US Look for NES Top Loader Repair

Hello!

I unfortunately did not have a successful time trying to apply the NES RGB mod to my Top Loader. After removing and socketing the PPU there is no longer any power being output through the regulator. I've tried a couple repairs myself, but it's time someone with more experience took a look at my poor non-functioning top loader.

For more information on the repairs I've tried, see this thread.
http://assemblergames.com/l/threads/nes-rgb-toploader-repair-help.58538/#post-838227

Thanks for looking!

 

Hey bobster! Before we get to far into it, have you verified your continuity on your A/C solders and sure that power is making it to the 7805? After this do you have a LED wired to the lower 5v plane right under the power switch? This really helps in diagnosing power issues.

 

Thanks for the response!

On the power jack itself, I'm getting 8 volts AC from it. If I'm correct about the 7805, looking at the bottom of the board the left pin is input power while the right pin is output with middle being ground correct? I'm getting ~15v AC (does it make sense to be that high?) on the input but nothing from the output on either AC or DC.

As for the A/C solders, I'm not sure where those are. I'm having a hard time finding information on the points on the board that pertain to the power. I'll gladly test them if you could show me where! I don't have any LEDs as this sort of thing is somewhat new to me. I might invest in some if you think it'll help. I'd need help finding those points as well.

As I said before, I'm a little over my head at this point in troubleshooting . Thanks so much for trying to help.

 

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Its all good man, there is a learning curve and I would rather help you learn then to just encourage you to let someone else do it when your obviously trying on your end. So lets see, lets be sure you are getting power and your major components are in working order before going anywhere else.

This board right here was attempted by someone else and sent to me to be fixed. There was a power issue right up front. This pin circled in red is your output voltage from the 7805. It feeds directly to a 5v plane. Everything from that plane should be receiving 5v. As long as you are making power through here we should be good to start looking into your other components.



Now use your leads to test between your a/c jack and your pin 22 on your PPU to be sure you are getting power. If you need to test from the bottom side of the board, you said its a RGB install correct? This board has one of Helders board mods on it. As long as you are receiving voltage here lets make sure your CPU is good. Turn the power on and the chip just above the PPU check it after a minute or two and see if its hot, if it is super hot to the touch it is probably bad. As long as you are getting power and these two are good we can go from there. If after a minute power is gone then your 25v 1500 uf capacitor at the top left corner there may be bad. I wire an LED to mine to be sure that power stays on while testing. If its bad it wont hold charge and the board will lose power or not turn on. If you have a meter to test a capacitor then you can avoid the LED if you wish. Let me know what results you get with making sure everything has power first.



To add... anyone on here with more experience please correct me if I am wrong. I am by no means a veteran and dont wish to be passing on bad information.

 

Got an opportunity to test this morning. Yes it is an NES RGB mod, but since the PPU is socketed you can just pop the whole thing off. Right now I'm working with the PPU socket with the original PPU plugged into it.

The 5v output at the 7805 I'm getting no power out of. For my testing I'm putting the negative lead on the middle pin with the positive on the output. I get no readings doing that. Doing that for the input I get approximately 15v. Could this indicate something further up the 5v plane is wrong?

Just for clarification, it's all DC up until the 7805 where it switches to AC correct? I know the rectifier portion does the change over, but I'm unclear exactly where that process is located in the chain. Just to make sure I'm measuring accurately.

Even though the 7805 isn't giving a reading, I went ahead and tested the other components for you. I managed to get a reading of 4.4v on the PPU using the method you describe. Does that mean it's actually getting power through the board? That would totally conflict with my thinking that no power was making it through the 7805. As for the CPU, it didn't appear to heat up at all for me. Good or bad sign? As for the capacitor, the power didn't drop after a couple minutes and I'm not entirely sure how to test the thing. I have a cheap multimeter I'm working with lol. It was replaced during my initial round of troubleshooting though.

For what it's worth, keep in mind this unit was tested working right before I went to mod it. It was after I pulled out the PPU and socketed that slot that this started happening. Perhaps that'll give you an idea on what potential issues might be.

 

Ok, now that we are sure its a problem with the install, any chance you could send up some pictures of the installation.

 

Here's some pictures. I had a bit of trouble getting the PPU out initially. Hopefully I didn't ruin any pads... I'm not sure if I mentioned it in the other thread but I managed to break one of the pins on the PPU as well. I soldered on a new lead in it's place.

http://imgur.com/a/TO8wC

That's a link to the album so you can see full size pictures.

 

I know this thread is super old, but I wanted to post that BlueShellDigital (here and on facebook https://www.facebook.com/blueshelldigital) helped me with repairs on my issue. Unfortunately I burnt off some traces and he didn't have the tools to repair traces. Despite that, when I got a replacement board he finished the mod for me and was super communicative through the entire process. He was very thorough and detail oriented. My RGB toploader came back in perfect shape.

Thanks everyone that tried to help me identify the issues!