Odd MV1 audio issue

[Billkwando]

Last night I installed the 2nd speaker in my cab (hand-screwing wood screws into MDF inside a marquee hole is not your friend). Both speakers worked fine in dual-mono (I think). I unplugged, flipped on the stereo switch, then plugged in the cab. The music kinda faded in and sounded static-y, so I rebooted the cart via unibios and it seemed like all was well.
Then I notice only half of the Neo Geo jingle (it pans left & right for you folks who don't stick your head between the speakers), so I power down and pull the cart and go into the sound test. The sound is coming out of the left speaker only very faintly.

At first I thought it was a bad wiring job on my part, but when I hook the speaker connector to the headphone 4-pin instead of the speaker 4-pin, it's stereo as hell.

I prolly shoulda powered down and flipped and reflipped the stereo switch in case it was hairy or shorty, but it was 3am and I needed sleep. I will try that tonight, but barring switch madness, does anyone have any theories on what's gone awry?

Thanks!

P.S. Is it safe to use contact cleaner on the cart slot and/or stereo switch? It's the Radio Shack kind.

 

[Billkwando]

I tried cleaning the switch with contact cleaner but the left channel audio is still out on the speaker connector.

 

[Xian Xi]

You sure you are using the right impedance speakers and they are connected right?

 

[Billkwando]

You sure you are using the right impedance speakers and they are connected right?

They're 4 inch 8ohm speakers AFAIK (one is unlabelled...can you read exact impedance with a multimeter that does ohms?). They're mismatched (and maybe different wattages) but they both came from Dynamo cabs. The 2 outside wires are going to the "+" on each speaker and the inside wires are each going to the "-". Don't forget that they work perfectly when connected to the headphone connector. I'll try headphones connected to the speaker connector, but I'm anticipating the same results.

 

[Billkwando]

They're 4 inch 8ohm speakers AFAIK (one is unlabelled...can you read exact impedance with a multimeter that does ohms?). They're mismatched (and maybe different wattages) but they both came from Dynamo cabs. The 2 outside wires are going to the "+" on each speaker and the inside wires are each going to the "-". Don't forget that they work perfectly when connected to the headphone connector. I'll try headphones connected to the speaker connector, but I'm anticipating the same results.

Ok, there may still be time to declare me retarded. I just hooked up headphones to the speaker connector and it works perfectly fine. I guess I better try to check the speakers with the multimeter. Off to google!

I'm watching this vid right now, and I don't know precisely why, but it makes me laugh. Maybe cos the guy manages to ramble for 9 minutes.

 

[Billkwando]

So I tried removing the 8ohm speaker and putting in a 4 ohm, and it did the same thing. Apparently, every time I adjust the volume, the left side volume drops out. It seems to come back after I restart the machine. I put the other speaker back in. I still don't know wtf is going on, but I'm assume if I leave it alone it'll be fine. I cleaned the stereo switch and volume sliders with the contact cleaner and they're not scratchy anymore.

Word of advice, from personal experience..... NEVER use Radio Shack Contact Cleaner AND LUBRICANT on carts or slots. I overlooked that last factoid. The spray contains mineral oil, and is highly pressurized, so you end up with baby oil spooge all over everything, and it never dries. I may or may not have killed my most personally valued cart, Waku Waku 7.

I went to plug in a cart that hadn't been sprayed, but had only previously been in a slot that had, and I found a dead fly stuck to the contacts. Luckily I looked first. This stuff is bad news and will only cause dust and other crap to stick to whatever you spray it on, making the problem worse.


Edit: Apparently there's a short somewhere. Just closing the control panel was enough to make the left speaker go out. Switching the machine off and back on always seems to fix it.