NEO GEO MVS-4 No cab sound just headphone sound only on re-capped board

I have a dedicated MVS-4 cabinet. All parts in it appear to be original.

I watched the video below and it mentioned that a Neo Geo with sound coming out of the headphones but not the cabinet was one of the reasons to re-cap the board. That is the problem I have. I have noticed that it appears that someone has already re-capped the board. At the end of the video it mentions checking the sound coming out of the amps first prior to re-capping. How do you check the amps?

http://www.youtube.com/watch?v=_UY5ouIXVQc

Thanks!

 

Yep - check the output of the amplifier first. IIRC there are only 4 electrolytics after the amp, anyway.

Your post was flagged by the auto-moderation system. You'll find your next few posts may be, too. If they don't appear immediately, be patient - a moderator will approve them eventually! I've moved the thread to the repairs section - the Neo Geo section is more for programming advice.

 

How do I check the output of the amplifier? What am I looking for? I do see around 5v on the wires powering the speakers...

 

Put speakers on it?

 

It's an all stock MVS-4 cabinet. Original speakers and wiring in the cabinet.

 

I bought a pair of cheap 5 watt 8 ohm speakers and wired them up where the originals were wired and still no sound. I ordered a cap kit even though it appears the caps were already replaced at one point. I can't think of anything else to try.

Any other ideas?

 

Replace the amp. And putting speakers where the originals were won't test the amp - if the caps are gone that didn't help at all. Bypass the caps.

 

Thanks for the reply.

Is there a way I can learn how to replace the amp? I don't know where it is on the board. I'm assuming where the heat syncs are. I don't know what to replace.

Thanks!

 

If you don't know what you're doing, I'd suggest getting someone else to do it.

I haven't looked in a while, but last time I checked, they were getting fairly expensive. Off the top of my head, I think it's an HA13001.

 

Amp failure is not common but old corrosion from prior recap can rear its ugly head when a chop shop or uninformed DIY cap kid hits a board. Surrounding components are more common for the issues.


Most if not all recapped systems boards etc I have seen coming from humid locations will function over time but soon will start to have shorts since prior tech did not clean the whole board or even a spot cleaning to neutralize and remove the acid.


In your best interest a full recap would help since you have no clue of the prior work or if the caps use where new or cannibalized,old stock. Clean any corrosion you find and cross your fingers.


To test the audio circuit get a small speaker from old ear buds or my kids furby.


Solder the black to any ground on the board and solder the red to a small wire. Cut the leg off some random resistor or cap to use as a probe. After solder tape around the solder connection so just the leg is exposed and start probing the circuit.


Other things to check are gates passing correct voltage around the amp.


Good luck and have fun.

 

It looks like the HA13001 also has been replaced before. The solder work looks good except for all the spare flux I cleaned from the board.

The sound via the headphones is perfect. I have a new cap kit I can try but I am concerned it won't fix anything since the sound is working via the headphones.

Can someone tell me what components could be failing? Is the HA13001 amp the only possible item?

 

I installed the cap kit. I now have sound! Thanks for your help.

 

Congrats on saving your board.