Philips/mag PR1920 .... RGB Complete

[MarkOZLAD]

Ok this is how I think it needs to be done.

Replace 3647, 3648 and 3649 with 680 Ohms 1/4W or better resistors
Replace jumpers 9653, 9654 and 9655 with 1n4148 diodes in each
Remove 68R SMD resistors 3640, 3641 and 3642 (factory "grounding resistors") I think that's the correct numbers. I'm sure you know which ones I refer to.
For inline mux resistors we will use 360 Ohm (1/4W or better)

For blanking we want to find a 3.3V source (point 1601 near 3V3 regulator) connect to an on/off switch, then to a 75 ohm resistor and then connect to jumper 9261. That will hopefully give us a bit over 2V to the blanking.

If that doesn't work I suggest fitting a 1n4148 diode (pointing away from Micom) at 9652 and then using a 1K resistor instead of the 75 Ohm.

[MarkOZLAD]

my generic understanding is the traditional rgb mod method is basically severing and hijacking into the r,b,g lines right before the jungle and leaving .1uF caps, or if you remove them to add them back on osd and ext rgb lines going into it, and the 4pdt switch just switches between the 2 rgb sources with also your blanking voltage on switch and 75ohm termination on ext rgb to ground.

That was how it was done until 2016. Some people still make videos doing it that way and then act like they've achieved something when what they've done is mutilate their set.

So how then would you genericly describe the muxing method? Instead of cutting and jacking into rgb, you instead seamlessly mix the external signal into the original circuitry?
This method is much more involved because you have to tune/match/attenuate signals to work with the jungle ic?

I'd describe it as:

....Instead of cutting and jacking into rgb, you instead seamlessly mix the external signal into the original circuitry?

Just needs some simple maths to be done or use my spreadsheet to calculate a mux resistor. The only concept in play is voltage division.

It's simpler, neater and gives you an OSD at all times including when in RGB mode.

[deezdrama]

my generic understanding is the traditional rgb mod method is basically severing and hijacking into the r,b,g lines right before the jungle and leaving .1uF caps, or if you remove them to add them back on osd and ext rgb lines going into it, and the 4pdt switch just switches between the 2 rgb sources with also your blanking voltage on switch and 75ohm termination on ext rgb to ground.

That was how it was done until 2016. Some people still make videos doing it that way and then act like they've achieved something when what they've done is mutilate their set.

So how then would you genericly describe the muxing method? Instead of cutting and jacking into rgb, you instead seamlessly mix the external signal into the original circuitry?
This method is much more involved because you have to tune/match/attenuate signals to work with the jungle ic?

I'd describe it as:

....Instead of cutting and jacking into rgb, you instead seamlessly mix the external signal into the original circuitry?

Just needs some simple maths to be done or use my spreadsheet to calculate a mux resistor. The only concept in play is voltage division.

It's simpler, neater and gives you an OSD at all times including when in RGB mode.

Awesome work! Ill have to order some diodes and switches... What program did you use for the diagram?
Do you have a collection of these diagrams for all the sets youve deciphered?

Thanks a million!

[MarkOZLAD]

What program did you use for the diagram?

Excel

Do you have a collection of these diagrams for all the sets youve deciphered?

There's plenty of my stuff here on SHMUPS. Sony BA5/BA5D/BA4/BA4D chassis, The 8 Bit Guy's Samsung mod was designed by me and is documented here on SHMUPS.

Thanks a million!

Hope it works!

[deezdrama]

What program did you use for the diagram?

Excel

Do you have a collection of these diagrams for all the sets youve deciphered?

There's plenty of my stuff here on SHMUPS. Sony BA5/BA5D/BA4/BA4D chassis, The 8 Bit Guy's Samsung mod was designed by me and is documented here on SHMUPS.

Thanks a million!

Hope it works!

Im getting it done today minus the diodes... they will be here in a couple days.
I will update here.
Was going to make a video for YT, is it ok to give you credit on there if I do?


Also...
Thinking about putting bnc connectors on front where the 2nd speaker is missing but its near the tube, would that be an issue with non shielded wires?

[deezdrama]

What program did you use for the diagram?

