Arcade Collecting > Restorations & repair

Macross PCB No Audio & CMOS Error ***Error Solved***

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Falken Hawke:
If anyone has an oscilloscope and working board, I was wondering if I could get a few waveforms verified?

If I could get the waveform from pin 38 on U33 (YM2203C), that would be appreciated :)

Also, U59 (74LS74), pins 3 & 11.

200mV @ 500uS x10


Falken Hawke:
So then...

I cleared my bench of arcade projects as my motorcycles each had something that needed to be done and since I daily ride, not having a motorcycle is a bigger issue than not having a fully working Macross.

Fast forward to setting up my bench to work on Macross again.  I'm getting out my notes and getting ready to make myself cross-eyed following traces when I power up the board.  I watch the screen for the intro and I get pummeled by the intro music!

I'll be honest, these are the kind of "fixes" I despise.  Basically I didn't isolate the issue with the sound before it decided to work again.  To be safe, I now need to go over everything again to isolate a good circuit compared with a malfunctioning one and hope I can pin down a failure point.


As I write this listening to MIDI "Do You Remember Love?" playing from my board, I will say at least I can enjoy the game a bit more now 😁

So, back to square one!

a pin was lifted off a pad somewhere and possible board flexion when it was put away and taken out caused it to make contact?

No don't go being defeatist about it!
You are at least at square one and a half.

Falken Hawke:
Stuck the Logic Analyzer on a few chips, two 6116's and a LS32.  One 6116 doesn't have activity on two I/O pins but the LS32 had a couple of outputs that didn't match their inputs.

Pulled the LS32 and plugged it into the tester, bad IC, gate 3 & gate 4 errors.

Since this is the first confirmed bad component, I'll start there and hopefully the graphics will be good and not something else down the line has failed as well.

Oh yeah, why did I choose those chips to test?  They were in the immediate vicinity of the A01 ROM chip, which I isolated earlier as the foreground graphics ROM.

Now if only I had a stash of LS32's...  The anticipation waiting for stuff is bad enough.  Waiting for parts is just cruel...


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