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Old 2nd May 2013, 05:24 PM   #3251
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The front panel has a brushed look that matches the volume knob. Hand sanded using 120grit sanding sponge. The fonts are silkscreened.
For the back panel fonts I use those scratch-transfer films...surprisingly they hold up well to light finger rubs (but not fingernail scratches, of course).
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Old 3rd May 2013, 04:19 AM   #3252
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Good photos
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availlyrics
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Old 4th May 2013, 09:28 PM   #3253
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I just sucessfully built an O2. Now my son just finished his build. He got U5 in backwards but he managed to desolder it and got it in right.

But now the gain switch is working backwards. When itīs pushed in the gain is lower...
And at full volume it is as loud as my O2 with the volume knob at 9 oīclock. And there is also a loud "pop" when turning on. Any suggestions???

//M
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Old 4th May 2013, 10:00 PM   #3254
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It has the same symptoms whether AC or battery powered?
From what you've written, I'd verify the U5 operation. Then I would inspect the gain-setting circuitry around U1 and S2 (although I could probably live with the backwards switch operation, if I found it was just that the R17/R19 resistors had swapped places). Is it possible the U5 problem cooked an op amp?
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Old 4th May 2013, 11:07 PM   #3255
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Sofaspud!
Itīs the same on AC and battery. Donīt know if the U5 problem has caused anything but the opamps were uninstalled at the time for de/re-solder of U5. Will compare the resistors to my O2. How about the smaller sized caps likeC21,C16 vs.C6,C7?

Cheers!
/M
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Old 4th May 2013, 11:28 PM   #3256
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I wouldn't suspect any of those little caps at this point. If the O2 was turned on while U5 was backwards, it may have applied incorrect voltages to the op amp supply pins. I would perform the voltage tests outlined in RocketScientist's build notes to find any catastrophic failures.
Then, if you don't have extra ICs to swap in, you could try the op amps one at a time in your working O2.
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Old 4th May 2013, 11:53 PM   #3257
ericj is offline ericj  United States
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For the record, plugging the o2 into DC did damage at least one battery. I went ahead and replaced both and have good battery life again.


Sent by pneumatic tubes
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Old 5th May 2013, 08:28 AM   #3258
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Sofaspud!
The O2 was never turned on, or powered in any way before correcting U5 and no opamps installed at this stage. What happens if you fry U5 while desoldering it?

//M
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Old 5th May 2013, 11:29 AM   #3259
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Frying U5 that way doesn't seem very likely. The problem presents itself with AC or battery, so the power supply isn't suspect. It is possible that you received a bad chip. A magnifying glass visual inspection of the board should rule out most construction errors. Heavy-handed soldering might damage small caps; finding the bad one could be tedious.
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Old 5th May 2013, 10:04 PM   #3260
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Thanks Sofaspud.

Looking a bit closer and measure it properly, I realized he had got most of the resistors in wrong. After teadious hours of desoldering (of cource I had to do it...) We got it working alright. Amazing how much abuse the board and components can take.

/M
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