GX4000 RGB out

[opossum]

The plug is a 5.5 x 2.1, you won't be able to plug it on the 5V port.
You need a5.5x2.5

Ok it will be done! ^_=

[opossum]

oK, i received this morning the CPC+ rgb cable+5v power supply kit from a trusty Spanish retroseller ... The results are far better than i thought.  GX400 now looks ultra sharp and brightful. Highly recommended upgrade! 

[waiwainl]

Link please? :-D

[Keir]

Just want to chime in and agree: the picture quality from my (Spanish) GX4000 is excellent via the Plus-compatible DIN, using a DIN-to-SCART lead. And powering via the GX4000's 5v input (needs a 5.5x2.5mm barrel connector by the way, 5.5x2.1mm definitely does not fit).


When I tried using SCART-to-SCART and a 9v PSU on the normal power input the display is washed out and has jittery horizontal sync. When I switched to DIN-to-SCART that cleared up but oddly I had to use the 5v power input as otherwise the display is very very dark indeed. Whereas I get excellent brighness when powering the console via the 5v input. I don't have an explanation for that.

[gerald]

When I tried using SCART-to-SCART and a 9v PSU on the normal power input the display is washed out and has jittery horizontal sync. When I switched to DIN-to-SCART that cleared up but oddly I had to use the 5v power input as otherwise the display is very very dark indeed. Whereas I get excellent brighness when powering the console via the 5v input. I don't have an explanation for that.

- When powered using the 5V input, the RGB DAC IREF pin is connected to a 6.98k Ohm resistor in parallel to a 68k Ohm.
- When powered using the 11V input, the 6.98k ohm resistor is disconnected (using two transistors).
That result in different amplitude for the RGB signals.

Also, if your GX4000 has an RF modulator, the 5V input cannot power that modulator/scart output properly. This part has it own 5V regulator that would only be powered trough a diode by the 5V input, resulting in a degraded power supply.

[Keir]

- When powered using the 5V input, the RGB DAC IREF pin is connected to a 6.98k Ohm resistor in parallel to a 68k Ohm.
- When powered using the 11V input, the 6.98k ohm resistor is disconnected (using two transistors).
That result in different amplitude for the RGB signals.

So the DAC is configured to output levels designed to feed the SCART/RF stage when powered from 11v input, and the DIN output is out of spec in that case?