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 Post subject: Re: TV RGB mod thread
PostPosted: Thu Jul 19, 2018 6:58 am 



Joined: 30 Jul 2017
Posts: 29
MarkOZLAD wrote:
What do IC502 and IC503 voltages read on their output pins?


IC502 on Pin 3 = 22 mV DC
IC503 on Pin 3 = -001 mV DC

I'm still going at it. Trying to think about it from different angles. I've pretty much redrawn most of the SMPS section by hand in an attempt to mentally process it and also just trying to educate myself on how these work. Worst case, I'll have to learn it all and calculate the target voltages from the start of it to the exit of the isolated section. Just redid of the voltage tests, so some of that stuff I put down earlier should be wrong: Do appear to be getting 120v up until the bridge rectifier and then it's all about 57v from there.

Actually, I just realized those random numbers on the schematic seem to be target voltages.. duur. Which kind of align with stuff I'm seeing on the mains side except at the transformer. Hmm.. now I have some actual targets to test for.

Edit: IC103 (RESET IC) = 5v DC in and out. This runs to the power button where I am also getting 5v. When the power button is pressed, it shorts to ground and drops 5v off Pin 6 (Key 1) at the Micon. I have 5v at Micon Pin 27 (RESET) and 0v at Pin 29 (POWER) on the Micon.

It appears that 5v should exit that pin and trigger the STAND BY SW (Q505) & STAND BY SW (Q509) transistors, which would then switch on the +12V SW (Q508), +5V SW (Q510), and +B SW (Q503) transistors to feed the 5v (IC503) and 9v (IC502) regulators etc etc. The POWER pin of the Micon is also tied to P FAIL.. and I have no idea what that is. It's infuriating that I can't find a datasheet for the Micon OEC7074A. But I feel like the fact the transformer has nothing on one side, I shouldn't really worry about outside of that I guess. I sort of got distracted with the rest of the board and perhaps I should refocus on power switching. Pull that big switching transistor off to test.

Seems like a lot of what I did before wasn't quite right but I think I got it down now..

Current state of things in Photoshop with following traces and checking voltages: Photoshop Schematic Images

Edit 2: So I pulled out the main power switching MOSFET (Q502), touch the ground to Source, positive to Drain and get OL. Touch the positive to Gate and then back to Drain, still nothing. This is apparently not correct so.. maybe this is the problem. Will order replacement (and spares) and hopefully end this hellish nightmare.


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 Post subject: Re: TV RGB mod thread
PostPosted: Sat Jul 21, 2018 12:43 am 


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Hello, can someone please tell me if I can inject RGB into this TV through the Z86128 closed caption controller? I tried to do an RGB mod on this TV but failed (I only had success with external red and green signals showing up on screen)... Looking at the schematic, I am confused about where am I supposed to feed +5V for blanking if the LA7673 jungle IC accepts the blue color and blanking signal at the same pin? When I connected +5V and a blue signal wire from my SCART connector to it, I got a solid blue screen and it ignored any SCART signal. I am also confused about the whole sync thing because this TV has RF only input (even though it's from 1996)... Here is the schematic for the TV (look at the CN-100/A/B/C/D part): https://elektrotanya.com/daewoo_chassis ... nload.html

Thanks in advance to whoever will help the inexperienced noob with this. :? :oops:


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 Post subject: Re: TV RGB mod thread
PostPosted: Sat Jul 21, 2018 3:45 am 


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Joined: 11 Jul 2018
Posts: 16
Location: Iowa
Seikenfreak wrote:
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:


Does the chirping keep going or just once? If it keeps going I had something similar. The set worked (was old and unknown condition from previous owner) after being on about 5 minutes it shut off, never to power on again. I think it was something on the power supply: (second post) https://www.electronicspoint.com/thread ... ing.59746/ I ended up scrapping the set as it was above my skill level at the time. It sounded like a small bird was in the set almost. I used a paper towel tube to pinpoint the sound and it sounded like it was coming from near the flyback on the board.


