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Green Bean problems, fried resistor

Started by Tuxedo3, July 05, 2016, 12:50:48 AM

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midwayfair

Quote from: wgc on July 06, 2016, 01:41:35 AM
Double check the orientation of your ic.

Dual op amps and components in line can get pretty hot if the ic is in backwards.

You can't always go by the circle if it has a flat bottom, sometimes (not often) it's just an ejection point when they mold it. (If the bottom is scooped, like a semi sphere, it is an indicator.) Check the sides to see if one is beveled along the top edge. When in doubt check the manufacturer's data sheet. Jon gave pretty good advice.

Probably worth swapping the ic either way. Also check for shorts under the socket and bottom of pcb.

Good luck!

His problem exists without the active components in the circuit. It's not the IC.

Tuxedo3

I unsoldered a few components to get a better view. All pots/the IC socket are all off. Something I noticed in that first picture is the square pad for the IC is coming off a little, kinda worries me.




wgc

Quote from: midwayfair on July 06, 2016, 03:06:07 PM
Quote from: wgc on July 06, 2016, 01:41:35 AM
Double check the orientation of your ic.

Dual op amps and components in line can get pretty hot if the ic is in backwards.

You can't always go by the circle if it has a flat bottom, sometimes (not often) it's just an ejection point when they mold it. (If the bottom is scooped, like a semi sphere, it is an indicator.) Check the sides to see if one is beveled along the top edge. When in doubt check the manufacturer's data sheet. Jon gave pretty good advice.

Probably worth swapping the ic either way. Also check for shorts under the socket and bottom of pcb.

Good luck!

His problem exists without the active components in the circuit. It's not the IC.

I mostly agree with you, but we haven't seen voltages from the IC, only the resistor.  The IC is a fast, easy change, and easy to verify.  Depending on where the short is, it may be damaged also.

All that said, looking at the pcb bottom, a solder short is the most likely problem.  The joints are mostly clean but lots of splatter. 

Easier to see shorts if you clean the flux off too.

always the beautiful answer who asks a more beautiful question.
e.e. cummings

Tuxedo3

Quote from: wgc on July 06, 2016, 07:31:00 PM
All that said, looking at the pcb bottom, a solder short is the most likely problem.  The joints are mostly clean but lots of splatter. 

Easier to see shorts if you clean the flux off too.

This was good advice, took a while to clean off the flux, but I did and now it's much cleaner. I still don't see any shorts though, everything looks fine. Even reflowed the joints.

wgc

glad it helped

no getting around a continuity check.  it takes some time and effort but great learning experience.  Checking data sheets is good practice too.

Also, for future reference, there's steps you can take to help people help you better:

http://www.madbeanpedals.com/forum/index.php?topic=902.0
always the beautiful answer who asks a more beautiful question.
e.e. cummings

Tuxedo3

Just an update on this for all those who contributed, I had a pad come completely off and just decided buy a new Green Bean PCB. I'm letting this be a lesson to myself, though. I really appreciate all the help with troubleshooting, you guys rule.