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Old 18th September 2012, 05:23 PM   #1
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Default No sound....

Hello all,
I have a '78 twin reverb with no sound.
All tubes have been replaced.
Red light is on.
Connection to speakers seems intact.
Yet no sound at all, even a hum. My experience in fixing amps is limited at best but any help that could be given on how to troubleshoot this would be great.
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Old 18th September 2012, 05:52 PM   #2
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A number of things could cause absolutely no sound. A defective stand-by switch is one. The speaker itself and/or the connecting wire and plug. Check these as a system by pulling out the speaker plug from the amp and measuring with an ohmmeter. Or use a 1Ĺ volt flashlight battery to check the speaker through the wire. It should make a scratching sound when connecting to the battery.

Are all the tubes lit up? Is there really no hum even with your ear right at the speaker and the volume up? Is there a second B+ fuse?
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Old 18th September 2012, 06:24 PM   #3
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All the tubes are lit up but there is zero hum even at high volume.
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Old 18th September 2012, 08:35 PM   #4
M Gregg is offline M Gregg  United Kingdom
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Is it one of these?

http://ampwares.com/schematics/65_tw..._@20manual.pdf

or this?

http://ampwares.com/schematics/twin_rev_ii.pdf

What power tubes is it running?
A schematic would help..

Possible maybe?
http://ampwares.com/amplifiers/fende...e-twin-reverb/

Just be careful these amps can hold high voltage..so don't poke about unless you know what you are doing!



Regards
M. Gregg
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Last edited by M Gregg; 18th September 2012 at 08:48 PM.
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Old 18th September 2012, 08:44 PM   #5
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Hi,
Did you check all the voltage A,B,C,D,E,F?
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Old 18th September 2012, 09:44 PM   #6
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Quote:
Originally Posted by M Gregg View Post
Is it one of these?

http://ampwares.com/schematics/65_tw..._@20manual.pdf

or this?

http://ampwares.com/schematics/twin_rev_ii.pdf

What power tubes is it running?
A schematic would help..

Possible maybe?
Fender Silverface Twin Reverb | Ampwares

Just be careful these amps can hold high voltage..so don't poke about unless you know what you are doing!



Regards
M. Gregg
Fender Silverface Twin Reverb | Ampwares
This is it
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Old 18th September 2012, 11:25 PM   #7
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open it up and re solder the broken lead. its a fender thing.
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Old 19th September 2012, 12:54 AM   #8
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I opened up the back and couldn't find any broken connections or wires requiring soldering
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Old 19th September 2012, 04:33 AM   #9
kevinkr is offline kevinkr  United States
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Per forum policy this thread belongs in Instruments And Amplifiers where I've moved it..

From the subheading at the top of Tubes / Valves:

Quote:
Tubes / Valves All about our sweet vacuum tubes Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum
And from Instruments And Amplifiers:

Quote:
Instruments and Amps Everything that makes music, Especially including instrument amps.
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Old 19th September 2012, 03:37 PM   #10
Brion55 is offline Brion55  United States
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With the guidance of an awesome school teacher, I started repairing and building tube amps when I was about 12. The first thing he told me was when you are testing the voltages on a tube amp, keep one hand in your pocket. It just may keep you alive. Good advice.
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