Excel

Do you have a collection of these diagrams for all the sets youve deciphered?

There's plenty of my stuff here on SHMUPS. Sony BA5/BA5D/BA4/BA4D chassis, The 8 Bit Guy's Samsung mod was designed by me and is documented here on SHMUPS.

Thanks a million!

Hope it works!

Besides removing the 68R grounding resistors from r,g,b in your note you mention remove from blanking as well.
So should I remove this 151 resistor? What about the cap next to it?

Thanks!

[MarkOZLAD]

Don’t remove the 151 from blanking.

[deezdrama]

Don’t remove the 151 from blanking.

Gotcha, what about the cap thats also grounded there to the blaning signal? Leave it too?

[MarkOZLAD]

Don’t remove the 151 from blanking.

Gotcha, what about the cap thats also grounded there to the blaning signal? Leave it too?

Leave it

[deezdrama]

Don’t remove the 151 from blanking.

Gotcha, what about the cap thats also grounded there to the blaning signal? Leave it too?

Leave it

I been busy but had time to pretty much complete the mod tonight.
Only thing left is to add 360 ohms of resistance to the rgb lines going to the bnc connectors.
How critical is this figure?
I have 330 ohm resistors that read 320 on the meter.
Would that be fine or should I add 47 ohm resistors in series onto them?

Thanks

[MarkOZLAD]

Critical if you want an OSD.

330 should be fine.

[matt]

I been busy but had time to pretty much complete the mod tonight.
Only thing left is to add 360 ohms of resistance to the rgb lines going to the bnc connectors.
How critical is this figure?
I have 330 ohm resistors that read 320 on the meter.
Would that be fine or should I add 47 ohm resistors in series onto them?

I find that while Mark's OSD mux chart is a good starting point, I usually have to tweak the resistor values a bit to get the OSD at the right brightness. Starting somewhere in the ballpark should be fine, just be prepared to adjust as needed.

I made a small breadboard device that I use to sort things out before hard wiring everything. It's handy if you want to do a bunch of different TV models.

[MarkOZLAD]

In this case I had actually calculated the resistors to give an OSD of closer to 1V so it’s fine to reduce the Mux resistor value.

[deezdrama]

I been busy but had time to pretty much complete the mod tonight.
Only thing left is to add 360 ohms of resistance to the rgb lines going to the bnc connectors.
How critical is this figure?
I have 330 ohm resistors that read 320 on the meter.
Would that be fine or should I add 47 ohm resistors in series onto them?

I find that while Mark's OSD mux chart is a good starting point, I usually have to tweak the resistor values a bit to get the OSD at the right brightness. Starting somewhere in the ballpark should be fine, just be prepared to adjust as needed.

I made a small breadboard device that I use to sort things out before hard wiring everything. It's handy if you want to do a bunch of different TV models.

Yeah, I definitely need to get a breadboard, going to grab a broadcast monitor and some pvms today, I might pick up a 36" jvc i spotted while im up there, and I have a panasonic tau so want to do at least 2 more rgb mods so a breadboard would come in handy.

Thanks guys

[MarkOZLAD]

I think you should be able to get away without a breadboard. Solder one leg of your 330 ohm resistors into the text port and solder wires onto the other legs. These wires go to your BNC connectors. The BNC connectors need both a signal and ground so you can ad the 75 ohm termination at the BNC.

[deezdrama]

I think you should be able to get away without a breadboard. Solder one leg of your 330 ohm resistors into the text port and solder wires onto the other legs. These wires go to your BNC connectors. The BNC connectors need both a signal and ground so you can ad the 75 ohm termination at the BNC.

I meant get a breadboard more for future rgb mods like this jvc av36850 I just picked up as ive been told theres no way to adjust brightness or contrast in the menu and have to control it by playing around with different resistor value,

I just added the 330ohm resistors to the rgb lines and have the mod complete,

Before attaching the blanking voltage I wanted to test voltage on it and with the 75 ohm resistor im getting 3.5v,
With the tv off im still pulling 3.35v from the 3.3v circuit.

I pulled 3.3v from cap 2600

Fed it to the switch , from the switch it has a 75ohm resistor inline and was going to put it back in circuit at header point 0219.


