NES sound

[Ismail Saeed]

Hey folks...

Okay.  Get this.  I had opened up my NES and cleaned the inside with half/half (isopropyl/water) fluid on lint free cloths and had dried it also.  The cartridge slot, I mean.  I had done this periodically and had put it off long enough that finally I went and did it again after over a year.

Things were fine that night after I put it back together.  Perfect as expected, in fact.

The *next* day (on a clean game, mind you).... sound was silent.  At first I merely checked the TV volume and the connection to the TV but both were fine.  ALL games were silent, although nothing else was wrong with their behavior.

The Zelda cartridge thing sounded very much like my thing except this is with ALL games, on clean cartridges.  I intend to check tomorrow (though I think I *did* re-clean later) to see if anything crept onto the connector (especially when I removed it)... it's unlikely given that it was fine the day before after being put back together, but I'm finding it unlikely that I only shorted one tiny thing on the NES board somehow without shorting more than just that, so the "one pin being affected" thing feels like something to check.

Is there anything anyone here might be able to tell me that can help what I'm trying to do?  I ran a cloth over the mobo esp. over the sound area just in case.  I'm not someone who would do soldering because I'd ruin stuff... no training or equipment, though I know someone who can solder if I *MUST*.  On the plus side, nothing else is going wrong with it... on the minus side, that hasn't brought the sound back.

In the interests of full disclosure it should be noted that I was using a Honeybee converter for the first time after cleaning it and the two Famicom cartridges I used with it, but that too was operating correctly and with sound the previous day to my recollection.  I can detail more about my usage of the converter if that's relevant.

I took some digital photographs of the inside of the NES but I don't know if any of them are close-view enough (or unobstructed enough by the flash) to be of use (I took the photos to compare with online photos of where the sound was so I could find the proper location to try cleaning it).

Ideas are welcome.  Help me? :P

[NeWmAn]

Hi,
Are you sure the cables you are using aren't defective?
Can you do what blackevilweredragon did (check output pin on CPU)?

[Ismail Saeed]

I've been really busy and was only able to finally get to trying things out with my NES today.  Hopefully somebody will still see this thread after this :).

Anyway, I did try cleaning things up and inspecting the edge connectors again and checking cable connections and so on, but the net result didn't restore sound.  I had noticed that the NTSC sticker was possibly covering part of the edge connector of the mobo, so I removed it, but it probably had been there to begin with.  As for the output pin on the CPU (wasn't it the cartridge for him) I uh... couldn't find anything wrong that I didn't run cleaning cloth over.  The system is still superbly responsive, but silent.  I would *like* to see if sound comes off the connectors, but as I said before, I have no soldering experience.  Can I have connections RESTING on those two sound tips to test if sound is coming out of them without actually "soldering" them on?  Is physical contact enough to do a test?  And if so, what kind of connectors do I use and what do I hook up to it?  I'd like to see if sound is coming out, since I'm not sure what else to do now unless anyone else has suggestions.  Again, I do have photos as mentioned previously, though nothing looks different than a normal NES board.

I realize there may be nothing I can do.  But if anyone has ideas or thinks I *can* do something, their help would be appreciated.

[blackevilweredragon]

The CPU is in the console..  The ant in my cartridge was causing a short that was somehow disabling the CPU's sound circuit..

Attack a speaker to the pins on the CPU  (one of the sound output pins...)..  If you can hear sound, then the short is somewhere elsewhere..

Cleaning cloth, on the circuit board?  Nooooooooooooo....  You should always clean with AIR..  What kind of cleaning cloth?  It probably had static buildup, and fried the CPUs sound circuit...

[NeWmAn]

Post the photos, maybe we can see what's the problem...

Can I have connections RESTING on those two sound tips to test if sound is coming out of them without actually "soldering" them on? Is physical contact enough to do a test?

