Members tcooper Posted March 29, 2015 Members Share Posted March 29, 2015 My Something very curious has happened. I have a 12 year old Vibro-King amp. I recently purchased a TopTone DG-2. After about a week of playing, the amp started crackling and popping when I engaged the pedal even if the volume on my guitar was to zero. Turned off the pedal and the crackling went away. With the pedal on the crackling also went away when I turned the master volume to zero on the amp. Just to check I hooked up my delay, chorus pedals individualy and no popping/crackling. I turned everything off and came back the next day. Same results. Then I decided to hook back up my TS9 Tube Screamer. No popping/crackling. Mmmm. So then I hooked back up my DG-2 and no popping/crackling! I played only five minutes so I do not if it will hold. Any ideas of what is going on. Is this a sign that the tubes are going bad? Capacitors? Link to comment Share on other sites More sharing options...
Members onelife Posted March 29, 2015 Members Share Posted March 29, 2015 The crackling and popping sounds are usually indicative of a bad preamp tube. I used to hit the top of my Twin Reverb with my fist when it made those sounds in the middle of a set as a result of a failing tube. In this case, however, the problem does not seem to be in the amplifier. Turning the master volume on the amp down to zero will prevent any noise being generated by the pedal or the early sages of the amplifier from getting through to the speaker. The first troubleshooting step would be to try the DG-2 with another amplifier in an effort to isolate the source of the noise. Link to comment Share on other sites More sharing options...
Members tcooper Posted March 29, 2015 Author Members Share Posted March 29, 2015 onelife. A bad preamp tube is my number one suspect given the age of the amp. I do not think it is a question of the output tubes. But the capacitors and resistors concern me. Question...can I buy one one preamp tube and then replace the existing preamp tubes one by one and resolve the bad tube or do I have to replace all preamp tubes? Let's assume there is one bad preamp tube. And do all preamp tubes have to be the same make and model? Or can I use another brand? Link to comment Share on other sites More sharing options...
Members steve f Posted March 29, 2015 Members Share Posted March 29, 2015 You can use different brands of preamp tubes with no problem. Replacing the tubes one by one is a good idea. Link to comment Share on other sites More sharing options...
Members tcooper Posted March 29, 2015 Author Members Share Posted March 29, 2015 Thanks Steve. I currently have 12AX7s for my preamp tubes. I will buy a replacement and replace each one and see if it clears up. If not I will buy a second one and replace. Are 12AX 7s a good replacement for a Vibro-King?onelife had a good suggestion I thought of. And that is to try to pedal with another tube amp. But i only have the Vibro-King at the moment. I will try with a friend in a few days and see what happens. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted March 30, 2015 Members Share Posted March 30, 2015 I suggest you clean your tube sockets with zero residue contact cleaner first. An am that's 12 years older is going to get dirty/oxidized sockets. Tube amps use convection to cool them. Cool air rises from the bottom and gets drawn up into the circuitry and it needs to be cleaned every couple of years. (Even your computer vents get caked with dust and dirt) Preamps tubes normally become microphonic before they go bad and will make a ping noise when you tap them. I've only gotten crackles when there are loose contacts. Power tubes do create allot of heat and because of that heat the solder contacts tend to become brittle and are susceptible to cracking from vibrations. A good inspection of all solder contacts and reflowing anything that looks suspicious can often eliminate intermittent noise. In fact when I did tube amp repairs for a living, I'd say a good 50% of the repairs I did were either poor contacts or items like jacks and pots that could be abused in one way or another. By the way, Pots should only be cleaned with lubricating contact cleaner. Tube sockets non lubricating. Power caps can cause popping when they start to go bad. If you look on the positive ends there should be a detent in the rubber. If its budging out or leaking white electrolyte (like an old batteries leak) That means the caps are going bad and need replacement. This should be done immediately before they short all together and possibly take out a power transformer. The rest of the possibilities need to be traced. You'd use an isolated audio amp, inject a signal and trace the signal from the input, through all amp stages to the output. If you have no pops before the amp stage and have it after then you're at the source of the noise. Be sure all cords are new too. Never ever use a guitar cord for the speaker. It will cool and become intermittent (and create pops and noise) or short completely and possibly take out your output transformer. Link to comment Share on other sites More sharing options...
