No sound on mv-1

Hi !

I'm new here, and i've just discovered the wonderful world of mvs.
I have 2 mv-1. One works great, but i can't have any sound with the other.
I tried all the connections the mv-1 has, from built-in speaker connector,
headphone connector to jamma speaker pins, but nothing... The only
thing i barely have is a "plop" when powering on.
I don't know where to look to find the problem.
Does anyone have some clue for me ?
Thank you

PS: Other informations:
- i've checked the volume potentiometers
- i tried mono and stereo with the switch with the same result
- the previous owner of the mv-1 said it used to works fine...

Are you running these in a cab(s) or supergun set up ?

Hi,

For now, i'm in a supergun configuration, i've just finished to build one.
But i've tried to connect 8ohm cab speaker to the jamma port and the
speaker port, or pc amplified speakers to headphone port.
None of them works with this one, but works fine on my other mv-1....

Is the cart slot squeaky clean.

http://hardmvs.com/html/slotCleaning.htm

The slot is clean.
After searching a lot in the forum archives, i've done some tests. Here is
the result:
- i have 12v on the pin 10 of the ha13001
- when i put a finger on the pin 3/4 of the ha13001 there's a hum in the speaker
- the output pin of the 7805 near the ha13001 is 5v

Hmmm...

What the heck... I decided to do some poking around with my multimeter on the 6-slot board that I'm slowly fixing and trace out some audio.

The sound is created by the YM2610 chip and then fed out from it in digital form to the YM3016 DAC chip. If you want to start from there then check pins 10/11 of the YM3016-D DAC chip with an oscilloscope. Those are the channel 1 and channel 2 outputs.

Pin 10 from the YM3016 goes to pin 5 on a BA10324 chip, a.k.a. an LM324 Op Amp. Pin 11 from the 3016 goes to pin 10 on that LM324 Op Amp. Check those pins for signal in to the Op Amp... Check pins 7 and 8 on the LM324 Op Amp for signal coming out of it. If there is no signal then check power/ground on the Op Amp (Pins 4 and 11) and if power is there, replace the Op Amp.

The outputs from the LM324 go through some electrolyic caps, other caps, and resistors and make their way down to another LM324, through it and out through some other electrolytic caps to the HA13001.

What I would do would be to use an oscilloscope and start tracing the audio flow. You'll see where it stops. If you don't have an oscilloscope you can try a high impedance audio amplifier and place it on the inputs and outputs of those Op Amps to trace down the audio problem.

RJ

The Z80 also processes the sound signals along with the Yamaha.

Broken traces around that area have been known to cause sound problems, and of course Z80 error messages. It would be worth looking around the associated memory SM1 and 6116.

Thanks for the tips, i will look at this right away.
Unfortunalty, i don't have an oscilloscope... i wish i have one.
For the high impedance amplifier, what can i use ? I've tested amplified pc
speakers on the input pin of the ha13001, but i had nothing. But i didn't know
if it was supposed to work...
Can a line input of an integrated audio amplifier can be used ? Or the phono input ?
Thanks for the help !

It seems that there's no BA10324 on my board but ba4558. There's 3 of them.
I looked for the pinout and check is there was +5v on the vcc pin. Eveything seems
ok for the 3 opamp. Should i look for a signal on the input pin on the opamp ?
As i asked before, can a amplified pc speaker should be ok or do i need
something else ?

Here's a picture of the board if it can helps.
Thank you

Hmmm...

The 4558 is a Dual Op Amp chip, where the LM324 is a Quad Op Amp chip. You can find a data sheet here:

http://www.datasheetarchive.com/datasheet/pdf/4328.html

One of those Op Amp chips will be used during the D/A conversion process by the YM3016 chip and the others will be used to amplify the signals for the various speaker/headphone connectors and yet another one (or 2!) will be used to as a pre-amp for the HA13001. I say "or 2" since I don't have one of those types of boards to trace down the circuit on.

As for the high-impedance amplifier... no, the computer speakers probably won't work. You need an amp with a high input impedance. Radio Shack used to sell one a few years ago but not any more... you may find one at your local electronics store.

RJ

Hi !

I'm still on this problem, tying to figure out what's going on with this mobo !!
I've got another mv-1 mobo, the same model of the one having the problem.
I tried to used pc amplified speakers to see if there's something on the input
of the opamp, and it's worked. On the pins 2 and 3 of some 4558 i can hear
music and sounds. Also, on the pin 10 of the YM3016 i hear the same thing.
When reproducing this tests on the mv-1 having the problem, i hear nothing...
If the ym3016 is the DAC the problem should be in the digital world. Am i right ?
any idea of another tests to do to locate the problem ?
Thanks !

Ok. So, back on the problem with new tools !
I've just had my ebay oscilloscope today ! So where should i start ?
Thanks !

Start by downloading and installing NTE QUICKCross 12.0 so you can look up part numbers and get the pinouts.

Next fire up the game with a cartridge that makes a LOT of sounds during attract mode or start up a game and test while it plays... One with background music would be best.

After that, check the outputs of the DAC chip and then the inputs & outputs of each of the OP Amps on the board. If you find that you have outputs from one but not inputs to the next one then look at the parts inbetween. You may have a bad electrolytic capacitor (either open or simply broken) or a broken resistor.

The resistors typically don't go bad on the pre-amp section - they typically get physically broken. The capacitors can go open but it's more likely the go leaky and cause static or they get physically broken. By this I mean one leg ripped out of it. Someone may have ripped the leg out and then stuck it back down inside by moving the cap back upgright on the board.

Good luck!

RJ

This may sound realy stupid, but did you flip the switch on the Mobo from stereo to mono? Jamma harness only outputs mono sound. You may want to try hooking your speakers to the 4 pin speaker connector to see if the sound chip is messed up or if its in the jamma connector/ harness. Hope this helps.

B