Worklog Booshman's N64 portable

[Yurusenai]

not sure where the short is, but there is a sliver on C87. noticed you shaved a little off the bottom by the jumper but didn't reconnect the 2 traces that are severed now.

 

[Somewaffles]

Those traces go from pins 88 and 93 of the CPU and go to pins 25 and 7 of the U6 chip respectively.

 

[Booshman]

not sure where the short is, but there is a sliver on C87. noticed you shaved a little off the bottom by the jumper but didn't reconnect the 2 traces that are severed now.

Those traces go from pins 88 and 93 of the CPU and go to pins 25 and 7 of the U6 chip respectively.

I've run magnet wire from those pins on the CPU to the U6. Still no idea on the short though.

This left edge as viewed from the bottom has a bit of a kink to it and I'd prefer to straighten it out. I also hope that might be where the issue is even though it feels very smooth. Can I trim at the red line without any issues or having to add more wires?

 

[Somewaffles]

No, you should not have to run wires after cutting to the red line.

Another thing you could do if you feel so inclined is to look towards the area(s) that you trimmed the last time and resand them. Might be shorting there for some reason.

 

[Booshman]

Good news, back in business! I took off the everdrive, still had the short. Trimmed a bit more, still had the short. A bit more, still the short. Then a final trim and IPA wash and the short was gone. Not sure if the trim did it or all the cleaning finally dislodged something but it did the trick. I've reattached the ED and got back to where I was before except now the mobo will fit in the case.

 

[Somewaffles]

Ayyy good new!!! Glad to hear you got it working again! Now all you need is to get another expansion pak

 

[Booshman]

Ayyy good new!!! Glad to hear you got it working again! Now all you need is to get another expansion pak

I ordered one a few days ago but the seller has been silent. I may have to find someone else, that's how it goes on taobao sometimes.

 

[Booshman]

So that seller ended up being a complete bell end to deal with. No response for a week, then tells me he longer has it, then threatens me for being displeased with his service. Looking for another expansion pak now but I don't want to pay over the odds so it might take a for one to come available. I missed out on another one while this guy was messing me around.

In other news I've wired a controller port up for testing and attached my amp. The audio is not as good as it was before the trim, lots of interference and hum. Going to use some wire from an audio cable and see if that clears it up a bit.

I also wired the video through one of my switches. The thing works a treat, I didn't have a second monitor set up but pushing the plunger in lost the signal as it should and the image comes back on when released.

I'm surprised that the audio is a off as it is. I used the same wire type as I did for the video and it looks fine, I'm guessing I have a grounding issue somewhere but I'll have to check that out later.

 

[Booshman]

I've been putting on and taking off wires for the audio to try and find a solution with no hum and the interference has gotten really bad. There is now a huge amount of static, like an old TV that's barely tuned in. I can hear the game playing but the interference is louder. Is there a chance the U1 chip could have crapped out with being repeatedly soldered to? I have been careful to not overheat it but it's the only thing I can think of. I even bought a new amp since they're only about 60 cents but it sounds the same as the one I had wired up before.

 

[Somewaffles]

I am no expert when it comes to this part so hopefully someone else can correct me/ help you better. But one thing I can think of is that you might need a low pass or high pass filter to help sort out the frequencies after the signal leaves the U1 chip. You might have cut resistors r18 and r20 on the back side of your board underneath the U1 chip. Those two could have been some sort of smoothing resistors. I believe they are 10k resistors that go to ground from left and from right. That being said, it almost sounds like the audio has gotten worse as you have been trying to fix it which makes me think it could be the u1 chip or something silly/ improbable like your wire being garbage or the solder joints getting bad for some odd reason. I know it’s not much help.

 

[Booshman]

I am no expert when it comes to this part so hopefully someone else can correct me/ help you better. But one thing I can think of is that you might need a low pass or high pass filter to help sort out the frequencies after the signal leaves the U1 chip. You might have cut resistors r18 and r20 on the back side of your board underneath the U1 chip. Those two could have been some sort of smoothing resistors. I believe they are 10k resistors that go to ground from left and from right. That being said, it almost sounds like the audio has gotten worse as you have been trying to fix it which makes me think it could be the u1 chip or something silly/ improbable like your wire being garbage or the solder joints getting bad for some odd reason. I know it’s not much help.

The resistors you mention are still in place. I have used some sheilded wire taken from a brand new audio/video cable I had spare. I've also switched back to the piece of wire I was using when the signal wasn't so bad. Sound is identical. Should the amp have it's own ground or can it share with other connection like the negative connector to the screen? When I had a full mobo, the G between the 2 audio ins went to the G on the AV out, now it's connected at a point with other components.

 

[Somewaffles]

I don't know whether that would cause an issue but I want to say that I have read somewhere before that it should have its own ground. Not 100% sure. I would say its worth wiring the gound from the amp to pin 3 of the U1 chip for kicks and giggles to see if that helps. Where was the G connected to before the last trim?

 

[Booshman]

I don't know whether that would cause an issue but I want to say that I have read somewhere before that it should have its own ground. Not 100% sure. I would say its worth wiring the gound from the amp to pin 3 of the U1 chip for kicks and giggles to see if that helps. Where was the G connected to before the last trim?

