Audio issue with Cameltry PCB

[Fredo]

I recently bought a Cameltry board, and the game works fine but there are some audio issue.

The sound effects seem to be at normal volume, but the musics are barely audible.

I tried working on my cab's audio circuit, but nothing changed. Then I plugged a headset directly on the jamma audio output without the sound going through the cab, and the problem remains.

I'm starting to get worried about the board, but then I saw the manual mentionning the -5V on the jamma pinout, which my cab does not provide.

Can somebody here confirm/infirm, that the Taito F1 board requires -5V ? Or is there something wrong with my board ?

Thanks

 

[ShootTheCore]

Check and see if there's a trace coming off of Pin 5 on the JAMMA connector on the board on both sides. If there's no trace coming off of the pin then -5V isn't used.

From the symptoms you're describing, It sounds to me that your board needs to have the electrolytic capacitors replaced, and possibly the OpAmp for the music chip as well.

 

[Fredo]

There is indeed a track with components on pin 5. Guess I'll have to build a - 5V adapter to find out.

 

[andynumbers]

Looks like you answered your own question.

Taito pretty much always used negative 5 volts on all of their JAMMA boards. Yes, it is required.

Using a negatron is an easy way to get negative 5 volts. https://www.dimensionengineering.com/products/negatron

Just tap your 12 volt line and adjust the negatron to output -5 volts.

 

[Fredo]

Sound confirmed working after building a -5V output!

Thank you guys!