TV RGB mod thread

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MarkOZLAD
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Re: TV RGB mod thread

Post by MarkOZLAD »

Cheers Ryeno,

No intention on rushing you, just keen.
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MarkOZLAD
OSD/External RGB Mux Diagram
OSD/External RGB Mux Resistor Value Table 0.7Vp-p : 0.5Vp-p

"Imagine toggle switch OSD modding a TV in 2019" - maxtherabbit
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cools
Posts: 2055
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Location: South Wales
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Re: TV RGB mod thread

Post by cools »

Ryeno wrote:First step is to measure from scart pin 16 to 21 for 75 ohms.
75 ohms between 16-21, and 16-18

Jungle Pin 29 to 32 - 1.45 V. Between 29 and 33/34/35 are all 3.6V. Between 44-43 2.1V, 44-42 2.3V, 44-41 2.4V

(Further, when in RGB mode red drive appears to be way too high, which is the only setting not accessible from the service menu. There's are some built in test screens for adjusting these that can display just a single horizontal line - blue and green are barely visible, as they should be, whereas red is clear and bright)
Image
MadeInHell1993
Posts: 1
Joined: Sun Jun 26, 2022 9:36 pm

Is this TV moddable? Thanks in advance!

Post by MadeInHell1993 »

Hey Everyone, I was looking for help with either RGB modding or S-Video/Component modding this TV. It is a 1991 Sanyo CRT Model No.AVM2101U, I couldn't find any service manual for it anywhere, I found an LXI tv and Fisher tv that both look identical to this one but with different branding... but no service manuals for them either. It has an OSD and I found 2 chips on the board, The first one is an "M50442-626SP" with no datasheet to be found online, the other one is an "LA7655N" Jungle Chip, I found it's datasheet. It has no RGB inputs at all, but it has R-Y,B-Y, G-Y and Y outputs that go to a ribbon cable running to the neck board. The ribbon cable also has 2 other pins, one labelled "E" and one isn't labelled at all. I will attach all the pictures I have and label anything I think might be helpful to anyone kind enough to lend me a hand here. (I was reffered here by someone on reddit who told me some guys named Markozlad and Syntax on these forums may be able to give some good insight so if anyone could let them know about this post I would really appreciate it!)
I would really like to attempt an RGB mod on this set but I'm also okay with S-video or component if possible. I also realize the many dangers in working on a CRT and I know how to safely discharge the anode cap and High voltage capacitors, so don't worry, I *probably* won't kill myself.
All jokes aside, I really appreciate any input or info anyone here has to offer and feel free to ask for more pictures or any info regarding the TV or this possible mod.

All pictures are here: https://imgur.com/a/q6DtNxR
Thunderbird98
Posts: 1
Joined: Mon Jun 27, 2022 4:34 pm

Re: TV RGB mod thread

Post by Thunderbird98 »

Hello, I have a trinitron KV29V10. I wired everything up for the rgb mod and got this:
https://imgur.com/Sc42Vsn
The control buttons are not responding at all. I have no clue where to start, I dont know if i fried this thing.
Taxman
Posts: 3
Joined: Mon Jun 27, 2022 9:55 pm

Re: TV RGB mod thread

Post by Taxman »

Hello! I got a failed RGB mod in my BA-4D chassis Sony KV-27v42.

The Problem: I attempted to apply the mux rgb method with a dedicated blanking switch, however when I turn on a connected console I have an out of sync picture for about 2 seconds then completely blank screen, something is getting overheated fast and so I have to immediately shut it off to avoid damage as I can hear some weird sounds coming from the set. Blanking is about the only thing working correctly. OSD is still functional. Another symptom is when I turn on the TV with no cables connected, there is a buzzing sound emitting from the speakers that completely goes away when I connect an scart cable to the connector.


What I have done thus far: Removed rgb inline ground SMD resistors R086, R087, and R088. I soldered external RGB signals directly to the inline SMD .01uf capacitors. For Blanking, I soldered to resistor 316 after finding a 5v test point to use. I soldered pin 20 of scart to S-video luma, and I grounded out the luma port as suggested in this guide (grounding or not grounding the svideo port as suggested makes no difference to my situation at the moment). https://crtdatabase.com/crts/sony/sony-kv-27s42 . For the Scart connector, I used 75ohm terminations to ground for each RGB line as well as included a 100nf cap on each one. I connected all grounds together (4,5,9,13,17,18,21) at the scart connector. I used 820ohm resistors for each external rgb signal.

