Trying to locate audio amp on a Namco PCB

MasterFygar

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This board (Namco y112960101, used in Ace Driver and some redemption games) works great, except for it appears the audio amp is dead (speakers and volume control getting voltage and all wires are fine, there's just no specific audio signal coming out of the PCB). There are no schematics for the actual board available, though, and I'm a PCB repair novice so I'm not sure which chip the audio amp would be... I mainly work with older games that have separate audio boards, haha. I do know the chip pointed out here involves sound, would this be it or would it be one of the pieces attached to the heatsinks at the top? Is it easy to tell from a glance which piece it would be for testing/replacement purposes? I can get individual chip numbers and IC positions if that helps (along with better pics) but I know audio amps are usually visibly different from the CPU and other chips so I thought maybe it would be simpler than that, I'm just too dumb to know what I'm looking for :D Thanks :)
 

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Yikes, I was way off. Thanks much, now I know my next steps! Just to clarify, you mean this Sanyo LA4470 correct?
 

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Excellent, I know where to buy those then! You're a lifesaver. This particular chip is an LA4470 3E2... does the second set of numbers (the 3E2) make any difference compatibility-wise? I have a source for LA4470s that are identical except for the second number stamped on, it appears from the datasheets I've pulled out that they're just model numbers but I don't want to fry anything on the board by replacing it with something totally different.
 
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LA4470 is all you need to match. Your problem could be one of the passive components in the audio section... but if you're getting no sound at all then a blown amp is fairly likely.
 
The first step in troubleshooting an audio amp is to run your fingers over the pins and see if it creates any noise. If not, it is either a blown amp or faulty capacitors associated with it.
 
Thanks so much for all the help guys! Absolutely no sound, and the finger test yields no crackling so it's looking likely that that's the problem. Somewhere down the line someone installed a separate volume control that went much higher in voltage than the original appeared to so I'm guessing that blew out the chip after a while. Is there any good way to check if it's the amp itself or a capacitor so I know which to order?
 
I'm assuming you mean resistance. Unfortunately without an ESR tester you can't really determine which at fault, luckily they are both fairly cheap fixes.
 
Sorry, yeah, I meant resistance. The amp is very hot to the touch when it runs and looks a bit singed at some of the pins so I'm almost sure it's the issue. I'll order a new one tonight :) thanks for all the help so far, I'd be totally lost without it!
 
Yeah, voltage to the chip is fine so it's either the chip or the cap. Either way both are good to have around so I ordered both. Will update this upon arrival... (and I ordered a lot of two LA4470s, so if anyone else needs one let me know).
 
YES! It was the amp indeed. The thermal grease under it had totally dried up over the years and the chip was dead, but the new one applied along with fresh 99.9% silver thermal compound works great and isn't getting get hot at all. So awesome to hear those sounds again!
 
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