Sammy AWSD Audio Issues

[jcmorris]

So Im getting intermittent audio issues with different PCBs on my AWSD. This is all in MONO, all original PCBS.

As an example, Battle Bakraid only output sounds through the Left channel unless I turn the volume on the PCB almost all the way off, then turn the volume in the cab all the way up. If the volume on the PCB is turned up , but volume in the cab is turned down below the 95% mark, the audio is only output through the left speaker channel. As soon as it is turned up past a certain point though it begins to come through both channels. While this works, its quite bothersome, especially for titles that it does not work with (see below). It also seems as if the volume knob doesn't directly correlate with the level of volume per se, but moreso the amount which is output from each channel.

Now as for other titles, let say Ketsui, Im getting NO audio from the left channel, only output through the right channel. Iv tried doing the same thing (volume down on PCB, up on cab) but the sound is never output through the other channel.

Another odd example is Dimahoo, which I have to flip the Mono/Stereo switch while the game is running in order for the audio to come on. It plays through both channels, but sounds completely silent until this is done after it has booted.

Another example, I tested multiple CAVE SH3 boards last night and they all have the same result: You have to first flip the Mono switch to stereo then back to mono, then sound comes from the left channel. No audio from the right channel unless the cab volume knob is turned all the way up and maxed out. Otherwise, the pot does nothing to the actual volume of the left speaker. The volume has to be controlled from the PCB volume pot.

The potentiometers have all been metered and check out fine. I have applied Deoxit d5 with no change in results.

Any help would be great, thanks so much!

[jcmorris]

weekend bump

[jcmorris]

Spent some time testing all other PGM based PCBS today, and all three (DDP DOJ, Ketsui, Espgaluda) all display the same symptoms; no sound coming from the left speaker channel under any circumstances.

[donluca]

It's definitely the volume potentiometer.

Try first with some deoxit (or similar product), give it some turns and let it stay for a couple of hours.

Otherwise look forward getting it replaced. Good pots are dirt cheap.

EDIT: although this might not be the case, you should also check the electrolytic capacitors. See if they have a bulge or, even better, check them with an ESR-meter.
Again, electrolytic capacitors are dirt cheap and it's not hard to replace them if you know how to get around with a soldering iron.

[jcmorris]

It's definitely the volume potentiometer.

Try first with some deoxit (or similar product), give it some turns and let it stay for a couple of hours.

Otherwise look forward getting it replaced. Good pots are dirt cheap.

EDIT: although this might not be the case, you should also check the electrolytic capacitors. See if they have a bulge or, even better, check them with an ESR-meter.
Again, electrolytic capacitors are dirt cheap and it's not hard to replace them if you know how to get around with a soldering iron.

I don't have any deoxit on hand, but ill order some and try that. I thought that testing it with an ohm meter and getting a good reading would rule that out? I tested all three potentiometers and they all read 100ohm when i read the wiper, and they read the corresponding ohms based on where the knob is turned (100 turned all the way, 50 around half way and 0 when all the way down.)

Which caps are you talking about checking? Ones on the PSU or...?? Its definitely not the audio section on any of the PCBS, as I have tried them and they work fine on two different Blast CItys, an Egret II, and a Windy.

Thanks

[donluca]

those are strange values for volume pots, they usually range from 1kΩ all the way up to 100KΩ and beyond. (also, why are there 3? It should be only one for controlling the volume, got a schematic of the cab circuitry?)

Anyway, if those are the original pots and they measure ok we can rule them out.
Giving them a run of deoxit wouldn't hurt still, it will prevent any rusting forming and keeping them turning smoothly.

You can see if there are caps around the potentiometer (shouldn't really, but who knows) and check if they are bad. PSU can't really be the culprit here, otherwise you would have noticed other strange behaviors while playing the game, unless the audio amps on the boards are the only circuit driven by the 12V rail (I highly doubt it).
In this case, there might be some issues on the PSU on the 12V rail which can be either the regulator (never seen one going bad though) or the filter caps (much more likely).

In any case, go step by step and never do lots of things altogether, because if something goes bad then it will be hard telling what went wrong.

EDIT: just throwing out random ideas... it might also be that there's a bad contact somewhere, either on the speakers themselves or on the JAMMA edge.

[jcmorris]

those are strange values for volume pots, they usually range from 1kΩ all the way up to 100KΩ and beyond. (also, why are there 3? It should be only one for controlling the volume, got a schematic of the cab circuitry?)

Anyway, if those are the original pots and they measure ok we can rule them out.
Giving them a run of deoxit wouldn't hurt still, it will prevent any rusting forming and keeping them turning smoothly.

You can see if there are caps around the potentiometer (shouldn't really, but who knows) and check if they are bad. PSU can't really be the culprit here, otherwise you would have noticed other strange behaviors while playing the game, unless the audio amps on the boards are the only circuit driven by the 12V rail (I highly doubt it).
In this case, there might be some issues on the PSU on the 12V rail which can be either the regulator (never seen one going bad though) or the filter caps (much more likely).

In any case, go step by step and never do lots of things altogether, because if something goes bad then it will be hard telling what went wrong.

EDIT: just throwing out random ideas... it might also be that there's a bad contact somewhere, either on the speakers themselves or on the JAMMA edge.

Yes the part # is 100OHMRPH10A , it is definitely a 100Ohm potentiometer; it is even stamped on the side of each one. The main pot is supposed to regulate the cabs overall volume, where the other two pots are supposed to correspond to the left and right channel overall volume but are only used on Stereo mode. Heres a link to the manual which has schematics on the last page:
http://wiki.arcadeotaku.com/w/File:Samm ... Manual.pdf

I bought some Deoxit D5 and applied it, theres no change whatsoever besides the pots turning a little more smoothly.

The PSU is not the issue, as I recently replaced it and have tested the voltages over time and under load extensively.

I am updating the OP with more info on other testing I have done as well.

[donluca]

Interesting! First time I see 3 volume pots for a cab.

On the schematics I can confirm that one is for Mono and the other two are for Stereo (one for each channel).

At this point I strongly suggest you checking the connections and soldering.

Connections: on the speakers and the jamma edge.

Soldering: check for opaque solder points where the pots are, as a last resort you might want to reflow them.

If everything fails I give up, have no idea what's going on.

[jcmorris]

So just in case any one digs this up in the future because they are having the same issue (I found quite a few threads where AWSD owners had similar issues):

I traced the wires from the service board back to speakers and found a few points where the factory zip ties were so tight that it had caused the wires to wear themselves bare over the years. This in turn, caused the + and - to the one speaker to get bridged together. From what I can tell, when they when they were touching like this, it was pushing the full 8ohms to one speaker and none to the other. Anyways, rewired it and completely fixed the problem.