https://i.imgur.com/P62fgeK.jpg
https://i.imgur.com/e1CYXBV.jpg
https://i.imgur.com/26tnUVt.jpg
https://i.imgur.com/ZNNkVPK.jpg
https://i.imgur.com/i5ETkeh.jpg

I would like to mention a few additional points though. The reason there are two ground wires is I was troubleshooting to see if my 28gauge stranded wire was sufficient or not so I added a 24 gauge solid core wire to see if that helped. It did not. There is also a switch wired to 5v source that is installed near the scart temporarily because the grey wire was originally connected to pin 16 for blanking through a 1k resistor but that only dimmed the display not blank it. I'll tackle that problem later after I get a stable picture. Also scart picture is hard to get the perfect angle but I promise you none of the signal/audio legs or wires are making contact or even close to the ground wires.
Any ideas?
Last edited by Taxman on Wed Jun 29, 2022 1:32 am, edited 2 times in total.
DJtheGamer
Posts: 17
Joined: Fri Jul 17, 2020 6:56 am

Re: TV RGB mod thread

Post by DJtheGamer »

Anyone know if the Panasonic CT-20SX11E is RGB moddable? The chip has unused rgb inputs but don’t know if they are usable and can’t find any information on this model online.
Ryeno
Posts: 89
Joined: Tue Nov 05, 2019 6:50 am

Re: TV RGB mod thread

Post by Ryeno »

Taxman wrote:Hello! I got a failed RGB mod in my BA-4D chassis Sony KV-27v42.

The Problem: I attempted to apply the mux rgb method with a dedicated blanking switch, however when I turn on a connected console I have an out of sync picture for about 2 seconds then completely blank screen, something is getting overheated fast and so I have to immediately shut it off to avoid damage as I can hear some weird sounds coming from the set. Blanking is about the only thing working correctly. OSD is still functional. Another symptom is when I turn on the TV with no cables connected, there is a buzzing sound emitting from the speakers that completely goes away when I connect an scart cable to the connector.


What I have done thus far: Removed rgb inline ground SMD resistors R086, R087, and R088. I soldered external RGB signals directly to the inline SMD .01uf capacitors. For Blanking, I soldered to resistor 316 after finding a 5v test point to use. I soldered pin 20 of scart to S-video luma, and I grounded out the luma port as suggested in this guide (grounding or not grounding the svideo port as suggested makes no difference to my situation at the moment). https://crtdatabase.com/crts/sony/sony-kv-27s42 . For the Scart connector, I used 75ohm terminations to ground for each RGB line as well as included a 100nf cap on each one. I connected all grounds together (4,5,9,13,17,18,21) at the scart connector. I used 820ohm resistors for each external rgb signal.

https://i.imgur.com/P62fgeK.jpg
https://i.imgur.com/e1CYXBV.jpg
https://i.imgur.com/26tnUVt.jpg
https://i.imgur.com/ZNNkVPK.jpg
https://i.imgur.com/i5ETkeh.jpg

I would like to mention a few additional points though. The reason there are two ground wires is I was troubleshooting to see if my 28gauge stranded wire was sufficient or not so I added a 24 gauge solid core wire to see if that helped. It did not. There is also a switch wired to 5v source that is installed near the scart temporarily because the grey wire was originally connected to pin 16 for blanking through a 1k resistor but that only dimmed the display not blank it. I'll tackle that problem later after I get a stable picture. Also scart picture is hard to get the perfect angle but I promise you none of the signal/audio legs or wires are making contact or even close to the ground wires.
Any ideas?
https://github.com/brendanseattle/SonyRGBMod
Taxman
Posts: 3
Joined: Mon Jun 27, 2022 9:55 pm

Re: TV RGB mod thread

Post by Taxman »

Ryeno wrote:
Taxman wrote:Hello! I got a failed RGB mod in my BA-4D chassis Sony KV-27v42.

The Problem: I attempted to apply the mux rgb method with a dedicated blanking switch, however when I turn on a connected console I have an out of sync picture for about 2 seconds then completely blank screen, something is getting overheated fast and so I have to immediately shut it off to avoid damage as I can hear some weird sounds coming from the set. Blanking is about the only thing working correctly. OSD is still functional. Another symptom is when I turn on the TV with no cables connected, there is a buzzing sound emitting from the speakers that completely goes away when I connect an scart cable to the connector.


