[TheCorfiot]

Good morning

 

Answers to your questions

 

1. Yes this is the way, dont double buffer or you will delay csync timing

2. Yes remove it

3. See VGPs response

[TheCorfiot]

Hi Felipe

ST and STe scart cables are notorious for sync issues where scart cables are concerned…

This is because they don’t natively have 5 or 12 Volts on the monitor connector which is usually used by other systems to derive the Fast blank switching voltage on scart Pin 16 which TV’s need to be informed to use RGB signalling instead of composite video.

Instead a “hack” which works most of the time was used using the Vsync signal and a 10uF capacitor to ground to provide a “rough” blanking voltage.

And Yes commercial cables used this.

The OSSC and Pro have no need for a fast blanking signal.

If you don’t mind trying an experiment…

Open your scart plug and look at pin 16… if it is connected by a wire then snip it.

Please double check your numbering….I cannot be held liable.

By all means upload a picture or 2 of your scart so we can advise further.

 

Most ST scart cables have

150R inline RGB resistors

330R inline CSYNC (pin20) resistor

• This reply was modified 1 month, 1 week ago by TheCorfiot.

[TheCorfiot]

Yes it can be a bit of a nightmare…

My advice is use the buffered sync from the scic board

Cut the tracks for RGB at the video out port then stick the rgb board in place.

Run the RGB signals from the mainboard as identified in the docs but use the scic out for csync

[TheCorfiot]

Installation of this type of board does really need a fine tip iron with good technical skills

5v shorted to red indicates the red output was shorted or cabled up incorrectly causing the chip to fail.

The soldering in general concerns me, there appears to be pcb damage to the one board near the chip leg pads…

I assume you have insulated the rear of the board using Kapton tape to prevent short circuits to the pcb.

 

Sometimes before starting such an install its a good idea to research it online and pickup done tips, do’s and dont’s on the way.

But well done you got it working

[TheCorfiot]

Hi There

I would try reflowing the 3 signal inputs using some liquid flux.

I also notice that you are using a megadrive cable. These cables have inline components and its recomended you remove the three resistors on the tmsrgb board and jumper them instead. If your cable also has a csync inline resistor you will need to connect to the other csync pad on the tmsrgb.

 

If you have carried out the above and confirmed continuity on the RGB lines from the tmsrgb output pads to the scart plug pins then its possible the tmsrgb board is not functioning correctly

[TheCorfiot]

At this point you could do with the use of a scope to confirm your connections to the tms pin b-y is good and signal appears.

You can also check the B output of the board with the scope.

 

But basically you are missing Blue

[TheCorfiot]

I dont think you are picking up the CSYNC signal from the right place

[TheCorfiot]

Hello There

As replied above, you can ignore R18 being replaced due to the cable you plan to use.

Regarding the RGB lines, it is your call tbh the vias alongside the resistors are indeed tracked to them.
some people shy away from soldering direct to VIA’s as they can be delicate, but if you use thin enough, eg AWG30 kynar you will be fine….

If a brightness mod is required then installers will take the rgb outs from the chip resistors and leave the vias free in order to hook up the pull down resistors required for the brightness mod

Regarding Q3, the capacitors should really be removed

• This reply was modified 2 years ago by TheCorfiot.

[TheCorfiot]

The Bridge has been seen on a few consoles, its a factory manufacturing issue however not a big deal as both those pins are ground anyway.
Advise removal before fitting the bypass board.

Before fitting the board to a junior you need clop the pins on 3 capacitors, the 2 in your picture and one further right.
Also ensure you insulate the underside of the board with tape.

Ensure you have fitted 1k2 resistors to the rgb pads as required and you can replace c11 with a 220nF capacitor to reducer ghosting.

I would reflow your rgb connections on the pcb socket header, remove existing solder first, you don’t need much but you do need to keep each pin heated for a good 6 or seven seconds to ensure a smooth even solder joint on all the parts.

Csync should be taken from pin 18 of the video encoder.

Finally ensure you have correctly set the jumpers for attenuation or csync buffering.

[TheCorfiot]

Silly question but have you flashed the current firmware ?

[TheCorfiot]

Are the jumpers set correctly for the right output frequency

[TheCorfiot]

I would say you are spot on…

[TheCorfiot]

Hi Andreas, its difficult to see the interference from the pictures but one thing for sure is that the regulator should not be getting hot like that.

It sounds like there is an over current situation going on somewhere.
Could you please upload some pictures of your installation on both sides of the board.

[TheCorfiot]

I’m pretty sure you have 5V and GND connected the wrong way on across C5.
Disconnect the wires and check the polarity across C5 and reconnect as necessary

[TheCorfiot]

Any issues with these boards tends to be bad contact in the VIC II Socket
You can also try cleaning the socket with contact cleaner.

And dont be afraid to fit the VIC II adapter firmly into place 🙂

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