You can remove the audio cable and touch the central pin (of the cable) to where the audio should be (Cpu IC pins or other parts of the PC), but be VERY careful to not cause a short circuit.

http://www.raphnet.net/electronique/nes_mo...d_en.php#stereo

[Guest]

I know the CPU is on the console... I mean, trying to identify which "black box" it is :).  Actually, rereading your ant story puzzles me... the ant was on the cartridge, right?  Yet sound still came out of the sound tips and only shorted further down the line inside the system?  On the other hand, if the ant was in the system, wouldn't there have been no sound even in other games?

Don't worry... this is just ordinary lint-free cloth like CD wipes.  While something along the connection may have been shorted, the NES sound is generated by the CPU and I doubt I shorted the CPU, since again, the system runs perfectly. - Anyway, it's been all over the system, and the system is fine.  And yes, I did originally clean with air... back when the sound died in the first place. :P

Which cable is the audio cable I should be removing?  I actually did see the place where you linked, which let me know where the sound was being sent out, but that cable in those photos is one affixed by the guy doing that mod, not a cable that was already there.  The other "cables" on the system either don't budge (and I'm wondering if they are removable so I didn't force them) or are the blue cable connector on that one side of the motherboard, which seems to be the power and anyway seems to be fine.  Do I touch the two little things there (as in the left photo) with shielded cable... and if so, where do I plug the other end of the shielded cable into?  Can that go directly into speakers, or...?

As for the photos... I'll try to post links to them later when I find a place to upload them to.  Looking at them though, I don't really see any physically remiss characteristics, and I wonder if some shots are too far away from relevant things to help.  Anyway, I'll try to do that in a bit but for now any of the above can be replied to? :)  I can take more specific photos if necessary also.

[blackevilweredragon]

I know the CPU is on the console... I mean, trying to identify which "black box" it is .  Actually, rereading your ant story puzzles me... the ant was on the cartridge, right?  Yet sound still came out of the sound tips and only shorted further down the line inside the system?  On the other hand, if the ant was in the system, wouldn't there have been no sound even in other games?

Don't worry... this is just ordinary lint-free cloth like CD wipes.  While something along the connection may have been shorted, the NES sound is generated by the CPU and I doubt I shorted the CPU, since again, the system runs perfectly. - Anyway, it's been all over the system, and the system is fine.  And yes, I did originally clean with air... back when the sound died in the first place.

Which cable is the audio cable I should be removing?  I actually did see the place where you linked, which let me know where the sound was being sent out, but that cable in those photos is one affixed by the guy doing that mod, not a cable that was already there.  The other "cables" on the system either don't budge (and I'm wondering if they are removable so I didn't force them) or are the blue cable connector on that one side of the motherboard, which seems to be the power and anyway seems to be fine.  Do I touch the two little things there (as in the left photo) with shielded cable... and if so, where do I plug the other end of the shielded cable into?  Can that go directly into speakers, or...?

As for the photos... I'll try to post links to them later when I find a place to upload them to.  Looking at them though, I don't really see any physically remiss characteristics, and I wonder if some shots are too far away from relevant things to help.  Anyway, I'll try to do that in a bit but for now any of the above can be replied to?  I can take more specific photos if necessary also.

The ant was in the game cartridge...

The CPU has two parts to it, the core, and the sound..  The sound can get fried, while the core still runs..  You haven't seen the weirdest things I have seen..  I've seen a PC boot up with a bad CPU!!  (only to crash when you load a game that used SSE)..

How are you connecting the NES to your TV?  Through the RF connection on the back, or the video/audio connection on the side?  You take the Audio cable on the side of the NES (that goes to your TV), and touch it's pin to the sound pin on the CPU...  (make sure the video cable is connected, you need it's ground!)

this side..

[Guest]

Is that really possible?  To just touch the RCA sound jack's metal part onto the CPU?  I thought the signal underwent some changing before it was really in the format for an RCA cable audio signal (In fact, I thought the power box also dealt with translating the signals).

Anyway, yes, I use RCA connections.  The video and audio quality improvement is not to be missed ;).  Actually, someone suggested trying to RF switch plug/coaxial connection to see if that worked, but I doubt it would since I think that gets downconverted from the RCA signal after a copy of that signal is first sent to the RCA jacks.  I'll admit I haven't done that check yet, but I've rarely gotten the time to deal with the NES... this "sound died" thing happened nearly a month ago now even though I've only had the time to try fixing it two or three times so far.

