Marshall avt20 problem

huizar82 · 25th October 2012, 12:17 PM

Hi guys. I'm new here and am trying to get some info about my amp problem. I am new to tube amps and a friend gave me a marshall avt 20 not working. I noticed the pin to the positive speaker lug came loose so I resoldered it. Still nothing. I'm getting power and I notice the leds coming on when I push the od switch. I was thinking that the loose speaker connection could have caused me to blow a resistor since I read that you can't run these things without a load. None of the resistors look burned though. Any advise on what to check?

revintage · 25th October 2012, 01:06 PM

Hey,
Note this is a solid state amp. AFAIK it only has a single 12AX7 in the overdrive circuit. Think you should seek help in the "Instruments & Amps" forum.

kevinkr · 25th October 2012, 04:46 PM

Belongs in Instruments and Amps, will move it there. (Moved)

Osvaldo de Banfield · 25th October 2012, 05:46 PM

Is there almost a "click" sound when power on or off the amp?

huizar82 · 25th October 2012, 08:07 PM

Quote:

Originally Posted by revintage

Hey,
Note this is a solid state amp. AFAIK it only has a single 12AX7 in the overdrive circuit. Think you should seek help in the "Instruments & Amps" forum.

Since it is a solid state amp, is it ok to have it on without the speaker load? Also, if the tube is in the overdrive circuit, does the clean channel bypass the tube? I'm not sure if the tube is good and I want to know how to test it or eliminate it as the problem.

huizar82 · 25th October 2012, 08:11 PM

I don't hear a click sound when I turn it on or off and I checked for a voltage across the pins for the speaker and I am getting a voltage. I did manage to get some sound, but only a weird whistling noise when I touch the end of the instrument cable.

huizar82 · 25th October 2012, 09:15 PM

I just tried using the headphone out and it worked. I also tested the speaker with a function generator. I guess there may be a problem with the speaker connection.

huizar82 · 25th October 2012, 09:15 PM

Going to check r59.

25th October 2012, 12:17 PM	#1
huizar82 diyAudio Member Join Date: Oct 2012	Marshall avt20 problem Hi guys. I'm new here and am trying to get some info about my amp problem. I am new to tube amps and a friend gave me a marshall avt 20 not working. I noticed the pin to the positive speaker lug came loose so I resoldered it. Still nothing. I'm getting power and I notice the leds coming on when I push the od switch. I was thinking that the loose speaker connection could have caused me to blow a resistor since I read that you can't run these things without a load. None of the resistors look burned though. Any advise on what to check?

25th October 2012, 04:46 PM	#3
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Belongs in Instruments and Amps, will move it there. (Moved) __________________ "Extraordinary claims require extraordinary evidence." - Carl Sagan

25th October 2012, 05:46 PM	#4
Osvaldo de Banfield diyAudio Member Join Date: Dec 2011 Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina	Is there almost a "click" sound when power on or off the amp? __________________ LW1DSE

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25th October 2012, 01:06 PM	#2
revintage diyAudio Member Join Date: May 2007	Hey, Note this is a solid state amp. AFAIK it only has a single 12AX7 in the overdrive circuit. Think you should seek help in the "Instruments & Amps" forum.

25th October 2012, 08:11 PM	#6
huizar82 diyAudio Member Join Date: Oct 2012	I don't hear a click sound when I turn it on or off and I checked for a voltage across the pins for the speaker and I am getting a voltage. I did manage to get some sound, but only a weird whistling noise when I touch the end of the instrument cable.

25th October 2012, 09:15 PM	#7
huizar82 diyAudio Member Join Date: Oct 2012	I just tried using the headphone out and it worked. I also tested the speaker with a function generator. I guess there may be a problem with the speaker connection.

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