Pilot lamp goes out.

[Guest HRB853370]

When I got my KBP tweed deluxe, after a little while of playing, the pilot light went out. Thinking it was a burnt out bulb, I contacted KBP and he mailed me some extra bulbs. The man stands behind his product. The next time I played it came back on with the original bulb. My light went out again when playing with Rich and Rusty on Tuesday. I fussed with it and it would not come back on. Tried a replacement bulb, no avail. The original bulb still has an intact filament. All the wires to that socket seem to be intact too. Not sure what is going on! Maybe too close to Halloween?

[Spectrum13]

Take me to the pilot. Does the amp still play?

[DetroitBlues]

Must be a bad wire or cold soldering joint some where.

[TalismanRich]

Now that you mention it, the amp did sound a little bit "dark"

[Guest HRB853370]

Now that you mention it, the amp did sound a little bit "dark"

 

VERY FUNNY!

[big bob]

If the amp still works try cleaning the contact points on the bulb and the fixture.

[Guest HRB853370]

If the amp still works try cleaning the contact points on the bulb and the fixture.

 

Amp works great, just the lamp is out.

[DetroitBlues]

KBP says not to pull the bulb while the amp is on. There could be some shocking results if you do. There might be a lose wire on the bulb socket...

[Trouble]

That's kind of a strange failure, I would check the contacts inside the bulb socket, probably have to get the chassis out for that, make sure one is not bent and simply not contacting the bulb. I'm not sure about the cold solder joint idea, if I'm not mistaken some of the downstream components are powered from this point, so if the amp works should be power to the lamp right?

 

Good luck would love to here what you come up with.

[kbp810]

Yeah the pilot lamp is powered off of the filament heater wires, and comes first in that chain. So as long as the tube filaments are lighting up, and the amp is working fine; that limits the fault to the pilot lamp itself - either a bad connection of the wires to the lamp base or a bad connection between the bulb and the base. (I'll rule out a bad bulb as it sounds like you've tried a few without success)

[Guest HRB853370]

Yeah the pilot lamp is powered off of the filament heater wires, and comes first in that chain. So as long as the tube filaments are lighting up, and the amp is working fine; that limits the fault to the pilot lamp itself - either a bad connection of the wires to the lamp base or a bad connection between the bulb and the base. (I'll rule out a bad bulb as it sounds like you've tried a few without success)

 

Any diagnostic steps recommended Brian?

[kbp810]

 

Any diagnostic steps recommended Brian?

I think a visual inspection might be about the only path - back panel off and check the wires at the lamp base to make sure they have a good connection.There should be no power or anything to bite you on the heater wires, but it's not sitting too far away from the rest of the circuit which can hold a lot of juice... so that being said, I would make sure to have the amp unplugged and drain the big caps first just to be safe, and/or use a non-conductive "stick" (chop stick) to poke around with only one hand while keeping the other behind your back to check. (sorry, I'm sure you know all that, I just always feel the need to throw all the saftey type stuff in there whenever talking about an open chassis).

[Guest HRB853370]

I think a visual inspection might be about the only path - back panel off and check the wires at the lamp base to make sure they have a good connection.There should be no power or anything to bite you on the heater wires, but it's not sitting too far away from the rest of the circuit which can hold a lot of juice... so that being said, I would make sure to have the amp unplugged and drain the big caps first just to be safe, and/or use a non-conductive "stick" (chop stick) to poke around with only one hand while keeping the other behind your back to check. (sorry, I'm sure you know all that, I just always feel the need to throw all the saftey type stuff in there whenever talking about an open chassis).

 

Hey Brian, all three wires at the base of the socket look very secure. The bulb seems to fit tightly in the socket, and with a gentle push, the little nub goes securely in the slot. Not sure what you mean by "drain the big caps first just to be safe, (how do I do that?) and/or use a non-conductive "stick" (chop stick) to poke around with only one hand while keeping the other behind your back to check." (What is the purpose of keeping one hand behind my back?)

[Thundersteel]

Not sure what you mean by "drain the big caps first just to be safe, (how do I do that?)

 

The big capacitors are drained by shorting their leads together for a few seconds. It's best to use a resistor to limit the current while doing so.

 

 

(What is the purpose of keeping one hand behind my back?)

 

That is so your body doesn't provide a path for current. By using only one hand, it protects you from being shocked.

