[Marzie]

I built a CKKIII recently and have been having an intermittent yet recurring problem. I notice a loud crackling, grating sound in the right channel on occasion. My thought is that I may have damaged the voltage regulators; I installed v1 in v2 position and vice versa. I had a heck of a time getting them out to put them in the other position. I bend the leads of anything before I solder to hold it in place, which probably wasn't necessary in this case... anyway, I really had to wrench on these things to get them out and I am assuming I damaged one or both of them in the process. I am going to order 2 new ones, but before I solder these in, is there anything I can check? Anyone have any knowledge on why this may or may not be the cause? I'm willing to post pics, if necessary...

Mike

 

[Clutz]

I have a hard time believing it's the voltage regulators. My guess is that they either work or they don't, and that there will be precious little in between. Take pictures of the boards top and bottom and post'm.

 

[akione]

It sounds like it might be a dry joint or maybe something overheating.

Firstly, I would check all the joints and reflow them if necessary, and maybe if not.

And give the board a good clean, after.

Second, see if anything is getting hot. Are the output transistors biased correctly ?
Try some small heatsinks, if they are getting hot.

 

[sbyers77]

I had a problem similar to yours when I built my CK2III (intermittent crackling on one channel). The funny thing was that taping the PCB made it go away so I assumed it was a faulty solder joint. Re-flowing suspect joints on that channel (particularly transistor joints) solved the problem.

 

[Marzie]

I circled a few suspect areas...

 

[Marzie]

I reflowed the solder and added some to the ones that seemed to be lacking... I have listened for over an hour and haven't heard the issue again yet, although it didn't happen very often to begin with. Thanks everyone!

 

[amb]

Clean the flux residue...

 

[Marzie]

After that was first mentioned, I did what Tangent said NOT to do, which is clean with less than 99% isopropyl alcohol, which did as I had seen it done in other pictures; it left a white sticky, filmy mess on the bottom of the PCB... awesome. I need to find a source for the purer stuff...

 

[tomb]

Quote:

Originally Posted by Marzie /img/forum/go_quote.gif After that was first mentioned, I did what Tangent said NOT to do, which is clean with less than 99% isopropyl alcohol, which did as I had seen it done in other pictures; it left a white sticky, filmy mess on the bottom of the PCB... awesome. I need to find a source for the purer stuff...

91% alcohol will do fine and you can purchase it in Walmart right next to the 70% rubbing alcohol.

That white, sticky stuff is dissolved flux spread around by the alcohol and left behind when the alcohol evaporated. Rinse it some more - and use a paper towel to towel it off inbetween. If you don't do that, all you're doing is continuing to spread dissolved flux around on the board. Your paper towel should turn yellowish-brown if there's flux in the alcohol while you're wiping. After toweling off, wait until the alcohol is almost dry, then rinse it again, towel off while the alcohol is still wet and repeat.

You may need to do this 4 or 5 times - or more - depending on the size of the board and how much flux you used in soldering.

 

[Marzie]

That is the very stuff I have so I will clean again following those steps. Thank you all very much (and look forward to seeing me in the Millett thread soon, I am ordering the parts this week...)

 

[Fitz]

I hate to hijack like this (sorry Marzie), but since we're on this subject, any of you have any tips for cleaning flux off protoboard/perfboard? A lot of the dissolved flux flowed through the numerous open holes and pooled up around the component leads on the other side. Had to spend a while with a qtip and a lot of flushing to get it all cleaned out. I guess I could use a tiny dab of solder on all the remaining holes to close them off, but that's almost as much work as the extra cleaning.

 

[dBel84]

My approach is to soak the board in pure ethanol for a while and then go at it with a tooth brush frequently dipped back in the ethanol bath. More difficult if you don't have an easy source of the good stuff..dB

 

[tomb]

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif My approach is to soak the board in pure ethanol for a while and then go at it with a tooth brush frequently dipped back in the ethanol bath. More difficult if you don't have an easy source of the good stuff..dB

Agreed - the toothbrush is fundamental.

 

[Fitz]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Agreed - the toothbrush is fundamental.

Unfortunately it does very little to keep the alcohol (with dissolved flux in it) from flowing through all the holes and onto the component side of the board. Getting the flux loosened and dissolved isn't the problem at all, as I'm using pure alcohol and a stiff natural bristle brush. Maybe if I hung upside down while scrubbing the protoboard... so gravity wouldn't be working against me.

 

[pinkfloyd4ever]

Quote:

Originally Posted by Fitz /img/forum/go_quote.gif Maybe if I hung upside down while scrubbing the protoboard... so gravity wouldn't be working against me.

HA that'd be a sight to see

but I don't like cleaning flux either for the same reason..I'm always afraid some alcohol/flux will get inside my pots, trimpots, or electrolytics, so the bottom of my Millett board is still kind of ugly with flux...still seems to work great tho, and I don't mid since I don't really spend alot of time looking at the bottom of the board