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 Post subject: Re: TV RGB mod thread
PostPosted: Sat Jul 21, 2018 6:16 am 



Joined: 30 Jul 2017
Posts: 29
It's just a single chirp. Bird chirp is a decent way to describe it but very quick and subtle. I tried to listen for where it was coming from but was never sure. Just sounds like something getting charged with a small amount of juice.

I actually found a big electronics supplier relatively close by who has new-old stock of the NEC 2SK3326 mosfet. Of course, I guess the company is so big that it doesn't look like people can just go and pick things up, so I have to pay $10 shipping and wait who knows how long to get parts from 30 mins away. Ordered a handful of them because why not. Trying not to get my hopes up. I'm really kinda sad that just as I was looking forward to plugging set back in as-is, borrowing the friends SFC, run the two systems at the same time, and then trying to take base reference shots and some side by side shots with my 20" for comparison and then some after the work.... Annnd then it's dead for no apparent reason. I still can't comprehend what could've happened. Curious if others have stories like this, maybe a anode discharge killing a TV or just.. something. All the other parts for the mod arrived today.

There is one spot on the board that I am hoping isn't going to be a problem: Keep in mind, I only started messing with this connection after I saw it was dead and was looking for issues. There is a ribbon cable (CP801) that is soldered to the board and goes to the CRT PCB. It's right at the edge of the main board and I wondered if maybe the cable was tweaked enough to cause an issue at the solder joints. Then I potentially made it worse or fixed it from there.. For some reason, the spot where that cable attached appeared to have old flux on it and the joints looked a little crusty. I thought I'd just go in there and clean it up and replace the solder but shame on me. As soon as I touched those points with the iron, it was crackling like bacon and it looked like two of the pads came loose. Greeeeaaaat. So now this went into full recovery mode, I removed the whole cable, two pads were half lifted, I cleaned it all up, scrapped a little mask away next to a couple pins to give them more solder surface, reattached it all with fresh solder and a small amount of hot glue between the cable clip and board to help give the cable some extra strength against all the flexing. Now all I can do is hope for the best.


Last edited by Seikenfreak on Sat Jul 21, 2018 9:18 pm, edited 3 times in total.

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 Post subject: Re: TV RGB mod thread
PostPosted: Sat Jul 21, 2018 7:56 am 



Joined: 18 May 2017
Posts: 400
Seikenfreak wrote:
Curious if others have stories like this, maybe a anode discharge killing a TV or just.. something.


Yep. Same thing last week. About to go on a similar journey of discovery when I get the time


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 Post subject: Re: TV RGB mod thread
PostPosted: Sun Jul 22, 2018 4:21 pm 


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Location: Iowa
I've exhausted my google abilities. Does anyone know where to find the datasheet for a 8893CSBNG7BR3 DIP64 chip? This is in the RCA J13805CL which is a 13" clear Institutional/Prison TV. I can't find a service manual for it either. Short of that, I may have to blindly look for capacitors and resistors near the chip if I can't find this. The set has an on screen menu and also claims to have analog closed caption capabilities, which would be a preferable way to inject the signal, but without the service manual, I'm kind of lost on what to do here.


Last edited by boogiemanspud on Mon Jul 23, 2018 3:00 am, edited 1 time in total.

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 Post subject: Re: TV RGB mod thread
PostPosted: Sun Jul 22, 2018 7:41 pm 


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boogiemanspud wrote:
I've exhausted my google abilities. Does anyone know where to find the datasheet for a 8893CSBNG7BR3 DIP64 chip? This is in the JVC J13805CL which is a 13" clear Institutional/Prison TV. I can't find a service manual for it either. Short of that, I may have to blindly look for capacitors and resistors near the chip if I can't find this. The set has an on screen menu and also claims to have analog closed caption capabilities, which would be a preferable way to inject the signal, but without the service manual, I'm kind of lost on what to do here.