[kbp810]

 

Hey Brian, all three wires at the base of the socket look very secure. The bulb seems to fit tightly in the socket, and with a gentle push, the little nub goes securely in the slot. Not sure what you mean by "drain the big caps first just to be safe, (how do I do that?) and/or use a non-conductive "stick" (chop stick) to poke around with only one hand while keeping the other behind your back to check." (What is the purpose of keeping one hand behind my back?)

If those wires are secure to the lamp base, then I wonder if it's the base itself thats gone bad? (pretty simple component, but I suppose it's possible)

 

The big electrolytic caps can retain a charge even after the amp if powered off; when working inside an amp that has been powered on at least once in it's life, you want to short the positive end of those caps to ground to "drain" them (usually with a big resistor in between to help avoid any sparks). By the chopstick thing, it's just something that doesn't conduct electricity that you poke around at connections with, without having to actually put your hand inside (just another better safe then sorry saftey tip). By keeping one hand behind your back... you keep it from accidentaly wandering around, and keeps it from grounding yourself to the chassis (you don't make your body part of the circuit)- that way if you do happen to get shocked, your more likely to just get "bit" by it (will sting/hurt like hell, possible leave a burn mark, but thats about it); where as if your other hand happens to be touching the chassis at the time, you give a path for the electricity to travel through your body from one hand to the other (this is a very, very, bad thing!)

[Guest HRB853370]

If those wires are secure to the lamp base, then I wonder if it's the base itself thats gone bad? (pretty simple component, but I suppose it's possible)

 

The big electrolytic caps can retain a charge even after the amp if powered off; when working inside an amp that has been powered on at least once in it's life, you want to short the positive end of those caps to ground to "drain" them (usually with a big resistor in between to help avoid any sparks). By the chopstick thing, it's just something that doesn't conduct electricity that you poke around at connections with, without having to actually put your hand inside (just another better safe then sorry saftey tip). By keeping one hand behind your back... you keep it from accidentaly wandering around, and keeps it from grounding yourself to the chassis (you don't make your body part of the circuit)- that way if you do happen to get shocked, your more likely to just get "bit" by it (will sting/hurt like hell, possible leave a burn mark, but thats about it); where as if your other hand happens to be touching the chassis at the time, you give a path for the electricity to travel through your body from one hand to the other (this is a very, very, bad thing!)

 

I was thinking of poking around there with my tongue, but now, I don't think I will do that.

 

I am not going to worry about it. If I ever have to get the amp serviced for something else, I will address it. But I do miss that cute green glow.

[Guest HRB853370]

If those wires are secure to the lamp base, then I wonder if it's the base itself thats gone bad? (pretty simple component, but I suppose it's possible)

 

The big electrolytic caps can retain a charge even after the amp if powered off; when working inside an amp that has been powered on at least once in it's life, you want to short the positive end of those caps to ground to "drain" them (usually with a big resistor in between to help avoid any sparks). By the chopstick thing, it's just something that doesn't conduct electricity that you poke around at connections with, without having to actually put your hand inside (just another better safe then sorry saftey tip). By keeping one hand behind your back... you keep it from accidentaly wandering around, and keeps it from grounding yourself to the chassis (you don't make your body part of the circuit)- that way if you do happen to get shocked, your more likely to just get "bit" by it (will sting/hurt like hell, possible leave a burn mark, but thats about it); where as if your other hand happens to be touching the chassis at the time, you give a path for the electricity to travel through your body from one hand to the other (this is a very, very, bad thing!)

Update! Finally found a local amp tech, took it there, he replaced the "base" and the lamp is working again. Funny how that could go bad. He said its not uncommon.$35 out the door fixed it. I waited around while he fixed it. Now I have my green glow again.

[big bob]

Bully for you! Now play that thing!

[smurph1]

When I got my KBP tweed deluxe, after a little while of playing, the pilot light went out. Thinking it was a burnt out bulb, I contacted KBP and he mailed me some extra bulbs. The man stands behind his product. The next time I played it came back on with the original bulb. My light went out again when playing with Rich and Rusty on Tuesday. I fussed with it and it would not come back on. Tried a replacement bulb, no avail. The original bulb still has an intact filament. All the wires to that socket seem to be intact too. Not sure what is going on! Maybe too close to Halloween?

Yeah that's it I'm sure..Seriously I have no idea..

[Trouble]

On a related note, I've always had trouble putting the bulb in the socket since it fits almost flush, is there a special tool or something? Currently the best I could do (short of pulling the socket to install the bulb) is stick it in there and screw the jewel down on top of it, which means the lamp only works when it wants to.

[tbonesullivan]

great to hear that it's fixed! I've had similar problems in the past, and most were easy fixes.