New to tube amps. Need advice. No sound.

krb813

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I have a Fender 68 Custom Deluxe Reverb. I’m getting no sound from the amp. I checked the fuse, power tubes look good and all light up. Could it be one of the preamp tubes causing the loss of sound? Or could it be something else?

Thanks in advance for any feedback.
 

corliss1

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Just because tubes 'look good' and are glowing, doesn't mean things are working well, and yes, a preamp tube could cause you to lose sound. Do you even get a slight hum at all indicating *something* is getting to the speaker? Ensure the speaker is also plugged in properly.
 

krb813

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I checked the standby, the fuse, both ends of the speaker connections. I do get a loud pop when switching it back to standby.
 

teleman1

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Grab an pencil with an eraser. Turn amp on, volume around 1-1&1/2.Tap the eraser on the preamp tubes. If one makes a noise, it just might be the culprit. If you are comfy changing tubes, remove each tube and place them back in.
 

Dacious

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Is this a new amp? If so, back to dealer.

If you get a pop turning standby on and off it suggests the rectifier and power tubes are working. If turning the volume knob up does not result in any hum/increase plus it's both channels it indicates the phase inverter tube may be dead.

That's the small 12AT7 next to the two power tubes. As an experiment.you could pull the 12AX7 tube on the right viewed from the rear- that's the Normal channel preamp and the Normal channel won't work. Put that in the position of the 12AT7. If the vibrato channel works it's the 12AT7. If it doesn't, then it's probably tech time.
 

krb813

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I tried
Have you tried all 4 inputs? Tried a different cable.
I tried all 4 inputs and different cables. I’ve had the amp for about 5 years. I’m not using any pedals at this time. No sound out of the amp except that loud pop when putting it back on standby.
 

Peegoo

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@krb813

Try this.

Stick a guitar cable into the input jack. Turn the amp power switch on and flip the standby to on. Allow the amp to warm up for about 20 seconds. Touch just the tip contact of the end of the guitar cable with a finger.

Any sound at all?

If not, power the amp off and allow the tubes to cool off for about five minutes. Remove and replace each tube one at a time; gently grip each tube and pull it straight out. Align the pins and reinstall it.

Power the amp back on, standby on, and do the cable test as above. Any change?
 

krb813

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@krb813

Try this.

Stick a guitar cable into the input jack. Turn the amp power switch on and flip the standby to on. Allow the amp to warm up for about 20 seconds. Touch just the tip contact of the end of the guitar cable with a finger.

Any sound at all?

If not, power the amp off and allow the tubes to cool off for about five minutes. Remove and replace each tube one at a time; gently grip each tube and pull it straight out. Align the pins and reinstall it.

Power the amp back on, standby on, and do the cable test as above. Any change?
Thanks. I’ll try it.
 

dan40

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I'm not positive if the input jack is mounted to a pcb board or not, but if it is, the jack may have broken loose from the board. This happens often with pcb mounted jacks. Does wiggling the cord in the jack create any static or pops through the speaker?
 

krb813

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I'm not positive if the input jack is mounted to a pcb board or not, but if it is, the jack may have broken loose from the board. This happens often with pcb mounted jacks. Does wiggling the cord in the jack create any static or pops through the speaker?
No static or pops from the jacks. Dead silent.
 

Milspec

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Rare condition, but the voice coil could have fully detached from the cone. Try a different speaker if you have one.
 

krb813

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That’s the thing. The amp worked about 3 weeks ago with no problems. It’s a relatively new Creamback Neo speaker.
 

Ten Over

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Symptoms:
No sound with any of the four inputs.

Observations so far:
Amp isn't completely dead--Mains fuse is good.
Heaters are glowing--Heater fuse is good.
Pop sound with Standby switch--Speaker is good, speaker cable is good, rectifier is good, at least one 6V6 is good.
_____

Valve 4 and/or Valve 6 malfunction can deaden both channels and the Standby switch can still pop. Simultaneous failure of both Valve 1 and Valve 2 is possible, but unlikely. If replacing Valves 4 and 6 with known good tubes doesn't restore normal operation, an examination of the internal electronics would seem to be a logical next step.
 

krb813

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Symptoms:
No sound with any of the four inputs.

Observations so far:
Amp isn't completely dead--Mains fuse is good.
Heaters are glowing--Heater fuse is good.
Pop sound with Standby switch--Speaker is good, speaker cable is good, rectifier is good, at least one 6V6 is good.
_____

Valve 4 and/or Valve 6 malfunction can deaden both channels and the Standby switch can still pop. Simultaneous failure of both Valve 1 and Valve 2 is possible, but unlikely. If replacing Valves 4 and 6 with known good tubes doesn't restore normal operation, an examination of the internal electronics would seem to be a logical next step.
Thanks. I’ll get some new tubes to try out.
 




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