If you've got a date of manufacture I'd look through jvc manuals around the same time, that's all I can give ya.
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 Post subject: Re: TV RGB mod thread
PostPosted: Sun Jul 22, 2018 11:40 pm 



Joined: 18 May 2017
Posts: 400
I'm assuming that's a TMPA8893

https://panassoder.blogspot.com/2016/06/data-pin-ic-chroma-tmpa-8893.html

Won't do RGB, MAY be able to mod for YCbCr.

I'm currently in the process of modding a TV with TMPA8823 for YCbCr. Most likely need to be able to turn on the YUV input from service menu to aqchieve this but MIGHT be possible to inject a blanking voltage to pin 18 to force YCbCr. I've seen documentation where Pin 18 (Page 34) is used for PIP YCbCr insertion but I cannot confirm it works. The TV I have allows for the YUV input to be turned on in Service Settings.


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 23, 2018 3:16 am 


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MarkOZLAD wrote:
I'm assuming that's a TMPA8893

https://panassoder.blogspot.com/2016/06/data-pin-ic-chroma-tmpa-8893.html

Won't do RGB, MAY be able to mod for YCbCr.

I'm currently in the process of modding a TV with TMPA8823 for YCbCr. Most likely need to be able to turn on the YUV input from service menu to aqchieve this but MIGHT be possible to inject a blanking voltage to pin 18 to force YCbCr. I've seen documentation where Pin 18 (Page 34) is used for PIP YCbCr insertion but I cannot confirm it works. The TV I have allows for the YUV input to be turned on in Service Settings.


Interesting, though kind of a letdown too :) I know the board is only populated for RF, but the case has the space for rca jacks, it's just that they are covered up. The board also has empty spots where it's missing components back there, so worse case scenario I might be able to get composite, best case component if it's a similar chip to yours. This tv says June 2010 for the manufacture. I'll have to also figure out how to get into the service menu, I imagine if I look up similar RCA sets I can find a button combination. Do you know where I could look to figure the chassis number? I googled all numbers on the motherboard that looked like part numbers etc and no results there either.

How would one go about figuring out what pins are input on the jungle chip? I easily found the RGB output as it goes to the neckboard and is conveniently labeled for the output.

I did do a small mod to this set. It was lacking a speaker and only had a headphone jack. I noticed a double pin header on the board right near where the headphone out is. I had a curb picked 13" rca, sure enough, it was the exact speaker that fit the housing perfectly. I had to modify the female end as it was physically too big to fit. I shaved it down and it then fit perfectly. It's kind of interesting as there were models with speakers and ones without. The unit functions exactly as it should, even muting the new internal speaker when the headphone jack is plugged in.

If this set only accepts component I suppose one could make a RGB to component board and install it in the TV. You could have a switch to go between RGB or component this way. The key on this mod will be super clean work though since it's a clear case the mod work will be on display.

Thanks for the info, it gives me something else to study for this set.

EDIT: forgot to add, the volume on the speaker is much lower than I feel it should be (compared to how it was on the consumer 13"). I'm going to study the consumer board and see if there is unpopulated places on the board for an amplifier IC. If not, I do have a ton of pre amp boards from some TOA amplifier/audio switching boards. Again, if I go this route, cleanliness of install will be key as it's all visable.


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 23, 2018 4:01 am 



Joined: 18 May 2017
Posts: 400
boogiemanspud wrote:
Interesting, though kind of a letdown too :)


If you can get into the service manual I think it likely possible to mod for composite and component (maybe even S-Video). I think that would be a pretty good result for a set that is currently RF only.

In my experience the component is good on TMPA88XX sets.

Any chance of posting some photos of the PCB top and bottom around Jungle and (currently unpopulated) AV ports?