It was located at a common point before the last trim. I just tried pin 3 and still the same. I was actually using pin 3 for the shielding on the audio wire to ground that there, but it didn't improve the sound. I didn't have time to do anything but relocate ground which did nothing as I mentioned, but I notice I have audio coming through both headphones even though I only have one channel connected, it's very confusing. Also, I have my RGB mod chip hot glued to the side of the edge of the mobo, the heat of detaching and attaching audio wired to U1 has caused some movement to the glue on the underside and its engulfed some of the resistors, including the ones you mentioned before. I don't know why this would be an issue, the chip is wrapped in kapton tape but I thought it worth mentioning. I might try removing all non essential components and after work and see if that does anything.

EDIT: Something else that just occurred to me is that I removed the everdrive for the last trim. Perhaps there is an issue with one or more of the pins there. I have image though so who knows, something to look into.

 

[Booshman]

OK i figured it out, I'm back to having a bit of analogue noise I want to clean up a bit but the crazy noise I had before is fixed. I redid the cartridge relocation and took off everything, didn't fix it. I decided to take off the 9480F and wouldn't you know it the pad for pin 8 was gone. The only time I did anything with that pin was mistaking it for ground and attaching and detaching a wire one time, but that must have been enough to muck it up. Anyway, I ran a wire to the leg of the chip and with power the mad distortion is gone.

Still looking for a cheap expansion pak locally and in my search I found this. In the listing there is no mention of N64 and I can't get hold of the seller to confirm but this to me looks like an RGB mod and sync separator combined. Could it be used to get vga video on N64?

 

[Somewaffles]

Ayy glad you figured out where the distortion was coming from. It looks to me like you could get vga output because you get r g b and h/v sync out. One thing to note is that I don’t think you will have deblur options or anything fancy like with ultra vga.

 

[Booshman]

Ayy glad you figured out where the distortion was coming from. It looks to me like you could get vga output because you get r g b and h/v sync out. One thing to note is that I don’t think you will have deblur options or anything fancy like with ultra vga.

The seller got back to me and said its not n64 compatible, but the listing has zero consoles listed in it. They have a note that if you don't know what this is for they have a zero troubleshooting assistance policy. So he may have been fobbing me off to avoid any further requests for assistance.

 

[Booshman]

So I have everything wired up all nicely for audio and with or without the extra grounding from the shielded cable it still doesn't sound too hot. I recorded a bit of audio from being off, turned on, through the everdrive menu and booting to Mario64. If anyone wants a listen maybe it will be a better indicator of the issue than me describing the background noise. Coming out of the small speakers it's not hideous but over headphones it's very distracting. Should I not be able to remedy this are there any digital audio options available that people can recommend?

https://mega.nz/file/nRtyFKpT#6db2NWmUiCkMjQpbUPQzT2qjXB5OyIfrV4dKnAI37ZQ

 

[Somewaffles]

So I have everything wired up all nicely for audio and with or without the extra grounding from the shielded cable it still doesn't sound too hot. I recorded a bit of audio from being off, turned on, through the everdrive menu and booting to Mario64. If anyone wants a listen maybe it will be a better indicator of the issue than me describing the background noise. Coming out of the small speakers it's not hideous but over headphones it's very distracting. Should I not be able to remedy this are there any digital audio options available that people can recommend?

https://mega.nz/file/nRtyFKpT#6db2NWmUiCkMjQpbUPQzT2qjXB5OyIfrV4dKnAI37ZQ

could you draw up like a basic schematic of how your audio setup is wired?

Only digital option I know of is to do what GMAN did with his newest portable n64 build. He used the uamp, with another chip, and that chip supplied the uamp with the WS? needed to produce digital audio. It’s been a while since I looked at it so I’m a little hazy on that.

 

[Booshman]

could you draw up like a basic schematic of how your audio setup is wired?

Only digital option I know of is to do what GMAN did with his newest portable n64 build. He used the uamp, with another chip, and that chip supplied the uamp with the WS? needed to produce digital audio. It’s been a while since I looked at it so I’m a little hazy on that.

Now you mention that I did read about what he did in his thread, sounds awesome but also like a one off. It's not the stock amp from the store anyhow which is a shame. He implemented some code to get aound the N64's quirks.

For my wiring it's pretty simple, just shielded wire from the U1 chip to the amp. I have resistors on each channel as without the volume is too high and distorts. I've tried grounded and not, straight connection or through a volume pot. The only thing I can think is it's the everdrive. I remember reading Bungles reduced wiring and it says to add more grounding wires if you use an everdrive. Here's the quote:

"Everdrive64: Pin 45 isn't needed to run most games (seems there are one or two that do need it) but it is needed for the Evderdrive64. Also, when wiring up an Everdrive64, you'll need to run more than one ground - pin 1 MUST be connected to ground, and pick at least two other ground pins to wire up. The reason is that the Everdrive64's circuit board layout has almost no grounding layer, making it vulnerable to RF interference. It's a good idea to wire up a couple of the 3.3v lines as well."

I have 4 power lines and 4 ground which I would have thought were enough.

 

[Booshman]

Well I've added 4 more ground wires and shortened the ones I had to as short as I can get them and the audio sounds identical how it's been. I am absolutely stumped as to what could be the problem.