EDIT..... Ok ... Looking at your diagram I remembered theres 2 grouded resistors on the blanking circuit on the board.... Will those reduce voltage? I know.... My electronics theory understanding is laughable lol

[MarkOZLAD]

For the blanking there are two concepts in play. Parallel resistance and voltage division.

[deezdrama]

For the blanking there are two concepts in play. Parallel resistance and voltage division.

My limited understanding is you can half voltage with 2 same value resistors in series grounded inbetween, so the blanking signal wire is putting out 3.5v with the 75 ohm resistor... Once its inserted back into the circuit between the 151r and 2.7k ohm grounded resistors that are on the board will the 3.5v be lowered?

I guess what im asking is if its safe to plug in and try at this point lol

[MarkOZLAD]

The parallel resistors 150 ohm and 2700 ohm in parallel result in 140 ohm

The 75 ohm and 140 ohm will work as pretty much a 1:2 voltage divider.

The 3.5V will come down to 2/3rd and be about 2.3V.

[deezdrama]

The parallel resistors 150 ohm and 2700 ohm in parallel result in 140 ohm

The 75 ohm and 140 ohm will work as pretty much a 1:2 voltage divider.

The 3.5V will come down to 2/3rd and be about 2.3V.

Awesome.... Starting to understand little by litte, I ask so many questions now so I wont have to in the future .... Well not so many anyway lol. Thanks!

[deezdrama]

Looking good!
At first it was out of sync and thought it didnt work but had to jiggle sync on composite port, hopefully just a cracked joint I will reflow. Need to replace a few caps on deflection circuit and will button this one up, have to finish recapping a pvm 1344q then going to tackle rgb mod on the jvc av36850

[MarkOZLAD]

Fantastic.

How’s the OSD look in RGB mode?

[deezdrama]

Fantastic.

How’s the OSD look in RGB mode?

Looks great when blanked. When switch is off the osd has a little shimmer around the edges.

[MarkOZLAD]

It’s possible it always shimmered. You probably weren’t looking at it critically prior to the mod.

[deezdrama]

It’s possible it always shimmered. You probably weren’t looking at it critically prior to the mod.

Its more like yellow colored pixels dancing around the green menu text but only when blanking switch is off and doesnt bother me at all because Its a dedicated rgb monitor now lol.
Thanks again!

[MarkOZLAD]

For anyone else who finds this thread I suggest using 270 ohm resistors in the place where 360 ohm are shown on the diagram.

[deezdrama]

https://youtu.be/uc7VobS1aik

[MarkOZLAD]

Love it.

I'd normally go with Mark OZ Lad like in the Wizard of Oz but I kinda like the way you say Mark "Oh Zee" LAD

The OZ is a reference to me being Australian.

Your implementation of the mod looks nice. Part of the reason I like to help others do these mods is because I always find it interesting and often learn something I can use in my own mods. In your implementation I was interested to see how you did the 75 ohm terminations.

[deezdrama]

Love it.

I'd normally go with Mark OZ Lad like in the Wizard of Oz but I kinda like the way you say Mark "Oh Zee" LAD

The OZ is a reference to me being Australian.

Your implementation of the mod looks nice. Part of the reason I like to help others do these mods is because I always find it interesting and often learn something I can use in my own mods. In your implementation I was interested to see how you did the 75 ohm terminations.

I wondered if you were Australian. Pronounciation noted for next shoutout I give ya LOL.
(Might need your brain on this 36" JVC 850 when I find time to mod it, Im going to replace a handful of caps on this Philips and also need to recap a pvm-1344q first to have room on the bench)

With the termination resistors... I was just trying to figure out what all I could solder in position first, had to lay the tube down flat to solder the grounding washer/tabs... Im sure there was a better way to do it but made things a little more difficult on myself by not using scart.
I wish we would of got scart here (did Australia have scart in 80s 90s?) But ive never owned a scart cable and invested into BNC cables at this point lol.

Anyway... Thanks again for the guidance!

[MarkOZLAD]

Happy to help with the JVC. Seems a popular one so worth documenting.

Can cover the theory a bit more if you like.