Altered Beast (another no sound) where to get replacement z80

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Altered Beast (another no sound) where to get replacement z80

I've had an Altered Beast for a few years now with no sound. i did a search and found that it's most likely the suicide battery and i'll need to replace my Z80B cpu and encryption chip (epr11686?).

Was just wondering where i could source replacements? and what the wallet damage would be.

I'm guessing i'll also need a 6800 cpu and chips for my Golden Axe tho the sound on that works fine.
 
I know I will have to replace mines sooner or later. So how often do you powerup your boards? I power mines up for at least 30mins a week. Its been like like 5 years since I got them. Dont know if its helping or not.
 
i rarely power them up, maybe once every 1-3 months, and normally for very short periods. 10-45minutes tops. not sure if that's a good thing either or not. i also STILL have to replace the batteries in my cps2 AvP and MvC sets but i've been putting it off as i'd like a new soldering iron before i do it. been looking at hakko 936's just haven't bit the bullet yet.
 
replaced my Z80 and EPR 11686 (a10), and checked the volume pot on the board, all i get is humming :( game runs great just infernal humming

golden axe works fine (with my sega 16 adapter) so it's definitely something in the board.

I've checked voltages and they're all good and where they should be at the edge connector.
 

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anyone? there's no visible board damage, and i heard that that could be a cause due to the sound tracers being very close to the edge/corners of the board...
 
Did you have the humming before the replacement parts?

Assuming that the replacement Z80 and ROM are good, I'd probably suspect either the caps in the sound section, or possibly the amp chip. The amp is the one with the heat sink and the Sega sticker, lower left in your picture.
 
before the z80 and sound prom replacement i don't remember their being any sound at all, i could pop in my dedicated original z80 and sound prom to re-check that tho i'm sure. i got the replacements from bobroberts. is there a way to test the amp chip? i'll have to look into how to test the caps too as i've never delved that far into board repair (mainly replacing eproms is the extent of my board repair).
 
An easy way to check the amp is to cut up and old pair of headphones and wire one (or both) signal wire(s) and ground to probes. Then probe the INPUT side of the amplifier and listen for sound (Carefully. It could be loud!)

I can't find schematics, so I can't tell you where/what the Amp chip is. I'd look up the Datasheet for it when you find it, and check your Power-In lines to make sure voltages are proper or atleast within tolerance of the part.
 
"Rise From Your Grave!" or don't because you don't have any sound to do so (lol).

ok revisiting this a little. I haven't gotten to try the headphone wire trick like windrake said, but i did get a 2nd replacement sound chip (a10) from another member here (thankyou very much sir you know who you are). popped it in there and there was no change at all :( volume pot is good as it makes the static/humming noise from my speakers and gets louder or quieter depending on which direction you turn it.

ready to kick babies on this thing here as it's a pain to dig out of the bottom of my cab (6 other games in there also). the manual is no help as winddrake said also (tho i have a kit manual on paper i'll have to look for any others if there are).


rise_from_your_grave.png
 
Grab your oscilloscope or logic probe and download data sheets for the audio chips - the YM2151 and the UPD7759 - from http://www.datasheetarchive.com

Check the outputs of the audio chips for activity. If there isn't any then troubleshoot the digital section. If there is, then follow the signals until they disappear.

RJ
 
I have neither of those unfortunately lol. I've been meaning to get a logic probe for a few months even tho i haven't the slightest clue how to use it, i'm sure i could figure it out with some youtube'n/reading.

I was also given the idea that maybe the replacement z80 i got from bobroberts might be bad, so i was trying to find it on mouser/digikey: (this is a stock photo my chip is nec mc8123b 703 instead of 704 not sure if that means anything)

nec_z80.jpg


Just looking for the standard/stock replacement for this which i believe is a Zilog z8400b PS 8329? (as that's what i got from bobroberts).

This is definitely turning into a project but a great learning experience at the same time. I know my way around a schematic and how to use a multi-meter but i've never gotten this deep into the goods.
 
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IIRC, you need a Z80H or Z84008 - the 8 or 10MHz version.
 
I know I will have to replace mines sooner or later. So how often do you powerup your boards? I power mines up for at least 30mins a week. Its been like like 5 years since I got them. Dont know if its helping or not.

Powering it up from time to time wont help at all, the batteries are not rechargeable, its just that some seem to have lasted a lot better than others. Out of all my System16 boards I only have one that is left on its original FD1094 and thats E-Swat.
 
OK so, little update.

Replace Z80 once and audio chip twice with no change.

Sent board out to my buddy Ray (Channelmanic up there) and he found the Z80 i replaced was bad still. Replaced it and now I really can Rise from my Grave!

Shout out to Channel and AJCRM for the help

 
w00t!

Glad I could be of service. :D

(And not in the Jow/Phet kind of way)
 
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