What I have done thus far: Removed rgb inline ground SMD resistors R086, R087, and R088. I soldered external RGB signals directly to the inline SMD .01uf capacitors. For Blanking, I soldered to resistor 316 after finding a 5v test point to use. I soldered pin 20 of scart to S-video luma, and I grounded out the luma port as suggested in this guide (grounding or not grounding the svideo port as suggested makes no difference to my situation at the moment). https://crtdatabase.com/crts/sony/sony-kv-27s42 . For the Scart connector, I used 75ohm terminations to ground for each RGB line as well as included a 100nf cap on each one. I connected all grounds together (4,5,9,13,17,18,21) at the scart connector. I used 820ohm resistors for each external rgb signal.

https://i.imgur.com/P62fgeK.jpg
https://i.imgur.com/e1CYXBV.jpg
https://i.imgur.com/26tnUVt.jpg
https://i.imgur.com/ZNNkVPK.jpg
https://i.imgur.com/i5ETkeh.jpg

I would like to mention a few additional points though. The reason there are two ground wires is I was troubleshooting to see if my 28gauge stranded wire was sufficient or not so I added a 24 gauge solid core wire to see if that helped. It did not. There is also a switch wired to 5v source that is installed near the scart temporarily because the grey wire was originally connected to pin 16 for blanking through a 1k resistor but that only dimmed the display not blank it. I'll tackle that problem later after I get a stable picture. Also scart picture is hard to get the perfect angle but I promise you none of the signal/audio legs or wires are making contact or even close to the ground wires.
Any ideas?
https://github.com/brendanseattle/SonyRGBMod
I'm familiar with that particular install approach, however I do not have diodes that'll suffice on hand so I chose the resistor values from the chart floating around for a diode-less install, which is why i went with 820ohm resistors. Is this an incorrect approach for this set?
Ryeno
Posts: 89
Joined: Tue Nov 05, 2019 6:50 am

Re: TV RGB mod thread

Post by Ryeno »

Taxman wrote:
Ryeno wrote:
Taxman wrote:Hello! I got a failed RGB mod in my BA-4D chassis Sony KV-27v42.

The Problem: I attempted to apply the mux rgb method with a dedicated blanking switch, however when I turn on a connected console I have an out of sync picture for about 2 seconds then completely blank screen, something is getting overheated fast and so I have to immediately shut it off to avoid damage as I can hear some weird sounds coming from the set. Blanking is about the only thing working correctly. OSD is still functional. Another symptom is when I turn on the TV with no cables connected, there is a buzzing sound emitting from the speakers that completely goes away when I connect an scart cable to the connector.


What I have done thus far: Removed rgb inline ground SMD resistors R086, R087, and R088. I soldered external RGB signals directly to the inline SMD .01uf capacitors. For Blanking, I soldered to resistor 316 after finding a 5v test point to use. I soldered pin 20 of scart to S-video luma, and I grounded out the luma port as suggested in this guide (grounding or not grounding the svideo port as suggested makes no difference to my situation at the moment). https://crtdatabase.com/crts/sony/sony-kv-27s42 . For the Scart connector, I used 75ohm terminations to ground for each RGB line as well as included a 100nf cap on each one. I connected all grounds together (4,5,9,13,17,18,21) at the scart connector. I used 820ohm resistors for each external rgb signal.

https://i.imgur.com/P62fgeK.jpg
https://i.imgur.com/e1CYXBV.jpg
https://i.imgur.com/26tnUVt.jpg
https://i.imgur.com/ZNNkVPK.jpg
https://i.imgur.com/i5ETkeh.jpg

I would like to mention a few additional points though. The reason there are two ground wires is I was troubleshooting to see if my 28gauge stranded wire was sufficient or not so I added a 24 gauge solid core wire to see if that helped. It did not. There is also a switch wired to 5v source that is installed near the scart temporarily because the grey wire was originally connected to pin 16 for blanking through a 1k resistor but that only dimmed the display not blank it. I'll tackle that problem later after I get a stable picture. Also scart picture is hard to get the perfect angle but I promise you none of the signal/audio legs or wires are making contact or even close to the ground wires.
Any ideas?
https://github.com/brendanseattle/SonyRGBMod
I'm familiar with that particular install approach, however I do not have diodes that'll suffice on hand so I chose the resistor values from the chart floating around for a diode-less install, which is why i went with 820ohm resistors. Is this an incorrect approach for this set?
You don't need diodes.
You also don't need the extra 100nf capacitors on each line since the jungle chip already has capacitors on it.
Also I wouldn't recommend sending blanking directly to the jungle chip because you're bypassing the 100 ohm R316 current limiting resistors. You also need a resistor between that and 5V to lower the voltage to the correct value.
Clearly you didn't follow the schematic corrctly which is why your unit isn't working right.
KPackratt2k
Posts: 211
Joined: Sun Apr 04, 2021 11:02 pm
Location: Seattle, WA, USA

Re: TV RGB mod thread

Post by KPackratt2k »

Thunderbird98 wrote:Hello, I have a trinitron KV29V10. I wired everything up for the rgb mod and got this:
https://imgur.com/Sc42Vsn
The control buttons are not responding at all. I have no clue where to start, I dont know if i fried this thing.
Here are a few ideas you could try for troubleshooting:

- Have you tested it with your mod disconnected? If it works without the mod, it's possible you either have a short somewhere in your wiring or have connected something to the wrong spot (i.e. mixing ground with one of your color channels). I'd double check with the service manual and your wiring to make sure everything is in the right place.

