the schematic is correct the Micom is sending 3.8V to the jungle blanking pin. The ISS133 diode has a 1.2V forward voltage.


Yea I found that TB1254N datasheet as well but noticed the RGB pins were different. I did happen to have a datasheet for the TB1253AN saved from the previous project, and that seemed to match up with whats in this thing.

I'm currently in the process of filling up a cart at Mouser. I've got 1n4148 diodes, 1.3 kOhm, 510 Ohm, 750 Ohm, 910 Ohm resistors. Anything else you think I should have around in case? Already have some resistors and caps leftover from previous TV. Also been trying to find these Optical/RCA jacks but either Mouser or Allied Electronics don't have them, or I don't know how they are listed (SPDIF, Toslink, Optical etc.) Amazon had one but its no longer available.


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 6:48 am 


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Seikenfreak wrote:
First, thank you for the helpful replies MarkOZLAD and BobWoggle. Both of you laid it out in a more concise way.

I've been sitting here going over what BobWoggle said and putting together a diagram to help me visualize it. Now I see your post Mark and you've introduced some other information I wasn't aware of:

- I didn't realize termination resistors (R139, R140 and R141 in my case) existed/were being replaced on the RGB signals. I hadn't seen anyone mention that so I just thought it was only on Blanking based on the Sanyo reference schematic. Plus, I didn't have to do that on the previous TV with the switch setup. So there's one piece of the puzzle I was missing.

- So the OSD RGB diodes aren't necessary, but are they recommended as a precaution? Maybe certain devices might cause an issue at some point. If so, then it seems smart to put them in place. Thanks Bob for pointing out that 1n4148 is the specific diode part number. I already had a set in my shopping cart before Amazon died and I lost my whole list.

- What's also messing with me is that the factory Blank run from Micon (Pin 33) to Jungle (Pin 19) doesn't appear to have a voltage divider? It just has the D107 diode and a single 1.8k (R615) termination resistor. So the Sanyo schematic is referencing an addtional inline resistor and I don't see one in my setup. And I can't find a datasheet for this Orion OEC7074A Micon to see what the output voltage is there. I suppose I could probe it if I had to. I of course could just still not understand how voltage divider is functioning.

- If the 5v off the console will handle the switching, then it seems like I won't add a switch myself. Unless there are issues or specific circumstances people have come across? Assuming I don't use a switch, that would mean I inject the SCART Blanking signal after the the termination resistor (R615, 1.8k)? Messing with the calculator, I could do a 1300 (R1), 510 (R2), with diode to get 0.708v into the Jungle IC.

I understand those of you who are more familiar with this stuff can get impatient with simple questions, but you have to understand this thread is nearly 60 pages of random people declaring random things, quotes referencing posts from forever ago, newer information that contradicts earlier stuff, different TVs having different requirements etc etc. It's a sea of garbled mess. It may seem straight forward to someone who has been here the whole time reading each post as they come in slowly, but not necessarily for someone reading a years worth of experimentation in a day.

Thanks again for the answers. This got me a lot closer to understanding how this functions.

I get the confusion, I was in the same spot less than a year ago.

Personally I haven't been messing with the existing blanking setup, just running ext. blanking straight to the jungle through a diode and maybe a voltage divider if it needs knocking down. The blanking signal isn't like the rgb signals, it's a logic switch (As far as I can tell? I might be an idiot). The set knows how to do the switching for osd, and ext. overrides it anyway, so no need to mess with it? Especially if there's a diode inline from the factory, just stick your scart blanking in after that and neither blanking line should mess with each other.
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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 7:08 am 



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This is how I think the blanking circuit should be done for Jungles that blank from about 1.0V-3.0V using Scart Pin 16 as external blanking source.

Image

The new circuit should work well with low blanking voltages from gscart switch and also work well with consoles that input 5V via a 180R resistor.

In the case of the console the 75R termination will cause a voltage division with the 180R

5V * 75/(180+75) = 1.47V


Last edited by MarkOZLAD on Wed Jul 18, 2018 1:48 am, edited 1 time in total.

