NES - no power light + audio pop

daihashidaihashi
in Help Wanted!
All,



I was working on the springs of my front loader yesterday, when one got away from me. It landed on the motherboard somewhere in the vicinity of the red box in the attached picture. The top was off the console, and it was plugged in but not powered on. When the spring landed on the mother board I heard a pop. I put everything back together, only to find that the power light did not come on and the tv screen stayed black. There is an audio pop that happens when I press the power button, so that's something.



I've measured the voltage regulator, and get about 11vdc input, and 4.98vdc output. I've also measured various points throughout the motherboard and I am able to consistently get 4.98vdc where I test.



I have another front loader from ebay on the way, but I'd really like to figure out what I fried. Does anyone have any insight into what I might have popped, or tips on what/how I should test next? Thanks!

Comments

  • MobiusstriptechMobiusstriptech
    That area, specifically those big pins there are your audio/video and power connections for the console. First things to look at are blown caps in the a/v and power box. You might have gotten lucky and just popped one. Also look at the caps on the main board. It's unlikely that you popped one of those but you could have.



    If it's not a blown cap, the search gets to be more fun. You will want to look for any sort of scorch/burn marks on any components inside that box or on the main board. If you still don't find any, it's literally time to start tracing. You probably have a short to ground or maybe an open just based on the no power led and audio pop sounds.
  • daihashidaihashi
    Originally posted by: Mobiusstriptech



    That area, specifically those big pins there are your audio/video and power connections for the console. First things to look at are blown caps in the a/v and power box. You might have gotten lucky and just popped one. Also look at the caps on the main board. It's unlikely that you popped one of those but you could have.



    If it's not a blown cap, the search gets to be more fun. You will want to look for any sort of scorch/burn marks on any components inside that box or on the main board. If you still don't find any, it's literally time to start tracing. You probably have a short to ground or maybe an open just based on the no power led and audio pop sounds.



    There were no scorch marks anywhere on the motherboard. I could not physically into the RF module to see the caps, but I measured all the points in the RF module and was getting either 4.98vdc or 11vdc... although I did come across 1-2 points that measured 0.5vdc. However to be fair I'm not sure all of those readings were normal as I have nothing to use for comparison. The points that had 0.5vdc were not the caps that people typically replace so I just wrote it off as "not the problem".



    Some questions:

    Any tips on how I can actually see into the top of the RF module so I can check things out in there?

    Forgive the following question if it seems dumb, but if I had an open/short to ground then would I still be seeing power on the motherboard?



    Thanks!

     
  • MobiusstriptechMobiusstriptech
    Depending on where the issue is, you might still see power at various points on the console. The only way to get into the rf unit aside from desoldering it completely is to remove the 2200uf cap and look inside. That doesn't give you a ton of open area but you can at least see the caps and replace them if necessary.
  • VGS_captmorgandrinkerVGS_captmorgandrinker
    When you mentioned hearing a pop the first thing I thought was blown cap as well.
  • daihashidaihashi
    Thanks guys... I'll desolder the big cap this weekend and have a look. In the mean time I managed to pick up 2 more working front loaders for $15.



    Appreciate the input. Thanks again.
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