mtshark7 Posted August 17, 2012 Share Posted August 17, 2012 So my friend gave me a NES toploader to fix for him and it does power on but shows a black screen with no sound. He asked if I AV modded it for him would that fix the problem. I assumed it would but I figured I'd post on here to be sure. I didn't realize all that goes into modding this console for AV output. I want to be sure the console actually works before doing this. Is there any trouble shooting techniques to figure out if the console works or not? Thanks! Quote Link to comment Share on other sites More sharing options...
fiddlepaddle Posted August 17, 2012 Share Posted August 17, 2012 Be sure to clean the slot real good (wrap thin cardboard or stiff plastic or maybe sheetmetal approx. same width or slightly smaller than cart connector) with cloth and soak in 91% or 70% alcohol and insert/remove/insert/remove several times in slot. If you want to you can take cover off and use a toothbrush saturated in alcohol. Look for any broken traces on the PC board. Might help. Quote Link to comment Share on other sites More sharing options...
mtshark7 Posted August 17, 2012 Author Share Posted August 17, 2012 Hmm well I heard something from an article I read while googling about the channel select switch could be corroded or the RF box could be corroded as well. They also mention about a big capacitor that usually dies? I just got the system last night and haven't gotten around to checking it out, I plan on doing that today after work. Quote Link to comment Share on other sites More sharing options...
mtshark7 Posted August 17, 2012 Author Share Posted August 17, 2012 Also with the AV mod is there any good resources on how to do this mod? Mostly with making the video circuit and places to buy all the components needed to do this? Thanks! Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted August 17, 2012 Share Posted August 17, 2012 I've done hundreds of them and black screen is bad, it usually means the cpu or ppu is bad. The 3-4 select switch is usually only the problem if the screen is nothing but static, not straight black. There is a picture of what the tv will look like if the cap is bad on my webpage for top loader mods. Here is the I made of how I do the mod. Quote Link to comment Share on other sites More sharing options...
Galeforcerm Posted August 17, 2012 Share Posted August 17, 2012 Does it use the same ppu and cpu as the toaster? I imagine it would not be an easy swap to do though. Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted August 17, 2012 Share Posted August 17, 2012 Yup, same cpu and ppu, most of the rest of the chips are the same too. Quote Link to comment Share on other sites More sharing options...
mtshark7 Posted August 18, 2012 Author Share Posted August 18, 2012 Ok so I opened up the console and it looks like one of the capacitors blew out....see pic. Also I noticed that the reset switch doesn't work either. Would I just need to replace the capacitor that blew in the pic? Also what capacitor would I need to replace it with? Thanks! Quote Link to comment Share on other sites More sharing options...
mtshark7 Posted August 18, 2012 Author Share Posted August 18, 2012 Also the capacitor is the green one in the pic Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted August 18, 2012 Share Posted August 18, 2012 That is the trim cap for the clock circuit, i've only had one with problems, but I still had video just garbled or staticy, can't remember. If I remember all I did was reflow it's connectors and it was fine, you can turn it as much as you want and it won't really do much one way or the other on a working system, so feel free to mess with it. A bad clock circuit will give black screen though, i'm currently working on one with no clock signal and black screen boot. It did have a bad cpu and 7805 though, and so far a fix for the clock circuit eludes me, all the 'main' components work on my test unit. The reset cap - c11 - can be bad, its a .47uF electro, but it usually gives grey screen or won't reset the console when bad, not black screen. Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted August 18, 2012 Share Posted August 18, 2012 Also, what you're seeing on the green cap is just corrosion, most likely something got spilled into the power or reset button area and that's what corroded the trim caps leg, its not an electro cap so its not 'blown' and may not even be bad. Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted August 19, 2012 Share Posted August 19, 2012 Is the fuse still good? The top loader should have a fuse located in the back, just check it for continuity and replace it if necessary. Quote Link to comment Share on other sites More sharing options...
Asaki Posted August 19, 2012 Share Posted August 19, 2012 (edited) Also with the AV mod is there any good resources on how to do this mod? http://forums.nesdev...4285b32f69a4ddb I don't remember which pages had the real meat-n-potatoes, but eventually I chime in with a bunch of noob questions =) The top loader did not originally have a power LED and some owners have complained it’s easy to accidentally leave the console on and not realize it. ...what? Do they just turn off their TV and walk away? The PowerPak is awesome, but it doesn't always work with the top loader because of one chip, the 74LS373.If you replace it with a 74HC373 then it will work fine. I was thinking about getting a PowerPak sometime...is that chip on the cart, or on the NES? Edited August 19, 2012 by Asaki Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted August 19, 2012 Share Posted August 19, 2012 I was thinking about getting a PowerPak sometime...is that chip on the cart, or on the NES? On the NES itself. Quote Link to comment Share on other sites More sharing options...
