Rocket indicator lamp problem

Express, Liverpool, Rocket, Dirty Little Monster, etc.

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JoeCon
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Rocket indicator lamp problem

Post by JoeCon »

Heres a weird one.

While my newly built Rocket sounds awesome and is pretty darn quiet there is one little problem. The indicator lamp, a neon 125V unit, causes the fuse to blow. So if the indicator lamp is in and I flick the power switch on, no standby, the light glows for a second and then pops the fuse. The lamp is not damaged though. So I take it out, replace the fuse and flick the switch and the amp comes on and plays nicely. Sans indicator lamp.

Now I put the lamp back in and plug the amp into my variac and bring the voltage up slowly to 120V and the lamp works fine and no fuse blows.

IS the inrush current shorting the lamp momentarily causing the fuse to pop?
IS there a way to prevent this?

Thanks....
In theory, theory is the same as practice. In practice it's different.
Bob S
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Re: Rocket indicator lamp problem

Post by Bob S »

Use a bulb that draws less current.
Sounds like you've got a high current, bright bulb there.
They do make LED versions too.
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HeeBGB
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Re: Rocket indicator lamp problem

Post by HeeBGB »

How many amps is the fuse rating? You could try putting in a fuse that it half an amp higher in rating or even one amp higher wod probably not hurt a anything. I would also try a new indicator just to be sure but check the fuse rating first. A 2 amp fuse should be adequate for a 30 watt amp
Last edited by HeeBGB on Sun Jun 30, 2013 4:59 pm, edited 1 time in total.
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BIG Dave
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Re: Rocket indicator lamp problem

Post by BIG Dave »

Is the fuse SLO BLO?
BIG Dave: '63 Princeton, '67 SFDR, '68 Marshall 4x12, '71 Marshall JMP50, etc...
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JoeCon
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Re: Rocket indicator lamp problem

Post by JoeCon »

Fuse is a 3 amp slow blow.
Bulb is a T 3 1/4 size drawing .04 amps.
Even if I turn the variac up too fast with the lamp in the fuse will pop.
Strange.
In theory, theory is the same as practice. In practice it's different.
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Reeltarded
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Re: Rocket indicator lamp problem

Post by Reeltarded »

After 10 minutes or so without the light is your PT kind of warm? Maybe too warm?

Don't get paranoid, jist a thought process. :)
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JoeCon
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Re: Rocket indicator lamp problem

Post by JoeCon »

Miles

No seems fairly cool, just like the amp!
I have another socket like this one maybe I'll change it out, if I can stop playing it long enuff...
In theory, theory is the same as practice. In practice it's different.
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JoeCon
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Re: Rocket indicator lamp problem

Post by JoeCon »

OK
I'm thinking the answer is to remove the 120V bulb and connection and connect to the 6.3V tap and run a 6.3V bulb ala Fender. The bulb is a bayonet type and should fit right into the holder already installed.

Oh boy, more soldering!!
In theory, theory is the same as practice. In practice it's different.
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