So which thing exactly would I touch the sound RCA jack to?  The "sound" thing in the photographs seems to have metal ends on two sides, and be two things to boot.  Also, can someone else confirm if this works before I actually try touching it to it?  I'd really rather not make things worse if that can happen :P.  As for the CPU, that brings me back to "which black thing on the mobo is it."

[Ismail Saeed]

Above guest is me.  Forgot to type in the name.

[blackevilweredragon]

Is that really possible?  To just touch the RCA sound jack's metal part onto the CPU?  I thought the signal underwent some changing before it was really in the format for an RCA cable audio signal (In fact, I thought the power box also dealt with translating the signals).

Anyway, yes, I use RCA connections.  The video and audio quality improvement is not to be missed .  Actually, someone suggested trying to RF switch plug/coaxial connection to see if that worked, but I doubt it would since I think that gets downconverted from the RCA signal after a copy of that signal is first sent to the RCA jacks.  I'll admit I haven't done that check yet, but I've rarely gotten the time to deal with the NES... this "sound died" thing happened nearly a month ago now even though I've only had the time to try fixing it two or three times so far.

So which thing exactly would I touch the sound RCA jack to?  The "sound" thing in the photographs seems to have metal ends on two sides, and be two things to boot.  Also, can someone else confirm if this works before I actually try touching it to it?  I'd really rather not make things worse if that can happen .  As for the CPU, that brings me back to "which black thing on the mobo is it."

there's multiple pins on the CPU for sound, the only changing is the mixing of them..  if you can atleast get sound from one of the pins by touching the pin on the RCA jack, then the sound is there, but the mixing is dead..

[NeWmAn]

Don't worry... this is just ordinary lint-free cloth like CD wipes.  While something along the connection may have been shorted, the NES sound is generated by the CPU and I doubt I shorted the CPU, since again, the system runs perfectly. -

The problem with using a cloth is related to static electricity: wiping the cloth builds up charge that can be fatal to IC chips.
Moreover you could have bent, snapped or accidentally shorted some of the parts that have long metal legs.

Which cable is the audio cable I should be removing?  I actually did see the place where you linked, which let me know where the sound was being sent out, but that cable in those photos is one affixed by the guy doing that mod, not a cable that was already there.

The cable you should be removing is the RCA connector on the back of the NES, like in blackevilweredragon's posted picture

and if so, where do I plug the other end of the shielded cable into?  Can that go directly into speakers, or...?

One end goes into your TV/AMP/Speaker, the tip of the other end goes to your test point on the PCB

So which thing exactly would I touch the sound RCA jack to? The "sound" thing in the photographs seems to have metal ends on two sides, and be two things to boot.

The sound things you are referring are the 2 resistors?


Check the stereo MOD photo and touch the same places where the modder has soldered the additional wires.

[Ismail Saeed]

Hey... so I just... had an interesting exercise in cable reach in order to have my NES open, upside down, with a cartridge in the slot, to be able to test this.  (It didn't help that there wasn't much separation allowed between the two leads of a "two head" RCA cable)...

First - the cable is fine.  Tested it with a camcorder and the sound and the video were both transmitted to the PC... including the oh so joyful feedback when I brought the camcorder too close to the TV. :P

Well, I have good news, I think.  Possibly a question mitigating that good news, though.

Those two resistors...

http://www.raphnet.net/electronique/nes_mo...ges/connect.jpg

On the side of them that is the upper part of this picture (the side where a letter and a number are printed, not the side where the 100 is printed) I get sound out of both of them.  I used Ghosts n' Goblins as a test case in stage 1 and I got a majority of the music and sfx on one of them and some of the accompaniment on the other (I'm familiar with the NES sound registers from NSF stuff, so I'm aware of the nature of the separation I was hearing).  Anyway, so that's good news, I got music and sfx off the board.