- Are you using a CSYNC cable with your console? If so, it's possible that you're feeding it unattenuated TTL CSYNC which could result in messed up sync (best case scenario) or even damage to the set (worst case scenario). The easiest way to check for CSYNC attenuation is by connecting the sync pin of the SCART connector to one end of a multimeter and the CSYNC pin of the console connector on the other end in resistance or continuity mode. If there's resistance of about 470 ohms, then it's attenuated. If there's no resistance or you get continuity, it's passing the CSYNC through unattenuated. Try a Sync on Composite or Luma cable if you have one, as there are some TVs that may not handle CSYNC correctly even with attenuation (no idea if yours is one of those, but considering I've tested attenuated CSYNC on four different RGB modded Sony TVs with success, it may not be the case with yours).
Taxman
Posts: 3
Joined: Mon Jun 27, 2022 9:55 pm

Re: TV RGB mod thread

Post by Taxman »

Taxman wrote:Hello! I got a failed RGB mod in my BA-4D chassis Sony KV-27v42.

The Problem: I attempted to apply the mux rgb method with a dedicated blanking switch, however when I turn on a connected console I have an out of sync picture for about 2 seconds then completely blank screen, something is getting overheated fast and so I have to immediately shut it off to avoid damage as I can hear some weird sounds coming from the set. Blanking is about the only thing working correctly. OSD is still functional. Another symptom is when I turn on the TV with no cables connected, there is a buzzing sound emitting from the speakers that completely goes away when I connect an scart cable to the connector.


What I have done thus far: Removed rgb inline ground SMD resistors R086, R087, and R088. I soldered external RGB signals directly to the inline SMD .01uf capacitors. For Blanking, I soldered to resistor 316 after finding a 5v test point to use. I soldered pin 20 of scart to S-video luma, and I grounded out the luma port as suggested in this guide (grounding or not grounding the svideo port as suggested makes no difference to my situation at the moment). https://crtdatabase.com/crts/sony/sony-kv-27s42 . For the Scart connector, I used 75ohm terminations to ground for each RGB line as well as included a 100nf cap on each one. I connected all grounds together (4,5,9,13,17,18,21) at the scart connector. I used 820ohm resistors for each external rgb signal.

https://i.imgur.com/P62fgeK.jpg
https://i.imgur.com/e1CYXBV.jpg
https://i.imgur.com/26tnUVt.jpg
https://i.imgur.com/ZNNkVPK.jpg
https://i.imgur.com/i5ETkeh.jpg

I would like to mention a few additional points though. The reason there are two ground wires is I was troubleshooting to see if my 28gauge stranded wire was sufficient or not so I added a 24 gauge solid core wire to see if that helped. It did not. There is also a switch wired to 5v source that is installed near the scart temporarily because the grey wire was originally connected to pin 16 for blanking through a 1k resistor but that only dimmed the display not blank it. I'll tackle that problem later after I get a stable picture. Also scart picture is hard to get the perfect angle but I promise you none of the signal/audio legs or wires are making contact or even close to the ground wires.
Any ideas?
Update: It just started working all of a sudden. I tried testing composite video to see if that still worked, and it didn't. So i disconnected my genesis to test on another tv, which worked fine. I connected the genesis back and composite worked on the modded tv again. Then I connected the scart cable and boom, crystal clear image. Damn. So I removed my temporary switch and installed the blanking line to pin 16 through a 1k resistor and moved the blanking injection point back a little bit to the back side of the factory 100ohm resistor. Switchless blanking works. I will still need a spst switch for the s-video luma grounding so I can switch back and forth between s-video and s-cart functionality, so it's not completely switchless but just about. Everything is working great. There is a slight amount of interference so I have already ordered much better quality wiring to redo it all, the cheap 28gauge ribbon cable just doesn't have enough insulation but the gauge size itself seems to be sufficient for an approximate 2.5ft length.
Ryeno
Posts: 89
Joined: Tue Nov 05, 2019 6:50 am

Re: TV RGB mod thread

Post by Ryeno »

Taxman wrote:
Taxman wrote:Hello! I got a failed RGB mod in my BA-4D chassis Sony KV-27v42.