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 23, 2018 4:26 am 



Joined: 18 May 2017
Posts: 400
Here is another document that may interest you.

https://datasheet4u.com/datasheet-pdf-file/1238985/Toshiba/TMPA8893CRCNG7D65/1

For my set you need to hold down the volume down button on the TV until it's muted, keep holding down that button and then press display on the remote.


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 23, 2018 2:13 pm 


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MarkOZLAD wrote:
Any chance of posting some photos of the PCB top and bottom around Jungle and (currently unpopulated) AV ports?


Here's some pics, if there's anything else you'd like to see better let me know and I can snap some more.

https://imgur.com/a/NTl6b6x (click open image in new tab to get full zoom)


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 24, 2018 12:31 am 



Joined: 18 May 2017
Posts: 400
boogiemanspud wrote:
MarkOZLAD wrote:
Any chance of posting some photos of the PCB top and bottom around Jungle and (currently unpopulated) AV ports?


Here's some pics, if there's anything else you'd like to see better let me know and I can snap some more.

https://imgur.com/a/NTl6b6x (click open image in new tab to get full zoom)


Had a look and the chassis appears to be a match for the one I am working on except yours appears to have surface mounts whereas mine is throughole.

Check out the schematic in this service manual

Also appears that most of the components are already in place for Component and Composite inputs.


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 24, 2018 2:39 pm 


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MarkOZLAD wrote:
Had a look and the chassis appears to be a match for the one I am working on except yours appears to have surface mounts whereas mine is throughole.

Check out the schematic in this service manual

Also appears that most of the components are already in place for Component and Composite inputs.


That's a great help. I'm goint to look over that service manual and start making a shopping list for the components I'll need that I don't already have. When I saw Cr Cb Y on the board, it made me quite happy. Hopefully between this new service manual and looking what's on the board I'll be able to figure out the components. This is the most major electronics thing I've done yet, a lot of fun but I'm sure I'll be scratching my head while piecing it together. :D


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 24, 2018 10:34 pm 


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Hey there! I've been reading this thread for a while now and decided to make an account here. I got a Toshiba CF20F40 from a friend, and have made a bit of progress in researching the ICs in it. I believe the jungler IC in it is the Toshiba TMP87CM34BN-3298. I found a service manual for a similar Toshiba CRT that uses the same chip(with a different four numbers at the end), and it seems to have an OSD RGB in that I can pull from, which is shown here:
Image

My only problem is that I can't figure out what the blanking pin is. If anyone could help me find it, I'd greatly appreciate it.

My CRT also uses a Toshiba TA1223AN IC, which can be seen in this service manual:
Image

What's weird is that this chip seems to have a pin named "RGB VCC" which I thought might be the blanking pin, but it doesn't make sense for it to be on a separate chip to me.

Here's a link to the full service manual: https://drive.google.com/open?id=1EYVJZ ... GXR55TKCWw

Thank you!


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 24, 2018 11:23 pm 



Joined: 18 May 2017
Posts: 400
boogiemanspud wrote:
MarkOZLAD wrote:
Had a look and the chassis appears to be a match for the one I am working on except yours appears to have surface mounts whereas mine is throughole.

Check out the schematic in this service manual

Also appears that most of the components are already in place for Component and Composite inputs.


That's a great help. I'm goint to look over that service manual and start making a shopping list for the components I'll need that I don't already have. When I saw Cr Cb Y on the board, it made me quite happy. Hopefully between this new service manual and looking what's on the board I'll be able to figure out the components. This is the most major electronics thing I've done yet, a lot of fun but I'm sure I'll be scratching my head while piecing it together. :D


Spend the bulk of your time on analysis. Try and find shortcuts wherever you can.

A couple of quick tips...

