Installing a 5k Vol. Pot ? Centipede with JAMMA adaptor making a speaker humm

[mrclean]

OK, so I have my centipede up and running, and It's wired JAMMA using a centipede to JAMMA adaptor, (I see on the adaptor it has a vol. control) All of the controls are working properly / trakball / buttons.. and also I have sound but my speaker is making a terribly loud humming / buzzing noise. I read somewhere that I can install a 5k vol. pot. to resolve this issue ?

would this be sufficient ? http://www.radioshack.com/product/in...ductId=2062356

If It's sufficient, what exactly do I need to do to wire it up correctly, I have the speaker wire coming from the JAMMA harness, and it's currently connected directly to the speaker wire which is connected to the speaker. I'm guessing one of the metal tabs is for ground on the 5k pot and one is for Left / Right Audio, but I'm still confused about installing it properly. Any help would be appreciated.

[mrclean]

update....

ok so after some more testing, and installing the 5k pot... I took the centipede board out of the cabinet, replaced it with another random JAMMA pcb, and I didn't have any sound Issues.. no speaker humm, sounded fine.. so I know everything is wired properly.

Which leaves me to believe that it's related to the Y-PLUS Technologies centipede to JAMMA adaptor.

On the adaptor I noticed the LM380N chip is HOT as hell.. not sure if it's supposed to be.. I'm not sure if any one else is using a centipede to JAMMA adaptor in a cab, but can you recommend an alternative to the most likely defective Y-PLUS one that I have ?

[SavannahLion]

I can't say how hot it's supposed to be but the spec sheet for the LM380N states that the center three pins on either side are actually heat sinks tied to ground. TBH, that strikes me as a dumb design choice, but whatever.   It's really hard to tell in the photo, but it looks like half the pins are just left to float when they should be tied to ground. Or more likely, the ground plane just isn't large enough to act as a heat sink.

You could try finding a small enough heat sink and some thermal compound adhesive to glue a heat sink directly onto the chip and see if that changes anything. I stress that one should use thermal compound adhesive and not just any old adhesive to affix the heat sink. I think Frys used to sell a very nice tube of TCA made by Arctic Silver.

If that isn't an option. Digikey sells the LM380N. Looks like the direct drop in would run you just short of $2.

[mrclean]

I was thinking maybe a way to bypass using the adaptor for the audio ? But I think on the smaller edge connector it's also used for sync / controls as well..

[SavannahLion]

I dunno. I suppose you could bypass it by removing the LM380N. I don't know enough about centipede, but there's probably a good reason why it's using an amplifier on the audio. IOW, if you bypass the LM380N, you'll probably need to get another amplifier from elsewhere. Maybe a PC speaker? I'll let someone who knows more about Centipede answer that question.

BTW, I took a peek at the spec sheet again. It does indeed show a heat sink is to be soldered to six of the pins. It even specifies the manufacturer of the heat sink. I don't understand enough of the graphs to know how it impacts performance though. I honestly don't dare say that I know more than whomever built that adapter, but I would say attaching a heat sink would be worth a shot.

[BobA]

Looking at the pic you have of the board it looks like they might have taken some liberties (gone cheap) with the reference design for the amp.    It does not look like there are enough caps.

Looking at the manual the reg board and amp board are combined so the centipede board alone does not have the drive for the speaker without an amp.

http://www.arcade-museum.com/manuals-videogames/C/Centipede.pdf

[RayB]

Contact yplus. I hear he's pretty good about replacing defective stuff, and you're not the first person I've heard complain about this adapter.

It has an onboard amp because the original Atari cabinet uses a seperate board to regulate both voltages, and audio amplification.

I don't know if you can bypass it and use another amp.

[mrclean]

I contacted "yaton62626@yahoo.ca" I didn't get a reply back. So close to getting this thing working.. Can anyone send me a centipede to JAMMA adaptor and if it works I'll pay you for it.. if not I'll just pay shipping both ways ? it's been sitting sooo long and all I need is the audio working / working adaptor. Technically I can play the game, but it's certainly not the same without the doop dapp chaa pow pow pow sounds. I don't really want to continue on with dumping any more money into this game until I can get the audio working... I also need that cardboard blue bezel that goes between the glass and the monitor. I know Arcadeshop sells them new for 25 + shipping I was hoping to score an original maybe someones parting one out ?

[mrclean]

Well not sure if he read this thread, but at 2am I got an email from him.. So I should be getting a replacement centipede to JAMMA adaptor hopefully it's tested before it's sent out and working when received.

[mvsfan]

Well not sure if he read this thread, but at 2am I got an email from him.. So I should be getting a replacement centipede to JAMMA adaptor hopefully it's tested before it's sent out and working when received.

anything you get from y plus is basically good products, but its a trial and error test it and find out whats wrong yourself if its anything somewhat custom.

from what i have gathered they dont speak english well. the experience is much the same as dealing with other good asian suppliers.

In all of my experiences, y plus sells great products, but if you arent doing something right, they have trouble explaining what is wrong.

i will say though, that i deal with other, similar places from time to time. if whatever place's response doesnt seem to make sense on its face, ask them if they can send it to you in (insert foreign language here.)

also, long before babble fish existed, i used to use a program called L+H simply translating deluxe, and i still use it.

i highly reccomend going and finding the last version of it on ebay. Does anyone remember yahoo auctions? I made a living back in college on tracking down Super Famicom stuff using L+H Japanese translator.

then, run it through babble fish and see if it makes sence.

[tbombaci]

Had a similar problem. This worked for me:

http://groups.google.com/group/rec.games.video.arcade.collecting/browse_thread/thread/f5f95121bacf724b/6d046a65206c045c?lnk=gst&q=centipede+jamma+sound#6d046a65206c045c

Tom

[mrclean]

Had a similar problem. This worked for me:

http://groups.google.com/group/rec.games.video.arcade.collecting/browse_thread/thread/f5f95121bacf724b/6d046a65206c045c?lnk=gst&q=centipede+jamma+sound#6d046a65206c045c

Tom

yeah I read that post, and I installed a 5k vol. pot, and it just lowers / raises the static it doesn't fix my issue. It's the bad amp on the Y-plus adaptor... and clearly other people are having trouble with it. It's just a cheap adaptor with bad parts... I'm hoping to get my replacement but I'm still waiting on another email. I don't mind spending money on another one so long as it's tested / working.

again... I tested it with other JAMMA pcb's and they don't have sound issues without using the adaptor from y-plus.