this guy did an RGB with TMS-RGB & a upscaler

[+hloberg]

here is a way to get a clear picture that I haven't heard of. It looks to work really well.

https://netzhansa.com/ti99-4a-color/

he uses a https://tms-rgb.com/

AA discussion in Coleco section:

and then an upscaler to get the sync. Looks like a good idea.

 

[+jedimatt42]

Now the demand for PAL 4A's will go up

[+hloberg]

Looks like someone has already been discussing it to some extent.

 

[ChildOfCv]

Yeah, though that one used the 9918 originally, so it needed some more TLC than a 9929 board would.

 

On the good side, this means it is now possible to mod either version.

[+OLD CS1]

For this, I could just sit a 9928A in a socket with the appropriate pins shunted.  Price depending, might be a neat mod for me.

[JJB]

Just confirming that TMS RGB works very well in my US TI after replacing the TMS9918A with a TMS9928A I purchased from Ebay. Pin 38 (CPUCLK) wasn't used for the sound processor so I just terminated it with a 560R resistor, same with pin 35 (EXTVDP). The composite video signal from pin 36 goes to a inductor (L202) first, I cut the incoming side and bent it out of the way. Right under that inductor is an unused wire link which can be conveniently used to terminate pin 36 with another 560R resistor. 

 

I re-used the existing TI video connector to provide RGB out  and made a custom DIN - SCART cable to connect to a cheap RGB - HDMI converter. SCART needs a positive potential on pin 16 (Fast Switching) to select RGB instead of CVIDEO but with a 5-pin DIN I didn't have a spare pin to carry 5V from the console. I just opened up the converter and connected pin 16 internally to a suitable 5V point via a current-limiting resistor.

 

Cheers,

 

Jochen
 

[macsonny]

On 1/26/2021 at 4:37 PM, JJB said:

Just confirming that TMS RGB works very well in my US TI after replacing the TMS9918A with a TMS9928A I purchased from Ebay. Pin 38 (CPUCLK) wasn't used for the sound processor so I just terminated it with a 560R resistor, same with pin 35 (EXTVDP). The composite video signal from pin 36 goes to a inductor (L202) first, I cut the incoming side and bent it out of the way. Right under that inductor is an unused wire link which can be conveniently used to terminate pin 36 with another 560R resistor. 

 

I re-used the existing TI video connector to provide RGB out  and made a custom DIN - SCART cable to connect to a cheap RGB - HDMI converter. SCART needs a positive potential on pin 16 (Fast Switching) to select RGB instead of CVIDEO but with a 5-pin DIN I didn't have a spare pin to carry 5V from the console. I just opened up the converter and connected pin 16 internally to a suitable 5V point via a current-limiting resistor.

 

Cheers,

 

Jochen
 

What was the wiring for your SCART to DIN ?

[JJB]

Let me check

[JJB]

4 hours ago, JJB said:

Let me check

WARNING!!! on an unmodified console pin 1 carries 12V, you don't want to connect that through! Make sure it's properly disconnected in the console; I am not responsible for blowing up your TI / Scaler / both or any other precious equipment 🙂

 

I think ideally you should have a separate ground for audio (I have a faint audio hum from supposedly a ground loop) but with only 5-pin connector choices are limited. I guess PAL machines have 6 pins so easy to add a separate ground.

 

My first cable used standard wiring and I did get some interference. I made a 2nd cable using an old VGA cable (COAX based), it did make a difference. It is fiddly to say the least to try to fit such a cable in a DIN harness, but it can be done. TIP: secure the DIN internals with hot glue (after testing  ).

 

[macsonny]

On 1/22/2023 at 3:10 PM, JJB said:

WARNING!!! on an unmodified console pin 1 carries 12V, you don't want to connect that through! Make sure it's properly disconnected in the console; I am not responsible for blowing up your TI / Scaler / both or any other precious equipment 🙂

 

I think ideally you should have a separate ground for audio (I have a faint audio hum from supposedly a ground loop) but with only 5-pin connector choices are limited. I guess PAL machines have 6 pins so easy to add a separate ground.

 

My first cable used standard wiring and I did get some interference. I made a 2nd cable using an old VGA cable (COAX based), it did make a difference. It is fiddly to say the least to try to fit such a cable in a DIN harness, but it can be done. TIP: secure the DIN internals with hot glue (after testing  ).

 

Thanks. Worked a treat. Appreciate the guidance.