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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 10:42 pm 


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djcalle wrote:
Start by locating the jungle and inspecting its datasheet, if it has ext analogue RGB input, shouldn't be too hard to sort it ouut from there


Thanks, that's what I had in mind. I'm probably going to wait til I get the sharp buttoned up before jumping into it though.

Quick quesion, I just tried to wire my sound and sync by soldering a wire from each onto the back of the rca ports. I get no sound and sync. Does anyone know off the top of their head how the jacks that sense something being plugged in usually work? I imagine I need to use a jumper wire somehow, I remember reading it somewhere in this thread but wow... it could be anywhere!


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 17, 2018 11:30 pm 


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boogiemanspud wrote:
djcalle wrote:
Start by locating the jungle and inspecting its datasheet, if it has ext analogue RGB input, shouldn't be too hard to sort it ouut from there


Thanks, that's what I had in mind. I'm probably going to wait til I get the sharp buttoned up before jumping into it though.

Quick quesion, I just tried to wire my sound and sync by soldering a wire from each onto the back of the rca ports. I get no sound and sync. Does anyone know off the top of their head how the jacks that sense something being plugged in usually work? I imagine I need to use a jumper wire somehow, I remember reading it somewhere in this thread but wow... it could be anywhere!


I think I said just last page but detector jacks work by shorting the input to ground when a plug isn't inserted. First thing to check is if you get sync and sound if you plug in some RCA cables on the same jacks you're trying to inject sync and audio.
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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Jul 18, 2018 12:08 am 



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Posts: 400
I have updated the OSD Ext RGB Mux diagram.

Image

The OSD Mux RGB Calculator Spreadsheet has been updated.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Jul 18, 2018 2:04 am 



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Just finished putting together these diagrams. This is just based on what I've read here and hopefully understood it correctly so not 100% sure it's correct yet. I can adjust or add more details later if needed. Probably be a week-ish til components start arriving for the project.

Edit: Mux was successfully put together in a later post with the 20" TV. Updated this picture with the working setup.

Image

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Last edited by Seikenfreak on Mon Aug 06, 2018 2:44 am, edited 2 times in total.

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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Jul 18, 2018 3:10 am 



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Looks good.

I wouldn’t be changing caps.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Jul 18, 2018 3:31 am 



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MarkOZLAD wrote:
Looks good.

I wouldn’t be changing caps.


Hmm. Well I changed them on the Toshiba 20AF41 set per Knuckleheadflow's suggestion. *long pause* gaaaaaaaaaasping for air.. Okay I found the post back on page 10. I guess via some potential suggestion from Voultar, Knuckle gave them a shot and seemed to to be pleased with the results. Can't hurt to put them on right? My 20AF41 set looks pretty good and all the circuitry on this one appears to be the same.

Edit: Spoiler'd to compact it.

Spoiler: show
KnuckleheadFlow wrote:
Sorry about the length, but I’m pretty amped up about this and nobody understands why I’m all of a sudden obsessed with cutting up 15+ year old TVs! I need an outlet.
My brother and I only started considering an CRT RGB setup with Sony P/BVMs (or other similar monitors) in the last few months. Turns out we're late to the party and it seems almost impossible to get one (reasonably) in our area. Guys posting them on Kijiji get like 5 replies within 5 minutes. We'd pretty much given up when I happened upon this thread. This is really cool, I want to thank mikejmoffitt, tjsynkral and especially Voultar for their information.
My brother wanted a 20" to fit on his desk and at first I was going to work on his generic RCA before deciding to get a test TV in case I screw up. I picked up this Toshiba 20AF41C for a week ago Saturday, it turned out way better than the RCA and came with a DVD player. Checking the service menu, its powered on time listed in hex was 0E8E, a mere 3,726 hours!
Image