The question is this, though.  In the stereo modding picture he had stuff connected to both sides of the resistors.  I checked both sides of each resistor, and as I said, the lettered side got me sound but the side numbered 100 did not (at first when I checked I realized my guy had just died so it was intentionally silent, so I waited until I was on the next life and tried again).  Am I supposed to get sound off both ends of each resistor, or is this normal?  Are the two other ends that DID get me sound ALL five channels (square1,square2,triangle,noise,dpcm)... aka all my sound is alive... or is "part" of my sound dead?  That's my question.  Ghosts n' Goblins stage 1 SOUNDED pretty  complete when I imagined mixing the two signals I got in my head, but that's not exactly a scientific verification for me :).

BTW... in the off chance that the other end was power... I didn't short the sound since I tested the lettered side again after retesting it, and yup, had sound.  So no worries about shorting there.

Lastly, the question that, should there be an easy answer, will end my woes once and for all... now that I know my sound is alive (and hopefully pending answer to the above question ALL of it is alive)... where do I look from here to see where the signal death occurs?  And when I find the spot (depending on whether it's on a printed path or in a component) what can I do with it to fix it?  Multitudes of printed paths on the circuit board don't exactly want me touching the RCA tip to any of it unless I know exactly which gold line to touch, as you can imagine :).  Also I'm not sure, given how many circuit paths there are, which component the sound goes to next, though that seems to be the logical next place to check.

Lastly, I realize I'm a difficult nut to crack.  I sound so needy, and I'm so personally unfamiliar with the inner workings of the board despite knowing computing otherwise... reading other threads here, I'm like a help me case where there isn't much I seem to know how to do on my own unlike many other things here :).  So I wanted to thank EVERYONE who has helped me in this thread so far (and anyone and everyone who ends up replying after this) for the help I've been given, whether this problem gets solved or not.

Incidentally, this was finally the nut that cracked that told me I should learn some basic soldering, to the point that I tried to find if the school I teach at has a basic electronics class that covers soldering that I could take as a "taught" introduction before I go wild with a soldering iron.  Oh, and if I need to use a soldering iron for this project for the time being, I'll take the instructions given for what to solder where and go to my friend who KNOWS soldering with those instructions rather than risk my NES further. :)

[kendrick]

Relax, Ismail. I don't have the knowledge to help you with your specific problem, but I can tell you that you're asking the right questions in the right way. The fact that you're willing to take risks and that you're willing to do your own work is a big plus and earns our respect. I perceive you as needy or annoying in any way, and I'm actually learning a lot by reading your posts. So relax, and in a minute 'dragon will be along to tell you what's what. :)

-KKC, who thinks we need more positive reinforcement around here...

[blackevilweredragon]

I remember testing directly on the pins, and getting sound.. So good, the CPU's sound generating circuit IS infact working properly, but the mixing is not...

[blackevilweredragon]

Ok, I just tested it..  On mine, there is no audio PAST the resistors either...

Do me a favor, just for the heck of it, can you try the RF output just in case?  If the RF output don't work either, then I will have to trace the circuit on mine for other points for you to test...

Quick Question, do you have a multimeter, and do you know how to use it?  If so, I am willing to have you trace some circuits on the AV module box (first step)...

If you do have a multimeter and can test it, do this for me..

Put a multimeter in the diode setting, or resistance setting (2000 or 2k)...

It should read around what my multimeter says..  If you have a hard time getting a reading with the probe in the RCA jack, do what I do sometimes, but a little bit of tin foil around the probe, and put that in the hole, allows it to get better contact...

http://blackevilweredragon.spymac.com/NESsound/1.jpg
http://blackevilweredragon.spymac.com/NESsound/2.jpg
http://blackevilweredragon.spymac.com/NESsound/3.jpg

BEFORE YOU DO THAT:  Please, discharge the NES..  Turn it on with no power brick on it, the power LCD should flash quickly once..  Once the LED is out, done, it's discharged..

[NeWmAn]

The "side numbered 100" of both resistors is connected to ground.
Besides doing what blackevilweredragon has suggested, please post the photos of your board (use imageshack to host them).

