sound works for about 30 min then quits....

zeropoint74

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Hello everyone! I hope someone can help me here or lead me in the right direction...
I have a target terror gold in a showcase cabinet. When I turn the switch on and it starts to boot up you here like a staticy sound through the speakers.... after game boots up I will have about 30 min of game play with good sound out of the speakers.. and then the sound will shut off and game play will continue to play as if I just hit a mute button.. what would cause this?
 
It could be a few different things but most likely something in the sound amplification circuitry is failing. It could be as simple as a recap or cold solder joints.
 
It could be a few different things but most likely something in the sound amplification circuitry is failing. It could be as simple as a recap or cold solder joints.

Yeah, sounds like cold solder joints to me. I have had something similar happen to me on two different boards and they both worked fine after reflowing the solder.
 
Ok...Is there a way to test to see if there is cold solder joints? I am new to this stuff also where will the solder joints be located in sound amplification circuitry?is that where the audio cable is plugged in to? will there be alot of them?
again I am a noob!

Thanks guys for all your help! I am new to this site and I love it already!
Ill check back here in a lil bit.....
 
The sound amplification is very likely near where the audio cable plugs in but I am not familiar with your boardset. There will be a lot of solder joints and 'cold solder joint' is a term that refers to cracked solder.

Usually the sound amp and it's components look different from the rest of the board. There are normally quite a few caps in the area and a pot for volume adjustment. Also the area is normally fed by 12v while the rest of the board normally runs off of 5v. If you post a picture of your board someone can point out the area.
 
Great! I will take a couple of pictures tonight when I get home and will post them
in the morning......Thanks again for your help!
Have A great rest of the day...
 
Got some good news.....

OK here is a pic of the logic board I couldn't get a great one.The light was bad in this style cabinet tried to hold flash light and take pic at same time...

any way I tried re seating all the plugs in the io board and the logic board..
turned it back on and now I am not getting any sound at all right off the bat!
I then pulled off the jamma harness off the io board took some rubbing alcohol 70% iso. and rubbed it on the contacts for that plug..then re seated the plug and turned it back on and still no sound...then i pulled the same plug off again looked in the plug it self to see if there was any thing blocking the contact and re seated it again and powered it up and now there is sound...before it would cut out after 20-30min I ran it last night for 1hr and half! and sound was still there the only other difference was for that hr and half I had the front door off and before when the sound would shut off the door was on... What do you think did re seating the jamma harness or keeping the door off fix the problem?
 

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My guess is the harness. I would take it back off and use a pink eraser to clean each pin of the jamma board connector. Make sure you get all of the eraser particles cleaned up. Then I would take a firm bristle toothbrush and dip it in alcohol and scrub the contacts on the inside of the harness. Allow everything to dry and then hook it back up. This should eliminate any issues in the future unless you disconnect that harness a lot. Then you will probably have to clean it every so often. Good luck and take care sir.
 
Thank you so much for your help! I will do those steps...
have a great day and you take care also...
 
Check your audio cable. The PCB is a basic CPU motherboard. One of mine would lose audio. Bad cable. It looks like your audio cable is the black one in the pic. I'd replace it with another to rule that out also. It should plug into the green audio plug on the motherboard and connect to the I/O PCB.
 
OK as far as the audio cable goes do i have to use a special one? looks just like a head phone jack cable if not where can I get one?

Thanks!
 
perfect! I will go pic one up....thanks again for all of your help!

take care and have a great night!
 
What do you think did re seating the jamma harness or keeping the door off fix the problem?

Sounds like the amp chip is overheating, this is usually because it is oscillating. It will still work as an amp but will get hotter and hotter until it shuts down or dies. The heatsink should be warm to the touch, if it is too hot to touch then you have a problem. There are two reasons why amps start oscillating, the most likely is high frequency noise on the 12v power rail, this is usual caused is bad or missing decoupling caps on the 12v rail near the amp chip. Usually there are two caps strung between the 12v rail and ground to mop up this interference, one will probably be the largest cap on the board, physically as well as capacity, usually 1000uF or 2200uF, the smaller one will be a small poly cap, in a few nanofarrads in size. If either is missing then you can get this problem, the large electrolytic is the most likely as it is easily knocked and damaged.

The second option is that the signal feeding the amp is picking up RF interference, with arcade PCBs this is unlikely as the audio section and amp is usually on one board, in your case I cant comment as the amplifier is not in the photo - what I will say is that you have the audio cable tied along side what looks like the mains feed - this is a very bad idea, you will get a huge amount of mains interference on the audio signal which can cause the amp to start oscillating.

The fact it runs ok with the door open suggests is just gets too hot with the door shut and is just about ok with the door open.

This isn't a heatsink problem, or a sign you need to fit a fan, the amp will eventually die if it is running long term like this. Simple way to test is to touch the heatsink after the board has been running for 5 mins, if you almost burn your finger then this is your problem.
 
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also where is the best rout for me to run the audio cable? are all the other cables ok to be by each other?
 
Are the caps and the amp chip on the IO board?

No idea what your set up is, you will need to post photos, find where the audio lead goes after leaving the PC motherboard, thats where the amp will be.

Run that cable anywhere except lying alongside a mains cable, ideally any audio carrying cable should cross a mains cable at right angles, thats the ideal anyway. Its scale from the ideal to the worst, running parallel alongside a mains cable is the worst option. In many cases it wont matter but something is upsetting your system.

The key question is whether the amp chip is getting farkin hot - check that before you do anything else.
 
I will take more pictures tonight and post them in the morning...

Thanks Womble for your help!
 
more pictures......

Here are a couple more pictures......

I didnt have a chance to re rout audio cable and run the machine last night...worked late... but I was able to take a couple more pictures of both boards...

Also I did for get to tell you the volume on the machine seams loud for the setting that it is on in the setup screen it shows volume like 1/32...the lower the number the quieter it is..I would think it should be set around 15/32 or something like that..If I go one lower than 1/32 it goes to no sound...so it is set on the lowest setting for sound. The game is in my basement and I can here it on the next level of the house....would the rf interference cause this due to how the audio cable is ran or bad caps by the amp chip? maybe its just a loud game?

Thanks!
 

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Ok......I changed the audio cable out and re routed it away from the mains cables...Then I booted it up and played for about an hr and the heat sink for the amp chip never got hot! I think that it is a good thing.... it never even got warm just stayed room temperature.....and sound never stoped working....
What is the next step? so realy the only thing I am getting is slight static only on the boot up and when playing it it sounds like the static goes away.....
I dont know could this just be normal?? Also I did not clean the jamma connector area on the board with the pink eraser yet nor clean the connector on the jamma harness with alcohol....
what do you think?
 
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