Using the service manual I found the OSD RGB lines and after a bit of continuity checking I plotted out the paths on the board and decided to desolder resistors R121, R122 and R123, attach the wires out to the switch from there and feed the RGB into the 0.1 µF caps C620, C621 and C622.
Micro:
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Jungle IC:
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Board wired up:
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The switch is kinda ugly, but it works. I was worried about interference with everything so close but in all the pictures I've seen of this no one else seems to care. Probably should've gone with DE-15 and VGA cables but decided to use BNCs because it's a ghetto BVM. It’s going RGB in, coax to switch where it's terminated with 75 O resistors. I soldered the shielding to the board for grounding and holding it in place, electrical tape for strain relief. The ends don’t budge so that’s good. OSD RGB comes into the top header pins, to the switch terminals over 4.7 kO resistors (replacing R121/2/3). Switch out goes out of the bottom header. 5v for blanking I got off the Jungle IC’s pin 2 to the blanking pin’s resistor. I left the blanking line untouched on account of the diodes. Sync is going into component Y. I’m thinking about feeding it directly to an IC, but I’m not sure where.
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So how’d it turn out? Pretty good, I’d say. This is from a model one Genesis, 75O and 220 µF inline on RGB and csync. The phone’s camera messes around with white balance and brightness, so it’s kind of hard to show what I’m seeing.
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The service menu has an “OSD horizontal” adjustment which I nudged a bit, but there’s a significant bit of cut off top and bottom. I don’t know if the vertical adjustment in the service menu will apply to the OSD but I’m adding a separate switch to the blanking line to see the game RGB with the service overlay, so I’ll see.
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Maybe it’s just my pickiness, but though it looks good but I think it can look better. I was always terrible at calibrating pictures, after a while of changing settings I can’t tell what looks good or bad anymore. It seems the colours are a little dull, too white? Not sharp enough? Maybe I was just expecting too much and this is as good as it gets. (Reds here are supposed to look redder, almost too red)
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So I’ve got four questions I’d like to throw out there:

I think Voultar mentioned a TV’s stock RGB decoupling capacitors might be insufficient. I’ve got some 1.5 µF SMT caps, maybe they’ll make it look better in place of the 0.1 µF?

Is there an advantage to running sync directly to an IC instead of using the Y component line, which seems ok horizontally? Should I put it in to pin 6 of the microprocessor? That pin is being fed from pin 33, sync out, on the Jungle IC.

I’m thinking of trying this on a TV with lots of horizontal lines, like the Sony P/BVMs have. Someone mentioned JVC’s 800 line AV-32Ds and I’m picking one up for $30 on Monday. The thing is, I’ll probably get rid of it after I modify it, since I’m looking to put something into my New Astro City. I’m willing to throw together a new bracket for the tube, but I think the 32” JVC will be just too big to fit without more modifications than I’m willing to do. Who knows if it’ll even compare favorably with the Nanao MS9 (which probably needs a cap kit anyway).
Anyone know of any other 800ish line TVs? I found references online to old articles from 1991 mentioning Panasonics with 800 lines but not much else and no one other than JVC advertised line count it seems. Are there other sources that list various TVs and more detailed specs?

Speaking of the NAC, am I correct in assuming this will also work well with JAMMA and MAME with an ArcadeVGA/JPAC?

Edit: Fixed giant images.
Edit 2: I put the 1.5 mic caps on last night before this post was approved. Yes, I do think they helped. To say the least!
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Last edited by Seikenfreak on Wed Jul 18, 2018 11:35 pm, edited 1 time in total.

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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Jul 18, 2018 3:36 am 



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It's your mod, do as you please. Seems it would be easier to leave the caps in, see how the picture looks and then decide if they need changing. I don't think I've seen caps with greater than than 100nF capacitance used on RGB lines on any schematic I've come across.

Will be interested in a comparison if you did it.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Jul 18, 2018 5:57 am 



Joined: 30 Jul 2017
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Yea I can give it a shot if you're interested. It's really hard trying to get pics of a CRT though that show any quality difference.

