f18a video board

[chart45]

i install this f18a video board pretty simple

 

 

but sometime i have hard time at the startup the image stay on the green f18a image then close the power and power on again and now start ok

 

is there a fix for that problem

 

video is verry good and color super bright

[ApolloBoy]

but sometime i have hard time at the startup the image stay on the green f18a image then close the power and power on again and now start ok

 

is there a fix for that problem

From the F18A website:

Due to the technology used to make the F18A, it is not possible for the F18A to power-on as quickly as the original 9918A/9928/9929 VDP. In some instances when a system is turned on and comes out of power-on reset before the F18A is ready, the system may hang or not start correctly. Usually a simple power-off / power-on will correct the problem, or if your system has a real reset button, that should also remedy the problem. The F18A needs about 100 milliseconds to come ready after power is applied, compared to the original VDP's power-on requirement of only a few microseconds.

 

Most systems use an resistor and capacitor as an RC-time constant to control the power-on reset time, and in systems with known fast power-on reset times, a simple modification to make the resistor or capacitor lager will extend the reset time and make a more reliable power-on for the F18A enabled system.

[chart45]

i read this but my question was more what people do to fix that problem like witch cap or resistor do i have to change or whatever part need to be mod cause i dont know mutch about electronic

[hardhat]

I'm not sure I can give you a useful answer to your question, but in my modified Adam with the 9958 video chip instead of the 9918, we added a delay circuit that held down the wait state on the clock at boot up until the board reset itself.

 

On the other hand the reset switch should probably do the trick, right?

[+grips03]

for F18a install I replaced C3 electrolytic cap with a 10uf 16v electrolytic cap and now no more garbled boot graphics for Frogger. Was 1uf.

[chart45]

thank ill give a try