mtshark7 Posted August 20, 2012 Author Share Posted August 20, 2012 what does the fuse look like and what type of fuse would I need to replace it with? Quote Link to comment Share on other sites More sharing options...
mtshark7 Posted August 20, 2012 Author Share Posted August 20, 2012 also if the green cap is bad what would I replace it with? Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted August 20, 2012 Share Posted August 20, 2012 what does the fuse look like and what type of fuse would I need to replace it with? There are NO fuses in the NES-001 or the NES-101, its not necessary since it can accept AC or DC input. Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted August 20, 2012 Share Posted August 20, 2012 also if the green cap is bad what would I replace it with? With the another 30pF trim cap, do you have an LCR meter to test it? Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted August 20, 2012 Share Posted August 20, 2012 The top loader did not originally have a power LED and some owners have complained it’s easy to accidentally leave the console on and not realize it. ...what? Do they just turn off their TV and walk away? It happens, yes, not every time of course, but rarely does a customer not request it when they get the AV and other mods done. Quote Link to comment Share on other sites More sharing options...
mtshark7 Posted August 20, 2012 Author Share Posted August 20, 2012 Yea I have a multimeter just haven't gotten around to testing it out yet...due to doing housework over the weekend...will test it out today after work. Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted August 20, 2012 Share Posted August 20, 2012 An LCR meter is not the same as a multimeter, most multimeters don't test capacitance and when they do they do it poorly or can't go down to 30pF, check the specs. Quote Link to comment Share on other sites More sharing options...
mtshark7 Posted August 22, 2012 Author Share Posted August 22, 2012 akaviolence: Oh ok....no I don't have one of those, just a multimeter and it has the option to test those components...I think with capacitors its off tho like you said. You're right there is no fuse in the top loader. I checked the CPU and PPU chips and the voltage is going through them and they don't seem like they are broken. I plan on soldering a wire to where the sound comes from and wiring that up to a AV Jack and plugging it into the tv to see if I get sound out of it today. If I do get sound and I end up doing the AV mod to it, would I finally get a picture? Quote Link to comment Share on other sites More sharing options...
R.Cade Posted August 22, 2012 Share Posted August 22, 2012 If it's broken, an AV mod is not going to "fix" it. You are wasting your time and effort. Quote Link to comment Share on other sites More sharing options...
mtshark7 Posted August 22, 2012 Author Share Posted August 22, 2012 I also checked the resistor values and they all seemed to be fine, the only thing that I can check with greater accuracy on my multimeter. Is there any way to test the reset switch with no picture or sound...say check a voltage across a certain point and hit reset and watch the values change? Is there also a way to figure out that the video output would work doing an AV mod before doing it? I'd hate to do all that work and get the same result of a blank screen. Ugh this system is driving me crazy! LOL Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted August 22, 2012 Share Posted August 22, 2012 You're right there is no fuse in the top loader. I checked the CPU and PPU chips and the voltage is going through them and they don't seem like they are broken. Just because there is voltage going to them does not mean they haven't failed, if they get really hot soon after turning on that's a bad sign, but not conclusive either. I plan on soldering a wire to where the sound comes from and wiring that up to a AV Jack and plugging it into the tv to see if I get sound out of it today. No need to solder to it, I show how I use alligator clips and such to test for video out of the ppu pin 21, same can be done for audio. Watch , there are a couple other 'repair' vids on my channel too if you're interested. If I do get sound and I end up doing the AV mod to it, would I finally get a picture? Probably not, the CPU does the sound and the PPU does the video so its possible to have sound with a bad PPU Is there any way to test the reset switch with no picture or sound...say check a voltage across a certain point and hit reset and watch the values change? Yes, the switch itself grounds the signal, just check for continuity to ground while pushing the button, the signal also runs down to the .47uF cap at the front edge of the board. You should not have continuity if the switch is not pushed down, but if you do not get continuity that isn't the problem, you just won't be able to reset the console by pushing the button. I think I already explained the cap issue above? Is there also a way to figure out that the video output would work doing an AV mod before doing it? Yes see above about the audio test, but if the video transitor has failed it may also pull down the source on pin 21 so that it won't register, you can also try to pull video from bottom leg of r3? I say something about that in the vid too, its a bit more amped from there and you get a bit brighter pic. Ugh this system is driving me crazy! LOL If you want just send it to me and i'll fix it up, I charge $15 each to replace cpu or ppu and $10 for srams or 373 or other smaller chips and only charge for ones that needed changed. I usually pull suspect chips and test them on another board where all the other chips are known good. I can also cheat and use a thermal camera to see hot chips soon after its powered on. The AV and other mod prices are on my website. Quote Link to comment Share on other sites More sharing options...
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