Another NGD - Yamaha AEX 1500 with Non-Working Electronics

Discussion in 'Bad Dog Cafe' started by mfowler314, Aug 13, 2019.

  1. mfowler314

    mfowler314 Tele-Meister

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    Shortly after my recent 1977 Ibanez SG copy NGD I stumbled on this listed on my local GC's used page. Was originally listed at $1100 (on the lower side of the usual $1500 I've seen on Reverb) but then marked down to $899 because the electronics did not work. I pointed out that I was taking on a lot of risk in buying this and that they are stuck with a "turkey" waiting for just the right buyer... I was that buyer and would take it for $700. Deal!

    Got it home... battery contacts looked corroded so I cleaned them but still no go. But it looked like I was getting voltage on the power cable *inside* the guitar (after taking off the access cover on the back) so I figured it must be a problem in the pre-amp. So I pulled preamp box out and then removed the circuit board from that. Got the schematic online and tested it on my bench with power supplied directly to the board. All seemed fine. Hmmmmm...

    So I went back to looking at the battery compartment and discovered that the spring contact inside it was bent and was not making good contact with the battery. Gravity made it contact when I initially turned the guitar over to check if I was getting power inside the guitar - which was the red herring that made me pull out the electronics! So I bent the spring contact back into shape and tested that I now reliably got power to the inside of the guitar. Then I put the whole thing back together - cursing all the way!

    Voila! Good as new for less than half the price of what they typically go for.

    Also used hot glue gun to fix a tattered portion of the case lining! Yamaha AEX 1500.jpg Preamp Control Panel.jpg Preamp Box.jpg Preamp Circuit Board.jpg Case Needing Repair.jpg Case After Hot Glue Repair.jpg
     
  2. Toast

    Toast Tele-Meister

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    That's a beauty. Love the color. Sounded to me like you put in about $200 worth of labor into it. Maybe not a labor of love either :) Congrats, cool guitar.
     
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  3. mfowler314

    mfowler314 Tele-Meister

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    Well... if I charged what I do for my EE consulting work it would be MUCH more than $200. But I actually enjoy doing this... the cursing was at myself for being tricked into needlessly taking out the electronics and then having to put them back in. That was a rookie error and I should know better than that! Other than that it was time spent doing things I liked to do - fuss with electronics and solve puzzles!
     
  4. richiek65

    richiek65 Tele-Afflicted

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    I have an AEX520, glorious guitar, those mini humbuckers absolutely sing, hey?
     
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  5. Toast

    Toast Tele-Meister

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    I was watching a couple of vids on diodes and capacitors and electronics 101 the other day. That's a rabbit hole I want to fall into, but I don't know if I have the memory space :). I'm at capacity just getting my guitar chops together. Still, I might investigate some basic electronics some more because it's fascinating.
     
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  6. esseff

    esseff Tele-Holic

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    Good score there, mfowler!
    I've bought a few guitars on eBay listed with non-working electrics and they've always been a simple fix. Of two from Gear4Music - a large UK instrument retail store - one was a simply a broken wire on the jack socket and the other just a broken selector switch. Both were brand new and heavily discounted. I once picked up a multi-effects pedal from a music store that was listed as spares or repairs only and all it needed was a loose mains plug connection tightening. Another was an old Yamaha G100 212 that wouldn't fire up. Cleaning the corrosion from the fuse contacts was all it took. A free quality amp for a couple of minutes work. :D
    The most difficult repair was a guitar with a push-pull coil tap pot on the tone switch. The guy had de-soldered most of the connections without identifying them, hence the give-away price. I fixed it eventually but to this day the tone control works in a reverse sense. I'll save that little job for when I need to sell the guitar.
     
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