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PostPosted: Thu Oct 19, 2017 2:09 pm 
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Hey everyone,

First post here, so I hope I'm posting in the right section.

Anyway, I'm gathering parts for some upcoming console mods that I'll likely tackle this winter break.

NES-wise I want to do a stereo mod, but I was also reading that the stereo channels are a bit quiet, which is how I stumbled upon this:

Image

A user on here made 2 of these, 1 for each audio channel, and I'm thinking about doing the same.

Parts-wise I noticed the schematic shows polar capacitors, but I wasn't able to find small rating capacitors that were polar. Is it just the schematic that's showing them polarized, but really it doesn't matter?

A quick picture I found of the NES motherboard makes me think the capacitors used aren't polarized:

Image

I'll probably have more questions, but that's it for now.

Thanks!


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PostPosted: Thu Oct 19, 2017 2:52 pm 
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Only the 1 and 10µF capacitors are polarized; the --|(-- notation doesn't necessarily imply polarized. (hence the extra +)

There's no particularly good reason to rebuild the entire NES-internal audio chain twice, as opposed to just using an opamp.


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PostPosted: Thu Oct 19, 2017 3:52 pm 
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I think the notation for a non-polar cap is --||--.


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PostPosted: Thu Oct 19, 2017 4:15 pm 
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A notation that's usually a non-polar cap is --||--

Only the visible + is a sign of something that's unambiguously polarized. A non-polarized cap can replace a polarized cap of similar ESR.


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PostPosted: Thu Oct 19, 2017 8:06 pm 
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Thanks everyone! Yeah, I was looking at the --| |-- vs --) |-- notation as well; good tip pointing out that "+" to differentiate between polar and nonpolar.

And yeah, I'm sure the audio could be amplified using another method, but I do like the idea of replicating the original hardware, and I happen to have almost all the parts anyway due to other mods...


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PostPosted: Thu Oct 19, 2017 8:18 pm 
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If you're removing the CIC at the same time, you could reuse one of the inverters in the 74HCU04 (since the CIC uses four; the audio amplifier here uses one; and the PPU uses one).


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PostPosted: Thu Oct 19, 2017 9:53 pm 
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lidnariq wrote:
If you're removing the CIC at the same time, you could reuse one of the inverters in the 74HCU04 (since the CIC uses four; the audio amplifier here uses one; and the PPU uses one).

I have disabled the lockout chip (not 100% sure if that's the same as the CIC), so that is a thought; good idea!


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PostPosted: Fri Oct 20, 2017 6:30 am 
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Yes, the Checking Integrated Circuit is the lockout chip.


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