The Problem: I attempted to apply the mux rgb method with a dedicated blanking switch, however when I turn on a connected console I have an out of sync picture for about 2 seconds then completely blank screen, something is getting overheated fast and so I have to immediately shut it off to avoid damage as I can hear some weird sounds coming from the set. Blanking is about the only thing working correctly. OSD is still functional. Another symptom is when I turn on the TV with no cables connected, there is a buzzing sound emitting from the speakers that completely goes away when I connect an scart cable to the connector.


What I have done thus far: Removed rgb inline ground SMD resistors R086, R087, and R088. I soldered external RGB signals directly to the inline SMD .01uf capacitors. For Blanking, I soldered to resistor 316 after finding a 5v test point to use. I soldered pin 20 of scart to S-video luma, and I grounded out the luma port as suggested in this guide (grounding or not grounding the svideo port as suggested makes no difference to my situation at the moment). https://crtdatabase.com/crts/sony/sony-kv-27s42 . For the Scart connector, I used 75ohm terminations to ground for each RGB line as well as included a 100nf cap on each one. I connected all grounds together (4,5,9,13,17,18,21) at the scart connector. I used 820ohm resistors for each external rgb signal.

https://i.imgur.com/P62fgeK.jpg
https://i.imgur.com/e1CYXBV.jpg
https://i.imgur.com/26tnUVt.jpg
https://i.imgur.com/ZNNkVPK.jpg
https://i.imgur.com/i5ETkeh.jpg

I would like to mention a few additional points though. The reason there are two ground wires is I was troubleshooting to see if my 28gauge stranded wire was sufficient or not so I added a 24 gauge solid core wire to see if that helped. It did not. There is also a switch wired to 5v source that is installed near the scart temporarily because the grey wire was originally connected to pin 16 for blanking through a 1k resistor but that only dimmed the display not blank it. I'll tackle that problem later after I get a stable picture. Also scart picture is hard to get the perfect angle but I promise you none of the signal/audio legs or wires are making contact or even close to the ground wires.
Any ideas?
Update: It just started working all of a sudden. I tried testing composite video to see if that still worked, and it didn't. So i disconnected my genesis to test on another tv, which worked fine. I connected the genesis back and composite worked on the modded tv again. Then I connected the scart cable and boom, crystal clear image. Damn. So I removed my temporary switch and installed the blanking line to pin 16 through a 1k resistor and moved the blanking injection point back a little bit to the back side of the factory 100ohm resistor. Switchless blanking works. I will still need a spst switch for the s-video luma grounding so I can switch back and forth between s-video and s-cart functionality, so it's not completely switchless but just about. Everything is working great. There is a slight amount of interference so I have already ordered much better quality wiring to redo it all, the cheap 28gauge ribbon cable just doesn't have enough insulation but the gauge size itself seems to be sufficient for an approximate 2.5ft length.
Good Job.

As long as you don't power on both consoles at the same time (s-video and scart), you don't need a switch if wire scart pin 16. Remove R004 10k resistor. Replace it with ~10k + 150 ohm resistors. Wire SCART Pin 16 between the 10k and 150 ohm resistors.

You might want to consider upgrading the 0.01uf caps to 0.1uf because it offsets the 820 ohm inline resistor.

You could also consider YUV modding the TV.

This is how I recommend injecting RGB into a BA-4D set.
https://imgur.com/5hiwuus
Remove the 680 ohm resistors then install the 820 resistors into the same hole as the 5.6k resistors.
There is a ground jumper right next to the 5.6k resistors so you can install the 75 ohm resistors onto it.
Then feed the RGB signal between the 2 resistors.
InfamousSabre
Posts: 12
Joined: Fri Jul 22, 2016 1:57 pm

Re: TV RGB mod thread

Post by InfamousSabre »

Alright I'm back again with yet another set. This is a GE 20GH250 with a CTC-176K2 chassis utilizing a Sanyo LA7610 jungle chip.
The schematic for this TV looks really odd to me though. I cant quite understand where I should inject RGB. Can anyone help me out here?

Image
User avatar
maxtherabbit
Posts: 1763
Joined: Mon Mar 05, 2018 4:03 pm

Re: TV RGB mod thread

Post by maxtherabbit »

InfamousSabre wrote:Alright I'm back again with yet another set. This is a GE 20GH250 with a CTC-176K2 chassis utilizing a Sanyo LA7610 jungle chip.
The schematic for this TV looks really odd to me though. I cant quite understand where I should inject RGB. Can anyone help me out here?

