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Issues with revived Yamaha SPX90
Old 4th June 2020
  #1
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Issues with revived Yamaha SPX90

Haven’t seen this problem in the countless SPX90 repair forums so I figured I’d make a new thread in hopes of solving my problem.

I recently revived an SPX90 from the dead by replacing the old caps in the power supply. The unit powers up once again, and works exactly as it should. The issue is the display is showing what appears to be Asian characters (or just random symbols). While trying to factory reset the unit I discovered the foot trigger and up key (between parameters and balance) don’t do anything but make the number display flash. All other keys function. The foot trigger LED is also on all the time.

I reflowed the solder joints, reseated the ribbon cables, checked for shorts and even sprayed it down with some deoxit just to be safe but there appears to be no obvious problem. Anyone ever encounter / solve this issue before? Do I just need a new button daughterboard?
Old 28th July 2020
  #2
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Wrong characters in the display and some functions don’t work as expected: sounds like the rom is corrupted. Have you tried to burn a new eprom?
Old 28th July 2020
  #3
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Quote:
Originally Posted by UpperLeft View Post
Wrong characters in the display and some functions don’t work as expected: sounds like the rom is corrupted. Have you tried to burn a new eprom?
Nah, how would one go about that?
Old 29th July 2020
  #4
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Rick Dalton's Avatar
Quote:
Originally Posted by mikewolfe View Post
Haven’t seen this problem in the countless SPX90 repair forums so I figured I’d make a new thread in hopes of solving my problem.

I recently revived an SPX90 from the dead by replacing the old caps in the power supply. The unit powers up once again, and works exactly as it should. The issue is the display is showing what appears to be Asian characters (or just random symbols). While trying to factory reset the unit I discovered the foot trigger and up key (between parameters and balance) don’t do anything but make the number display flash. All other keys function. The foot trigger LED is also on all the time.

I reflowed the solder joints, reseated the ribbon cables, checked for shorts and even sprayed it down with some deoxit just to be safe but there appears to be no obvious problem. Anyone ever encounter / solve this issue before? Do I just need a new button daughterboard?
battery?
Old 29th July 2020
  #5
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Quote:
Originally Posted by Rick Dalton View Post
battery?
Haven’t replaced but it’s reading the correct voltage. Also most people say to factory reset after which I can’t because the foot trigger button won’t respond.
Old 29th July 2020
  #6
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Rick Dalton's Avatar
Quote:
Originally Posted by mikewolfe View Post
Haven’t replaced but it’s reading the correct voltage. Also most people say to factory reset after which I can’t because the foot trigger button won’t respond.
is the foot trigger button hard to get at? I mean that complete membrane? All those probably need cleaned, just carbon contacts, I'm sure.
Old 29th July 2020
  #7
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Quote:
Originally Posted by Rick Dalton View Post
is the foot trigger button hard to get at? I mean that complete membrane? All those probably need cleaned, just carbon contacts, I'm sure.
It wasn’t hard to get at. I cleaned, reflowed and removed the outer button to try to press the actual tactile switch and nothing
Old 29th July 2020
  #8
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Rick Dalton's Avatar
Quote:
Originally Posted by mikewolfe View Post
It wasn’t hard to get at. I cleaned, reflowed and removed the outer button to try to press the actual tactile switch and nothing
This is quoted. have you tried using canned air. or alcohol and exercise them.

This unit passed all of the tests, except for the panel buttons which seem to double trigger occasionally.
http://madtheory.com/site/repairing-a-yamaha-spx90ii/
Old 29th July 2020
  #9
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Rick Dalton's Avatar
I've taken those little bastards apart before and the are just a carbon/rubber contact. Its not jammed is it? If you need to take it apart, just use an razor on each corner and pry, then clean it, and use a soldering iron and some small pieces of plastic to melt the four corner teddies back.
Old 29th July 2020
  #10
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Quote:
Originally Posted by Rick Dalton View Post
This is quoted. have you tried using canned air. or alcohol and exercise them.

This unit passed all of the tests, except for the panel buttons which seem to double trigger occasionally.
http://madtheory.com/site/repairing-a-yamaha-spx90ii/
No I haven’t tried that, I’ll pop open the switches again and try some of your suggestions. Think 70% isopropyl will be okay if I give it 24 hours to dry?
Old 29th July 2020
  #11
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Also they’re not jammed, they physically press and the up key even makes the number display flicker but don’t actually function as they should
Old 29th July 2020
  #12
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Rick Dalton's Avatar
Quote:
Originally Posted by mikewolfe View Post
No I haven’t tried that, I’ll pop open the switches again and try some of your suggestions. Think 70% isopropyl will be okay if I give it 24 hours to dry?
Yep. Also if that whole board will come off easy, just the switch assembly board, just take it out and soak it in some real warmish hot, not to soapy water, slosh it around some while in there, then when you take it out, sling it around (dont let it get away from you though) and that will get most all the water out, then use a blowdryer or place it on an AC vent switches facing down for awhile, to dry.
EDIT. Also exercise all the switches while soaking.
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