Posted by ZangTumbTumb on 5, 2001 at 11:42 AM:
In Reply to: Re: Try putting 220uf capacitors in the R/G/B lines posted by MrTomcat on 5, 2001 at 7:24 AM:
Thanks guys for the input, it's been most helpful.
FYI I spoke to a hardware engineer where I work and showed him the schematic to my monitor. The problem is that the RGB inputs to the monitor are DC biased and need the DC blocking 220uF capacitors to get round this. He also said that using the 470uF wouldn't be a problem but you need to make sure the voltage rating is high enough; e.g. 16v should be ok, but 25v would be better.
He also said that it would be better to put two 470uF caps in series (giving 235uF total capacitance). To put them in series you need to connect the two positives together (Yes, thats right, the positives!) One end of the negative you connect to, eg, Red on the JAMMA connector AND the other end you connect to the repsective, eg, Red monitor input wire. Something like this...
JAMMA_CONR NEG --####-- POS POS --####-- NEG MONITOR
(Appologies for the poor pic quality!)
Doing this means that you don't have to worry which way round the DC bias is and is therefore a safer solution.
Regarding the RGB gain pots, he said that I could try fiddling with these, it will make a difference.
Mark (ZTT)