Image
So it would appear the RGB inputs get pulled up to 700mV and the microcontroller actually grounds them by way of those transistors

In order to achieve a mux, you would need to basically delete every component in the highlighted sections of your schematics except for the input coupling caps at the jungle (C2707-9) and the 1k series resistors from the micon (R3310, R3318, R3320). Then you'd have to build your mux circuit around those following the diagram. I'd strongly recommend using diodes and installing them across the base-emitter pads of where the transistors used to be
Ryeno
Posts: 89
Joined: Tue Nov 05, 2019 6:50 am

Re: TV RGB mod thread

Post by Ryeno »

maxtherabbit wrote:
InfamousSabre wrote:Alright I'm back again with yet another set. This is a GE 20GH250 with a CTC-176K2 chassis utilizing a Sanyo LA7610 jungle chip.
The schematic for this TV looks really odd to me though. I cant quite understand where I should inject RGB. Can anyone help me out here?

Image
So it would appear the RGB inputs get pulled up to 700mV and the microcontroller actually grounds them by way of those transistors

In order to achieve a mux, you would need to basically delete every component in the highlighted sections of your schematics except for the input coupling caps at the jungle (C2707-9) and the 1k series resistors from the micon (R3310, R3318, R3320). Then you'd have to build your mux circuit around those following the diagram. I'd strongly recommend using diodes and installing them across the base-emitter pads of where the transistors used to be
Couldn't he put another capacitor (100nF?) between the jungle chip and the existing capacitor (1uF) then run his signal between the 2 caps? + 75 ohm termination resistors.

According to the datasheet for LA7615, Pin 39 is Fast Blanking (Ys) and it requires 2V.

External Switch
I would get 2 diodes. Install 1 diode on R3311 + existing 1K resistor. Then grab 5V, run that through a second diode, and inject between the first diode and 1k resistor in R3311.

SCART Switching
I would still add the 1st diode onto R3311 but then add a 120 ohm resistor between R3322 and ground. Wire SCART-16 between R3322 1K resistor and 120 ohm resistor.
Minitron
Posts: 16
Joined: Fri Apr 01, 2022 2:25 am

Re: TV RGB mod thread

Post by Minitron »

Hey guys, im about to attempt an RGB mux mod on a Sanyo DS31520.

A couple questions though. The chip's accepted RGB lines appear to be 1.5v. Is this an issue? I believe the SCART lines are 0.7v.

Second question. It appears as though the chip's blank line is 0v. Is this just the default, before the blank is sent?
Ryeno
Posts: 89
Joined: Tue Nov 05, 2019 6:50 am

Re: TV RGB mod thread

Post by Ryeno »

Minitron wrote:Hey guys, im about to attempt an RGB mux mod on a Sanyo DS31520.

A couple questions though. The chip's accepted RGB lines appear to be 1.5v. Is this an issue? I believe the SCART lines are 0.7v.

Second question. It appears as though the chip's blank line is 0v. Is this just the default, before the blank is sent?
https://www.manualslib.com/manual/90907 ... 31520.html

Is this the service manual? If so the RGB resistors are 5600 and 820 (R842-R844). I believe these resistors are SMD. If so you must remove them and replace them with 820 ohm + 75 ohm through hole resistors. Inject RGB between the 820 and 75 ohm resistors. If they are through hole then you can lift 1 leg and add the 75 ohm resistor on the ground side and inject RGB between the 2 resistors.

As for blanking, it appears to be ~2.5V. Assuming you want SCART blanking, you must add a 150 ohm resistor between R841 and ground and connect that to SCART-16. Since it's likely that R841 is a surface mount device, you'll probably want to remove it and replace it with 820 ohm + 150 ohm through hole resistors.

You need 4 820 ohm resistors, 3 75 ohm resistors and 1 150 ohm resistor.
Minitron
Posts: 16
Joined: Fri Apr 01, 2022 2:25 am

Re: TV RGB mod thread

Post by Minitron »

Ryeno wrote:
https://www.manualslib.com/manual/90907 ... 31520.html

Is this the service manual? If so the RGB resistors are 5600 and 820 (R842-R844). I believe these resistors are SMD. If so you must remove them and replace them with 820 ohm + 75 ohm through hole resistors. Inject RGB between the 820 and 75 ohm resistors. If they are through hole then you can lift 1 leg and add the 75 ohm resistor on the ground side and inject RGB between the 2 resistors.

