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NFG Forums => RGB + Video Discussions => Topic started by: nevarna on June 20, 2010, 10:13:27 AM

Title: mmmonkey n64 rgb amp capacitor wrong way round ?
Post by: nevarna on June 20, 2010, 10:13:27 AM
Does anyone know if mmmonkeys n64 rgb electrolytic capacitors are in the right direction negative is going to the console and positive to scart connector\tv ?

People have suggested using electrolytic capacitors on the rgb lines to filter the rgb lines on scart everywhere i looked people say positive to console negative to scart and tv

I've gotten very strange results using this amp with my pc engine colors were vibrant then would change to over saturation of  reds then blues then greens. all at different times

http://www.mmmonkey.co.uk/console/nintendo/ntsc-n64-rbg-booster1.htm (http://www.mmmonkey.co.uk/console/nintendo/ntsc-n64-rbg-booster1.htm)
Title: Re: mmmonkey n64 rgb amp capacitor wrong way round ?
Post by: albino_vulpix on June 20, 2010, 12:07:54 PM
Usually, the positive side goes towards the console. Their purpose is to remove DC offset and let the AC signal through. Putting polarised capacitors the wrong way can potentially blow them up, but I don't think this is likely with the low DC voltage they're intended to filter. Still, positive to console side just to be sure.
Title: Re: mmmonkey n64 rgb amp capacitor wrong way round ?
Post by: nevarna on June 20, 2010, 12:25:16 PM
Ok thanks for your help i opened my psx scart cable and they are wired + to console - to scart/tv opposite to mmmonkey.
Title: Re: mmmonkey n64 rgb amp capacitor wrong way round ?
Post by: hellbelly on June 21, 2010, 07:58:59 AM
I don't have an NTSC N64 anymore, when you finish the amp with the caps the other way around could you post results so I can add info to the page?

ta
Pete
Title: Re: mmmonkey n64 rgb amp capacitor wrong way round ?
Post by: albino_vulpix on June 21, 2010, 12:56:07 PM
It should make no difference to the output signal, just prevent blowing up :p
Title: Re: mmmonkey n64 rgb amp capacitor wrong way round ?
Post by: RGB32E on June 22, 2010, 09:18:57 AM
Quote from: albino_vulpix on June 21, 2010, 12:56:07 PM
It should make no difference to the output signal, just prevent blowing up :p

The polarity of eletrolytic capacitors depends upon the circuit.  For the NJM amp, the capacitor before input has negative towards the signal input, and negative towards the output... so don't be put off by his circuit....  though I tried it and it didn't work.  Go for the NJM amp instead...  it's results are nearly perfect, and the circuit is relatively easy to assemble.