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Kickin' Wing
01-20-2009, 06:37 PM
Just picked up a Gunbird 2 pcb and am getting a lot of feedback out of my speakers. It very noticeably comes on when I start the cab and stays on after that.

I've tried it in 2 cabs and have the same problem on both. :edit: Turning the sound all the way down the PCB gets rid of it, but turning it up slightly the feedback resumes.

Not sure if this is at all helpful, but here's a crappy recording I made with my digicam, the *clunk* sound is me turning on the cab:

http://s130.photobucket.com/albums/p258/kickin1wing/?action=view&current=MVI_0001.flv

Any help would be appreciated.

-wiNg+thanks

Marshall
01-21-2009, 01:54 AM
Well, it's very hard to identify why this feedback is on, just from your recording.
Could be just oxidation of volume or some dusts causing electrical resistance on PCB, slow puncuture of ceramic capacitor on sound circuit or some part of legs of capacitor there being bent and disattached, having faliure contacting the circuit, bad electrical resistor or bad amplifier, bad sound chip. You'll never know only from that recording.

Upload some pics in closeups of sound circuit from upside and backside(of PCB) for more info. Someone might notice something.

Try to clean whole PCB once again by air carefully and remove all dust as you can, and see how it goes.

Kickin' Wing
01-21-2009, 04:31 AM
Well, it's very hard to identify why this feedback is on, just from your recording.
Could be just oxidation of volume or some dusts causing electrical resistance on PCB, slow puncuture of ceramic capacitor on sound circuit or some part of legs of capacitor there being bent and disattached, having faliure contacting the circuit, bad electrical resistor or bad amplifier, bad sound chip. You'll never know only from that recording.

Upload some pics in closeups of sound circuit from upside and backside(of PCB) for more info. Someone might notice something.

Try to clean whole PCB once again by air carefully and remove all dust as you can, and see how it goes.
Took some pics of the PCB, noticed some "goo" around a few parts near the edge so I circled those with my mad photoshop skillz. Not sure if they're causing any trouble but some of it is going over traces.

http://i130.photobucket.com/albums/p258/kickin1wing/Tech/GB2-SoundP.jpg
http://i130.photobucket.com/albums/p258/kickin1wing/Tech/GB2-SoundS.jpg
http://i130.photobucket.com/albums/p258/kickin1wing/Tech/GB2-EdgeP.jpg
http://i130.photobucket.com/albums/p258/kickin1wing/Tech/GB2-EdgeS.jpg

I'll take some air to it tomorrow and try playing around again.

-|wiNg

channelmaniac
01-21-2009, 10:56 AM
That's rosin flux, left over from soldering.

If you tap the sound chip (Yamaha) or the big chip that feeds it do you get changes in the noise? Maybe one of the chips needs reflowing.

This is where it would help to have a couple of pieces of test gear, notably an audio probe and an oscilloscope.

RJ

Kickin' Wing
01-21-2009, 06:55 PM
That's rosin flux, left over from soldering.

If you tap the sound chip (Yamaha) or the big chip that feeds it do you get changes in the noise? Maybe one of the chips needs reflowing.

This is where it would help to have a couple of pieces of test gear, notably an audio probe and an oscilloscope.

RJ
Mr. CM,

Threw it in again and tapped the chips, didn't seem to have any affect. Not quite sure what the problem is, may have to end up sending it out.

Thanks for the help,
-|wiNg

Hewitson
01-21-2009, 08:27 PM
An audio probe really is essential for problems like these. I suggest making one.

Marshall
01-22-2009, 12:43 PM
Some pics are over exposured by flashlight so, hard to see all,but can't find any bad point from what I can see. I could notice some repaired point as you circled, but they don't seem to bother. Are all ceramic capacitors soldered well? Does the feedback differs when you carfully turns volume? Many PCB's gets more feedback simply after aging deterioration so, no way to determine, if you can't see any bad point from outside. You should just have them fixed, or get another board, if it doesn't bother you.

skate323k137
12-15-2015, 11:12 PM
NECRO BUMMMMMMP

I'm having this exact same problem with a gunbird 2 PCB I just picked up. The interference is not from the volume pot as far as I can tell because it gets louder / quieter based on how the pot is set. It also seems to go away when the screen is black and comes back when the PCB is outputting video.

Tested the board in 2 different cabs with 2 different audio amp setups, exact same issue. Both of those cabs have crystal clear audio from other boards (and video is OK from the gunbird 2 pcb on both)

I'll try some basic stuff like cleaning the edge connector (which deoixt product do I want again?)... if that doesn't work it's down to washing the board and/or starting to recap.

If anyone else has had or fixed this issue on a psikyo pcb, post up.

_rm_
12-16-2015, 03:41 AM
If i remember correctly, my Gunbird 2 also has a bit of "hum" noise when i play, nothing too agressive but it's definitely there.

Let me know if you find anything.

xsq
12-16-2015, 08:05 AM
I'll try some basic stuff like cleaning the edge connector (which deoixt product do I want again?)
D5 for the edge connector and if you're going to clean the pot you could use F5 faderlube.

kuze
12-03-2019, 12:43 PM
NECRO BUMMMMMMP

I'm having this exact same problem with a gunbird 2 PCB I just picked up. The interference is not from the volume pot as far as I can tell because it gets louder / quieter based on how the pot is set. It also seems to go away when the screen is black and comes back when the PCB is outputting video.

Tested the board in 2 different cabs with 2 different audio amp setups, exact same issue. Both of those cabs have crystal clear audio from other boards (and video is OK from the gunbird 2 pcb on both)

I'll try some basic stuff like cleaning the edge connector (which deoixt product do I want again?)... if that doesn't work it's down to washing the board and/or starting to recap.

If anyone else has had or fixed this issue on a psikyo pcb, post up.

I'm having similar issues with my Gunbird 2 and recently re-capped it, but it hasn't resolved the issue.

I noticed that capacitor "C1" is missing on my board and looks to have been possibly snapped off at some point. Is yours missing too by chance?

It seems to be video related interference that is getting picked up by the amplifier, or maybe bad filtering on the sound ROM (could be due to C1 missing).

If anyone has a Gunbird 2 board with "C1" populated, can you provide the values or a pic of it please?

Edit: Rewrite provided me the value of C1 (it's a 25v 100uF), but even with that added in there's no difference.

egg_sanwich
12-03-2019, 11:33 PM
Iíll chime in to say my Gunbird 2 has the exact same issue.

In my experience, my Psikyo pcbs have been some of the most troublesome, constantly developing issues. Anyone else feel the same?

kuze
12-04-2019, 10:16 PM
I’ll chime in to say my Gunbird 2 has the exact same issue.



I wonder if they are actually all like this? Does anyone have one that doesn't exhibit this issue?

Neodogg
12-05-2019, 05:45 PM
Can take a look at my board later...

I don’t remember any audio issue but am running it through a super gun...

Neodogg
12-05-2019, 08:56 PM
here is a pic of my C1 cap...it's a little different than what kuze was told...looks like a 16v, not sure what kind of difference that would make.

https://i.imgur.com/YhEYEbU.jpg

I don't really notice any feedback, there is a "static" sound but seems like normal. Let me know if y'all need different pics of something...

kuze
12-06-2019, 12:49 AM
Thanks Neodogg, to my understanding it is ok to replace a capacitor with a higher voltage rating, as long as the capacitance is the same. It probably doesn't get more than 5v through it anyways.

The 'static' sound is probably the same thing. If you crank up the volume pot past like 15 to 25% it gets really noticeable unless you're playing on a supergun setup.