As for blanking, it appears to be ~2.5V. Assuming you want SCART blanking, you must add a 150 ohm resistor between R841 and ground and connect that to SCART-16. Since it's likely that R841 is a surface mount device, you'll probably want to remove it and replace it with 820 ohm + 150 ohm through hole resistors.

You need 4 820 ohm resistors, 3 75 ohm resistors and 1 150 ohm resistor.
You are the absolute best. I ordered the wrong values again lmao :roll: time for another order!
InfamousSabre
Posts: 12
Joined: Fri Jul 22, 2016 1:57 pm

Re: TV RGB mod thread

Post by InfamousSabre »

maxtherabbit wrote:
InfamousSabre wrote:Alright I'm back again with yet another set. This is a GE 20GH250 with a CTC-176K2 chassis utilizing a Sanyo LA7610 jungle chip.
The schematic for this TV looks really odd to me though. I cant quite understand where I should inject RGB. Can anyone help me out here?

Image
So it would appear the RGB inputs get pulled up to 700mV and the microcontroller actually grounds them by way of those transistors

In order to achieve a mux, you would need to basically delete every component in the highlighted sections of your schematics except for the input coupling caps at the jungle (C2707-9) and the 1k series resistors from the micon (R3310, R3318, R3320). Then you'd have to build your mux circuit around those following the diagram. I'd strongly recommend using diodes and installing them across the base-emitter pads of where the transistors used to be
That's what it looked like to me too. Wouldn't that mean that the transistor is effectively inverting the signal?
Also if I remove everything from the circuit except those two components, why would I need a diode across the transistor pads?
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maxtherabbit
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Re: TV RGB mod thread

Post by maxtherabbit »

InfamousSabre wrote:
maxtherabbit wrote:
InfamousSabre wrote:Alright I'm back again with yet another set. This is a GE 20GH250 with a CTC-176K2 chassis utilizing a Sanyo LA7610 jungle chip.
The schematic for this TV looks really odd to me though. I cant quite understand where I should inject RGB. Can anyone help me out here?

Image
So it would appear the RGB inputs get pulled up to 700mV and the microcontroller actually grounds them by way of those transistors

In order to achieve a mux, you would need to basically delete every component in the highlighted sections of your schematics except for the input coupling caps at the jungle (C2707-9) and the 1k series resistors from the micon (R3310, R3318, R3320). Then you'd have to build your mux circuit around those following the diagram. I'd strongly recommend using diodes and installing them across the base-emitter pads of where the transistors used to be
That's what it looked like to me too. Wouldn't that mean that the transistor is effectively inverting the signal?
Also if I remove everything from the circuit except those two components, why would I need a diode across the transistor pads?
I'm just suggesting using the pads to hold it physically. Electrically you'd set it up like the mux with diodes in Ozlads sig schematic
MarkOZLAD
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Re: TV RGB mod thread

Post by MarkOZLAD »

InfamousSabre wrote:Alright I'm back again with yet another set. This is a GE 20GH250 with a CTC-176K2 chassis utilizing a Sanyo LA7610 jungle chip.
The schematic for this TV looks really odd to me though. I cant quite understand where I should inject RGB. Can anyone help me out here?

Image
If it were me I'd try and cheat by just removing the R2712, R2714 and R2716 and doing a twist method with 1500R and 75R into the holes left by their removal.
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InfamousSabre
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Re: TV RGB mod thread

Post by InfamousSabre »

MarkOZLAD wrote:
InfamousSabre wrote:Alright I'm back again with yet another set. This is a GE 20GH250 with a CTC-176K2 chassis utilizing a Sanyo LA7610 jungle chip.
The schematic for this TV looks really odd to me though. I cant quite understand where I should inject RGB. Can anyone help me out here?

Image
If it were me I'd try and cheat by just removing the R2712, R2714 and R2716 and doing a twist method with 1500R and 75R into the holes left by their removal.
Unfortunately these are surface mount so it'd be a little more involved, but I can still try that.
Would that be leaving the 1500R on the 7.5v side or the jungle side?
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Re: TV RGB mod thread

Post by MarkOZLAD »

Oh 7.5V? I didn’t notice that!

Disregard my comment.
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InfamousSabre
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Re: TV RGB mod thread

Post by InfamousSabre »

MarkOZLAD wrote:Oh 7.5V? I didn’t notice that!

Disregard my comment.
Lol, yeah that's what has me so confused. Even though I know the LA7610 is moddable (Others in this thread have had success), the way this particular chassis is wired doesn't seem like the standard setup at all. It seems as though the transistor is being used to invert the signal?
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Re: TV RGB mod thread

Post by maxtherabbit »

InfamousSabre wrote:
MarkOZLAD wrote:Oh 7.5V? I didn’t notice that!

