OutRun Deluxe Upright - Jittery Sound

gzsfrk

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Hello arcade gurus!

I recently realized a long-time dream of mine and acquired my own original OutRun Deluxe Upright. It was pretty rough, though, both in terms of the exterior and with regard to some technical issues. The shaker motor doesn't work, the monitor's burnt in and the colors are a bit off, and most importantly, the sound wasn't working. Some quick investigating revealed that the cause of the absent audio was simple: the sound amp had been yanked from the unit. Not too big a deal; I'm in the process of trying to purchase a replacement.

However, in the meantime I wanted to be able to play the game while enjoying the fantastic soundtrack and effects, so I spliced together a quick little cable that let me catch the audio stream coming from the PCB and output to a pair of self-powered computer speakers. Only grabbed the right channel, actually, then split the signal to L&R outputs. For some reason, couldn't get the signal for left channel to work. (That could be a helpful point for referring back to later.)

So everything was working pretty well when I first turned it on. Heard the initial tire screech, then heard the audio of the cars passing by--awesome! Went into the sound test menu, and all of the sound effects played perfectly. Then I got to the music, and this is where things started to get spotty. Magical Sound Shower starts out playing perfect, but as soon as it gets to the PCM drum hits, those sounds suddenly cut out. It's not a huge issue, but it is quite noticeable. Then I moved on to Splash Wave, and that track was having serious issues, the most prominent being a recurring, light "popping" sound (like when you first turn on a set of speakers), and lots of missing sounds. Passing Breeze is by far the worst, as the popping and missing sounds is very grating.

Now I realize that part of the issue could be that I'm only able to capture and output one channel (R), which might explain some of the missing sounds. However, there's an additional symptom. When you start a game, and thus have both the background music and the effects playing, the music plays fairly constantly, but the sound effects are constantly cutting in and out in a way that does not happen when you play the individual sounds in the test menu. I'm not sure, but it's almost like the YM2151 and/or PCM chips start to freak out when the audio gets "busy".

See below for a video example:



http://www.youtube.com/watch?v=R9dL5ebxwTM

I'm quite new to arcade games, and OutRun is just my second full cabinet (first was an awesome Speed Buggy I picked up for just $30!). So I'm hoping that someone (or a combination of people) might be able to help me get this sorted out. One possibility that occurred to me was this: aside from the YM2151 and PCM chips, is there another chip that's subsequently responsible for mixing the two audio inputs together? And if so, where is it located?

Another symptom that may or may not be related that I'll describe is that, sometimes, when playing the game and especially during the entering of your name for high score, there will be brief, flickering vertical lines of garbled characters popping around on the screen. It's not too bad, but you might can see a bit of it in the above video.

I'll point out that I have yet to try re-seating all the chips, as I'm honestly a bit terrified of breaking off a leg when trying to extract them. However, if someone can provide a bit of guidance as to which chips exactly are the most likely to need reseating given the above symptoms, I might could work up the courage. :)

Thanks in advance for any help!
 
Hey! Been a long time since I visited this thread, but I thought I'd go ahead and update it with my findings since I finally got around to doing some in-depth checking.

As it turned out, there were a couple of problems with the sound. First off, someone obviously was working on the board at some point and, in the processing of replacing the EPROMs, accidentally overlapped the pins of the 10189 chip into the channel of the 10190 chip. Those both contain speech data, which explains why my sound went all wonky as soon as the digital drum hits were reached when playing any song.

Secondly, and possibly less importantly, one of the legs on chip 10191 was crinkled up:

SQWpsm7.jpg


I can only assume that it wasn't supposed to be like that. (I have seen situations where an unused leg is pushed straight out, but this looked completely accidental.)

In any case, I fixed those two problems and my issue with the distorted, crackling sound are now completely fixed. My sound amp still doesn't work, but outputting to the computer speakers, the music and SFX now sound completely perfect.

Unfortunately, another issue has now arisen, but I'll save that discussion for another thread to be started here shortly...
 
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