Members tcooper Posted March 30, 2015 Author Members Share Posted March 30, 2015 Good advice. I have the contact cleaner and will start with that this evening when I get home. At the same time I will inspect the power caps as you described and look over the solder contacts. Very helpful. Thanks. Link to comment Share on other sites More sharing options...
Members onelife Posted March 30, 2015 Members Share Posted March 30, 2015 Power tubes do create allot of heat and because of that heat the solder contacts tend to become brittle and are susceptible to cracking from vibrations... True but, in this case, the problem goes away when the Volume control, which is well before the power stage, get turned all the way down. Link to comment Share on other sites More sharing options...
Members tcooper Posted March 31, 2015 Author Members Share Posted March 31, 2015 Before I take the next step I thought I would give an update. I removed the preamp tubes. I used contact cleaner and sprayed the sockets. I sprayed the pins of the tube itself. I inserted the tubes back, removed, inserted, and repeated a few times. There are five preamp tubes and two of them seemed very "sandy" or gritty. Then I turned the amp on and wow what a difference. It sounded so clean and playing was such a joy. Then I turned on the DG-2 pedal and almost no crackling/popping. Just a tiny bit but so much better. I hit a note...and...no sound. So I replaced it with the Tube Screamer and it sounded great. I used my other pedals (delay, chorus, etc.) and they all sounded great. So great that I would up playing for a while. I have 4 brand new preamp tubes and I was planning to replace the tubes. My plan was to replace position #1 and see it that made a difference. If not move it to position #2 and so on. If no change after 5 positions then I would put it back in position #1 and then put another new tube in position #2. So now I would have new tubes in positions # 1 and 2. If nothing then move from position #2 to #3 and so on. Now I wonder can the problem be with the pedal. I played so much that the tubes are too hot to handle right now. So in the meantime I thought I would give an update to the group and see if you have any suggestions. My recommendation to anyone who is reading this....clean your sockets! It will make a huge difference. Link to comment Share on other sites More sharing options...
Members onelife Posted March 31, 2015 Members Share Posted March 31, 2015 My recommendation to anyone who is reading this....clean your sockets! It will make a huge difference. This is a great place to come for advice - we are fortunate to have posters like WRGKMC who are willing to share their knowledge and experience. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted March 31, 2015 Members Share Posted March 31, 2015 Thanks, one life. It just Troubleshooting 101. Get the simple stuff out of the way first and see if there's any need to go farther. TC, It sounds to me like you have a problem with that pedal. If the Tube screamer works, and then you put the DG-2 in its place and its dead, that pretty much wraps up something wrong right there. The pops and crackles from dirty tube sockets was simply a secondary symptom having nothing to do with the pedals. Occasionally (I mean real rarely) you may have some DC voltage leakage through some pedals that can get to the amp and do some strange things, but once that DC hits the first coupling cap, its filtered out. Bad wall warts can also pump AC ripple to an amp and not only hum but do some weird things too, if the amp is weak to begin with. I doubt those are your issues. My guess is the pedal has a problem. #1 problems on pedals - Damaged wall wart plug or the wrong polarity wall wart. Luckily most manufacturers have been switching to a common polarity with a negative tip and positive sleeve. Some manufacturers like old Ibanez and a few others have been giving up trying to buck the wind and have the polarities reversed. Their goal was to make people buy their wall warts and it only wound up with allot of warrantee claims with people hooking up the wrong adaptor and blowing up the pedals. Anyway, check and see if it works with a battery and or Adaptor. The plug for the adaptor is switched. If you have an oddball sleeve size on the adaptor, it may not engage the switch and power the pedal. Make sure the adaptor is about 300ua and zero hum. If you're using some generic piece of crap, it may not supply the right current to power the pedal. Next would be to