Disregard my comment.
Lol, yeah that's what has me so confused. Even though I know the LA7610 is moddable (Others in this thread have had success), the way this particular chassis is wired doesn't seem like the standard setup at all. It seems as though the transistor is being used to invert the signal?
No I'm pretty sure the micon is still active high for the OSD. Just delete all the BS and build a "diode type" mux from scratch it should work fine. Ignore what I said about the transistor pads if it's SMD
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Re: TV RGB mod thread

Post by InfamousSabre »

maxtherabbit wrote:
InfamousSabre wrote:
MarkOZLAD wrote:Oh 7.5V? I didn’t notice that!

Disregard my comment.
Lol, yeah that's what has me so confused. Even though I know the LA7610 is moddable (Others in this thread have had success), the way this particular chassis is wired doesn't seem like the standard setup at all. It seems as though the transistor is being used to invert the signal?
No I'm pretty sure the micon is still active high for the OSD. Just delete all the BS and build a "diode type" mux from scratch it should work fine. Ignore what I said about the transistor pads if it's SMD
I'm getting started on that right now. The micon is socketed so I'd hoped to just unsocket it, bend up the 3 output pins, then resocket, but its stuck in there pretty tight and theres a metal shield all around it so I cant slip a screwdriver underneath to pry it up like usual. Going to just desolder that first resistor (3310, 3318, 3320) to disconnect the micon from the rest of that circuit. Then, on the jungle side, that 1uf capacitor is through-hole so ill pull up the micon-facing leg, removing the jungle from the circuit. After that I can get wires running out to a breadboard and look at creating the mux circuit like you said.

At the micon, on the RED-OSD, GRN-OSD, and BLU-OSD pins, it says 0V. If there's 0 volts coming out of those pins, how on earth does it work? Or am I just reading it improperly?
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Re: TV RGB mod thread

Post by MarkOZLAD »

Might be worth trying to simulate the circuit in an online circuit simulation program.
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InfamousSabre
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Re: TV RGB mod thread

Post by InfamousSabre »

MarkOZLAD wrote:Might be worth trying to simulate the circuit in an online circuit simulation program.
We're on the save wavelength. I tried that earlier but using 0V on that line does nothing in the simulation.

I'm trying to figure out what to do with Sync now though. This TV has no S-Video or Composite-In. (I have triple-checked and made sure that this is not a hot-chassis board) There is a Y-In pin on the LA7610, however. I haven't seen anyone in here directly connect to the jungle for sync yet though, so my question now is: What should go between the SCART sync pin and the jungle's Y-In?
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Re: TV RGB mod thread

Post by KPackratt2k »

InfamousSabre wrote:There is a Y-In pin on the LA7610, however. I haven't seen anyone in here directly connect to the jungle for sync yet though, so my question now is: What should go between the SCART sync pin and the jungle's Y-In?
Try putting a 0.1uF capacitor inline on the sync wire and terminate the sync pin of your SCART head with a 75 ohm resistor just like you would on the RGB lines. I don't know for certain that this would be all it would take, but it's worth a shot to try. If this doesn't work right away, you might have to add additional components on your sync wire (maybe some resistors).

Find out where the tuner is sending video into the Y pin of the jungle chip and isolate the circuit. You may also try injecting sync somewhere in that line.
Ryeno
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Re: TV RGB mod thread

Post by Ryeno »

InfamousSabre wrote:
I'm getting started on that right now. The micon is socketed so I'd hoped to just unsocket it, bend up the 3 output pins, then resocket, but its stuck in there pretty tight and theres a metal shield all around it so I cant slip a screwdriver underneath to pry it up like usual. Going to just desolder that first resistor (3310, 3318, 3320) to disconnect the micon from the rest of that circuit. Then, on the jungle side, that 1uf capacitor is through-hole so ill pull up the micon-facing leg, removing the jungle from the circuit. After that I can get wires running out to a breadboard and look at creating the mux circuit like you said.

At the micon, on the RED-OSD, GRN-OSD, and BLU-OSD pins, it says 0V. If there's 0 volts coming out of those pins, how on earth does it work? Or am I just reading it improperly?

Easiest way to RGB mod is to use as 4PDT Switch at the 1uF input caps. This method will work 100% but you'll lose OSD in RGB mod.

The other option is to remove 120 ohm grounding resistors and replace them with 75 ohm and 43 ohm and inject RGB between the 2 resistors. Is the Micon 5V or 7.5V?
Last edited by Ryeno on Sat Jul 02, 2022 9:16 am, edited 1 time in total.
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