1) First confirm you can get into the Service menu. you pretty much can't do this mod otherwise.
2) Your board is missing R909 and R910. They are 75 Ohm termination resistors. They don't have to be added where the board has them, you could use 75R throughole resistors to ground at your RCA ports
3) Ground is available all over the place. Use a multimeter to confirm ground by confirming there is zero ohms resistance between the test point and the outer case of the RF tuner
4) If anything is not clear get the multimetre out and start testing for continuity.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Jul 25, 2018 7:53 pm 



Joined: 30 Jul 2017
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Good and bad news I guess. Good news is my friend came over with his 1chip SFC, I set my 20" Toshiba back up and we messed with that. There was some slight geometry issues that were bothering me, and I guess I got too impatient to fix them before, but I decided to pop the back off and have another go at it. Success! Ended up redoing pretty much all the color settings and tweaking the geometry with a little magnet and yoke help. Definitely better than it was. Still not perfect but its good enough. It's really annoying that something like Streets of Rage on Genesis will cut into the overscan part a bit, so you shrink the picture down, and then other games will have boarders that aren't supposed to be showing. The other thing that sucks is the 480i flicker. Feels like it only stands out with white text on a black background, but boy is it noticeable. Nothing that can be done about this right?

Bad news: Replacement 2SK3326 mosfet arrived today, first tested it (more than one) on my DMM and same result. So I guess my DMM isn't capable of testing these for some reason. Maybe their gate voltage is too high or something. /smashfacedesk So I put it back in anyway and still no power. Super depressing. Pulled up all my schematics and Photoshop stuff back out and went back to probing. Kind of at a loss at this point. I really need to know the innards of the Orion micon IC to see if and how I should be getting voltage to the POWER pin. Haven't been able to find any related Orion IC datasheet. I still think whatever is wrong has to be so incredibly obvious but not to me.

Edit: Guess I'll take this to the next level and start probing the working 20" TV for some sort of general reference. It appears I do not get 5v at the POWER pin on Micon until the set is turned on. That answers that question.


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 Post subject: Re: TV RGB mod thread
PostPosted: Mon Jul 30, 2018 5:22 pm 



Joined: 31 Mar 2018
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Hi All. I have a 27" Toshiba - 27af43. The mod is successful and everything looks really good. I have some wavy lines/noise/interference on some grey/gray backgrounds. If I adjust the brightness it appears that it is always there but only visible on certain colors. I have played around with ground points, sync termination, cable length, and various other things that I have picked up from these forums but I am not able to get rid of it. It is on present on the s-video, component, or composite inputs. Any other suggestions on what I can do to get rid of this wavy lines/noise/interference?


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 31, 2018 1:51 am 



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Sorry to post back to back but its been a week and this is separate I guess.

Decided to try the mux on the working, previously switch-modded 20" Toshiba. All hooked up now annnd I've got no color. Wired it up like the diagram I made earlier. 910 ohms on each of the scart color lines. Diodes added on the OSD side. 75 ohm on each to ground at the socket. Blanking has a 1.3k, then 510 to ground, followed by the diode. Injected before the factory termination resistor (R615) into the chip if that matters. It appears I do have color in the OSD overlay itself. I think I can see color from the game in there. Rest of screen is B&W.

Oh yea, I should've asked earlier but, does this disable the regular component jacks per say? Tried something plugged into it and its just giving me an unsync'd image in purple.


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 31, 2018 9:33 am 



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Seikenfreak wrote:
Sorry to post back to back but its been a week and this is separate I guess.

Decided to try the mux on the working, previously switch-modded 20" Toshiba. All hooked up now annnd I've got no color. Wired it up like the diagram I made earlier. 910 ohms on each of the scart color lines. Diodes added on the OSD side. 75 ohm on each to ground at the socket. Blanking has a 1.3k, then 510 to ground, followed by the diode. Injected before the factory termination resistor (R615) into the chip if that matters. It appears I do have color in the OSD overlay itself. I think I can see color from the game in there. Rest of screen is B&W.

Oh yea, I should've asked earlier but, does this disable the regular component jacks per say? Tried something plugged into it and its just giving me an unsync'd image in purple.


