Sega Afterburner Sound Amp

ItsJustaGame

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hi, I've been working for a while now on resurrecting a 1987 Sega Afterburner.

Almost there, but there's a slight sound problem. I'm pretty sure it's the amp. The part number is Sega 839-0035-01 and I've attached a picture. I've checked the wiring and connections, and they're fine.

Anyway, the right channel works great, but the left channel is really weak (barely audible). I'm having a difficult time finding the schematics for this amp and really have no clue which component of the board might be bad.

Can anybody here either help me ... or maybe I can get you to repair my little amp for me? Also, just pointing me in the right direction of sound amp schematics would be good.

Or, to save everybody time, if you have one of these for sale that works, I'd be interested in buying it.

Thanks! You guys have always been a big help in the past.
 

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I tried looking at the manual but it is very hard to see but I would check the dac (ic7) and ic5.

Riptor is the parts guy close to us and he probably can put that part in for you if he is not busy with other projects.
 
Whats the part number on the amp chips? They are the two IC's that are attached to the heatsink. I would suggest replacing all the caps on the board as well. The header pins appear like they might be cruddy too. That pcb kinda appears like it got some battery acid on it because of the dark spots on the solder mask.
 
Ha! That's not a pic of my board. It's one I found on the web as reference. Mine is a bit cleaner.

The amp chips have this printed on them:

Japan
MB3733
8727 M21

I probably need to replace them? Also the 19 (yes 19) caps on this 4"x4" board, too, huh. Sheesh.

Sounds like I should just wait around until I find someone parting out a Sega machine and buy one that works.

I'll tell you one thing, with my clumsy fingers if I tried to repair all THAT it would look like a piece of swiss cheese with smoke coming out of it.

How's this for a crazy notion? Would it be possible to somehow pipe the audio from the main game board through a different amp or something? I've seen guys online doing this with amplified computer speakers and such things. If that were possible, I wouldn't need that damn sound amp. It shouldn't be such a hassle to have stereo sound, but if I could re-route the motherboard sound to a set of amped speakers, that might just work for me. Is that possible with this sort of game?
 
I have the amps in stock...
http://www.twistywristarcade.com/sound-amps/838-mb3733.html

If you want to send the board to me I can test the caps and replace them. I can meter the amps and see if either of them is shorted or have any off readings.
Yeah you could probably pull the input signal and run it through a different amp but I would just repair the original one.
 
Awesome!

That would be absolutely great of you! I will put it in a box and mail it your way! I'd much rather keep the machine original, and if you are skilled in fixing these things, that would be just great.

PM me the address where I can ship it along with an estimate on the cost of your effort and I'll ship it right away!

Thanks again, man.
 
That would be absolutely great of you! I will put it in a box and mail it your way! I'd much rather keep the machine original, and if you are skilled in fixing these things, that would be just great.

PM me the address where I can ship it along with an estimate on the cost of your effort and I'll ship it right away!

Thanks again, man.

You see why I endorse him now :).
 
Yes, I do! Thank you so much for the recommendation.

And thank you Riptor. The board is already in the mail and should be to you in 2-3 days.

The right channel is working great, but the left channel not so much.

I've also attached my rough sketch here of the pin outs if you can use this to test it. Please keep in mind that I'm not skilled at this, so you might want to double check, but this is sort of what I've been able to determine from the diagrams in the manual (which are available here: http://dweeb.net/afterburner/owners_manual/)

Thanks again. I'm stoked about full stereo Afterburner. :)
 

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Yeah I downloaded the manual for the pinout prior to sending you the pm. It should not be too much trouble to bench test it.
 
So let us know, was everything good once installing the repaired sound amp?

Um, yes it was AWESSOMMMOOMMEEEE!!! Thanks, Riptor. Basically, once you got finished working on it, I plugged it in and heard that full-bore, stereo Sega sound that is so awesome on that game. It was like a new board.

Excellent work, and I've left feedback for you. Everybody, I recommend Riptor as the MAN when it comes to fixing things like this.

I may have some projects in the future for you. My back-up Asteroids Deluxe board has a shaky picture because some idiot (could have been me, but I'm not saying) tried to re-cap it and failed. PM me if you have time to clean up that board for me. It works, but I need somebody to go over it and clean it up. I'd love to have that board working again. It's my machine's original board.

Also, I'm going to be a regular customer at your store, Riptor. I just ordered an amp and something else. I'm sure you'll have plenty of orders from me in the future.

Thanks again!
 
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