Having said that, since I can't do anything else with it at the moment, I might as well stick the board back in and take some base reference shots without mod. Friend also offered to lend me his SFC so I could compare my modded 20" set to the unmodded 24". I figured that might be a little apples to oranges though because I've tweaked a bunch of settings on the 20" already. Hmm.

...and of course, I hooked it all back up and it's not turning on. Interesting. Haven't done anything to it except sit on my bench. Not seeing any obvious issues yet. Probably a lost cause because if it isn't obvious, I don't have the know-how or experience to figure it out :cry:


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Jul 18, 2018 8:01 pm 


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BobWoggle wrote:
I think I said just last page but detector jacks work by shorting the input to ground when a plug isn't inserted. First thing to check is if you get sync and sound if you plug in some RCA cables on the same jacks you're trying to inject sync and audio.


Ah, that makes sense. I noticed that when I tested the center pin I got continuity between the ground on one of the three pins. I thought that was strange, it had been a long day and it wasn't registering in my head what was going on :lol: Thanks!

EDIT: Ok, so I feel really stupid. I was trying to send sync to the middle pin on the Y of the component jack. It was the leftmost connector that needed it. Same with audio. So it all works now, still have too bright of a picture though. I mean, it's livable, but it's probably 25% too bright. I tried pots in line with the rgb lines and basically you can't dim them. It goes from too bright to no picture either way. I believe the jungle chip must somehow be amplifying the signals (or after the chip).

So has anyone had experience with a sharp 32uc4? I can't get it into the service menu. The manual says to hold volume - and channel up while plugging the cord into the wall. I've tried it with the buttons on front of the set as well as the remote and get nothing. I'm wondering if the remote isn't for a different model, as the service manual shows PIP on the remote, which this lacks. The remote controls all functions fine though, so I'm surprised it won't go into the service menu.


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 Post subject: Re: TV RGB mod thread
PostPosted: Thu Jul 19, 2018 12:00 am 



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boogiemanspud wrote:
So has anyone had experience with a sharp 32uc4? I can't get it into the service menu. The manual says to hold volume - and channel up while plugging the cord into the wall. I've tried it with the buttons on front of the set as well as the remote and get nothing.


My Sharp SX76NF8 has the exact same procedure, hold volume down and channel up buttons whilst powering on from the wall socket. I can report that it works on my set.

I also have a Tevion MD 81299 Universal Remote that, amazingly, had a button on it that got into the service manual after doing a manual code search on the remote.


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 Post subject: Re: TV RGB mod thread
PostPosted: Thu Jul 19, 2018 1:34 am 



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So I've been ripping my hair out all day trying to figure out this problem. Did nothing to the TV or board prior to this. Discharged the CRT like normal, into the ground strap. Didn't touch the board with a probe or iron. Now power button does nothing and the only noise I hear from the board is when I physically plug/unplug the power, it's a tiny chirp from the flyback I think. Been poking and prodding, taking voltage and continuity tests I guess. It feels like there is no rhyme or reason to the numbers, I'm more used to fairly simple automotive circuits. Does it switch over to DC on the one side of the transformer? (nevermind, I believe it should be after the bridge rectifier?) Because the numbers make even less sense on that end. Negative readings on the DMM, "normal" readings, super high readings, fluctuating readings etc.

Anyway, I just started dumping info into Photoshop to try and make any sense of it. Either the entire board blew up somehow, without any marks, smells, smoke, or indication.. or there is something so obviously dumb that I can't see it. Why am I immediately getting 64v at the fuse? Fuse appears to be fine, 0 resistance and has continuity. If anyone can make any sense of this, that'd be great. Not finding much helpful info on the net. Had to vent a bit.

Edit: Deleted image because it was basically all wrong. This whole post can probably be ignored. :oops:


Last edited by Seikenfreak on Thu Jul 19, 2018 6:57 pm, edited 3 times in total.

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 Post subject: Re: TV RGB mod thread
PostPosted: Thu Jul 19, 2018 5:49 am 



Joined: 18 May 2017
Posts: 400
What do IC502 and IC503 voltages read on their output pins?


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