Your blanking circuit is wrong. I estimate you have about 0.6V after the diode.

Have a look at my latest diagram I posted. I revised the blanking circuit. Give it a shot.


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 31, 2018 6:27 pm 


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So I finally was able to get into service manual for the Sharp 32uc4. Service manual says hold vol - and channel up while plugging the tv into the wall. What I had to do was hold those buttons and plug and unplug the tv in about 20 times and then it went into service manual. Until it decides to go into it, the two buttons do nothing, then all of a sudden one time you plug it in, it powers on in service mode.

Does anyone know what setting will control the RGB throught the jungle chip? I'd assume it's the same one as the OSD, but I don't see anything relating. I've tried V06, V07, V08, V46, V47, V48 with no luck. The problem is that the image is rediculously bright and no fiddling with trim pots can get RGB levels decent. It's either too bright or colors almost dissapear. If anyone's dealt with a sharp or can make sense of what setting I should try, I'd really appreaciate the info.
Service Manual:
https://data2.manualslib.com/pdf3/70/69 ... adcc974155


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 Post subject: Re: TV RGB mod thread
PostPosted: Tue Jul 31, 2018 7:26 pm 



Joined: 30 Jul 2017
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MarkOZLAD wrote:
Your blanking circuit is wrong. I estimate you have about 0.6V after the diode.

Have a look at my latest diagram I posted. I revised the blanking circuit. Give it a shot.


Ah right I forgot you did that. I think I mentioned that my TV blanking line doesn't have anything inline except the factory diode and the 1.8k termination resistor. Without any of my stuff connected, blanking pin on the Jungle gets 0.9v when OSD is on.

MarkOZLAD wrote:
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.


I gave this a shot. I removed all the resistors and the diode on the external blanking line. Comes straight off the SCART and goes into the TV before the termination resistor. That got me color. The brightness is low, so I need to adjust the RGB resistors? I assume, because the OSD looks okay, that I should adjust the external color resistors? I know other people were having brightness issues earlier so I'll probably go back and read through some posts.

Thanks for the heads up.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Aug 01, 2018 12:04 am 



Joined: 18 May 2017
Posts: 400
Straight to the OSD Mux RGB Calculator to find some options.....


Image

Image

Image

Image

Image

Image


Need to change both the OSD resistors and your external RGB resistors in unison. I think the 1600/270 option should be good.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Aug 01, 2018 12:38 am 



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Oh yea btw, I have a bunch of #NAME? with an error Unknown Function:'IFNA' for some of those cells. I'm not getting half the information you have shown there. A lot of the results on the blanking side. The external blanking resistor stuff, current, and power dissipation info. On the external resistor calculations tab, the next higher value box. Some other stuff here and there. The main RGB resistor calculations on the main tab looks good. Viewing it in Google Sheets.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Aug 01, 2018 1:46 am 



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Seikenfreak wrote:
Oh yea btw, I have a bunch of #NAME? with an error Unknown Function:'IFNA' for some of those cells. I'm not getting half the information you have shown there. A lot of the results on the blanking side. The external blanking resistor stuff, current, and power dissipation info. On the external resistor calculations tab, the next higher value box. Some other stuff here and there. The main RGB resistor calculations on the main tab looks good. Viewing it in Google Sheets.


thanks for reporting that. Google Sheets doesn't have an "IFNA" function, instead I have changed it to "IFERROR" which works in both excel and google sheets. Give it another try please.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Aug 01, 2018 2:06 am 



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Thanks, all appears good on the calculator now.

I hadn't quite prepared to do this much tweaking so I only have the handful of specific resistor values on hand. I did buy some trim pots but they're only 1k. Knowing this now, I'll use the calculator to find a few different resistor combos I guess and order a few 5k trim pots as a backup I guess.

