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Main => Main Forum => Topic started by: danny_galaga on December 27, 2008, 09:07:50 pm

Title: starting up your mame cab using a capacitor
Post by: danny_galaga on December 27, 2008, 09:07:50 pm

anyone else do this?

 to start up the cab, i had a relay connected to the 'soft on'. used to work (most of the time). stopped working. so i decided to replace the relay with a small capacitor which id read about here (http://forum.arcadecontrols.com/index.php?topic=19304.0). that seemed to work. however, while playing raiden i noticed a funny sound every now and then. first i thought it was the game. but since i was a little wary of the cap trick, i thought id lift the lid of the cab while playing. sure enough, the sound was of the freakin reader head hitting the platter! well, maybe not, maybe it was trying to park or summink. so i jumped out of raiden and sure enough, the computer had frozen. incidentally, isnt it cool that mame roms keep working (presumably its all loaded in ram) while windows has crashed :lol  after a couple of goes, i was able to restart the machine no worries. just 'hotwiring' it. ill leave that cap off until i understand more.

anyway, i cut the cap off again. looking at it closely, i realised its probably polarised. this is the part.

http://www.dse.com.au/cgi-bin/dse.storefront/en/product/R4745

 the one i bought is second from the left. i noticed a small stripe on it, which might indicate polarity. have i maybe just put it the wrong way around? i bought a tantalum because i thought they WERENT polarised, and thus i wouldnt have to worry about that.
Title: Re: starting up your mame cab using a capacitor
Post by: SavannahLion on December 27, 2008, 11:22:22 pm
Did this happen only once or is it happening on a regular basis with the cap in place? If it happened only once, make note and keep playing. It is, after all, Windows. :banghead:
Title: Re: starting up your mame cab using a capacitor
Post by: danny_galaga on December 28, 2008, 01:14:49 am

i didnt want to risk wrecking the drive to find out! like you say, it could just be a coincidence. im waiting until i can find the easiest, most 'tard proof way of making an image of this drive. this drive was actually a copy that a friend was good enough to make for me. the first long ago died. so i better bear that lesson in mind.
Title: Re: starting up your mame cab using a capacitor
Post by: SirPeale on December 28, 2008, 07:15:20 pm
The cap shouldn't have anything to do with the hard drive.  Sounds like the drive is on the way out.

I'm interested that you used a tant cap.  I've always used electrolytic.
Title: Re: starting up your mame cab using a capacitor
Post by: danny_galaga on December 28, 2008, 11:54:32 pm

yeah, i was actually thinking they were the same as a disk ceramic. ill pick up an electrolytic and try again.

savannah, i guess its the hard drive itself. i cant blame windows for this. its a 4gig fireball. i would say its had a good innings  ;D
Title: Re: starting up your mame cab using a capacitor
Post by: danny_galaga on January 01, 2009, 03:28:32 am

hotwired the cab last night for some new years fun. its at a friends. his living room is nicer than my garage so till stay there for a while. this morning i soldered in an electrolytic just like peales site suggests, and which i should have looked at before  :D

http://www.pealefamily.net/tech/captrick/