Paperboy with no sound

sohchx

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I have a Paperboy with a sound issue that runs an ARIII. When running a self test everything checks out fine.There is an audible hiss coming from the speaker thats loud enough to suggest that the volume is turned all the way up but oddly when trying to turn it down through the volume pot there is no change. I disconnected the volume pot and tested it and it works fine,so why do I have no volume adjustment? The 6502 and Pokeys all check out fine. Anyone have suggestions on what I should look for next before buying a whole new ARIII?
 
A pot is a voltage divider when hooked up for volume.

If you're changing the settings on the pot and have no audio adjustment, your Amplifier IC is probably shot.
 
You would'nt happen to know the location of the amp IC for this game would you?

Edit:nevermind figured it out,thanks. I think one of the amp IC's was already replaced but not the other two. I may have to look into those once I find out what they control.
 
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I'm not coming up with any luck finding a manual, so I'll have to go off just general knowledge.

First, I'd probe your amp input lines. Do this with an old set of earphones (pref. ones with volume adjustment so you can save your ears!). Just wire up cheap DMM probes to ground and signal, then check input to the amp. You should hear your game. If not, then there's something wrong with the sound section of the board Pre-Amplifier.
 
I'm not coming up with any luck finding a manual, so I'll have to go off just general knowledge.

First, I'd probe your amp input lines. Do this with an old set of earphones (pref. ones with volume adjustment so you can save your ears!). Just wire up cheap DMM probes to ground and signal, then check input to the amp. You should hear your game. If not, then there's something wrong with the sound section of the board Pre-Amplifier.

http://www.crazykong.com/manuals/Paperboy.man.pdf
 
I always forget about the Crazykong database. Argh!

Man, that scan is terrible! It's hard to make out some of the ARIII.

Anyhow, my previous statement stands.

Looks like PB is an ARIII board and uses a TDA2030 Audio Amplifier (Q1 & Q2) to amplify the left and right channels.

You'll want to probe Pin 1 (Non-Inverting Input) with a headset to listen for your game.

You'll also want to check the resistors near the TDA2030's for open or fragged values, as the Amp appears to be setup in a fixed-gain mode (The pot varies the input voltage instead of controlling gain.) Specifically Resistors R4, R5, R8, R9, R12, R13, R18, R22. These are all 3/4 Watt 100k-Ohm post-decoupling biasing resistors (which set your amp gain).

Not sure what the pinouts are, but with an O-Scope, you could find the Audio signal that comes off the PCB stack pretty easily. Admittedly the Schema's fail there. :(
 
I always forget about the Crazykong database. Argh!

Man, that scan is terrible! It's hard to make out some of the ARIII.

Anyhow, my previous statement stands.

Looks like PB is an ARIII board and uses a TDA2030 Audio Amplifier (Q1 & Q2) to amplify the left and right channels.

You'll want to probe Pin 1 (Non-Inverting Input) with a headset to listen for your game.

You'll also want to check the resistors near the TDA2030's for open or fragged values, as the Amp appears to be setup in a fixed-gain mode (The pot varies the input voltage instead of controlling gain.) Specifically Resistors R4, R5, R8, R9, R12, R13, R18, R22. These are all 3/4 Watt 100k-Ohm post-decoupling biasing resistors (which set your amp gain).

Not sure what the pinouts are, but with an O-Scope, you could find the Audio signal that comes off the PCB stack pretty easily. Admittedly the Schema's fail there. :(


I should be probing pin 1 of Q1 and Q2? All of the resistors near TDA2030 check fine. I do not own an O-scope and cannot source one.
 
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