[Guest]

Oh, I wasn't freaked out.  I just wanted to apologize for the "Feed me, feed ME!" tone I felt my posts had.

So the "100" side of these resistors really ISN'T supposed to give me any sound?  That relieves me quite a bit.  I was much heartened earlier today but then got concerned at what might be necessary (like removing and soldering new resistors in) if one side was broken.

I don't have a multimeter with me, but I'm finding out if anyone I know does.

I'll check the RF switch thing this weekend... hopefully tomorrow, Sunday if absolutely necessary.

For photography purposes, what should I focus on and make sure isn't blurred or obstructed by flash reflection?

[Ismail Saeed]

Above is me... HAVE to remember to type the name in.

[blackevilweredragon]

Oh, I wasn't freaked out.  I just wanted to apologize for the "Feed me, feed ME!" tone I felt my posts had.

So the "100" side of these resistors really ISN'T supposed to give me any sound?  That relieves me quite a bit.  I was much heartened earlier today but then got concerned at what might be necessary (like removing and soldering new resistors in) if one side was broken.

I don't have a multimeter with me, but I'm finding out if anyone I know does.

I'll check the RF switch thing this weekend... hopefully tomorrow, Sunday if absolutely necessary.

For photography purposes, what should I focus on and make sure isn't blurred or obstructed by flash reflection?

Focus on both the bottom of the AV module, and the bottom side of the NES motherboard...  (i want to see the traces, and see if they are in tact)...

[Ismail Saeed]

This is possibly a premature update, but just so you know:

I tested the rf switch jack and it's silent that way too.

I found that I need to tighten the controller connections inside the system (I once had to do this in the past) because controllers plugged in won't work and the system locks at points where it actually "wants" controller input... looks like it's not major and will be fixable as soon as I open up... I'll make sure it's okay before I close back up again.  Don't worry about that one unless I mention it again :)

Still seeing if anyone has a multimeter.  There is the "buying one" option but I'd like to be sure of the need before doing so.

Photography will be done when I next open the system.  When you say the bottom of the motherboard, do you mean just the notable side of the motherboard in general or focusing on a particular edge of the relevant "side" of the motherboard?

Depending on what you need, my existing photography may be fine for this.

[blackevilweredragon]

This is possibly a premature update, but just so you know:

I tested the rf switch jack and it's silent that way too.

I found that I need to tighten the controller connections inside the system (I once had to do this in the past) because controllers plugged in won't work and the system locks at points where it actually "wants" controller input... looks like it's not major and will be fixable as soon as I open up... I'll make sure it's okay before I close back up again.  Don't worry about that one unless I mention it again

Still seeing if anyone has a multimeter.  There is the "buying one" option but I'd like to be sure of the need before doing so.

Photography will be done when I next open the system.  When you say the bottom of the motherboard, do you mean just the notable side of the motherboard in general or focusing on a particular edge of the relevant "side" of the motherboard?

Depending on what you need, my existing photography may be fine for this.

Pictures of the motherboard should be the "component side", where all the IC's are located..  Try and get a "overview" shot, so we can see the whole board...

[Ismail Saeed]

For the moment, let me show you the pictures I took before starting this thread in case they're useful.  If I need new pictures, let me know.  Granted I've tried things since these pictures, but the only things I've tried were to test the resistors and to remove the NTSC sticker you see in these photos.  Other than the sticker, it all looks like this.

http://members.cox.net/slipgate/P9040004.JPG - possibly too far away, holistic shot

http://members.cox.net/slipgate/P9040012.JPG - closer up holistic shot

http://members.cox.net/slipgate/P9040006.JPG - extreme closeup of one corner, possibly not needed but kept in if useful

http://members.cox.net/slipgate/P9040010.JPG - extreme closeup of a relevant side... if the orientation obstructs your view rather than just being able to flip vertical I can take another picture from the other side.

http://members.cox.net/slipgate/P9040011.JPG - camera following left a bit to see the power box in the corner and such.

