... cutting out. Maddeningly.
The history might or might not be relevant: I bought it on this forum and it was shipped with minimal packing. Well, it was in a cardboard box, but with absolutely zero shock absorption by way of polystyrene or the like. In addition, the upgraded speaker had been fixed to the baffle from the wrong side so became entirely detached in transit. It took out the power valve. The amp had had some mods, with a gain control added, a switch for standard or 5E1 circuit, and a negative feedback switch.
I can't discern any pattern to the cutting out. Switching on and off sometimes seems to help.
Just interested to see if it might be something simple that doesn't need an amp tech. Having some experience of simple electronics in the distant past I do know one end of a soldering iron from the other, but also have a healthy respect for electricity.
Any help / thoughts gratefully welcomed.
Comments
Do you have another speaker cab you could try it with?
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
If rocking it back and forth (gently? I assume) make it come and go, then it's something which is making a bad connection and has enough mass to move slightly depending on the angle it's hanging at. If the speaker test above shows it's actually transformer hum you're hearing, it could still be the speaker cable or connections - not necessarily at the connectors. But if the hum is definitely coming from the speaker, then it must be something inside the amp - most likely near the output end of the circuit if it goes pretty quiet.
If so, you'll need to poke around inside with the amp running and live, so if you're not comfortable with that, you need a tech unfortunately. If you are, then there are ways to keep yourself safe when doing it.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
I was just rocking/tipping the amp back, not back and forth - very gentle.
So does that suggest the speaker cable/connections?
Thanks again for your patience and help.
One possibility is a damaged speaker - if it was thrown about so violently that it was ripped off the baffle, that's certainly something that could have happened. The cone braids may be damaged, either where they join the terminals or where they pass in to the cone. Try reaching under the frame and *very gently* moving them (don't pull hard on them) and see if the sound cuts out or comes back.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
I put a meter on the little speaker cable - all good. Opened the amp up and checked the speaker jack socket - squeezed the tip connector in lest that was the issue. Right, off to gently do the speaker test you suggest.
At this point I think you may have to open it up and poke around inside. Do you have something insulated like a wooden chopstick?
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
The Fender Champ 600 kit is extremely simple to install and gives the amp more usability and tones at lower volumes.
Master Volume: The original Volume control becomes the ‘Gain’ control which determines the amount of pre-amp gain. The new Master Volume controls the signal into the output tube. This provides crunch/break up at low volumes.Gain/AA764/5E1: The Fender Champ 600 has tone stack rather like the AA764 circuit but with fixed values. The Fender Champ 600 Gain/5E1/AA764 kit is extremely simple to install and allows the player to switch between the standard ‘AA764’ circuit and a close match to a ‘5E1’ circuit which gives the amp a different tone and more gain. The two capacitors supplied with the kit improve both the ‘5E1’ and ‘AA764’ tone.Negative Feedback: The Fender Champ 600 has a Negative Feedback (NFB) circuit that works to eliminate distortion. The NFB mod that lets you choose whether to run the amp with or without negative feedback. Switching out the NFB circuit opens up the amp’s tone and gives it more crunch.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
If I open up the amp, what would be the plan with the chopstick?
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein