MV-1C Low Right Channel

[Neo Alec]

I did the stereo mod from Jamma Nation X on my MV-1C and it was working well. I wanted to add a headphone amp to my consolized MVS project, and that's where the trouble began. I ended up ditching the amp idea because it didn't work well. Quality was poor.

However, now when I went back to the normal stereo mod with line level audio, it no longer works correctly. The left channel seems to be loud enough, although there might be more buzzing sound than before. And the right channel is basically nonexistent. You can hear it very faintly.

I thought at first I needed to change the caps AC1, AC3 and AC4, but it appears with the stereo mod in place, those caps aren't used.

Did I fry the 9480F chip? Is this fixable, or do I need a whole new MV-1C board? Will replacing the chip with one of these from China fix the problem? Will the sound quality with this replacement be suitable?

http://www.ebay.com/itm/5PCS-BU9480...035569?hash=item58bb1804f1:g:108AAOSw7ThUpAJf

 

[Xian Xi]

You could have damaged it with whatever headphone you connected to it if the impedance was too low. I'd swap it out. You're lucky they have them on ebay now. Before you'd have to special order them from Japan or steal them from N64s.

 

[Neo Alec]

Thanks as always for your advice, Xian.

So AC1, AC3 and AC4 can be removed?

 

[nic034]

Hello,

You can also use this tiny 3w amp when your issue will be repaired :
http://www.ebay.fr/itm/152223963228?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
This works fine with stereo mod from Jamma Nation X.

Bye

 

[Neo Alec]

That's what I used. It probably would've been fine, but I tried to replace the pot.

 

[Neo Alec]

The buzzing gets worse when the screen is brighter. It doesn't matter that I'm using video ground for the audio, does it? Should I just use common ground for everything?

 

[Xian Xi]

The buzzing gets worse when the screen is brighter. It doesn't matter that I'm using video ground for the audio, does it? Should I just use common ground for everything?

Use a bigger ground.

 

[nic034]

Hello

Use real ground instead of video ground.
I've no issue with this one.

Bye

 

[Neo Alec]

I put in a 9480F from a dead N64 and it's working well again. Thank you for your help.

However, now I have a new problem. Ever since I changed the Unibios chip from a 3.2 chip I made to an official 3.3 one, the system won't boot past the hardware test. According to the screen, the test mode switch (the one on the jamma edge, not the 8 dip switches on the board) is stuck turned on. However, there is nothing near pin 15 on the jamma edge, nor has there ever been. The Unibios 3.3 I ordered was meant for an AES, but I don't think that makes any difference. I already tried swapping back to the old bios and clearing the backup ram several times with no results.

Also, the LED indicators on this test screen are red and are constantly changing. Is that normal? Any ideas why my test switch is stuck down?

 

[Xian Xi]

It's either the resistor array is bad(hopefully) or the YSA2 chip is bad.

 

[Neo Alec]

Nevermind. Fixed the test switch. There was a short on the memory card.

Is it normal for LED to be red and jumping around on that screen when it's not connected?

 

[Xian Xi]

Nevermind. Fixed the test switch. There was a short on the memory card.

Is it normal for LED to be red and jumping around on that screen when it's not connected?

Yes, you mean flipping through numbers? Yup.

 

[Neo Alec]

Okay, all good now. Thanks a lot for your help, as always.