Are those useful?  Do they reveal anything?  Do you need a better view of the metal AV box? (I never opened it before)

In other news, I may have found a friend (sort of a friend of a friend, really) that fixes stuff all the time (RV's, etc.) and probably has a multimeter, so if he does have a multimeter he also probably knows how to use it and may be able to help me do the testing you want.  I'm finding out if he even has one first though.

[blackevilweredragon]

Being I am not home right now, I won't be of much help for now (ill be back home late tomorrow)...

I'm trying to go through the NES schematics, and figure if there is an easy way to test points with the multimeter..  the one I suggested before, with the multimeter, is the best bet at the time...

The AV box will need to be opened (look at my pics, to see the orientation i had the NES, so you know which side opens, as one side does not open)..

[Ismail Saeed]

In this picture (http://blackevilweredragon.spymac.com/NESsound/1.jpg) is the little thing pointed at by the red arrow on the right where I should open from?  Or is that a multimeter test point?

It's okay if you can't get to it till tomorrow, I probably can't get back to it till then anyway (though I plan to correct the controller issue today, and test while the box is still open to make sure it's fixed).

[blackevilweredragon]

In this picture (http://blackevilweredragon.spymac.com/NESsound/1.jpg) is the little thing pointed at by the red arrow on the right where I should open from?  Or is that a multimeter test point?

It's okay if you can't get to it till tomorrow, I probably can't get back to it till then anyway (though I plan to correct the controller issue today, and test while the box is still open to make sure it's fixed).

My bad, forgot, you don't have to open the AV box to do this test, sorry..

Those red arrows, are pointing directly at which point to test with the multimeter...

If the multimeter shows the rating (or close too) mine did (when set to the same settings specified), then the AV box is fine..  the short is somewhere on the motherboard then..

[Guest]

Oh I see, the two cables on the multimeter should be hooked to those two spots.

Are we sure this is a voltage thing?  Will there BE voltage in a system that's off and not even connected to power, as well as discharged already?  If a component has bricked somewhere like this, will the voltage indicate that?

Also, is that a 5.89 or a 589?  I realize there's no decimal there, but I figured it was worth asking in case the multimeter I ultimately get my hands on differs in its display characteristics.

I look forward to narrowing this down .

I'm still perplexed by the fact that when this problem originated, it didn't exist when I first put the system back together and played it that night but existed the next day.  Still, I've determined that it's not on a cartridge, so...

(Hah, I should find out what Heavy Barrel actually sounds like... it was the first game that was silent the day we discovered this issue)

[blackevilweredragon]

Oh I see, the two cables on the multimeter should be hooked to those two spots.

Are we sure this is a voltage thing?  Will there BE voltage in a system that's off and not even connected to power, as well as discharged already?  If a component has bricked somewhere like this, will the voltage indicate that?

Also, is that a 5.89 or a 589?  I realize there's no decimal there, but I figured it was worth asking in case the multimeter I ultimately get my hands on differs in its display characteristics.

I look forward to narrowing this down .

I'm still perplexed by the fact that when this problem originated, it didn't exist when I first put the system back together and played it that night but existed the next day.  Still, I've determined that it's not on a cartridge, so...

(Hah, I should find out what Heavy Barrel actually sounds like... it was the first game that was silent the day we discovered this issue)

the multimeter won't be measuring voltage, but it will be measuring resistance..

if there is complete resistance (no connection), it will read a "1", if there is no resistance "a straight connection between those points", it will read a "0"..  but you should receieve a resistance about what I got, because there is parts between those pins (amp, RF modulator, etc), so it should be about half resistance..  but if you get complete resistance (multimeter doesn't change at all and stays showing a "1", then the AV module is the cause for no sound, and that board needs to be looked at..

[Guest]

The video and power and RF and such work, as you know.  Will the sound not working still potentially make it be a "1" reading despite the rest being okay or will the fact that most of the stuff in there is definitely okay possibly corrupt the result?

Also, what are the chances that it recognizes the sound isn't working in terms of resistance but the actual cause is before it gets into the AV box?  Will the AV box have a regular resistance result for sure as long as the problem isn't from it?

Did those sentences make sense for what I'm asking?

Anyway, looking into getting the whole multimeter thing.  That admittedly may take some time as one friend asks another .

