Howdy folks,
I am trying to figure out the source of this intermittent static noise coming from my Music Man 212 HD 130 amplifier.
Follow the Soundcloud link here: https://soundcloud.com/user-664724274/music-man-hd-130-intermittent-static
What I have done so far:
1. A local tech installed new power tubes and biased them. However, I noticed the amp was still pretty noisy even after being serviced, including this intermittent static sound. So...
2. I replaced the power capacitors and the filter capacitors. (I wanted a challenge and read up on this forum and elsewhere how best to get this done.) The amp sounded a whole lot better after this was done. However, this intermittent static was still present. So...
3. I cleaned all the tube sockets and pots with deoxit.
Still, the problem persists.
I am considering the following problems:
- Bad solder joint somewhere
- Bad resistor somewhere
- Bad potentiometer somewhere
- Transformer going bad
Follow this link to see some photos of the inside of the chassis: https://imgur.com/a/WwdTqae
(Note: The pictures were taken before I replaced the power and filter capacitors)
I am grateful for any suggestions you might have!
-GLS
Intermittent Staic on 212 HD 130
Yeah... that static and underlying hiss sounds familiar. I would love to know the solution as well.
Glad I'm not the only one.
Glad I'm not the only one.
I'll be opening up the amp again here soon and try measuring some of the components to see if anything is bad... As far as I can see, the solder points all look okay, but I'm no professional in that regard. I'll keep tinkering and update with any progress I make.
If any others have suggestions, please chime in!
You're on the right track
From my electronics experience, it sounds like either a dirty input jack, a cracked resistor or a "cold" solder joint. If you have Deoxit and QTips, try cleaning all of the jacks. Next try doing the "tap" test on all resistors. Use a pencil and listen for a change in the static as you lightly tap tap tap each resistor. Be careful and don't accidentally shock yourself with hi voltage. Lastly, check for cold solder joints. You'll need to flip the main board over to inspect (with power off for safety). Good Luck. -mgriffin
Thanks for these suggestions!
Thanks for these suggestions! I've got deoxit and I've got q-tips. I'll get to work on that, tap testing the resistors, and checking underneath the main board for cold solder connections. I'll report back.
Thanks again!
I think I figured it out.
I think I figured it out.
Cleaned out the jacks with deoxit, but the sound remained. I tap tested the resistors, but it had no effect on the static sound as far as I could tell.
I unscrewed the main board and re-flowed the solder connections in a couple of spots that looked off. Some of the connections around the bias trim pot looked suspect. I then re-flowed the solder connections on the tube sockets. I looked at the rectifier board and noticed that where the red wire from the power transformer connects to the driver board looked like it needed some help. I re-soldered that connection. I'm including picture in this post to show the connection I'm referring to. It's the red wire on the far right.
After re-flowing the connections on the tube sockets, I biased the tubes.
I played for about an hour or so last night without any noticeable return of the dreaded intermittent static. I'll play some more later today and provide an update.
Question: I am sure there is a better way to determine if a solder connection has gone cold. How can I use my multimeter to see if a connection has gone cold?
Thanks again for any suggestions. I hope this thread can help others who encounter a similar issue in their amps.
The Eyes Have It.
Nothing beats a thorough visual inspection to find cold solder joints. If you're not the original owner, who knows who's been in there poking around with a soldering iron. Good soldering technique is a valuable skill and all techs are not created equal. Just keep an open mind when TShooting circuits. Good work! -mgriffin
Still sounding good!
It's been a couple of days and I've played the amp for about four or five hours without any issue. Thanks for your help, mgriffin! I needed to be steered in the right direction and you helped get me there.
Now my next project is to figure out why the tremolo wants to work only half the time...