check the internal wiring to the jacks. The input jack is switched and turns on the battery if you're using one. Next would be the switch. They do wear out depending on the type. From there it could be just about anything. The DG-2 pedal runs on germanium transistors which are highly susceptible to temp changes. If the pedal is cold it may fail to power up properly. This was a big issue with older pedals using germanium like the Moserite Fuzzrite and others. Besides being flakey when it comes to temp they are not nearly as durable as silicone when it comes to applying power. The transistors can be blown much more easily with over voltages, especially with some wall warts that may apply more voltage then what's stated on its casing. I've tested many wall warts with a 9Vdc rating and seen them read as much as 10V, especially if they are an old design based on 110vac instead of 120V. Even the power company can pump the voltage up an extra 10v and since those wall warts are unregulated, feed the pedal with the extra voltage and pop goes the weasel on germanium transistors. You can usually see the black type transistors have gone bad. They either discolor or crack. Close inspection may help. If you suspect the transistors are bad, see if you can get the part numbers. Germanium are hard to find these days and a manufacturer may stick any kind of transistor in there, weather it meets the proper values or not, just to fill orders. Link to comment Share on other sites More sharing options...
Members tcooper Posted April 1, 2015 Author Members Share Posted April 1, 2015 Another update. Tonight I was able to play though a Super Reverb (1975) and a Line6 solid state amp. Same results. All the other pedals played just fine but when I engaged the DG-2...nothing. But the Tube Screamer worked just fine and it is a vintage Tube Screamer. So I took WRGKMC's advice. I was using a Boss AC adapter for the DG-2. I put a new 9v battery in it, disconnected the Boss AC adapter and had the same results. The pedal MUST be the problem. Whether it is AC or DC, it will not play when engaged. I just bought the pedal and received it just two weeks ago. Brand new. For the first week it sounded great, even with the dirty sockets. But with the now cleaned sockets I'm falling in love with my Tube Screamer again! And remember why I got it in the first place. I will email the company and get a replacement for the DG-2. I also bought the TopTone Shine Boost SB-1 and it is working great but the DG-2 seems to be defective. In the meantime I will inspect the DG-2 based upon WRGKMC's recommendations. There is something to be learned from those recommendations. I will take that on. This exercise reminds me of my first car...a 1967 Camaro. When something goes wrong you try the most simple things first and go from there. And from this exercise I got my amp back! Link to comment Share on other sites More sharing options...
Members onelife Posted April 1, 2015 Members Share Posted April 1, 2015 Link to comment Share on other sites More sharing options...
Members WRGKMC Posted April 1, 2015 Members Share Posted April 1, 2015 Good deal. Its likely those Germanium transistors in that box are bad. They sound great but can be flakey. You can read about stories of the original Fuzz boxes fading out just being set on a cold floor. Many of the early boxes ran on batteries only. This insured they ran quietly and with the proper maximum voltage. Connecting an adaptor with reverse voltages can almost guarantee you blow those transistors whereas silicone are more durable and less likely to blow from that of voltage spikes. Once wall warts became popular, adding things like a zenar diode in the pedal box and extra capacitance can help maintain and filter the voltage. If the box is built from a vintage battery circuit then those additional components are less likely to have been added. I've found two power adaptors that do well with vintage boxes. Boss and Dan Electro Zero Hum adaptors are the only single pedal adaptors I'll use. For multiple pedals the Spot One works well so long as the pedals don't draw too much current. I've had some pedals that wont work with the spot one, especially noise gates and vintage pedals. For those I use the Boss and Dan Electro without issues. Its also wise to connect those adaptors to a power strip with power filtering. Computer stores sell them for under $10 and they will do a good job protecting gear from voltage spikes. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.