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7800 not playing Pokey sounds


Dreamstate

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Hi folks,

i have a 7800 that works perfect except that Pokey sounds will not play. I don’t see any obvious issues on the motherboard and was wondering if someone could give me some ideas of what to check. It is an NTSC model.  
 

Thanks in advance!

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I guess that the obvious question here is are you using POKEY enhanced carts like Ballblazer, Commando, a homebrew with a POKEY chip installed on its own gameboard, or a multi-cart with an installed (or emulated) POKEY?  The 7800 motherboard itself contains no POKEY chip and it needs some form of exterior one in order to play POKEY sounds.

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3 hours ago, Dreamstate said:

Hi folks,

i have a 7800 that works perfect except that Pokey sounds will not play. I don’t see any obvious issues on the motherboard and was wondering if someone could give me some ideas of what to check. It is an NTSC model.  
 

Thanks in advance!

Is the console composite or S-video modded? If so, the mod is probably done incorrectly and failed to tie in the Cartridge Audio line properly.

 

If the console is NOT modded, it could be an issue with the cartridge connector, the trace from the connector to the Cart Audio resistor, or the resistor itself. Something like that - 7800 schematics are available here on AtariAge. Should be a pretty easy fix if it's not an issue with the cart connector. 

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It is not modded yet.  I need to track down the path on the schematics. I tested from the cart to the first resister, but I could not figure out where it went from there.  Is the Pokey its own separate path from the cart slot? (Separate from the tia traffic). Let me see what I can find on the drawings. Thanks. 

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Posted (edited)
4 hours ago, DrVenkman said:

Is the console composite or S-video modded? If so, the mod is probably done incorrectly and failed to tie in the Cartridge Audio line properly.

 

If the console is NOT modded, it could be an issue with the cartridge connector, the trace from the connector to the Cart Audio resistor, or the resistor itself. Something like that - 7800 schematics are available here on AtariAge. Should be a pretty easy fix if it's not an issue with the cart connector. 

So, i found the schematics and figured out the path. Low and behold, the cart goes to a capacitor C10 that then goes to resistor R5.  R5 was not there, like it had never been installed at the factory.  Weird.  Happen to have a single resistor of the right size so I soldered it in and BAM, now it works!  Thanks for the advice, but weird it was just missing. 

Edited by Dreamstate
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