[blackevilweredragon]

The video and power and RF and such work, as you know.  Will the sound not working still potentially make it be a "1" reading despite the rest being okay or will the fact that most of the stuff in there is definitely okay possibly corrupt the result?

Also, what are the chances that it recognizes the sound isn't working in terms of resistance but the actual cause is before it gets into the AV box?  Will the AV box have a regular resistance result for sure as long as the problem isn't from it?

Did those sentences make sense for what I'm asking?

Anyway, looking into getting the whole multimeter thing.  That admittedly may take some time as one friend asks another .

This test is just to narrow down the possibilities..  I admit, it isn't a perfect test, but it does help...

If it reads a 1, that means the AV box itself has a short..  If it reads the normal resistance, close to mine, that means the AV box is fine, and there's a short on the NES motherboard...

Of course, it could show a good reading, but still have a problem in the AV box, but from my experience, highly unlikely...

Make sure you have the probes exactly how I have mine, meaning the red where my red was, and the black where my black was...  i haven't tested it the other way around, but if the AV box has a diode, you'll read a false positive...

[Ismail Saeed]

Well, I'm investigating if the person who possibly has a multimeter can possibly come help me out in the next couple of days sometime.

I was thinking about what I can do until then.  Although the short is possibly in the AV box, if you can find any other points to test along the motherboard that might be something I can do until this guy can come over (again assuming he has a multimeter).  I realize that puts some work on your shoulders... but I was just thinking out loud of something I can do over the next few days rather than sit on my own butt.  We can just wait on testing this too.

So did the pictures communicate anything?  Do you need pictures with the motherboard flipped around so you can see that side of it better?  I'm guessing nothing looks out of the ordinary to you.

Actually, since you have the pictures here, let me ask: Are those red spots normal?  In http://members.cox.net/slipgate/P9040012.JPG there's a red spot along the silver edge of the motherboard (lower right corner in our viewing), and another one on a brown doohicky (I don't know exactly what it is, sorry ) that's to our (viewing) right of the external port that's on the bottom... there's another also... it's on the far side so you may not see it well, but there's also a red spot on another brown doohicky near the AV box... the one to our right of it and a little down.  You can see it as a tiny speckle of red because of the extreme vertical angle.  They don't seem to be something to wipe off, and I'm not sure they're OF concern because I *think* (but I can't be sure) that I've seen them before anyway.  They aren't literally the thing fried or something are they?  I just remembered them again looking at my picture.

[blackevilweredragon]

the brown things are ceramic disc capacitors..

i think those just show test passed at the factory when it was built (from a red marker)...

the pictures, from what i saw, show it's ok...  the other person who requested the pics shoulld come around and check himself...  there's nothing i can think of to check right now...

i gotta head out, heading to seaworld, so i will be back later in the day...

[NeWmAn]

I've checked the photos and found nothing wrong in them, a further test with the RCA audio cable (poking in just before the AV box), would rule out the possibility of a damaged board. (Still the problem could be in the AV box)

BUT...
Looking at what happened with the ant, it seems that in case of irregular power supply the NES cuts out the audio but still works.
Since the audio was working right after the cleaning, I think that the problem would be either in the power supply or maybe in the cartridge connector.

If it reads a 1, that means the AV box itself has a short..

A "1" on the display would mean that the value measured is outside of the range, it could also mean the the circuit is open, but not that there's a short.

[Ismail Saeed]

So where should I poke the RCA tip at just before the AV box?  Which spot?  Is the mixing done before the AV box or in it?


Well, by the power supply do you mean the AC adaptor cable or, again, the AV box?  I do have a replacement cartridge connector I bought once upon a time and then first cleaned my cartridge connector personally... seeing how well it worked, I decided to save the replacement connector for when cleaning wouldn't solve the problem.  I'm not convinced that's the issue here just yet, but if it proves to be the issue I'll try replacing it at that time.

Either way, a "1" would be the undesirable result and tell me potentially where the problem is, right?