Seeing as crispytreat has his Toshiba up and running, I'd be curious to know his whole setup. Not sure if the circuits are any different.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Aug 01, 2018 4:54 am 



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Seikenfreak wrote:
Thanks, all appears good on the calculator now.

I hadn't quite prepared to do this much tweaking so I only have the handful of specific resistor values on hand. I did buy some trim pots but they're only 1k. Knowing this now, I'll use the calculator to find a few different resistor combos I guess and order a few 5k trim pots as a backup I guess.

Seeing as crispytreat has his Toshiba up and running, I'd be curious to know his whole setup. Not sure if the circuits are any different.


What sizes do you have? Might be able to work something out with running them in parallel or series.


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Aug 01, 2018 8:43 am 



Joined: 30 Jul 2017
Posts: 29
MarkOZLAD wrote:
What sizes do you have? Might be able to work something out with running them in parallel or series.


Eh don't worry about it. Already ordered the stuff before you posted. And I'd like to keep it as neat and tidy as possible so less components the better.

I was thinking though, I'm using the TB1253AN datasheet and it has 0.74-3.3v noted on the blanking input pin. I measured 4.5v at the pin with the system running. Think I might overdrive the chip and damage it over time? It definitely gets hot to the touch when I switch on a system.. not sure if that is any more than usual though. Not hot enough that I can't keep my finger on it. I suppose I could test putting just the diode back in to chop 0.7v off that? Hmm..


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Aug 01, 2018 1:07 pm 



Joined: 18 May 2017
Posts: 400
Seikenfreak wrote:
MarkOZLAD wrote:
What sizes do you have? Might be able to work something out with running them in parallel or series.


Eh don't worry about it. Already ordered the stuff before you posted. And I'd like to keep it as neat and tidy as possible so less components the better.

I was thinking though, I'm using the TB1253AN datasheet and it has 0.74-3.3v noted on the blanking input pin. I measured 4.5v at the pin with the system running. Think I might overdrive the chip and damage it over time? It definitely gets hot to the touch when I switch on a system.. not sure if that is any more than usual though. Not hot enough that I can't keep my finger on it. I suppose I could test putting just the diode back in to chop 0.7v off that? Hmm..


Did you put the 75R to ground on the blanking line as per the diagram. If your Scart port has a 180R on the 5V line going to pin 16 it should divide the voltage to around 1.5V


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 Post subject: Re: TV RGB mod thread
PostPosted: Wed Aug 01, 2018 6:25 pm 



Joined: 30 Jul 2017
Posts: 29
MarkOZLAD wrote:
Did you put the 75R to ground on the blanking line as per the diagram. If your Scart port has a 180R on the 5V line going to pin 16 it should divide the voltage to around 1.5V


With the 75R termination in the blanking line and no diode, I get 1v and lose color. With the diode and no 75R termination, I get 3.8v and color.

Edit #812: I wired a pot in. Anything below 3.2v on the blanking line gets me no color. Anything above that and I have color. Based on measuring the pot, 70 ohms inline got my 3.2v. That is with no 75R termination resistor. This is basically what it used to be with the switch, just feeding 5v straight into the blanking pin now that I think about it. I was under the impression that the blanking was affecting whether the OSD was visible or not over the external color signals which is why the blanking line was more complex than before. I guess just muxing the RGB signals correctly is the only necessary thing on my setup?

If you run the 75R termination resistor right off the socket, before anything else, it just sends the signal straight to ground and I get 1v. Only other component between the SCART and the jungle should be the 1.8k termination resistor.

For cables, I'm using Solaris JP-21 console cables, into a retro_console_accessories (ebay seller) JP-21 -> SCART cable, then into the SCART socket on the TV. Rather than wire the TV for JP-21, I like having the adapter cable there so I'm not plugging and unplugging a lot from the TV socket directly. Plus it functions as an extension so you don't need to get right behind the TV. Oh and my Jaguar cable is SCART.


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