[Ismail Saeed]

Believe it or not, I was doing a little unrelated reading (I remembered that the triangle wave of the NES was used as "bass" and was trying to remember what the square waves generally got used as) and I found out which component is the last one before the sound goes into the AV box.  It's the resistor marked FC1 just near the AV box.  When next I open the system (which may be tomorrow evening just due to priorities with work... I'm also going to save controller correction for then) I'll test that tip with the RCA jack.  It'll probably be an easier reach since it's actually NEAR where the video plug is plugged in.

I must say I'm curious as to whether I'll hear the sound or not. :P  I'm wondering if the fix job will be easier if the break is before that or after that, since I don't know what kind of component replacement/rerouting options one would have in either case.

Ironically enough I got the information from an article I read about stereo separation on an NES YEARS ago - which died at the original link but was reprinted by the folks from gamesx.com here: http://www.gamesx.com/wiki/doku.php?id=av:...o_sound_for_nes

I'll report my results when I have them.

[NeWmAn]

I found out which component is the last one before the sound goes into the AV box.  It's the resistor marked FC1 just near the AV box. 

Well, FC1 insn't a resistor, but you are right. You can tap the signal there or on the AV box.

Well, by the power supply do you mean the AC adaptor cable or, again, the AV box?

:unsure: I don't know, it could be one or the other.
Do you have another AC adapter to try?

Either way, a "1" would be the undesirable result and tell me potentially where the problem is, right?

If it reads the normal resistance, close to mine, that means the AV box is fine

[Ismail Saeed]

Hey folks,

So I got a chance to do the narrowing down.

Tapping FC1 didn't produce results (other than a bit of a buzz on the wrong side of it or whatever), so the sound dies before then.  In trying some other resistors I found between the two sides, I happened to find that R7 and R8 are the two sound channels, still as intact as they were at their originating point.  R7 and R8 are visible on http://members.cox.net/slipgate/P9040011.JPG near the communication port on the bottom of the system.  It's "above" the communication port in this image, but if you were to orient it so that the text printed on the motherboard wasn't upside-down it would be below.  That's where I was able to tap and get sound still, from both channels.  So the point of break is somewhere between those two, either that or at FC1 itself granted but you know what I mean.  I'm not sure what else and where else I can successfully tap from here.

Should the AV box multimeter test still be done?  Is there perhaps another spot on the motherboard that should be tested instead now?  I'm just wondering if the multimeter is still relevant now that I've determined it isn't the AV box.  I imagine it could be used to determine the resistance somewhere else but where to check would be good.  (I have the potential opportunity to meet with the friend that has it tomorrow night, but if there's no definite idea of when to test then I'd just meet with him later rather than meeting with him needlessly)

Anyway, now that we have a general locality, what sort of procedure would hypothetically be involved in fixing it?  Is this likely a component replacement, or is it likely a "put a little solder down to have a communication pathway become open again," OR is it more likely that I'd try to attach something to R7/R8 to bypass the faulty part?

I'm going to go see what Heavy Barrel sounds like before I close the thing.

[blackevilweredragon]

I'm going into my NES right now..

A resistor shouldn't be labeled FC anything..  A resistor is going to begin with an R..  what you tapped is something else..  I will test it myself, and see what the FC is..

[Ismail Saeed]

Well it is the sound point, as confirmed here and by others, in that it normally has the final mixed audio before it goes into the AV box.

See if you find any multimeter test spots or sound signal spots after R7/R8.

[blackevilweredragon]

No, don't bother with the AV box test, the problem isnt there..  It may be the audio preamp...

This is the preamp chip..  TEST here..  One pin is the amped pin, and the other is the unamped pin...  If you get audio from the unamped pin, but nothing from the amped pin, the preamp is dead.  (the unamped side will be soft to hear, so you may need to raise the TV volume, I had too)..

http://blackevilweredragon.spymac.com/NESpreamp.jpg

(Hint:  The amped pin, goes to FC1..  I know FC1 is the audio spot, but it's not a resistor..)

FC1 is a Ferrad Capacitor, i think...

[Ismail Saeed]

Neither the unamped pin nor the preamped pin get me anything.